expressions. The method "prefix" on a RegExp behaves exactly the same
as the "exec" method except it returns "undefined" if the match failed
because there was an insufficient number of characters in the
input. E.g.
/^foo/.prefix("foo") => ["foo"] (just like exec)
/^foo/.prefix("fox") => null (just like exec)
/^foo/.prefix("fo") => undefined (whereas exec returns null)
Subject:
[Rhino] Question
Date:
Tue, 30 Jan 2001 20:18:21 +0900
From:
"get21" <get21@secsm.org>
Organization:
Another Netscape Collabra Server User
Newsgroups:
netscape.public.mozilla.jseng
I found something unusual to me when I hacking the Rhino source code.
In tagify method of NativeString Class,
When it adds tag to its string(this.string), it does not use quotation
marks.
For example, the result of tagify("A HREF", "A", value) in
jsFunction_link(String value) is
<A HREF=Some Value>Original String Value</A>
Not,
<A HREF="Some Value">Original String Value</A>
This question might sound silly, but I'm curious why.
Thanks in advance,
Nam
--
email : get21@secsm.org
home : http://get21.secsm.org
phone : 011-9092-1802
- Optimize compile (parse+emit) operation to generate code for each top-level
statement or function in turn, recycling JSParseNodes as we go for greatly
reduced "long linear script" footprint.
- Fix O(n**2) growth problems in bytecode and srcnote generation.
- Add js_ParseTokenStream entry point to compiler, for tree-generation without
code-generation. Move JSOP_EVAL instruction selection from code-generator to
parser, to match other such specializations and enable js_ParseTokenStream.
- Fix js_CompileTokenStream (and get it right in new js_ParseTokenStream) to
respect JSOPTION_VAROBJFIX.
- Clean up bracing, multi-line conditions, and overlong lines.
Some other small fixes are included. Here is the list...
- Make nsIJSID::id [noscript] because xpconnect automatically builds a nsIJSID
wrapper around nsid values. However, xpconnect does not maintain a table of
those wrappers. So, given the same id twice it will make two nsIJSID wrappers.
This means that property walking could get foo.id.id.id... and not detect that
the different objects represent the same id. nsIJSID already exposes 'number'
so that JS can get the stringified value of the nsid. The nsid struct returned
by 'id' is useful for C++, but only causes problems for JS.
- Fix the nsIXPCScriptable 'IGNORE' handler for GetAttributes to not fail
silently.
- Add 'Components' to global objects as a non-enumerable property for backwards
compatibility and to avoid additional work in property enumeration (esp. in
win.toSource!)
- Expose toSource on wrapped native JSObjects. This just returns an empty object
string: '{}'. It can be overridden by an interface method if present.
- Expose toString on wrapped native JSObjects. It can be overridden by an
interface method if present. Previously we only did this as part of the
Convert op. Now someWrapper.toString will return a callable function.
- Extend the toString behaviour to also print the address of the wrapper in
DEBUG builds only: e.g. "xpconnect wrapped nsIFoo @ 0x12345678". mccabe
convinced me this would be useful. Release build behaviour is unchanged - we
worried that exposing addresses might contribute to possible security exploits.
- Have wrapped native JSObjects use Object.prototype as their proto rather than
have a null proto. Originally this was going to allow delegation to
Object.prototype.toSource, but even without that, this seems like a good thing.
This is implemented by getting Object.prototype from the global object each
time we create a wrapper to allow for spify JS dynamic craziness.
- Use 16bit values in wrappednative property descriptors to save space. It was
only possible to use 16 bits of the pointer-sized ints in the structs anyway.
- Do a security check at enumeration time and only expose those properties that
the caller can actually 'Get'. This fixes the toSource security exception
problem.
- Add a big comment about the problem of reporting uncaught exceptions.
- Fix crashing bug for case where object has no enumerable properties and
xpconnect failed to fill in the zero count.
- Fix NewInstanceJSObject to dig in and find the 'ultimate' parent when
parenting new wrapper JSObject. The old scheme was ending up with hugely
long parent chains in some cases.
r=jst, sr=brendan
- Optimize integer ++ and -- to avoid double-to-int, which is quite costly for
some compilers (ftol on Windows with MSVC).
- Optimized arguments[i] and arguments.length references to use bytecodes that
avoid creating an arguments object for the current frame. This entailed
simplifying the compiler to avoid flagging functions and scripts that set
arguments, since we have code in jsfun.c to catch such sets at runtime.
- The code generator now eliminates useless expression statements, giving a
strict warning about them.
- Rationalized jsemit.c's LookupArgOrVar to have well-defined results in *pn.
Eliminate bytecode specializations for argument and local variable gets and
sets from jsparse.c -- these precede jsemit.c's LookupArgOrVar and frustrate
it, by setting pn_slot non-negative too early.
- Code generation errors set report->filename and report->lineno, rather than
hacking "{0}, line {1}: " into the localized message.
- Bogus JSFRAME_VAROBJBUG removed, JSOPTION_VAROBJFIX is sufficient.
- Spruce up jsinterp.c macros to use JS_BEGIN/END_MACRO brackets if possible.
- Avoid calling JS_PropertyStub. The call is too costly compared to a branch
in the caller.
- Optimize integer ++ and -- to avoid double-to-int, which is quite costly for
some compilers (ftol on Windows with MSVC).
- Optimized arguments[i] and arguments.length references to use bytecodes that
avoid creating an arguments object for the current frame. This entailed
simplifying the compiler to avoid flagging functions and scripts that set
arguments, since we have code in jsfun.c to catch such sets at runtime.
- The code generator now eliminates useless expression statements, giving a
strict warning about them.
- Rationalized jsemit.c's LookupArgOrVar to have well-defined results in *pn.
- Code generation errors set report->filename and report->lineno, rather than
hacking "{0}, line {1}: " into the localized message.
- Bogus JSFRAME_VAROBJBUG removed, JSOPTION_VAROBJFIX is sufficient.
- Spruce up jsinterp.c macros to use JS_BEGIN/END_MACRO brackets if possible.
- Avoid calling JS_PropertyStub. The call is too costly compared to a branch
in the caller.
Subject:
minor Rhino bug
Date:
Tue, 23 Jan 2001 13:14:51 -0800
From:
dave russo <d-russo@ti.com>
To:
nboyd@atg.com
CC:
d-russo@ti.com
Norris,
While using the new Rhino debugger (from the latest tip) I started to get "No
Context associated with current Thread" exceptions when expanding host objects
in the "Context:" debugger window.
In looking at the code, I discovered that NativeObject.toString seems to assume
that Context.getContext() may return null. In fact, getContext() always returns
a non-null context or throws an exception.
I changed NativeObject.toString to never throw an exception (see below) and this
eliminated the problem I was seeing (of course).
It would be nice to incorporate this in a future Rhino tip or, if this change is
inappropriate, any guidance would be appreciated. Thanks in advance.
I changed NativeObject.toString to:
public String toString() {
try {
Context cx = Context.getContext();
return jsFunction_toString(cx, this, null, null);
}
catch (Exception e) {
return "[object " + getClassName() + "]";
}
}
from:
public String toString() {
Context cx = Context.getContext();
if (cx != null)
return jsFunction_toString(cx, this, null, null);
else
return "[object " + getClassName() + "]";
}
