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gecko-dev/db/mdb/public/mdb.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is mozilla.org code.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Blake Ross (blake@blakeross.com)
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef _MDB_
#define _MDB_ 1
#include "nscore.h"
#include "nsISupports.h"
//3456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789
// { %%%%% begin scalar typedefs %%%%%
typedef unsigned char mdb_u1; // make sure this is one byte
typedef unsigned short mdb_u2; // make sure this is two bytes
typedef short mdb_i2; // make sure this is two bytes
typedef PRUint32 mdb_u4; // make sure this is four bytes
typedef PRInt32 mdb_i4; // make sure this is four bytes
typedef PRWord mdb_ip; // make sure sizeof(mdb_ip) == sizeof(void*)
typedef mdb_u1 mdb_bool; // unsigned byte with zero=false, nonzero=true
/* canonical boolean constants provided only for code clarity: */
#define mdbBool_kTrue ((mdb_bool) 1) /* actually any nonzero means true */
#define mdbBool_kFalse ((mdb_bool) 0) /* only zero means false */
typedef mdb_u4 mdb_id; // unsigned object identity in a scope
typedef mdb_id mdb_rid; // unsigned row identity inside scope
typedef mdb_id mdb_tid; // unsigned table identity inside scope
typedef mdb_u4 mdb_token; // unsigned token for atomized string
typedef mdb_token mdb_scope; // token used to id scope for rows
typedef mdb_token mdb_kind; // token used to id kind for tables
typedef mdb_token mdb_column; // token used to id columns for rows
typedef mdb_token mdb_cscode; // token used to id charset names
typedef mdb_u4 mdb_seed; // unsigned collection change counter
typedef mdb_u4 mdb_count; // unsigned collection member count
typedef mdb_u4 mdb_size; // unsigned physical media size
typedef mdb_u4 mdb_fill; // unsigned logical content size
typedef mdb_u4 mdb_more; // more available bytes for larger buffer
#define mdbId_kNone ((mdb_id) -1) /* never a valid Mork object ID */
typedef mdb_u4 mdb_percent; // 0..100, with values >100 same as 100
typedef mdb_u1 mdb_priority; // 0..9, for a total of ten different values
// temporary substitute for NS_RESULT, for mdb.h standalone compilation:
typedef nsresult mdb_err; // equivalent to NS_RESULT
// sequence position is signed; negative is useful to mean "before first":
typedef mdb_i4 mdb_pos; // signed zero-based ordinal collection position
#define mdbPos_kBeforeFirst ((mdb_pos) -1) /* any negative is before zero */
// order is also signed, so we can use three states for comparison order:
typedef mdb_i4 mdb_order; // neg:lessthan, zero:equalto, pos:greaterthan
typedef mdb_order (* mdbAny_Order)(const void* inA, const void* inB,
const void* inClosure);
// } %%%%% end scalar typedefs %%%%%
// { %%%%% begin C structs %%%%%
#ifndef mdbScopeStringSet_typedef
typedef struct mdbScopeStringSet mdbScopeStringSet;
#define mdbScopeStringSet_typedef 1
#endif
/*| mdbScopeStringSet: a set of null-terminated C strings that enumerate some
**| names of row scopes, so that row scopes intended for use by an application
**| can be declared by an app when trying to open or create a database file.
**| (We use strings and not tokens because we cannot know the tokens for any
**| particular db without having first opened the db.) The goal is to inform
**| a db runtime that scopes not appearing in this list can be given relatively
**| short shrift in runtime representation, with the expectation that other
**| scopes will not actually be used. However, a db should still be prepared
**| to handle accessing row scopes not in this list, rather than raising errors.
**| But it could be quite expensive to access a row scope not on the list.
**| Note a zero count for the string set means no such string set is being
**| specified, and that a db should handle all row scopes efficiently.
**| (It does NOT mean an app plans to use no content whatsoever.)
|*/
#ifndef mdbScopeStringSet_struct
#define mdbScopeStringSet_struct 1
struct mdbScopeStringSet { // vector of scopes for use in db opening policy
// when mScopeStringSet_Count is zero, this means no scope constraints
mdb_count mScopeStringSet_Count; // number of strings in vector below
const char** mScopeStringSet_Strings; // null-ended ascii scope strings
};
#endif /*mdbScopeStringSet_struct*/
#ifndef mdbOpenPolicy_typedef
typedef struct mdbOpenPolicy mdbOpenPolicy;
#define mdbOpenPolicy_typedef 1
#endif
#ifndef mdbOpenPolicy_struct
#define mdbOpenPolicy_struct 1
struct mdbOpenPolicy { // policies affecting db usage for ports and stores
mdbScopeStringSet mOpenPolicy_ScopePlan; // predeclare scope usage plan
mdb_bool mOpenPolicy_MaxLazy; // nonzero: do least work
mdb_bool mOpenPolicy_MinMemory; // nonzero: use least memory
};
#endif /*mdbOpenPolicy_struct*/
#ifndef mdbTokenSet_typedef
typedef struct mdbTokenSet mdbTokenSet;
#define mdbTokenSet_typedef 1
#endif
#ifndef mdbTokenSet_struct
#define mdbTokenSet_struct 1
struct mdbTokenSet { // array for a set of tokens, and actual slots used
mdb_count mTokenSet_Count; // number of token slots in the array
mdb_fill mTokenSet_Fill; // the subset of count slots actually used
mdb_more mTokenSet_More; // more tokens available for bigger array
mdb_token* mTokenSet_Tokens; // array of count mdb_token instances
};
#endif /*mdbTokenSet_struct*/
#ifndef mdbUsagePolicy_typedef
typedef struct mdbUsagePolicy mdbUsagePolicy;
#define mdbUsagePolicy_typedef 1
#endif
/*| mdbUsagePolicy: another version of mdbOpenPolicy which uses tokens instead
**| of scope strings, because usage policies can be constructed for use with a
**| db that is already open, while an open policy must be constructed before a
**| db has yet been opened.
|*/
#ifndef mdbUsagePolicy_struct
#define mdbUsagePolicy_struct 1
struct mdbUsagePolicy { // policies affecting db usage for ports and stores
mdbTokenSet mUsagePolicy_ScopePlan; // current scope usage plan
mdb_bool mUsagePolicy_MaxLazy; // nonzero: do least work
mdb_bool mUsagePolicy_MinMemory; // nonzero: use least memory
};
#endif /*mdbUsagePolicy_struct*/
#ifndef mdbOid_typedef
typedef struct mdbOid mdbOid;
#define mdbOid_typedef 1
#endif
#ifndef mdbOid_struct
#define mdbOid_struct 1
struct mdbOid { // identity of some row or table inside a database
mdb_scope mOid_Scope; // scope token for an id's namespace
mdb_id mOid_Id; // identity of object inside scope namespace
};
#endif /*mdbOid_struct*/
#ifndef mdbRange_typedef
typedef struct mdbRange mdbRange;
#define mdbRange_typedef 1
#endif
#ifndef mdbRange_struct
#define mdbRange_struct 1
struct mdbRange { // range of row positions in a table
mdb_pos mRange_FirstPos; // position of first row
mdb_pos mRange_LastPos; // position of last row
};
#endif /*mdbRange_struct*/
#ifndef mdbColumnSet_typedef
typedef struct mdbColumnSet mdbColumnSet;
#define mdbColumnSet_typedef 1
#endif
#ifndef mdbColumnSet_struct
#define mdbColumnSet_struct 1
struct mdbColumnSet { // array of column tokens (just the same as mdbTokenSet)
mdb_count mColumnSet_Count; // number of columns
mdb_column* mColumnSet_Columns; // count mdb_column instances
};
#endif /*mdbColumnSet_struct*/
#ifndef mdbYarn_typedef
typedef struct mdbYarn mdbYarn;
#define mdbYarn_typedef 1
#endif
#ifdef MDB_BEGIN_C_LINKAGE_define
#define MDB_BEGIN_C_LINKAGE_define 1
#define MDB_BEGIN_C_LINKAGE extern "C" {
#define MDB_END_C_LINKAGE }
#endif /*MDB_BEGIN_C_LINKAGE_define*/
/*| mdbYarn_mGrow: an abstract API for growing the size of a mdbYarn
**| instance. With respect to a specific API that requires a caller
**| to supply a string (mdbYarn) that a callee fills with content
**| that might exceed the specified size, mdbYarn_mGrow is a caller-
**| supplied means of letting a callee attempt to increase the string
**| size to become large enough to receive all content available.
**|
**|| Grow(): a method for requesting that a yarn instance be made
**| larger in size. Note that such requests need not be honored, and
**| need not be honored in full if only partial size growth is desired.
**| (Note that no nsIMdbEnv instance is passed as argument, although one
**| might be needed in some circumstances. So if an nsIMdbEnv is needed,
**| a reference to one might be held inside a mdbYarn member slot.)
**|
**|| self: a yarn instance to be grown. Presumably this yarn is
**| the instance which holds the mYarn_Grow method pointer. Yarn
**| instancesshould only be passed to grow methods which they were
**| specifically designed to fit, as indicated by the mYarn_Grow slot.
**|
**|| inNewSize: the new desired value for slot mYarn_Size in self.
**| If mYarn_Size is already this big, then nothing should be done.
**| If inNewSize is larger than seems feasible or desirable to honor,
**| then any size restriction policy can be used to grow to some size
**| greater than mYarn_Size. (Grow() might even grow to a size
**| greater than inNewSize in order to make the increase in size seem
**| worthwhile, rather than growing in many smaller steps over time.)
|*/
typedef void (* mdbYarn_mGrow)(mdbYarn* self, mdb_size inNewSize);
// mdbYarn_mGrow methods must be declared with C linkage in C++
/*| mdbYarn: a variable length "string" of arbitrary binary bytes,
**| whose length is mYarn_Fill, inside a buffer mYarn_Buf that has
**| at most mYarn_Size byte of physical space.
**|
**|| mYarn_Buf: a pointer to space containing content. This slot
**| might never be nil when mYarn_Size is nonzero, but checks for nil
**| are recommended anyway.
**| (Implementations of mdbYarn_mGrow methods should take care to
**| ensure the existence of a replacement before dropping old Bufs.)
**| Content in Buf can be anything in any format, but the mYarn_Form
**| implies the actual format by some caller-to-callee convention.
**| mYarn_Form==0 implies US-ASCII iso-8859-1 Latin1 string content.
**|
**|| mYarn_Size: the physical size of Buf in bytes. Note that if one
**| intends to terminate a string with a null byte, that it must not
**| be written at or after mYarn_Buf[mYarn_Size] because this is after
**| the last byte in the physical buffer space. Size can be zero,
**| which means the string has no content whatsoever; note that when
**| Size is zero, this is a suitable reason for Buf==nil as well.
**|
**|| mYarn_Fill: the logical content in Buf in bytes, where Fill must
**| never exceed mYarn_Size. Note that yarn strings might not have a
**| terminating null byte (since they might not even be C strings), but
**| when they do, such terminating nulls are considered part of content
**| and therefore Fill will count such null bytes. So an "empty" C
**| string will have Fill==1, because content includes one null byte.
**| Fill does not mean "length" when applied to C strings for this
**| reason. However, clients using yarns to hold C strings can infer
**| that length is equal to Fill-1 (but should take care to handle the
**| case where Fill==0). To be paranoid, one can always copy to a
**| destination with size exceeding Fill, and place a redundant null
**| byte in the Fill position when this simplifies matters.
**|
**|| mYarn_Form: a designation of content format within mYarn_Buf.
**| The semantics of this slot are the least well defined, since the
**| actual meaning is context dependent, to the extent that callers
**| and callees must agree on format encoding conventions when such
**| are not standardized in many computing contexts. However, in the
**| context of a specific mdb database, mYarn_Form is a token for an
**| atomized string in that database that typically names a preferred
**| mime type charset designation. If and when mdbYarn is used for
**| other purposes away from the mdb interface, folks can use another
**| convention system for encoding content formats. However, in all
**| contexts is it useful to maintain the convention that Form==0
**| implies Buf contains US-ASCII iso-8859-1 Latin1 string content.
**|
**|| mYarn_Grow: either a mdbYarn_mGrow method, or else nil. When
**| a mdbYarn_mGrow method is provided, this method can be used to
**| request a yarn buf size increase. A caller who constructs the
**| original mdbYarn instance decides whether a grow method is necessary
**| or desirable, and uses only grow methods suitable for the buffering
**| nature of a specific mdbYarn instance. (For example, Buf might be a
**| staticly allocated string space which switches to something heap-based
**| when grown, and subsequent calls to grow the yarn must distinguish the
**| original static string from heap allocated space, etc.) Note that the
**| method stored in mYarn_Grow can change, and this might be a common way
**| to track memory managent changes in policy for mYarn_Buf.
|*/
#ifndef mdbYarn_struct
#define mdbYarn_struct 1
struct mdbYarn { // buffer with caller space allocation semantics
void* mYarn_Buf; // space for holding any binary content
mdb_fill mYarn_Fill; // logical content in Buf in bytes
mdb_size mYarn_Size; // physical size of Buf in bytes
mdb_more mYarn_More; // more available bytes if Buf is bigger
mdb_cscode mYarn_Form; // charset format encoding
mdbYarn_mGrow mYarn_Grow; // optional method to grow mYarn_Buf
// Subclasses might add further slots after mYarn_Grow in order to
// maintain bookkeeping needs, such as state info about mYarn_Buf.
};
#endif /*mdbYarn_struct*/
// } %%%%% end C structs %%%%%
// { %%%%% begin class forward defines %%%%%
class nsIMdbEnv;
class nsIMdbObject;
class nsIMdbErrorHook;
class nsIMdbCompare;
class nsIMdbThumb;
class nsIMdbFactory;
class nsIMdbFile;
class nsIMdbPort;
class nsIMdbStore;
class nsIMdbCursor;
class nsIMdbPortTableCursor;
class nsIMdbCollection;
class nsIMdbTable;
class nsIMdbTableRowCursor;
class nsIMdbRow;
class nsIMdbRowCellCursor;
class nsIMdbBlob;
class nsIMdbCell;
class nsIMdbSorting;
// } %%%%% end class forward defines %%%%%
// { %%%%% begin C++ abstract class interfaces %%%%%
/*| nsIMdbObject: base class for all message db class interfaces
**|
**|| factory: all nsIMdbObjects from the same code suite have the same factory
**|
**|| refcounting: both strong and weak references, to ensure strong refs are
**| acyclic, while weak refs can cause cycles. CloseMdbObject() is
**| called when (strong) use counts hit zero, but clients can call this close
**| method early for some reason, if absolutely necessary even though it will
**| thwart the other uses of the same object. Note that implementations must
**| cope with close methods being called arbitrary numbers of times. The COM
**| calls to AddRef() and release ref map directly to strong use ref calls,
**| but the total ref count for COM objects is the sum of weak & strong refs.
|*/
#define NS_IMDBOBJECT_IID_STR "5533ea4b-14c3-4bef-ac60-22f9e9a49084"
#define NS_IMDBOBJECT_IID \
{0x5533ea4b, 0x14c3, 0x4bef, \
{ 0xac, 0x60, 0x22, 0xf9, 0xe9, 0xa4, 0x90, 0x84}}
class nsIMdbObject : public nsISupports { // msg db base class
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBOBJECT_IID)
// { ===== begin nsIMdbObject methods =====
// { ----- begin attribute methods -----
NS_IMETHOD IsFrozenMdbObject(nsIMdbEnv* ev, mdb_bool* outIsReadonly) = 0;
// same as nsIMdbPort::GetIsPortReadonly() when this object is inside a port.
// } ----- end attribute methods -----
// { ----- begin factory methods -----
NS_IMETHOD GetMdbFactory(nsIMdbEnv* ev, nsIMdbFactory** acqFactory) = 0;
// } ----- end factory methods -----
// { ----- begin ref counting for well-behaved cyclic graphs -----
NS_IMETHOD GetWeakRefCount(nsIMdbEnv* ev, // weak refs
mdb_count* outCount) = 0;
NS_IMETHOD GetStrongRefCount(nsIMdbEnv* ev, // strong refs
mdb_count* outCount) = 0;
NS_IMETHOD AddWeakRef(nsIMdbEnv* ev) = 0;
NS_IMETHOD AddStrongRef(nsIMdbEnv* ev) = 0;
NS_IMETHOD CutWeakRef(nsIMdbEnv* ev) = 0;
NS_IMETHOD CutStrongRef(nsIMdbEnv* ev) = 0;
NS_IMETHOD CloseMdbObject(nsIMdbEnv* ev) = 0; // called at strong refs zero
NS_IMETHOD IsOpenMdbObject(nsIMdbEnv* ev, mdb_bool* outOpen) = 0;
// } ----- end ref counting -----
// } ===== end nsIMdbObject methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbObject, NS_IMDBOBJECT_IID)
/*| nsIMdbErrorHook: a base class for clients of this API to subclass, in order
**| to provide a callback installable in nsIMdbEnv for error notifications. If
**| apps that subclass nsIMdbErrorHook wish to maintain a reference to the env
**| that contains the hook, then this should be a weak ref to avoid cycles.
**|
**|| OnError: when nsIMdbEnv has an error condition that causes the total count
**| of errors to increase, then nsIMdbEnv should call OnError() to report the
**| error in some fashion when an instance of nsIMdbErrorHook is installed. The
**| variety of string flavors is currently due to the uncertainty here in the
**| nsIMdbBlob and nsIMdbCell interfaces. (Note that overloading by using the
**| same method name is not necessary here, and potentially less clear.)
|*/
class nsIMdbErrorHook : public nsISupports{ // env callback handler to report errors
public:
// { ===== begin error methods =====
NS_IMETHOD OnErrorString(nsIMdbEnv* ev, const char* inAscii) = 0;
NS_IMETHOD OnErrorYarn(nsIMdbEnv* ev, const mdbYarn* inYarn) = 0;
// } ===== end error methods =====
// { ===== begin warning methods =====
NS_IMETHOD OnWarningString(nsIMdbEnv* ev, const char* inAscii) = 0;
NS_IMETHOD OnWarningYarn(nsIMdbEnv* ev, const mdbYarn* inYarn) = 0;
// } ===== end warning methods =====
// { ===== begin abort hint methods =====
NS_IMETHOD OnAbortHintString(nsIMdbEnv* ev, const char* inAscii) = 0;
NS_IMETHOD OnAbortHintYarn(nsIMdbEnv* ev, const mdbYarn* inYarn) = 0;
// } ===== end abort hint methods =====
};
/*| nsIMdbCompare: a caller-supplied yarn comparison interface. When two yarns
**| are compared to each other with Order(), this method should return a signed
**| long integer denoting relation R between the 1st and 2nd yarn instances
**| such that (First R Second), where negative is less than, zero is equal to,
**| and positive is greater than. Note that both yarns are readonly, and the
**| Order() method should make no attempt to modify the yarn content.
|*/
class nsIMdbCompare { // caller-supplied yarn comparison
public:
// { ===== begin nsIMdbCompare methods =====
NS_IMETHOD Order(nsIMdbEnv* ev, // compare first to second yarn
const mdbYarn* inFirst, // first yarn in comparison
const mdbYarn* inSecond, // second yarn in comparison
mdb_order* outOrder) = 0; // negative="<", zero="=", positive=">"
NS_IMETHOD AddStrongRef(nsIMdbEnv* ev) = 0; // does nothing
NS_IMETHOD CutStrongRef(nsIMdbEnv* ev) = 0; // does nothing
// } ===== end nsIMdbCompare methods =====
};
/*| nsIMdbHeap: abstract memory allocation interface.
**|
**|| Alloc: return a block at least inSize bytes in size with alignment
**| suitable for any native type (such as long integers). When no such
**| block can be allocated, failure is indicated by a null address in
**| addition to reporting an error in the environment.
**|
**|| Free: deallocate a block allocated or resized earlier by the same
**| heap instance. If the inBlock parameter is nil, the heap should do
**| nothing (and crashing is strongly discouraged).
|*/
class nsIMdbHeap { // caller-supplied memory management interface
public:
// { ===== begin nsIMdbHeap methods =====
NS_IMETHOD Alloc(nsIMdbEnv* ev, // allocate a piece of memory
mdb_size inSize, // requested byte size of new memory block
void** outBlock) = 0; // memory block of inSize bytes, or nil
NS_IMETHOD Free(nsIMdbEnv* ev, // free block from Alloc or Resize()
void* ioBlock) = 0; // block to be destroyed/deallocated
NS_IMETHOD HeapAddStrongRef(nsIMdbEnv* ev) = 0;
NS_IMETHOD HeapCutStrongRef(nsIMdbEnv* ev) = 0;
// } ===== end nsIMdbHeap methods =====
};
/*| nsIMdbCPlusHeap: Alloc() with global ::new(), Free() with global ::delete().
**| Resize() is done by ::new() followed by ::delete().
|*/
class nsIMdbCPlusHeap { // caller-supplied memory management interface
public:
// { ===== begin nsIMdbHeap methods =====
NS_IMETHOD Alloc(nsIMdbEnv* ev, // allocate a piece of memory
mdb_size inSize, // requested size of new memory block
void** outBlock); // memory block of inSize bytes, or nil
NS_IMETHOD Free(nsIMdbEnv* ev, // free block allocated earlier by Alloc()
void* inBlock);
NS_IMETHOD HeapAddStrongRef(nsIMdbEnv* ev);
NS_IMETHOD HeapCutStrongRef(nsIMdbEnv* ev);
// } ===== end nsIMdbHeap methods =====
};
/*| nsIMdbThumb:
|*/
#define NS_IMDBTHUMB_IID_STR "6d3ad7c1-a809-4e74-8577-49fa9a4562fa"
#define NS_IMDBTHUMB_IID \
{0x6d3ad7c1, 0xa809, 0x4e74, \
{ 0x85, 0x77, 0x49, 0xfa, 0x9a, 0x45, 0x62, 0xfa}}
class nsIMdbThumb : public nsISupports { // closure for repeating incremental method
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBTHUMB_IID)
// { ===== begin nsIMdbThumb methods =====
NS_IMETHOD GetProgress(nsIMdbEnv* ev,
mdb_count* outTotal, // total somethings to do in operation
mdb_count* outCurrent, // subportion of total completed so far
mdb_bool* outDone, // is operation finished?
mdb_bool* outBroken // is operation irreparably dead and broken?
) = 0;
NS_IMETHOD DoMore(nsIMdbEnv* ev,
mdb_count* outTotal, // total somethings to do in operation
mdb_count* outCurrent, // subportion of total completed so far
mdb_bool* outDone, // is operation finished?
mdb_bool* outBroken // is operation irreparably dead and broken?
) = 0;
NS_IMETHOD CancelAndBreakThumb( // cancel pending operation
nsIMdbEnv* ev) = 0;
// } ===== end nsIMdbThumb methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbThumb, NS_IMDBTHUMB_IID)
/*| nsIMdbEnv: a context parameter used when calling most abstract db methods.
**| The main purpose of such an object is to permit a database implementation
**| to avoid the use of globals to share information between various parts of
**| the implementation behind the abstract db interface. An environment acts
**| like a session object for a given calling thread, and callers should use
**| at least one different nsIMdbEnv instance for each thread calling the API.
**| While the database implementation might not be threaded, it is highly
**| desirable that the db be thread-safe if calling threads use distinct
**| instances of nsIMdbEnv. Callers can stop at one nsIMdbEnv per thread, or they
**| might decide to make on nsIMdbEnv instance for every nsIMdbPort opened, so that
**| error information is segregated by database instance. Callers create
**| instances of nsIMdbEnv by calling the MakeEnv() method in nsIMdbFactory.
**|
**|| tracing: an environment might support some kind of tracing, and this
**| boolean attribute permits such activity to be enabled or disabled.
**|
**|| errors: when a call to the abstract db interface returns, a caller might
**| check the number of outstanding errors to see whether the operation did
**| actually succeed. Each nsIMdbEnv should have all its errors cleared by a
**| call to ClearErrors() before making each call to the abstract db API,
**| because outstanding errors might disable further database actions. (This
**| is not done inside the db interface, because the db cannot in general know
**| when a call originates from inside or outside -- only the app knows this.)
**|
**|| error hook: callers can install an instance of nsIMdbErrorHook to receive
**| error notifications whenever the error count increases. The hook can
**| be uninstalled by passing a null pointer.
**|
|*/
#define NS_IMDBENV_IID_STR "a765e46b-efb6-41e6-b75b-c5d6bd710594"
#define NS_IMDBENV_IID \
{0xa765e46b, 0xefb6, 0x41e6, \
{ 0xb7, 0x5b, 0xc5, 0xd6, 0xbd, 0x71, 0x05, 0x94}}
class nsIMdbEnv : public nsISupports { // db specific context parameter
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBENV_IID)
// { ===== begin nsIMdbEnv methods =====
// { ----- begin attribute methods -----
NS_IMETHOD GetErrorCount(mdb_count* outCount,
mdb_bool* outShouldAbort) = 0;
NS_IMETHOD GetWarningCount(mdb_count* outCount,
mdb_bool* outShouldAbort) = 0;
NS_IMETHOD GetEnvBeVerbose(mdb_bool* outBeVerbose) = 0;
NS_IMETHOD SetEnvBeVerbose(mdb_bool inBeVerbose) = 0;
NS_IMETHOD GetDoTrace(mdb_bool* outDoTrace) = 0;
NS_IMETHOD SetDoTrace(mdb_bool inDoTrace) = 0;
NS_IMETHOD GetAutoClear(mdb_bool* outAutoClear) = 0;
NS_IMETHOD SetAutoClear(mdb_bool inAutoClear) = 0;
NS_IMETHOD GetErrorHook(nsIMdbErrorHook** acqErrorHook) = 0;
NS_IMETHOD SetErrorHook(
nsIMdbErrorHook* ioErrorHook) = 0; // becomes referenced
NS_IMETHOD GetHeap(nsIMdbHeap** acqHeap) = 0;
NS_IMETHOD SetHeap(
nsIMdbHeap* ioHeap) = 0; // becomes referenced
// } ----- end attribute methods -----
NS_IMETHOD ClearErrors() = 0; // clear errors beore re-entering db API
NS_IMETHOD ClearWarnings() = 0; // clear warnings
NS_IMETHOD ClearErrorsAndWarnings() = 0; // clear both errors & warnings
// } ===== end nsIMdbEnv methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbEnv, NS_IMDBENV_IID)
/*| nsIMdbFactory: the main entry points to the abstract db interface. A DLL
**| that supports this mdb interface need only have a single exported method
**| that will return an instance of nsIMdbFactory, so that further methods in
**| the suite can be accessed from objects returned by nsIMdbFactory methods.
**|
**|| mdbYarn: note all nsIMdbFactory subclasses must guarantee null
**| termination of all strings written into mdbYarn instances, as long as
**| mYarn_Size and mYarn_Buf are nonzero. Even truncated string values must
**| be null terminated. This is more strict behavior than mdbYarn requires,
**| but it is part of the nsIMdbFactory interface.
**|
**|| envs: an environment instance is required as per-thread context for
**| most of the db method calls, so nsIMdbFactory creates such instances.
**|
**|| rows: callers must be able to create row instances that are independent
**| of storage space that is part of the db content graph. Many interfaces
**| for data exchange have strictly copy semantics, so that a row instance
**| has no specific identity inside the db content model, and the text in
**| cells are an independenty copy of unexposed content inside the db model.
**| Callers are expected to maintain one or more row instances as a buffer
**| for staging cell content copied into or out of a table inside the db.
**| Callers are urged to use an instance of nsIMdbRow created by the nsIMdbFactory
**| code suite, because reading and writing might be much more efficient than
**| when using a hand-rolled nsIMdbRow subclass with no relation to the suite.
**|
**|| ports: a port is a readonly interface to a specific database file. Most
**| of the methods to access a db file are suitable for a readonly interface,
**| so a port is the basic minimum for accessing content. This makes it
**| possible to read other external formats for import purposes, without
**| needing the code or competence necessary to write every such format. So
**| we can write generic import code just once, as long as every format can
**| show a face based on nsIMdbPort. (However, same suite import can be faster.)
**| Given a file name and the first 512 bytes of a file, a factory can say if
**| a port can be opened by this factory. Presumably an app maintains chains
**| of factories for different suites, and asks each in turn about opening a
**| a prospective file for reading (as a port) or writing (as a store). I'm
**| not ready to tackle issues of format fidelity and factory chain ordering.
**|
**|| stores: a store is a mutable interface to a specific database file, and
**| includes the port interface plus any methods particular to writing, which
**| are few in number. Presumably the set of files that can be opened as
**| stores is a subset of the set of files that can be opened as ports. A
**| new store can be created with CreateNewFileStore() by supplying a new
**| file name which does not yet exist (callers are always responsible for
**| destroying any existing files before calling this method).
|*/
#define NS_IMDBFACTORY_IID_STR "2b80395c-b91e-4990-b1a7-023e99ab14e9"
#define NS_IMDBFACTORY_IID \
{0xf04aa4ab, 0x1fe, 0x4115, \
{ 0xa4, 0xa5, 0x68, 0x19, 0xdf, 0xf1, 0x10, 0x3d}}
class nsIMdbFactory : public nsISupports { // suite entry points
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBFACTORY_IID)
// { ===== begin nsIMdbFactory methods =====
// { ----- begin file methods -----
NS_IMETHOD OpenOldFile(nsIMdbEnv* ev, nsIMdbHeap* ioHeap,
const char* inFilePath,
mdb_bool inFrozen, nsIMdbFile** acqFile) = 0;
// Choose some subclass of nsIMdbFile to instantiate, in order to read
// (and write if not frozen) the file known by inFilePath. The file
// returned should be open and ready for use, and presumably positioned
// at the first byte position of the file. The exact manner in which
// files must be opened is considered a subclass specific detail, and
// other portions or Mork source code don't want to know how it's done.
NS_IMETHOD CreateNewFile(nsIMdbEnv* ev, nsIMdbHeap* ioHeap,
const char* inFilePath,
nsIMdbFile** acqFile) = 0;
// Choose some subclass of nsIMdbFile to instantiate, in order to read
// (and write if not frozen) the file known by inFilePath. The file
// returned should be created and ready for use, and presumably positioned
// at the first byte position of the file. The exact manner in which
// files must be opened is considered a subclass specific detail, and
// other portions or Mork source code don't want to know how it's done.
// } ----- end file methods -----
// { ----- begin env methods -----
NS_IMETHOD MakeEnv(nsIMdbHeap* ioHeap, nsIMdbEnv** acqEnv) = 0; // acquire new env
// ioHeap can be nil, causing a MakeHeap() style heap instance to be used
// } ----- end env methods -----
// { ----- begin heap methods -----
NS_IMETHOD MakeHeap(nsIMdbEnv* ev, nsIMdbHeap** acqHeap) = 0; // acquire new heap
// } ----- end heap methods -----
// { ----- begin compare methods -----
NS_IMETHOD MakeCompare(nsIMdbEnv* ev, nsIMdbCompare** acqCompare) = 0; // ASCII
// } ----- end compare methods -----
// { ----- begin row methods -----
NS_IMETHOD MakeRow(nsIMdbEnv* ev, nsIMdbHeap* ioHeap, nsIMdbRow** acqRow) = 0; // new row
// ioHeap can be nil, causing the heap associated with ev to be used
// } ----- end row methods -----
// { ----- begin port methods -----
NS_IMETHOD CanOpenFilePort(
nsIMdbEnv* ev, // context
// const char* inFilePath, // the file to investigate
// const mdbYarn* inFirst512Bytes,
nsIMdbFile* ioFile, // db abstract file interface
mdb_bool* outCanOpen, // whether OpenFilePort() might succeed
mdbYarn* outFormatVersion) = 0; // informal file format description
NS_IMETHOD OpenFilePort(
nsIMdbEnv* ev, // context
nsIMdbHeap* ioHeap, // can be nil to cause ev's heap attribute to be used
// const char* inFilePath, // the file to open for readonly import
nsIMdbFile* ioFile, // db abstract file interface
const mdbOpenPolicy* inOpenPolicy, // runtime policies for using db
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental port open
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then call nsIMdbFactory::ThumbToOpenPort() to get the port instance.
NS_IMETHOD ThumbToOpenPort( // redeeming a completed thumb from OpenFilePort()
nsIMdbEnv* ev, // context
nsIMdbThumb* ioThumb, // thumb from OpenFilePort() with done status
nsIMdbPort** acqPort) = 0; // acquire new port object
// } ----- end port methods -----
// { ----- begin store methods -----
NS_IMETHOD CanOpenFileStore(
nsIMdbEnv* ev, // context
// const char* inFilePath, // the file to investigate
// const mdbYarn* inFirst512Bytes,
nsIMdbFile* ioFile, // db abstract file interface
mdb_bool* outCanOpenAsStore, // whether OpenFileStore() might succeed
mdb_bool* outCanOpenAsPort, // whether OpenFilePort() might succeed
mdbYarn* outFormatVersion) = 0; // informal file format description
NS_IMETHOD OpenFileStore( // open an existing database
nsIMdbEnv* ev, // context
nsIMdbHeap* ioHeap, // can be nil to cause ev's heap attribute to be used
// const char* inFilePath, // the file to open for general db usage
nsIMdbFile* ioFile, // db abstract file interface
const mdbOpenPolicy* inOpenPolicy, // runtime policies for using db
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental store open
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then call nsIMdbFactory::ThumbToOpenStore() to get the store instance.
NS_IMETHOD
ThumbToOpenStore( // redeem completed thumb from OpenFileStore()
nsIMdbEnv* ev, // context
nsIMdbThumb* ioThumb, // thumb from OpenFileStore() with done status
nsIMdbStore** acqStore) = 0; // acquire new db store object
NS_IMETHOD CreateNewFileStore( // create a new db with minimal content
nsIMdbEnv* ev, // context
nsIMdbHeap* ioHeap, // can be nil to cause ev's heap attribute to be used
// const char* inFilePath, // name of file which should not yet exist
nsIMdbFile* ioFile, // db abstract file interface
const mdbOpenPolicy* inOpenPolicy, // runtime policies for using db
nsIMdbStore** acqStore) = 0; // acquire new db store object
// } ----- end store methods -----
// } ===== end nsIMdbFactory methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbFactory, NS_IMDBFACTORY_IID)
extern "C" nsIMdbFactory* MakeMdbFactory();
/*| nsIMdbFile: abstract file interface resembling the original morkFile
**| abstract interface (which was in turn modeled on the file interface
**| from public domain IronDoc). The design of this file interface is
**| complicated by the fact that some DB's will not find this interface
**| adequate for all runtime requirements (even though this file API is
**| enough to implement text-based DB's like Mork). For this reason,
**| more methods have been added to let a DB library force the file to
**| become closed so the DB can reopen the file in some other manner.
**| Folks are encouraged to suggest ways to tune this interface to suit
**| DB's that cannot manage to pull their maneuvers even given this API.
**|
**|| Tell: get the current i/o position in file
**|
**|| Seek: change the current i/o position in file
**|
**|| Eof: return file's total length in bytes
**|
**|| Read: input inSize bytes into outBuf, returning actual transfer size
**|
**|| Get: read starting at specific file offset (e.g. Seek(); Read();)
**|
**|| Write: output inSize bytes from inBuf, returning actual transfer size
**|
**|| Put: write starting at specific file offset (e.g. Seek(); Write();)
**|
**|| Flush: if written bytes are buffered, push them to final destination
**|
**|| Path: get file path in some string representation. This is intended
**| either to support the display of file name in a user presentation, or
**| to support the closing and reopening of the file when the DB needs more
**| exotic file access than is presented by the nsIMdbFile interface.
**|
**|| Steal: tell this file to close any associated i/o stream in the file
**| system, because the file ioThief intends to reopen the file in order
**| to provide the MDB implementation with more exotic file access than is
**| offered by the nsIMdbFile alone. Presumably the thief knows enough
**| from Path() in order to know which file to reopen. If Steal() is
**| successful, this file should probably delegate all future calls to
**| the nsIMdbFile interface down to the thief files, so that even after
**| the file has been stolen, it can still be read, written, or forcibly
**| closed (by a call to CloseMdbObject()).
**|
**|| Thief: acquire and return thief passed to an earlier call to Steal().
|*/
#define NS_IMDBFILE_IID_STR "f04aa4ab-1fe7-4115-a4a5-6819dff1103d"
#define NS_IMDBFILE_IID \
{0xf04aa4ab, 0x1fe, 0x4115, \
{ 0xa4, 0xa5, 0x68, 0x19, 0xdf, 0xf1, 0x10, 0x3d}}
class nsIMdbFile : public nsISupports { // minimal file interface
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBFILE_IID)
// { ===== begin nsIMdbFile methods =====
// { ----- begin pos methods -----
NS_IMETHOD Tell(nsIMdbEnv* ev, mdb_pos* outPos) const = 0;
NS_IMETHOD Seek(nsIMdbEnv* ev, mdb_pos inPos, mdb_pos *outPos) = 0;
NS_IMETHOD Eof(nsIMdbEnv* ev, mdb_pos* outPos) = 0;
// } ----- end pos methods -----
// { ----- begin read methods -----
NS_IMETHOD Read(nsIMdbEnv* ev, void* outBuf, mdb_size inSize,
mdb_size* outActualSize) = 0;
NS_IMETHOD Get(nsIMdbEnv* ev, void* outBuf, mdb_size inSize,
mdb_pos inPos, mdb_size* outActualSize) = 0;
// } ----- end read methods -----
// { ----- begin write methods -----
NS_IMETHOD Write(nsIMdbEnv* ev, const void* inBuf, mdb_size inSize,
mdb_size* outActualSize) = 0;
NS_IMETHOD Put(nsIMdbEnv* ev, const void* inBuf, mdb_size inSize,
mdb_pos inPos, mdb_size* outActualSize) = 0;
NS_IMETHOD Flush(nsIMdbEnv* ev) = 0;
// } ----- end attribute methods -----
// { ----- begin path methods -----
NS_IMETHOD Path(nsIMdbEnv* ev, mdbYarn* outFilePath) = 0;
// } ----- end path methods -----
// { ----- begin replacement methods -----
NS_IMETHOD Steal(nsIMdbEnv* ev, nsIMdbFile* ioThief) = 0;
NS_IMETHOD Thief(nsIMdbEnv* ev, nsIMdbFile** acqThief) = 0;
// } ----- end replacement methods -----
// { ----- begin versioning methods -----
NS_IMETHOD BecomeTrunk(nsIMdbEnv* ev) = 0;
// If this file is a file version branch created by calling AcquireBud(),
// BecomeTrunk() causes this file's content to replace the original
// file's content, typically by assuming the original file's identity.
// This default implementation of BecomeTrunk() does nothing, and this
// is appropriate behavior for files which are not branches, and is
// also the right behavior for files returned from AcquireBud() which are
// in fact the original file that has been truncated down to zero length.
NS_IMETHOD AcquireBud(nsIMdbEnv* ev, nsIMdbHeap* ioHeap,
nsIMdbFile** acqBud) = 0; // acquired file for new version of content
// AcquireBud() starts a new "branch" version of the file, empty of content,
// so that a new version of the file can be written. This new file
// can later be told to BecomeTrunk() the original file, so the branch
// created by budding the file will replace the original file. Some
// file subclasses might initially take the unsafe but expedient
// approach of simply truncating this file down to zero length, and
// then returning the same morkFile pointer as this, with an extra
// reference count increment. Note that the caller of AcquireBud() is
// expected to eventually call CutStrongRef() on the returned file
// in order to release the strong reference. High quality versions
// of morkFile subclasses will create entirely new files which later
// are renamed to become the old file, so that better transactional
// behavior is exhibited by the file, so crashes protect old files.
// Note that AcquireBud() is an illegal operation on readonly files.
// } ----- end versioning methods -----
// } ===== end nsIMdbFile methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbFile, NS_IMDBFILE_IID)
/*| nsIMdbPort: a readonly interface to a specific database file. The mutable
**| nsIMdbStore interface is a subclass that includes writing behavior, but
**| most of the needed db methods appear in the readonly nsIMdbPort interface.
**|
**|| mdbYarn: note all nsIMdbPort and nsIMdbStore subclasses must guarantee null
**| termination of all strings written into mdbYarn instances, as long as
**| mYarn_Size and mYarn_Buf are nonzero. Even truncated string values must
**| be null terminated. This is more strict behavior than mdbYarn requires,
**| but it is part of the nsIMdbPort and nsIMdbStore interface.
**|
**|| attributes: methods are provided to distinguish a readonly port from a
**| mutable store, and whether a mutable store actually has any dirty content.
**|
**|| filepath: the file path used to open the port from the nsIMdbFactory can be
**| queried and discovered by GetPortFilePath(), which includes format info.
**|
**|| export: a port can write itself in other formats, with perhaps a typical
**| emphasis on text interchange formats used by other systems. A port can be
**| queried to determine its preferred export interchange format, and a port
**| can be queried to see whether a specific export format is supported. And
**| actually exporting a port requires a new destination file name and format.
**|
**|| tokens: a port supports queries about atomized strings to map tokens to
**| strings or strings to token integers. (All atomized strings must be in
**| US-ASCII iso-8859-1 Latin1 charset encoding.) When a port is actually a
**| mutable store and a string has not yet been atomized, then StringToToken()
**| will actually do so and modify the store. The QueryToken() method will not
**| atomize a string if it has not already been atomized yet, even in stores.
**|
**|| tables: other than string tokens, all port content is presented through
**| tables, which are ordered collections of rows. Tables are identified by
**| row scope and table kind, which might or might not be unique in a port,
**| depending on app convention. When tables are effectively unique, then
**| queries for specific scope and kind pairs will find those tables. To see
**| all tables that match specific row scope and table kind patterns, even in
**| the presence of duplicates, every port supports a GetPortTableCursor()
**| method that returns an iterator over all matching tables. Table kind is
**| considered scoped inside row scope, so passing a zero for table kind will
**| find all table kinds for some nonzero row scope. Passing a zero for row
**| scope will iterate over all tables in the port, in some undefined order.
**| (A new table can be added to a port using nsIMdbStore::NewTable(), even when
**| the requested scope and kind combination is already used by other tables.)
**|
**|| memory: callers can request that a database use less memory footprint in
**| several flavors, from an inconsequential idle flavor to a rather drastic
**| panic flavor. Callers might perform an idle purge very frequently if desired
**| with very little cost, since only normally scheduled memory management will
**| be conducted, such as freeing resources for objects scheduled to be dropped.
**| Callers should perform session memory purges infrequently because they might
**| involve costly scanning of data structures to removed cached content, and
**| session purges are recommended only when a caller experiences memory crunch.
**| Callers should only rarely perform a panic purge, in response to dire memory
**| straits, since this is likely to make db operations much more expensive
**| than they would be otherwise. A panic purge asks a database to free as much
**| memory as possible while staying effective and operational, because a caller
**| thinks application failure might otherwise occur. (Apps might better close
**| an open db, so panic purges only make sense when a db is urgently needed.)
|*/
class nsIMdbPort : public nsISupports {
public:
// { ===== begin nsIMdbPort methods =====
// { ----- begin attribute methods -----
NS_IMETHOD GetIsPortReadonly(nsIMdbEnv* ev, mdb_bool* outBool) = 0;
NS_IMETHOD GetIsStore(nsIMdbEnv* ev, mdb_bool* outBool) = 0;
NS_IMETHOD GetIsStoreAndDirty(nsIMdbEnv* ev, mdb_bool* outBool) = 0;
NS_IMETHOD GetUsagePolicy(nsIMdbEnv* ev,
mdbUsagePolicy* ioUsagePolicy) = 0;
NS_IMETHOD SetUsagePolicy(nsIMdbEnv* ev,
const mdbUsagePolicy* inUsagePolicy) = 0;
// } ----- end attribute methods -----
// { ----- begin memory policy methods -----
NS_IMETHOD IdleMemoryPurge( // do memory management already scheduled
nsIMdbEnv* ev, // context
mdb_size* outEstimatedBytesFreed) = 0; // approximate bytes actually freed
NS_IMETHOD SessionMemoryPurge( // request specific footprint decrease
nsIMdbEnv* ev, // context
mdb_size inDesiredBytesFreed, // approximate number of bytes wanted
mdb_size* outEstimatedBytesFreed) = 0; // approximate bytes actually freed
NS_IMETHOD PanicMemoryPurge( // desperately free all possible memory
nsIMdbEnv* ev, // context
mdb_size* outEstimatedBytesFreed) = 0; // approximate bytes actually freed
// } ----- end memory policy methods -----
// { ----- begin filepath methods -----
NS_IMETHOD GetPortFilePath(
nsIMdbEnv* ev, // context
mdbYarn* outFilePath, // name of file holding port content
mdbYarn* outFormatVersion) = 0; // file format description
NS_IMETHOD GetPortFile(
nsIMdbEnv* ev, // context
nsIMdbFile** acqFile) = 0; // acquire file used by port or store
// } ----- end filepath methods -----
// { ----- begin export methods -----
NS_IMETHOD BestExportFormat( // determine preferred export format
nsIMdbEnv* ev, // context
mdbYarn* outFormatVersion) = 0; // file format description
// some tentative suggested import/export formats
// "ns:msg:db:port:format:ldif:ns4.0:passthrough" // necessary
// "ns:msg:db:port:format:ldif:ns4.5:utf8" // necessary
// "ns:msg:db:port:format:ldif:ns4.5:tabbed"
// "ns:msg:db:port:format:ldif:ns4.5:binary" // necessary
// "ns:msg:db:port:format:html:ns3.0:addressbook" // necessary
// "ns:msg:db:port:format:html:display:verbose"
// "ns:msg:db:port:format:html:display:concise"
// "ns:msg:db:port:format:mork:zany:verbose" // necessary
// "ns:msg:db:port:format:mork:zany:atomized" // necessary
// "ns:msg:db:port:format:rdf:xml"
// "ns:msg:db:port:format:xml:mork"
// "ns:msg:db:port:format:xml:display:verbose"
// "ns:msg:db:port:format:xml:display:concise"
// "ns:msg:db:port:format:xml:print:verbose" // recommended
// "ns:msg:db:port:format:xml:print:concise"
NS_IMETHOD
CanExportToFormat( // can export content in given specific format?
nsIMdbEnv* ev, // context
const char* inFormatVersion, // file format description
mdb_bool* outCanExport) = 0; // whether ExportSource() might succeed
NS_IMETHOD ExportToFormat( // export content in given specific format
nsIMdbEnv* ev, // context
// const char* inFilePath, // the file to receive exported content
nsIMdbFile* ioFile, // destination abstract file interface
const char* inFormatVersion, // file format description
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental export
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the export will be finished.
// } ----- end export methods -----
// { ----- begin token methods -----
NS_IMETHOD TokenToString( // return a string name for an integer token
nsIMdbEnv* ev, // context
mdb_token inToken, // token for inTokenName inside this port
mdbYarn* outTokenName) = 0; // the type of table to access
NS_IMETHOD StringToToken( // return an integer token for scope name
nsIMdbEnv* ev, // context
const char* inTokenName, // Latin1 string to tokenize if possible
mdb_token* outToken) = 0; // token for inTokenName inside this port
// String token zero is never used and never supported. If the port
// is a mutable store, then StringToToken() to create a new
// association of inTokenName with a new integer token if possible.
// But a readonly port will return zero for an unknown scope name.
NS_IMETHOD QueryToken( // like StringToToken(), but without adding
nsIMdbEnv* ev, // context
const char* inTokenName, // Latin1 string to tokenize if possible
mdb_token* outToken) = 0; // token for inTokenName inside this port
// QueryToken() will return a string token if one already exists,
// but unlike StringToToken(), will not assign a new token if not
// already in use.
// } ----- end token methods -----
// { ----- begin row methods -----
NS_IMETHOD HasRow( // contains a row with the specified oid?
nsIMdbEnv* ev, // context
const mdbOid* inOid, // hypothetical row oid
mdb_bool* outHasRow) = 0; // whether GetRow() might succeed
NS_IMETHOD GetRowRefCount( // get number of tables that contain a row
nsIMdbEnv* ev, // context
const mdbOid* inOid, // hypothetical row oid
mdb_count* outRefCount) = 0; // number of tables containing inRowKey
NS_IMETHOD GetRow( // access one row with specific oid
nsIMdbEnv* ev, // context
const mdbOid* inOid, // hypothetical row oid
nsIMdbRow** acqRow) = 0; // acquire specific row (or null)
// NS_IMETHOD
// GetPortRowCursor( // get cursor for all rows in specific scope
// nsIMdbEnv* ev, // context
// mdb_scope inRowScope, // row scope for row ids
// nsIMdbPortRowCursor** acqCursor) = 0; // all such rows in the port
NS_IMETHOD FindRow(nsIMdbEnv* ev, // search for row with matching cell
mdb_scope inRowScope, // row scope for row ids
mdb_column inColumn, // the column to search (and maintain an index)
const mdbYarn* inTargetCellValue, // cell value for which to search
mdbOid* outRowOid, // out row oid on match (or {0,-1} for no match)
nsIMdbRow** acqRow) = 0; // acquire matching row (or nil for no match)
// can be null if you only want the oid
// FindRow() searches for one row that has a cell in column inColumn with
// a contained value with the same form (i.e. charset) and is byte-wise
// identical to the blob described by yarn inTargetCellValue. Both content
// and form of the yarn must be an exact match to find a matching row.
//
// (In other words, both a yarn's blob bytes and form are significant. The
// form is not expected to vary in columns used for identity anyway. This
// is intended to make the cost of FindRow() cheaper for MDB implementors,
// since any cell value atomization performed internally must necessarily
// make yarn form significant in order to avoid data loss in atomization.)
//
// FindRow() can lazily create an index on attribute inColumn for all rows
// with that attribute in row space scope inRowScope, so that subsequent
// calls to FindRow() will perform faster. Such an index might or might
// not be persistent (but this seems desirable if it is cheap to do so).
// Note that lazy index creation in readonly DBs is not very feasible.
//
// This FindRow() interface assumes that attribute inColumn is effectively
// an alternative means of unique identification for a row in a rowspace,
// so correct behavior is only guaranteed when no duplicates for this col
// appear in the given set of rows. (If more than one row has the same cell
// value in this column, no more than one will be found; and cutting one of
// two duplicate rows can cause the index to assume no other such row lives
// in the row space, so future calls return nil for negative search results
// even though some duplicate row might still live within the rowspace.)
//
// In other words, the FindRow() implementation is allowed to assume simple
// hash tables mapping unqiue column keys to associated row values will be
// sufficient, where any duplication is not recorded because only one copy
// of a given key need be remembered. Implementors are not required to sort
// all rows by the specified column.
// } ----- end row methods -----
// { ----- begin table methods -----
NS_IMETHOD HasTable( // supports a table with the specified oid?
nsIMdbEnv* ev, // context
const mdbOid* inOid, // hypothetical table oid
mdb_bool* outHasTable) = 0; // whether GetTable() might succeed
NS_IMETHOD GetTable( // access one table with specific oid
nsIMdbEnv* ev, // context
const mdbOid* inOid, // hypothetical table oid
nsIMdbTable** acqTable) = 0; // acquire specific table (or null)
NS_IMETHOD HasTableKind( // supports a table of the specified type?
nsIMdbEnv* ev, // context
mdb_scope inRowScope, // rid scope for row ids
mdb_kind inTableKind, // the type of table to access
mdb_count* outTableCount, // current number of such tables
mdb_bool* outSupportsTable) = 0; // whether GetTableKind() might succeed
// row scopes to be supported include the following suggestions:
// "ns:msg:db:row:scope:address:cards:all"
// "ns:msg:db:row:scope:mail:messages:all"
// "ns:msg:db:row:scope:news:articles:all"
// table kinds to be supported include the following suggestions:
// "ns:msg:db:table:kind:address:cards:main"
// "ns:msg:db:table:kind:address:lists:all"
// "ns:msg:db:table:kind:address:list"
// "ns:msg:db:table:kind:news:threads:all"
// "ns:msg:db:table:kind:news:thread"
// "ns:msg:db:table:kind:mail:threads:all"
// "ns:msg:db:table:kind:mail:thread"
NS_IMETHOD GetTableKind( // access one (random) table of specific type
nsIMdbEnv* ev, // context
mdb_scope inRowScope, // row scope for row ids
mdb_kind inTableKind, // the type of table to access
mdb_count* outTableCount, // current number of such tables
mdb_bool* outMustBeUnique, // whether port can hold only one of these
nsIMdbTable** acqTable) = 0; // acquire scoped collection of rows
NS_IMETHOD
GetPortTableCursor( // get cursor for all tables of specific type
nsIMdbEnv* ev, // context
mdb_scope inRowScope, // row scope for row ids
mdb_kind inTableKind, // the type of table to access
nsIMdbPortTableCursor** acqCursor) = 0; // all such tables in the port
// } ----- end table methods -----
// { ----- begin commit methods -----
NS_IMETHOD ShouldCompress( // store wastes at least inPercentWaste?
nsIMdbEnv* ev, // context
mdb_percent inPercentWaste, // 0..100 percent file size waste threshold
mdb_percent* outActualWaste, // 0..100 percent of file actually wasted
mdb_bool* outShould) = 0; // true when about inPercentWaste% is wasted
// ShouldCompress() returns true if the store can determine that the file
// will shrink by an estimated percentage of inPercentWaste% (or more) if
// CompressCommit() is called, because that percentage of the file seems
// to be recoverable free space. The granularity is only in terms of
// percentage points, and any value over 100 is considered equal to 100.
//
// If a store only has an approximate idea how much space might be saved
// during a compress, then a best guess should be made. For example, the
// Mork implementation might keep track of how much file space began with
// text content before the first updating transaction, and then consider
// all content following the start of the first transaction as potentially
// wasted space if it is all updates and not just new content. (This is
// a safe assumption in the sense that behavior will stabilize on a low
// estimate of wastage after a commit removes all transaction updates.)
//
// Some db formats might attempt to keep a very accurate reckoning of free
// space size, so a very accurate determination can be made. But other db
// formats might have difficulty determining size of free space, and might
// require some lengthy calculation to answer. This is the reason for
// passing in the percentage threshold of interest, so that such lengthy
// computations can terminate early as soon as at least inPercentWaste is
// found, so that the entire file need not be groveled when unnecessary.
// However, we hope implementations will always favor fast but imprecise
// heuristic answers instead of extremely slow but very precise answers.
//
// If the outActualWaste parameter is non-nil, it will be used to return
// the actual estimated space wasted as a percentage of file size. (This
// parameter is provided so callers need not call repeatedly with altered
// inPercentWaste values to isolate the actual wastage figure.) Note the
// actual wastage figure returned can exactly equal inPercentWaste even
// when this grossly underestimates the real figure involved, if the db
// finds it very expensive to determine the extent of wastage after it is
// known to at least exceed inPercentWaste. Note we expect that whenever
// outShould returns true, that outActualWaste returns >= inPercentWaste.
//
// The effect of different inPercentWaste values is not very uniform over
// the permitted range. For example, 50 represents 50% wastage, or a file
// that is about double what it should be ideally. But 99 represents 99%
// wastage, or a file that is about ninety-nine times as big as it should
// be ideally. In the smaller direction, 25 represents 25% wastage, or
// a file that is only 33% larger than it should be ideally.
//
// Callers can determine what policy they want to use for considering when
// a file holds too much wasted space, and express this as a percentage
// of total file size to pass as in the inPercentWaste parameter. A zero
// likely returns always trivially true, and 100 always trivially false.
// The great majority of callers are expected to use values from 25 to 75,
// since most plausible thresholds for compressing might fall between the
// extremes of 133% of ideal size and 400% of ideal size. (Presumably the
// larger a file gets, the more important the percentage waste involved, so
// a sliding scale for compress thresholds might use smaller numbers for
// much bigger file sizes.)
// } ----- end commit methods -----
// } ===== end nsIMdbPort methods =====
};
/*| nsIMdbStore: a mutable interface to a specific database file.
**|
**|| tables: one can force a new table to exist in a store with NewTable()
**| and nonzero values for both row scope and table kind. (If one wishes only
**| one table of a certain kind, then one might look for it first using the
**| GetTableKind() method). One can pass inMustBeUnique to force future
**| users of this store to be unable to create other tables with the same pair
**| of scope and kind attributes. When inMustBeUnique is true, and the table
**| with the given scope and kind pair already exists, then the existing one
**| is returned instead of making a new table. Similarly, if one passes false
**| for inMustBeUnique, but the table kind has already been marked unique by a
**| previous user of the store, then the existing unique table is returned.
**|
**|| import: all or some of another port's content can be imported by calling
**| AddPortContent() with a row scope identifying the extent of content to
**| be imported. A zero row scope will import everything. A nonzero row
**| scope will only import tables with a matching row scope. Note that one
**| must somehow find a way to negotiate possible conflicts between existing
**| row content and imported row content, and this involves a specific kind of
**| definition for row identity involving either row IDs or unique attributes,
**| or some combination of these two. At the moment I am just going to wave
**| my hands, and say the default behavior is to assign all new row identities
**| to all imported content, which will result in no merging of content; this
**| must change later because it is unacceptable in some contexts.
**|
**|| commits: to manage modifications in a mutable store, very few methods are
**| really needed to indicate global policy choices that are independent of
**| the actual modifications that happen in objects at the level of tables,
**| rows, and cells, etc. The most important policy to specify is which sets
**| of changes are considered associated in a manner such that they should be
**| applied together atomically to a given store. We call each such group of
**| changes a transaction. We handle three different grades of transaction,
**| but they differ only in semantic significance to the application, and are
**| not intended to nest. (If small transactions were nested inside large
**| transactions, that would imply that a single large transaction must be
**| atomic over all the contained small transactions; but actually we intend
**| smalls transaction never be undone once commited due to, say, aborting a
**| transaction of greater significance.) The small, large, and session level
**| commits have equal granularity, and differ only in risk of loss from the
**| perspective of an application. Small commits characterize changes that
**| can be lost with relatively small risk, so small transactions can delay
**| until later if they are expensive or impractical to commit. Large commits
**| involve changes that would probably inconvenience users if lost, so the
**| need to pay costs of writing is rather greater than with small commits.
**| Session commits are last ditch attempts to save outstanding changes before
**| stopping the use of a particular database, so there will be no later point
**| in time to save changes that have been delayed due to possible high cost.
**| If large commits are never delayed, then a session commit has about the
**| same performance effect as another large commit; but if small and large
**| commits are always delayed, then a session commit is likely to be rather
**| expensive as a runtime cost compared to any earlier database usage.
**|
**|| aborts: the only way to abort changes to a store is by closing the store.
**| So there is no specific method for causing any abort. Stores must discard
**| all changes made that are uncommited when a store is closed. This design
**| choice makes the implementations of tables, rows, and cells much less
**| complex because they need not maintain a record of undobable changes. When
**| a store is closed, presumably this precipitates the closure of all tables,
**| rows, and cells in the store as well. So an application can revert the
**| state of a store in the user interface by quietly closing and reopening a
**| store, because this will discard uncommited changes and show old content.
**| This implies an app that closes a store will need to send a "scramble"
**| event notification to any views that depend on old discarded content.
|*/
#define NS_IMDBSTORE_IID_STR "726618d3-f15b-49b9-9f4a-efcc9db53d0d"
#define NS_IMDBSTORE_IID \
{0x726618d3, 0xf15b, 0x49b9, \
{0x9f, 0x4a, 0xef, 0xcc, 0x9d, 0xb5, 0x3d, 0x0d}}
class nsIMdbStore : public nsIMdbPort {
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBSTORE_IID)
// { ===== begin nsIMdbStore methods =====
// { ----- begin table methods -----
NS_IMETHOD NewTable( // make one new table of specific type
nsIMdbEnv* ev, // context
mdb_scope inRowScope, // row scope for row ids
mdb_kind inTableKind, // the type of table to access
mdb_bool inMustBeUnique, // whether store can hold only one of these
const mdbOid* inOptionalMetaRowOid, // can be nil to avoid specifying
nsIMdbTable** acqTable) = 0; // acquire scoped collection of rows
NS_IMETHOD NewTableWithOid( // make one new table of specific type
nsIMdbEnv* ev, // context
const mdbOid* inOid, // caller assigned oid
mdb_kind inTableKind, // the type of table to access
mdb_bool inMustBeUnique, // whether store can hold only one of these
const mdbOid* inOptionalMetaRowOid, // can be nil to avoid specifying
nsIMdbTable** acqTable) = 0; // acquire scoped collection of rows
// } ----- end table methods -----
// { ----- begin row scope methods -----
NS_IMETHOD RowScopeHasAssignedIds(nsIMdbEnv* ev,
mdb_scope inRowScope, // row scope for row ids
mdb_bool* outCallerAssigned, // nonzero if caller assigned specified
mdb_bool* outStoreAssigned) = 0; // nonzero if store db assigned specified
NS_IMETHOD SetCallerAssignedIds(nsIMdbEnv* ev,
mdb_scope inRowScope, // row scope for row ids
mdb_bool* outCallerAssigned, // nonzero if caller assigned specified
mdb_bool* outStoreAssigned) = 0; // nonzero if store db assigned specified
NS_IMETHOD SetStoreAssignedIds(nsIMdbEnv* ev,
mdb_scope inRowScope, // row scope for row ids
mdb_bool* outCallerAssigned, // nonzero if caller assigned specified
mdb_bool* outStoreAssigned) = 0; // nonzero if store db assigned specified
// } ----- end row scope methods -----
// { ----- begin row methods -----
NS_IMETHOD NewRowWithOid(nsIMdbEnv* ev, // new row w/ caller assigned oid
const mdbOid* inOid, // caller assigned oid
nsIMdbRow** acqRow) = 0; // create new row
NS_IMETHOD NewRow(nsIMdbEnv* ev, // new row with db assigned oid
mdb_scope inRowScope, // row scope for row ids
nsIMdbRow** acqRow) = 0; // create new row
// Note this row must be added to some table or cell child before the
// store is closed in order to make this row persist across sesssions.
// } ----- end row methods -----
// { ----- begin inport/export methods -----
NS_IMETHOD ImportContent( // import content from port
nsIMdbEnv* ev, // context
mdb_scope inRowScope, // scope for rows (or zero for all?)
nsIMdbPort* ioPort, // the port with content to add to store
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental import
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the import will be finished.
NS_IMETHOD ImportFile( // import content from port
nsIMdbEnv* ev, // context
nsIMdbFile* ioFile, // the file with content to add to store
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental import
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the import will be finished.
// } ----- end inport/export methods -----
// { ----- begin hinting methods -----
NS_IMETHOD
ShareAtomColumnsHint( // advise re shared column content atomizing
nsIMdbEnv* ev, // context
mdb_scope inScopeHint, // zero, or suggested shared namespace
const mdbColumnSet* inColumnSet) = 0; // cols desired tokenized together
NS_IMETHOD
AvoidAtomColumnsHint( // advise column with poor atomizing prospects
nsIMdbEnv* ev, // context
const mdbColumnSet* inColumnSet) = 0; // cols with poor atomizing prospects
// } ----- end hinting methods -----
// { ----- begin commit methods -----
NS_IMETHOD SmallCommit( // save minor changes if convenient and uncostly
nsIMdbEnv* ev) = 0; // context
NS_IMETHOD LargeCommit( // save important changes if at all possible
nsIMdbEnv* ev, // context
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental commit
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the commit will be finished. Note the store is effectively write
// locked until commit is finished or canceled through the thumb instance.
// Until the commit is done, the store will report it has readonly status.
NS_IMETHOD SessionCommit( // save all changes if large commits delayed
nsIMdbEnv* ev, // context
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental commit
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the commit will be finished. Note the store is effectively write
// locked until commit is finished or canceled through the thumb instance.
// Until the commit is done, the store will report it has readonly status.
NS_IMETHOD
CompressCommit( // commit and make db physically smaller if possible
nsIMdbEnv* ev, // context
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental commit
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the commit will be finished. Note the store is effectively write
// locked until commit is finished or canceled through the thumb instance.
// Until the commit is done, the store will report it has readonly status.
// } ----- end commit methods -----
// } ===== end nsIMdbStore methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbStore, NS_IMDBSTORE_IID)
/*| nsIMdbCursor: base cursor class for iterating row cells and table rows
**|
**|| count: the number of elements in the collection (table or row)
**|
**|| seed: the change count in the underlying collection, which is synced
**| with the collection when the iteration position is set, and henceforth
**| acts to show whether the iter has lost collection synchronization, in
**| case it matters to clients whether any change happens during iteration.
**|
**|| pos: the position of the current element in the collection. Negative
**| means a position logically before the first element. A positive value
**| equal to count (or larger) implies a position after the last element.
**| To iterate over all elements, set the position to negative, so subsequent
**| calls to any 'next' method will access the first collection element.
**|
**|| doFailOnSeedOutOfSync: whether a cursor should return an error if the
**| cursor's snapshot of a table's seed becomes stale with respect the table's
**| current seed value (which implies the iteration is less than total) in
**| between to cursor calls that actually access collection content. By
**| default, a cursor should assume this attribute is false until specified,
**| so that iterations quietly try to re-sync when they loose coherence.
|*/
#define NS_IMDBCURSOR_IID_STR "a0c37337-6ebc-474c-90db-e65ea0b850aa"
#define NS_IMDBCURSOR_IID \
{0xa0c37337, 0x6ebc, 0x474c, \
{0x90, 0xdb, 0xe6, 0x5e, 0xa0, 0xb8, 0x50, 0xaa}}
class nsIMdbCursor : public nsISupports { // collection iterator
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBCURSOR_IID)
// { ===== begin nsIMdbCursor methods =====
// { ----- begin attribute methods -----
NS_IMETHOD GetCount(nsIMdbEnv* ev, mdb_count* outCount) = 0; // readonly
NS_IMETHOD GetSeed(nsIMdbEnv* ev, mdb_seed* outSeed) = 0; // readonly
NS_IMETHOD SetPos(nsIMdbEnv* ev, mdb_pos inPos) = 0; // mutable
NS_IMETHOD GetPos(nsIMdbEnv* ev, mdb_pos* outPos) = 0;
NS_IMETHOD SetDoFailOnSeedOutOfSync(nsIMdbEnv* ev, mdb_bool inFail) = 0;
NS_IMETHOD GetDoFailOnSeedOutOfSync(nsIMdbEnv* ev, mdb_bool* outFail) = 0;
// } ----- end attribute methods -----
// } ===== end nsIMdbCursor methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbCursor, NS_IMDBCURSOR_IID)
#define NS_IMDBPORTTABLECURSOR_IID_STR = "f181a41e-933d-49b3-af93-20d3634b8b78"
#define NS_IMDBPORTTABLECURSOR_IID \
{0xf181a41e, 0x933d, 0x49b3, \
{0xaf, 0x93, 0x20, 0xd3, 0x63, 0x4b, 0x8b, 0x78}}
/*| nsIMdbPortTableCursor: cursor class for iterating port tables
**|
**|| port: the cursor is associated with a specific port, which can be
**| set to a different port (which resets the position to -1 so the
**| next table acquired is the first in the port.
**|
|*/
class nsIMdbPortTableCursor : public nsISupports { // table collection iterator
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBPORTTABLECURSOR_IID)
// { ===== begin nsIMdbPortTableCursor methods =====
// { ----- begin attribute methods -----
NS_IMETHOD SetPort(nsIMdbEnv* ev, nsIMdbPort* ioPort) = 0; // sets pos to -1
NS_IMETHOD GetPort(nsIMdbEnv* ev, nsIMdbPort** acqPort) = 0;
NS_IMETHOD SetRowScope(nsIMdbEnv* ev, // sets pos to -1
mdb_scope inRowScope) = 0;
NS_IMETHOD GetRowScope(nsIMdbEnv* ev, mdb_scope* outRowScope) = 0;
// setting row scope to zero iterates over all row scopes in port
NS_IMETHOD SetTableKind(nsIMdbEnv* ev, // sets pos to -1
mdb_kind inTableKind) = 0;
NS_IMETHOD GetTableKind(nsIMdbEnv* ev, mdb_kind* outTableKind) = 0;
// setting table kind to zero iterates over all table kinds in row scope
// } ----- end attribute methods -----
// { ----- begin table iteration methods -----
NS_IMETHOD NextTable( // get table at next position in the db
nsIMdbEnv* ev, // context
nsIMdbTable** acqTable) = 0; // the next table in the iteration
// } ----- end table iteration methods -----
// } ===== end nsIMdbPortTableCursor methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbPortTableCursor,
NS_IMDBPORTTABLECURSOR_IID)
/*| nsIMdbCollection: an object that collects a set of other objects as members.
**| The main purpose of this base class is to unify the perceived semantics
**| of tables and rows where their collection behavior is similar. This helps
**| isolate the mechanics of collection behavior from the other semantics that
**| are more characteristic of rows and tables.
**|
**|| count: the number of objects in a collection is the member count. (Some
**| collection interfaces call this attribute the 'size', but that can be a
**| little ambiguous, and counting actual members is harder to confuse.)
**|
**|| seed: the seed of a collection is a counter for changes in membership in
**| a specific collection. This seed should change when members are added to
**| or removed from a collection, but not when a member changes internal state.
**| The seed should also change whenever the internal collection of members has
**| a complex state change that reorders member positions (say by sorting) that
**| would affect the nature of an iteration over that collection of members.
**| The purpose of a seed is to inform any outstanding collection cursors that
**| they might be stale, without incurring the cost of broadcasting an event
**| notification to such cursors, which would need more data structure support.
**| Presumably a cursor in a particular mdb code suite has much more direct
**| access to a collection seed member slot that this abstract COM interface,
**| so this information is intended more for clients outside mdb that want to
**| make inferences similar to those made by the collection cursors. The seed
**| value as an integer magnitude is not very important, and callers should not
**| assume meaningful information can be derived from an integer value beyond
**| whether it is equal or different from a previous inspection. A seed uses
**| integers of many bits in order to make the odds of wrapping and becoming
**| equal to an earlier seed value have probability that is vanishingly small.
**|
**|| port: every collection is associated with a specific database instance.
**|
**|| cursor: a subclass of nsIMdbCursor suitable for this specific collection
**| subclass. The ability to GetCursor() from the base nsIMdbCollection class
**| is not really as useful as getting a more specifically typed cursor more
**| directly from the base class without any casting involved. So including
**| this method here is more for conceptual illustration.
**|
**|| oid: every collection has an identity that persists from session to
**| session. Implementations are probably able to distinguish row IDs from
**| table IDs, but we don't specify anything official in this regard. A
**| collection has the same identity for the lifetime of the collection,
**| unless identity is swapped with another collection by means of a call to
**| BecomeContent(), which is considered a way to swap a new representation
**| for an old well-known object. (Even so, only content appears to change,
**| while the identity seems to stay the same.)
**|
**|| become: developers can effectively cause two objects to swap identities,
**| in order to effect a complete swap between what persistent content is
**| represented by two oids. The caller should consider this a content swap,
**| and not identity wap, because identities will seem to stay the same while
**| only content changes. However, implementations will likely do this
**| internally by swapping identities. Callers must swap content only
**| between objects of similar type, such as a row with another row, and a
**| table with another table, because implementations need not support
**| cross-object swapping because it might break object name spaces.
**|
**|| dropping: when a caller expects a row or table will no longer be used, the
**| caller can tell the collection to 'drop activity', which means the runtime
**| object can have it's internal representation purged to save memory or any
**| other resource that is being consumed by the collection's representation.
**| This has no effect on the collection's persistent content or semantics,
**| and is only considered a runtime effect. After a collection drops
**| activity, the object should still be as usable as before (because it has
**| NOT been closed), but further usage can be expensive to re-instate because
**| it might involve reallocating space and/or re-reading disk space. But
**| since this future usage is not expected, the caller does not expect to
**| pay the extra expense. An implementation can choose to implement
**| 'dropping activity' in different ways, or even not at all if this
**| operation is not really feasible. Callers cannot ask objects whether they
**| are 'dropped' or not, so this should be transparent. (Note that
**| implementors might fear callers do not really know whether future
**| usage will occur, and therefore might delay the act of dropping until
**| the near future, until seeing whether the object is used again
**| immediately elsewhere. Such use soon after the drop request might cause
**| the drop to be cancelled.)
|*/
class nsIMdbCollection : public nsISupports { // sequence of objects
public:
// { ===== begin nsIMdbCollection methods =====
// { ----- begin attribute methods -----
NS_IMETHOD GetSeed(nsIMdbEnv* ev,
mdb_seed* outSeed) = 0; // member change count
NS_IMETHOD GetCount(nsIMdbEnv* ev,
mdb_count* outCount) = 0; // member count
NS_IMETHOD GetPort(nsIMdbEnv* ev,
nsIMdbPort** acqPort) = 0; // collection container
// } ----- end attribute methods -----
// { ----- begin cursor methods -----
NS_IMETHOD GetCursor( // make a cursor starting iter at inMemberPos
nsIMdbEnv* ev, // context
mdb_pos inMemberPos, // zero-based ordinal pos of member in collection
nsIMdbCursor** acqCursor) = 0; // acquire new cursor instance
// } ----- end cursor methods -----
// { ----- begin ID methods -----
NS_IMETHOD GetOid(nsIMdbEnv* ev,
mdbOid* outOid) = 0; // read object identity
NS_IMETHOD BecomeContent(nsIMdbEnv* ev,
const mdbOid* inOid) = 0; // exchange content
// } ----- end ID methods -----
// { ----- begin activity dropping methods -----
NS_IMETHOD DropActivity( // tell collection usage no longer expected
nsIMdbEnv* ev) = 0;
// } ----- end activity dropping methods -----
// } ===== end nsIMdbCollection methods =====
};
/*| nsIMdbTable: an ordered collection of rows
**|
**|| row scope: an integer token for an atomized string in this database
**| that names a space for row IDs. This attribute of a table is intended
**| as guidance metainformation that helps with searching a database for
**| tables that operate on collections of rows of the specific type. By
**| convention, a table with a specific row scope is expected to focus on
**| containing rows that belong to that scope, however exceptions are easily
**| allowed because all rows in a table are known by both row ID and scope.
**| (A table with zero row scope is never allowed because this would make it
**| ambiguous to use a zero row scope when iterating over tables in a port to
**| indicate that all row scopes should be seen by a cursor.)
**|
**|| table kind: an integer token for an atomized string in this database
**| that names a kind of table as a subset of the associated row scope. This
**| attribute is intended as guidance metainformation to clarify the role of
**| this table with respect to other tables in the same row scope, and this
**| also helps search for such tables in a database. By convention, a table
**| with a specific table kind has a consistent role for containing rows with
**| respect to other collections of such rows in the same row scope. Also by
**| convention, at least one table in a row scope has a table kind purporting
**| to contain ALL the rows that belong in that row scope, so that at least
**| one table exists that allows all rows in a scope to be interated over.
**| (A table with zero table kind is never allowed because this would make it
**| ambiguous to use a zero table kind when iterating over tables in a port to
**| indicate that all table kinds in a row scope should be seen by a cursor.)
**|
**|| port: every table is considered part of some port that contains the
**| table, so that closing the containing port will cause the table to be
**| indirectly closed as well. We make it easy to get the containing port for
**| a table, because the port supports important semantic interfaces that will
**| affect how content in table is presented; the most important port context
**| that affects a table is specified by the set of token to string mappings
**| that affect all tokens used throughout the database, and which drive the
**| meanings of row scope, table kind, cell columns, etc.
**|
**|| cursor: a cursor that iterates over the rows in this table, where rows
**| have zero-based index positions from zero to count-1. Making a cursor
**| with negative position will next iterate over the first row in the table.
**|
**|| position: given any position from zero to count-1, a table will return
**| the row ID and row scope for the row at that position. (One can use the
**| GetRowAllCells() method to read that row, or else use a row cursor to both
**| get the row at some position and read its content at the same time.) The
**| position depends on whether a table is sorted, and upon the actual sort.
**| Note that moving a row's position is only possible in unsorted tables.
**|
**|| row set: every table contains a collection of rows, where a member row is
**| referenced by the table using the row ID and row scope for the row. No
**| single table owns a given row instance, because rows are effectively ref-
**| counted and destroyed only when the last table removes a reference to that
**| particular row. (But a row can be emptied of all content no matter how
**| many refs exist, and this might be the next best thing to destruction.)
**| Once a row exists in a least one table (after NewRow() is called), then it
**| can be added to any other table by calling AddRow(), or removed from any
**| table by calling CutRow(), or queried as a member by calling HasRow(). A
**| row can only be added to a table once, and further additions do nothing and
**| complain not at all. Cutting a row from a table only does something when
**| the row was actually a member, and otherwise does nothing silently.
**|
**|| row ref count: one can query the number of tables (and/or cells)
**| containing a row as a member or a child.
**|
**|| row content: one can access or modify the cell content in a table's row
**| by moving content to or from an instance of nsIMdbRow. Note that nsIMdbRow
**| never represents the actual row inside a table, and this is the reason
**| why nsIMdbRow instances do not have row IDs or row scopes. So an instance
**| of nsIMdbRow always and only contains a snapshot of some or all content in
**| past, present, or future persistent row inside a table. This means that
**| reading and writing rows in tables has strictly copy semantics, and we
**| currently do not plan any exceptions for specific performance reasons.
**|
**|| sorting: note all rows are assumed sorted by row ID as a secondary
**| sort following the primary column sort, when table rows are sorted.
**|
**|| indexes:
|*/
#define NS_IMDBTABLE_IID_STR = "fe11bc98-d02b-4128-9fac-87042fdf9639"
#define NS_IMDBTABLE_IID \
{0xfe11bc98, 0xd02b, 0x4128, \
{0x9f, 0xac, 0x87, 0x04, 0x2f, 0xdf, 0x96, 0x39}}
class nsIMdbTable : public nsIMdbCollection { // a collection of rows
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBTABLE_IID)
// { ===== begin nsIMdbTable methods =====
// { ----- begin meta attribute methods -----
NS_IMETHOD SetTablePriority(nsIMdbEnv* ev, mdb_priority inPrio) = 0;
NS_IMETHOD GetTablePriority(nsIMdbEnv* ev, mdb_priority* outPrio) = 0;
NS_IMETHOD GetTableBeVerbose(nsIMdbEnv* ev, mdb_bool* outBeVerbose) = 0;
NS_IMETHOD SetTableBeVerbose(nsIMdbEnv* ev, mdb_bool inBeVerbose) = 0;
NS_IMETHOD GetTableIsUnique(nsIMdbEnv* ev, mdb_bool* outIsUnique) = 0;
NS_IMETHOD GetTableKind(nsIMdbEnv* ev, mdb_kind* outTableKind) = 0;
NS_IMETHOD GetRowScope(nsIMdbEnv* ev, mdb_scope* outRowScope) = 0;
NS_IMETHOD GetMetaRow(
nsIMdbEnv* ev, // context
const mdbOid* inOptionalMetaRowOid, // can be nil to avoid specifying
mdbOid* outOid, // output meta row oid, can be nil to suppress output
nsIMdbRow** acqRow) = 0; // acquire table's unique singleton meta row
// The purpose of a meta row is to support the persistent recording of
// meta info about a table as cells put into the distinguished meta row.
// Each table has exactly one meta row, which is not considered a member
// of the collection of rows inside the table. The only way to tell
// whether a row is a meta row is by the fact that it is returned by this
// GetMetaRow() method from some table. Otherwise nothing distinguishes
// a meta row from any other row. A meta row can be used anyplace that
// any other row can be used, and can even be put into other tables (or
// the same table) as a table member, if this is useful for some reason.
// The first attempt to access a table's meta row using GetMetaRow() will
// cause the meta row to be created if it did not already exist. When the
// meta row is created, it will have the row oid that was previously
// requested for this table's meta row; or if no oid was ever explicitly
// specified for this meta row, then a unique oid will be generated in
// the row scope named "m" (so obviously MDB clients should not
// manually allocate any row IDs from that special meta scope namespace).
// The meta row oid can be specified either when the table is created, or
// else the first time that GetMetaRow() is called, by passing a non-nil
// pointer to an oid for parameter inOptionalMetaRowOid. The meta row's
// actual oid is returned in outOid (if this is a non-nil pointer), and
// it will be different from inOptionalMetaRowOid when the meta row was
// already given a different oid earlier.
// } ----- end meta attribute methods -----
// { ----- begin cursor methods -----
NS_IMETHOD GetTableRowCursor( // make a cursor, starting iteration at inRowPos
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
nsIMdbTableRowCursor** acqCursor) = 0; // acquire new cursor instance
// } ----- end row position methods -----
// { ----- begin row position methods -----
NS_IMETHOD PosToOid( // get row member for a table position
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
mdbOid* outOid) = 0; // row oid at the specified position
NS_IMETHOD OidToPos( // test for the table position of a row member
nsIMdbEnv* ev, // context
const mdbOid* inOid, // row to find in table
mdb_pos* outPos) = 0; // zero-based ordinal position of row in table
NS_IMETHOD PosToRow( // test for the table position of a row member
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
nsIMdbRow** acqRow) = 0; // acquire row at table position inRowPos
NS_IMETHOD RowToPos( // test for the table position of a row member
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow, // row to find in table
mdb_pos* outPos) = 0; // zero-based ordinal position of row in table
// } ----- end row position methods -----
// { ----- begin oid set methods -----
NS_IMETHOD AddOid( // make sure the row with inOid is a table member
nsIMdbEnv* ev, // context
const mdbOid* inOid) = 0; // row to ensure membership in table
NS_IMETHOD HasOid( // test for the table position of a row member
nsIMdbEnv* ev, // context
const mdbOid* inOid, // row to find in table
mdb_bool* outHasOid) = 0; // whether inOid is a member row
NS_IMETHOD CutOid( // make sure the row with inOid is not a member
nsIMdbEnv* ev, // context
const mdbOid* inOid) = 0; // row to remove from table
// } ----- end oid set methods -----
// { ----- begin row set methods -----
NS_IMETHOD NewRow( // create a new row instance in table
nsIMdbEnv* ev, // context
mdbOid* ioOid, // please use minus one (unbound) rowId for db-assigned IDs
nsIMdbRow** acqRow) = 0; // create new row
NS_IMETHOD AddRow( // make sure the row with inOid is a table member
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow) = 0; // row to ensure membership in table
NS_IMETHOD HasRow( // test for the table position of a row member
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow, // row to find in table
mdb_bool* outHasRow) = 0; // whether row is a table member
NS_IMETHOD CutRow( // make sure the row with inOid is not a member
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow) = 0; // row to remove from table
NS_IMETHOD CutAllRows( // remove all rows from the table
nsIMdbEnv* ev) = 0; // context
// } ----- end row set methods -----
// { ----- begin hinting methods -----
NS_IMETHOD SearchColumnsHint( // advise re future expected search cols
nsIMdbEnv* ev, // context
const mdbColumnSet* inColumnSet) = 0; // columns likely to be searched
NS_IMETHOD SortColumnsHint( // advise re future expected sort columns
nsIMdbEnv* ev, // context
const mdbColumnSet* inColumnSet) = 0; // columns for likely sort requests
NS_IMETHOD StartBatchChangeHint( // advise before many adds and cuts
nsIMdbEnv* ev, // context
const void* inLabel) = 0; // intend unique address to match end call
// If batch starts nest by virtue of nesting calls in the stack, then
// the address of a local variable makes a good batch start label that
// can be used at batch end time, and such addresses remain unique.
NS_IMETHOD EndBatchChangeHint( // advise before many adds and cuts
nsIMdbEnv* ev, // context
const void* inLabel) = 0; // label matching start label
// Suppose a table is maintaining one or many sort orders for a table,
// so that every row added to the table must be inserted in each sort,
// and every row cut must be removed from each sort. If a db client
// intends to make many such changes before needing any information
// about the order or positions of rows inside a table, then a client
// might tell the table to start batch changes in order to disable
// sorting of rows for the interim. Presumably a table will then do
// a full sort of all rows at need when the batch changes end, or when
// a surprise request occurs for row position during batch changes.
// } ----- end hinting methods -----
// { ----- begin searching methods -----
NS_IMETHOD FindRowMatches( // search variable number of sorted cols
nsIMdbEnv* ev, // context
const mdbYarn* inPrefix, // content to find as prefix in row's column cell
nsIMdbTableRowCursor** acqCursor) = 0; // set of matching rows
NS_IMETHOD GetSearchColumns( // query columns used by FindRowMatches()
nsIMdbEnv* ev, // context
mdb_count* outCount, // context
mdbColumnSet* outColSet) = 0; // caller supplied space to put columns
// GetSearchColumns() returns the columns actually searched when the
// FindRowMatches() method is called. No more than mColumnSet_Count
// slots of mColumnSet_Columns will be written, since mColumnSet_Count
// indicates how many slots are present in the column array. The
// actual number of search column used by the table is returned in
// the outCount parameter; if this number exceeds mColumnSet_Count,
// then a caller needs a bigger array to read the entire column set.
// The minimum of mColumnSet_Count and outCount is the number slots
// in mColumnSet_Columns that were actually written by this method.
//
// Callers are expected to change this set of columns by calls to
// nsIMdbTable::SearchColumnsHint() or SetSearchSorting(), or both.
// } ----- end searching methods -----
// { ----- begin sorting methods -----
// sorting: note all rows are assumed sorted by row ID as a secondary
// sort following the primary column sort, when table rows are sorted.
NS_IMETHOD
CanSortColumn( // query which column is currently used for sorting
nsIMdbEnv* ev, // context
mdb_column inColumn, // column to query sorting potential
mdb_bool* outCanSort) = 0; // whether the column can be sorted
NS_IMETHOD GetSorting( // view same table in particular sorting
nsIMdbEnv* ev, // context
mdb_column inColumn, // requested new column for sorting table
nsIMdbSorting** acqSorting) = 0; // acquire sorting for column
NS_IMETHOD SetSearchSorting( // use this sorting in FindRowMatches()
nsIMdbEnv* ev, // context
mdb_column inColumn, // often same as nsIMdbSorting::GetSortColumn()
nsIMdbSorting* ioSorting) = 0; // requested sorting for some column
// SetSearchSorting() attempts to inform the table that ioSorting
// should be used during calls to FindRowMatches() for searching
// the column which is actually sorted by ioSorting. This method
// is most useful in conjunction with nsIMdbSorting::SetCompare(),
// because otherwise a caller would not be able to override the
// comparison ordering method used during searchs. Note that some
// database implementations might be unable to use an arbitrarily
// specified sort order, either due to schema or runtime interface
// constraints, in which case ioSorting might not actually be used.
// Presumably ioSorting is an instance that was returned from some
// earlier call to nsIMdbTable::GetSorting(). A caller can also
// use nsIMdbTable::SearchColumnsHint() to specify desired change
// in which columns are sorted and searched by FindRowMatches().
//
// A caller can pass a nil pointer for ioSorting to request that
// column inColumn no longer be used at all by FindRowMatches().
// But when ioSorting is non-nil, then inColumn should match the
// column actually sorted by ioSorting; when these do not agree,
// implementations are instructed to give precedence to the column
// specified by ioSorting (so this means callers might just pass
// zero for inColumn when ioSorting is also provided, since then
// inColumn is both redundant and ignored).
// } ----- end sorting methods -----
// { ----- begin moving methods -----
// moving a row does nothing unless a table is currently unsorted
NS_IMETHOD MoveOid( // change position of row in unsorted table
nsIMdbEnv* ev, // context
const mdbOid* inOid, // row oid to find in table
mdb_pos inHintFromPos, // suggested hint regarding start position
mdb_pos inToPos, // desired new position for row inRowId
mdb_pos* outActualPos) = 0; // actual new position of row in table
NS_IMETHOD MoveRow( // change position of row in unsorted table
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow, // row oid to find in table
mdb_pos inHintFromPos, // suggested hint regarding start position
mdb_pos inToPos, // desired new position for row inRowId
mdb_pos* outActualPos) = 0; // actual new position of row in table
// } ----- end moving methods -----
// { ----- begin index methods -----
NS_IMETHOD AddIndex( // create a sorting index for column if possible
nsIMdbEnv* ev, // context
mdb_column inColumn, // the column to sort by index
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental index building
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the index addition will be finished.
NS_IMETHOD CutIndex( // stop supporting a specific column index
nsIMdbEnv* ev, // context
mdb_column inColumn, // the column with index to be removed
nsIMdbThumb** acqThumb) = 0; // acquire thumb for incremental index destroy
// Call nsIMdbThumb::DoMore() until done, or until the thumb is broken, and
// then the index removal will be finished.
NS_IMETHOD HasIndex( // query for current presence of a column index
nsIMdbEnv* ev, // context
mdb_column inColumn, // the column to investigate
mdb_bool* outHasIndex) = 0; // whether column has index for this column
NS_IMETHOD EnableIndexOnSort( // create an index for col on first sort
nsIMdbEnv* ev, // context
mdb_column inColumn) = 0; // the column to index if ever sorted
NS_IMETHOD QueryIndexOnSort( // check whether index on sort is enabled
nsIMdbEnv* ev, // context
mdb_column inColumn, // the column to investigate
mdb_bool* outIndexOnSort) = 0; // whether column has index-on-sort enabled
NS_IMETHOD DisableIndexOnSort( // prevent future index creation on sort
nsIMdbEnv* ev, // context
mdb_column inColumn) = 0; // the column to index if ever sorted
// } ----- end index methods -----
// } ===== end nsIMdbTable methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbTable, NS_IMDBTABLE_IID)
/*| nsIMdbSorting: a view of a table in some particular sort order. This
**| row order closely resembles a readonly array of rows with the same row
**| membership as the underlying table, but in a different order than the
**| table's explicit row order. But the sorting's row membership changes
**| whenever the table's membership changes (without any notification, so
**| keep this in mind when modifying the table).
**|
**|| table: every sorting is associated with a particular table. You
**| cannot change which table is used by a sorting (just ask some new
**| table for a suitable sorting instance instead).
**|
**|| compare: the ordering method used by a sorting, wrapped up in a
**| abstract plug-in interface. When this was never installed by an
**| explicit call to SetNewCompare(), a compare object is still returned,
**| and it might match the compare instance returned by the factory method
**| nsIMdbFactory::MakeCompare(), which represents a default sort order
**| (which we fervently hope is consistently ASCII byte ordering).
**|
**|| cursor: in case callers are more comfortable with a cursor style
**| of accessing row members, each sorting will happily return a cursor
**| instance with behavior very similar to a cursor returned from a call
**| to nsIMdbTable::GetTableRowCursor(), but with different row order.
**| A cursor should show exactly the same information as the pos methods.
**|
**|| pos: the PosToOid() and PosToRow() methods are just like the table
**| methods of the same name, except they show rows in the sort order of
**| the sorting, rather than that of the table. These methods are like
**| readonly array position accessor's, or like a C++ operator[].
|*/
class nsIMdbSorting : public nsIMdbObject { // sorting of some table
public:
// { ===== begin nsIMdbSorting methods =====
// { ----- begin attribute methods -----
// sorting: note all rows are assumed sorted by row ID as a secondary
// sort following the primary column sort, when table rows are sorted.
NS_IMETHOD GetTable(nsIMdbEnv* ev, nsIMdbTable** acqTable) = 0;
NS_IMETHOD GetSortColumn( // query which col is currently sorted
nsIMdbEnv* ev, // context
mdb_column* outColumn) = 0; // col the table uses for sorting (or zero)
NS_IMETHOD SetNewCompare(nsIMdbEnv* ev,
nsIMdbCompare* ioNewCompare) = 0;
// Setting the sorting's compare object will typically cause the rows
// to be resorted, presumably in a lazy fashion when the sorting is
// next required to be in a valid row ordering state, such as when a
// call to PosToOid() happens. ioNewCompare can be nil, in which case
// implementations should revert to the default sort order, which must
// be equivalent to whatever is used by nsIMdbFactory::MakeCompare().
NS_IMETHOD GetOldCompare(nsIMdbEnv* ev,
nsIMdbCompare** acqOldCompare) = 0;
// Get this sorting instance's compare object, which handles the
// ordering of rows in the sorting, by comparing yarns from the cells
// in the column being sorted. Since nsIMdbCompare has no interface
// to query the state of the compare object, it is not clear what you
// would do with this object when returned, except maybe compare it
// as a pointer address to some other instance, to check identities.
// } ----- end attribute methods -----
// { ----- begin cursor methods -----
NS_IMETHOD GetSortingRowCursor( // make a cursor, starting at inRowPos
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
nsIMdbTableRowCursor** acqCursor) = 0; // acquire new cursor instance
// A cursor interface turning same info as PosToOid() or PosToRow().
// } ----- end row position methods -----
// { ----- begin row position methods -----
NS_IMETHOD PosToOid( // get row member for a table position
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
mdbOid* outOid) = 0; // row oid at the specified position
NS_IMETHOD PosToRow( // test for the table position of a row member
nsIMdbEnv* ev, // context
mdb_pos inRowPos, // zero-based ordinal position of row in table
nsIMdbRow** acqRow) = 0; // acquire row at table position inRowPos
// } ----- end row position methods -----
// } ===== end nsIMdbSorting methods =====
};
/*| nsIMdbTableRowCursor: cursor class for iterating table rows
**|
**|| table: the cursor is associated with a specific table, which can be
**| set to a different table (which resets the position to -1 so the
**| next row acquired is the first in the table.
**|
**|| NextRowId: the rows in the table can be iterated by identity alone,
**| without actually reading the cells of any row with this method.
**|
**|| NextRowCells: read the next row in the table, but only read cells
**| from the table which are already present in the row (so no new cells
**| are added to the row, even if they are present in the table). All the
**| cells will have content specified, even it is the empty string. No
**| columns will be removed, even if missing from the row (because missing
**| and empty are semantically equivalent).
**|
**|| NextRowAllCells: read the next row in the table, and access all the
**| cells for this row in the table, adding any missing columns to the row
**| as needed until all cells are represented. All the
**| cells will have content specified, even it is the empty string. No
**| columns will be removed, even if missing from the row (because missing
**| and empty are semantically equivalent).
**|
|*/
#define NS_IMDBTABLEROWCURSOR_IID_STR = "4f325dad-0385-4b62-a992-c914ab93587e"
#define NS_IMDBTABLEROWCURSOR_IID \
{0x4f325dad, 0x0385, 0x4b62, \
{0xa9, 0x92, 0xc9, 0x14, 0xab, 0x93, 0x58, 0x7e}}
class nsIMdbTableRowCursor : public nsISupports { // table row iterator
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBTABLEROWCURSOR_IID)
// { ===== begin nsIMdbTableRowCursor methods =====
// { ----- begin attribute methods -----
// NS_IMETHOD SetTable(nsIMdbEnv* ev, nsIMdbTable* ioTable) = 0; // sets pos to -1
// Method SetTable() cut and made obsolete in keeping with new sorting methods.
NS_IMETHOD GetTable(nsIMdbEnv* ev, nsIMdbTable** acqTable) = 0;
// } ----- end attribute methods -----
// { ----- begin duplicate row removal methods -----
NS_IMETHOD CanHaveDupRowMembers(nsIMdbEnv* ev, // cursor might hold dups?
mdb_bool* outCanHaveDups) = 0;
NS_IMETHOD MakeUniqueCursor( // clone cursor, removing duplicate rows
nsIMdbEnv* ev, // context
nsIMdbTableRowCursor** acqCursor) = 0; // acquire clone with no dups
// Note that MakeUniqueCursor() is never necessary for a cursor which was
// created by table method nsIMdbTable::GetTableRowCursor(), because a table
// never contains the same row as a member more than once. However, a cursor
// created by table method nsIMdbTable::FindRowMatches() might contain the
// same row more than once, because the same row can generate a hit by more
// than one column with a matching string prefix. Note this method can
// return the very same cursor instance with just an incremented refcount,
// when the original cursor could not contain any duplicate rows (calling
// CanHaveDupRowMembers() shows this case on a false return). Otherwise
// this method returns a different cursor instance. Callers should not use
// this MakeUniqueCursor() method lightly, because it tends to defeat the
// purpose of lazy programming techniques, since it can force creation of
// an explicit row collection in a new cursor's representation, in order to
// inspect the row membership and remove any duplicates; this can have big
// impact if a collection holds tens of thousands of rows or more, when
// the original cursor with dups simply referenced rows indirectly by row
// position ranges, without using an explicit row set representation.
// Callers are encouraged to use nsIMdbCursor::GetCount() to determine
// whether the row collection is very large (tens of thousands), and to
// delay calling MakeUniqueCursor() when possible, until a user interface
// element actually demands the creation of an explicit set representation.
// } ----- end duplicate row removal methods -----
// { ----- begin oid iteration methods -----
NS_IMETHOD NextRowOid( // get row id of next row in the table
nsIMdbEnv* ev, // context
mdbOid* outOid, // out row oid
mdb_pos* outRowPos) = 0; // zero-based position of the row in table
// } ----- end oid iteration methods -----
// { ----- begin row iteration methods -----
NS_IMETHOD NextRow( // get row cells from table for cells already in row
nsIMdbEnv* ev, // context
nsIMdbRow** acqRow, // acquire next row in table
mdb_pos* outRowPos) = 0; // zero-based position of the row in table
NS_IMETHOD PrevRowOid( // get row id of previous row in the table
nsIMdbEnv* ev, // context
mdbOid* outOid, // out row oid
mdb_pos* outRowPos) = 0; // zero-based position of the row in table
// } ----- end oid iteration methods -----
// { ----- begin row iteration methods -----
NS_IMETHOD PrevRow( // get row cells from table for cells already in row
nsIMdbEnv* ev, // context
nsIMdbRow** acqRow, // acquire previous row in table
mdb_pos* outRowPos) = 0; // zero-based position of the row in table
// } ----- end row iteration methods -----
// { ----- begin copy iteration methods -----
// NS_IMETHOD NextRowCopy( // put row cells into sink only when already in sink
// nsIMdbEnv* ev, // context
// nsIMdbRow* ioSinkRow, // sink for row cells read from next row
// mdbOid* outOid, // out row oid
// mdb_pos* outRowPos) = 0; // zero-based position of the row in table
//
// NS_IMETHOD NextRowCopyAll( // put all row cells into sink, adding to sink
// nsIMdbEnv* ev, // context
// nsIMdbRow* ioSinkRow, // sink for row cells read from next row
// mdbOid* outOid, // out row oid
// mdb_pos* outRowPos) = 0; // zero-based position of the row in table
// } ----- end copy iteration methods -----
// } ===== end nsIMdbTableRowCursor methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbTableRowCursor, NS_IMDBTABLEROWCURSOR_IID)
/*| nsIMdbRow: a collection of cells
**|
|*/
#define NS_IMDBROW_IID_STR "271e8d6e-183a-40e3-9f18-36913b4c7853"
#define NS_IMDBROW_IID \
{0x271e8d6e, 0x183a, 0x40e3, \
{0x9f, 0x18, 0x36, 0x91, 0x3b, 0x4c, 0x78, 0x53}}
class nsIMdbRow : public nsIMdbCollection { // cell tuple
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBROW_IID)
// { ===== begin nsIMdbRow methods =====
// { ----- begin cursor methods -----
NS_IMETHOD GetRowCellCursor( // make a cursor starting iteration at inCellPos
nsIMdbEnv* ev, // context
mdb_pos inCellPos, // zero-based ordinal position of cell in row
nsIMdbRowCellCursor** acqCursor) = 0; // acquire new cursor instance
// } ----- end cursor methods -----
// { ----- begin column methods -----
NS_IMETHOD AddColumn( // make sure a particular column is inside row
nsIMdbEnv* ev, // context
mdb_column inColumn, // column to add
const mdbYarn* inYarn) = 0; // cell value to install
NS_IMETHOD CutColumn( // make sure a column is absent from the row
nsIMdbEnv* ev, // context
mdb_column inColumn) = 0; // column to ensure absent from row
NS_IMETHOD CutAllColumns( // remove all columns from the row
nsIMdbEnv* ev) = 0; // context
// } ----- end column methods -----
// { ----- begin cell methods -----
NS_IMETHOD NewCell( // get cell for specified column, or add new one
nsIMdbEnv* ev, // context
mdb_column inColumn, // column to add
nsIMdbCell** acqCell) = 0; // cell column and value
NS_IMETHOD AddCell( // copy a cell from another row to this row
nsIMdbEnv* ev, // context
const nsIMdbCell* inCell) = 0; // cell column and value
NS_IMETHOD GetCell( // find a cell in this row
nsIMdbEnv* ev, // context
mdb_column inColumn, // column to find
nsIMdbCell** acqCell) = 0; // cell for specified column, or null
NS_IMETHOD EmptyAllCells( // make all cells in row empty of content
nsIMdbEnv* ev) = 0; // context
// } ----- end cell methods -----
// { ----- begin row methods -----
NS_IMETHOD AddRow( // add all cells in another row to this one
nsIMdbEnv* ev, // context
nsIMdbRow* ioSourceRow) = 0; // row to union with
NS_IMETHOD SetRow( // make exact duplicate of another row
nsIMdbEnv* ev, // context
nsIMdbRow* ioSourceRow) = 0; // row to duplicate
// } ----- end row methods -----
// { ----- begin blob methods -----
NS_IMETHOD SetCellYarn(nsIMdbEnv* ev, // synonym for AddColumn()
mdb_column inColumn, // column to write
const mdbYarn* inYarn) = 0; // reads from yarn slots
// make this text object contain content from the yarn's buffer
NS_IMETHOD GetCellYarn(nsIMdbEnv* ev,
mdb_column inColumn, // column to read
mdbYarn* outYarn) = 0; // writes some yarn slots
// copy content into the yarn buffer, and update mYarn_Fill and mYarn_Form
NS_IMETHOD AliasCellYarn(nsIMdbEnv* ev,
mdb_column inColumn, // column to alias
mdbYarn* outYarn) = 0; // writes ALL yarn slots
NS_IMETHOD NextCellYarn(nsIMdbEnv* ev, // iterative version of GetCellYarn()
mdb_column* ioColumn, // next column to read
mdbYarn* outYarn) = 0; // writes some yarn slots
// copy content into the yarn buffer, and update mYarn_Fill and mYarn_Form
//
// The ioColumn argument is an inout parameter which initially contains the
// last column accessed and returns the next column corresponding to the
// content read into the yarn. Callers should start with a zero column
// value to say 'no previous column', which causes the first column to be
// read. Then the value returned in ioColumn is perfect for the next call
// to NextCellYarn(), since it will then be the previous column accessed.
// Callers need only examine the column token returned to see which cell
// in the row is being read into the yarn. When no more columns remain,
// and the iteration has ended, ioColumn will return a zero token again.
// So iterating over cells starts and ends with a zero column token.
NS_IMETHOD SeekCellYarn( // resembles nsIMdbRowCellCursor::SeekCell()
nsIMdbEnv* ev, // context
mdb_pos inPos, // position of cell in row sequence
mdb_column* outColumn, // column for this particular cell
mdbYarn* outYarn) = 0; // writes some yarn slots
// copy content into the yarn buffer, and update mYarn_Fill and mYarn_Form
// Callers can pass nil for outYarn to indicate no interest in content, so
// only the outColumn value is returned. NOTE to subclasses: you must be
// able to ignore outYarn when the pointer is nil; please do not crash.
// } ----- end blob methods -----
// } ===== end nsIMdbRow methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbRow, NS_IMDBROW_IID)
/*| nsIMdbRowCellCursor: cursor class for iterating row cells
**|
**|| row: the cursor is associated with a specific row, which can be
**| set to a different row (which resets the position to -1 so the
**| next cell acquired is the first in the row.
**|
**|| NextCell: get the next cell in the row and return its position and
**| a new instance of a nsIMdbCell to represent this next cell.
|*/
#define NS_IMDBROWCELLCURSOR_IID_STR "b33371a7-5d63-4d10-85a8-e44dffe75c28"
#define NS_IMDBROWCELLCURSOR_IID \
{0x271e8d6e, 0x5d63, 0x4d10 , \
{0x85, 0xa8, 0xe4, 0x4d, 0xff, 0xe7, 0x5c, 0x28}}
class nsIMdbRowCellCursor : public nsISupports{ // cell collection iterator
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBROWCELLCURSOR_IID)
// { ===== begin nsIMdbRowCellCursor methods =====
// { ----- begin attribute methods -----
NS_IMETHOD SetRow(nsIMdbEnv* ev, nsIMdbRow* ioRow) = 0; // sets pos to -1
NS_IMETHOD GetRow(nsIMdbEnv* ev, nsIMdbRow** acqRow) = 0;
// } ----- end attribute methods -----
// { ----- begin cell creation methods -----
NS_IMETHOD MakeCell( // get cell at current pos in the row
nsIMdbEnv* ev, // context
mdb_column* outColumn, // column for this particular cell
mdb_pos* outPos, // position of cell in row sequence
nsIMdbCell** acqCell) = 0; // the cell at inPos
// } ----- end cell creation methods -----
// { ----- begin cell seeking methods -----
NS_IMETHOD SeekCell( // same as SetRow() followed by MakeCell()
nsIMdbEnv* ev, // context
mdb_pos inPos, // position of cell in row sequence
mdb_column* outColumn, // column for this particular cell
nsIMdbCell** acqCell) = 0; // the cell at inPos
// } ----- end cell seeking methods -----
// { ----- begin cell iteration methods -----
NS_IMETHOD NextCell( // get next cell in the row
nsIMdbEnv* ev, // context
nsIMdbCell** acqCell, // changes to the next cell in the iteration
mdb_column* outColumn, // column for this particular cell
mdb_pos* outPos) = 0; // position of cell in row sequence
NS_IMETHOD PickNextCell( // get next cell in row within filter set
nsIMdbEnv* ev, // context
nsIMdbCell* ioCell, // changes to the next cell in the iteration
const mdbColumnSet* inFilterSet, // col set of actual caller interest
mdb_column* outColumn, // column for this particular cell
mdb_pos* outPos) = 0; // position of cell in row sequence
// Note that inFilterSet should not have too many (many more than 10?)
// cols, since this might imply a potential excessive consumption of time
// over many cursor calls when looking for column and filter intersection.
// } ----- end cell iteration methods -----
// } ===== end nsIMdbRowCellCursor methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbRowCellCursor, NS_IMDBROWCELLCURSOR_IID)
/*| nsIMdbBlob: a base class for objects composed mainly of byte sequence state.
**| (This provides a base class for nsIMdbCell, so that cells themselves can
**| be used to set state in another cell, without extracting a buffer.)
|*/
class nsIMdbBlob : public nsISupports { // a string with associated charset
public:
// { ===== begin nsIMdbBlob methods =====
// { ----- begin attribute methods -----
NS_IMETHOD SetBlob(nsIMdbEnv* ev,
nsIMdbBlob* ioBlob) = 0; // reads inBlob slots
// when inBlob is in the same suite, this might be fastest cell-to-cell
NS_IMETHOD ClearBlob( // make empty (so content has zero length)
nsIMdbEnv* ev) = 0;
// clearing a yarn is like SetYarn() with empty yarn instance content
NS_IMETHOD GetBlobFill(nsIMdbEnv* ev,
mdb_fill* outFill) = 0; // size of blob
// Same value that would be put into mYarn_Fill, if one called GetYarn()
// with a yarn instance that had mYarn_Buf==nil and mYarn_Size==0.
NS_IMETHOD SetYarn(nsIMdbEnv* ev,
const mdbYarn* inYarn) = 0; // reads from yarn slots
// make this text object contain content from the yarn's buffer
NS_IMETHOD GetYarn(nsIMdbEnv* ev,
mdbYarn* outYarn) = 0; // writes some yarn slots
// copy content into the yarn buffer, and update mYarn_Fill and mYarn_Form
NS_IMETHOD AliasYarn(nsIMdbEnv* ev,
mdbYarn* outYarn) = 0; // writes ALL yarn slots
// AliasYarn() reveals sensitive internal text buffer state to the caller
// by setting mYarn_Buf to point into the guts of this text implementation.
//
// The caller must take great care to avoid writing on this space, and to
// avoid calling any method that would cause the state of this text object
// to change (say by directly or indirectly setting the text to hold more
// content that might grow the size of the buffer and free the old buffer).
// In particular, callers should scrupulously avoid making calls into the
// mdb interface to write any content while using the buffer pointer found
// in the returned yarn instance. Best safe usage involves copying content
// into some other kind of external content representation beyond mdb.
//
// (The original design of this method a week earlier included the concept
// of very fast and efficient cooperative locking via a pointer to some lock
// member slot. But let's ignore that complexity in the current design.)
//
// AliasYarn() is specifically intended as the first step in transferring
// content from nsIMdbBlob to a nsString representation, without forcing extra
// allocations and/or memory copies. (A standard nsIMdbBlob_AsString() utility
// will use AliasYarn() as the first step in setting a nsString instance.)
//
// This is an alternative to the GetYarn() method, which has copy semantics
// only; AliasYarn() relaxes a robust safety principle only for performance
// reasons, to accomodate the need for callers to transform text content to
// some other canonical representation that would necessitate an additional
// copy and transformation when such is incompatible with the mdbYarn format.
//
// The implementation of AliasYarn() should have extremely little overhead
// besides the virtual dispatch to the method implementation, and the code
// necessary to populate all the mdbYarn member slots with internal buffer
// address and metainformation that describes the buffer content. Note that
// mYarn_Grow must always be set to nil to indicate no resizing is allowed.
// } ----- end attribute methods -----
// } ===== end nsIMdbBlob methods =====
};
/*| nsIMdbCell: the text in a single column of a row. The base nsIMdbBlob
**| class provides all the interface related to accessing cell text.
**|
**|| column: each cell in a row appears in a specific column, where this
**| column is identified by the an integer mdb_scope value (generated by
**| the StringToScopeToken() method in the containing nsIMdbPort instance).
**| Because a row cannot have more than one cell with the same column,
**| something must give if one calls SetColumn() with an existing column
**| in the same row. When this happens, the other cell is replaced with
**| this cell (and the old cell is closed if it has outstanding refs).
**|
**|| row: every cell instance is a part of some row, and every cell knows
**| which row is the parent row. (Note this should be represented by a
**| weak backpointer, so that outstanding cell references cannot keep a
**| row open that should be closed. Otherwise we'd have ref graph cycles.)
**|
**|| text: a cell can either be text, or it can have a child row or table,
**| but not both at once. If text is read from a cell with a child, the text
**| content should be empty (for AliasYarn()) or a description of the type
**| of child (perhaps "mdb:cell:child:row" or "mdb:cell:child:table").
**|
**|| child: a cell might reference another row or a table, rather than text.
**| The interface for putting and getting children rows and tables was first
**| defined in the nsIMdbTable interface, but then this was moved to this cell
**| interface as more natural.
|*/
#define NS_IMDBCELL_IID \
{0xa3b62f71, 0xa181, 0x4a91, \
{0xb6, 0x6b, 0x27, 0x10, 0x9b, 0x88, 0x98, 0x35}}
#define NS_IMDBCELL_IID_STR = "a3b62f71-a181-4a91-b66b-27109b889835"
class nsIMdbCell : public nsIMdbBlob { // text attribute in row with column scope
public:
NS_DECLARE_STATIC_IID_ACCESSOR(NS_IMDBTABLEROWCURSOR_IID)
// { ===== begin nsIMdbCell methods =====
// { ----- begin attribute methods -----
NS_IMETHOD SetColumn(nsIMdbEnv* ev, mdb_column inColumn) = 0;
NS_IMETHOD GetColumn(nsIMdbEnv* ev, mdb_column* outColumn) = 0;
NS_IMETHOD GetCellInfo( // all cell metainfo except actual content
nsIMdbEnv* ev,
mdb_column* outColumn, // the column in the containing row
mdb_fill* outBlobFill, // the size of text content in bytes
mdbOid* outChildOid, // oid of possible row or table child
mdb_bool* outIsRowChild) = 0; // nonzero if child, and a row child
// Checking all cell metainfo is a good way to avoid forcing a large cell
// in to memory when you don't actually want to use the content.
NS_IMETHOD GetRow(nsIMdbEnv* ev, // parent row for this cell
nsIMdbRow** acqRow) = 0;
NS_IMETHOD GetPort(nsIMdbEnv* ev, // port containing cell
nsIMdbPort** acqPort) = 0;
// } ----- end attribute methods -----
// { ----- begin children methods -----
NS_IMETHOD HasAnyChild( // does cell have a child instead of text?
nsIMdbEnv* ev,
mdbOid* outOid, // out id of row or table (or unbound if no child)
mdb_bool* outIsRow) = 0; // nonzero if child is a row (rather than a table)
NS_IMETHOD GetAnyChild( // access table of specific attribute
nsIMdbEnv* ev, // context
nsIMdbRow** acqRow, // child row (or null)
nsIMdbTable** acqTable) = 0; // child table (or null)
NS_IMETHOD SetChildRow( // access table of specific attribute
nsIMdbEnv* ev, // context
nsIMdbRow* ioRow) = 0; // inRow must be bound inside this same db port
NS_IMETHOD GetChildRow( // access row of specific attribute
nsIMdbEnv* ev, // context
nsIMdbRow** acqRow) = 0; // acquire child row (or nil if no child)
NS_IMETHOD SetChildTable( // access table of specific attribute
nsIMdbEnv* ev, // context
nsIMdbTable* inTable) = 0; // table must be bound inside this same db port
NS_IMETHOD GetChildTable( // access table of specific attribute
nsIMdbEnv* ev, // context
nsIMdbTable** acqTable) = 0; // acquire child table (or nil if no child)
// } ----- end children methods -----
// } ===== end nsIMdbCell methods =====
};
NS_DEFINE_STATIC_IID_ACCESSOR(nsIMdbCell, NS_IMDBTABLEROWCURSOR_IID)
// } %%%%% end C++ abstract class interfaces %%%%%
//3456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789
#endif /* _MDB_ */
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