darling-libobjc2/selector_table.c

/**
 * Handle selector uniquing.
 *
 * When building, you may define TYPE_DEPENDENT_DISPATCH to enable message
 * sends to depend on their types.
 */
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include <ctype.h>
#include "lock.h"
#include "sarray2.h"
#include "objc/runtime.h"
#include "method_list.h"
#include "class.h"
#include "selector.h"

#ifdef TYPE_DEPENDENT_DISPATCH
#	define TDD(x) x
#else
#	define TDD(x)
#endif

#define fprintf(...)


// Define the pool allocator for selectors.  This is a simple bump-the-pointer
// allocator for low-overhead allocation.
#define POOL_NAME selector
#define POOL_TYPE struct objc_selector
#include "pool.h"


/**
 * The number of selectors currently registered.  When a selector is
 * registered, its name field is replaced with its index in the selector_list
 * array.
 */
static uint32_t selector_count = 1;
/**
 * Mapping from selector numbers to selector names.
 */
static SparseArray *selector_list  = NULL;

// Get the functions for string hashing
#include "string_hash.h"

inline static BOOL isSelRegistered(SEL sel)
{
	if ((uintptr_t)sel->name < (uintptr_t)selector_count)
	{
		return YES;
	}
	return NO;
}

/**
 * Skip anything in a type encoding that is irrelevant to the comparison
 * between selectors, including type qualifiers and argframe info.
 */
static const char *skip_irrelevant_type_info(const char *t)
{
	switch (*t)
	{
		default: return t;
		case 'r': case 'n': case 'N': case 'o': case 'O': case 'R':
		case 'V': case '!': case '0'...'9':
			return skip_irrelevant_type_info(t+1);
	}
}

static BOOL selector_types_equal(const char *t1, const char *t2)
{
	if (t1 == NULL || t2 == NULL) { return t1 == t2; }

	while (('\0' != *t1) && ('\0' != *t1))
	{
		t1 = skip_irrelevant_type_info(t1);
		t2 = skip_irrelevant_type_info(t2);
		if (*t1 != *t2)
		{
			return NO;
		}

		if ('\0' != *t1) { t1++; }
		if ('\0' != *t2) { t2++; }
	}
	return YES;
}

#ifdef TYPE_DEPENDENT_DISPATCH

static BOOL selector_types_equivalent(const char *t1, const char *t2)
{
	// We always treat untyped selectors as having the same type as typed
	// selectors, for dispatch purposes.
	if (t1 == NULL || t2 == NULL) { return YES; }

	return selector_types_equal(t1, t2);
}
#endif

/**
 * Compare whether two selectors are identical.
 */
static int selector_identical(const void *k,
                              const SEL value)
{
	SEL key = (SEL)k;
	fprintf(stderr, "Comparing %s %s, %s %s\n", sel_getName(key), sel_getName(value), sel_getType_np(key), sel_getType_np(value));
	return string_compare(sel_getName(key), sel_getName(value)) &&
		selector_types_equal(sel_getType_np(key), sel_getType_np(value));
}

/**
 * Compare selectors based on whether they are treated as equivalent for the
 * purpose of dispatch.
 */
static int selector_equal(const void *k,
                            const SEL value)
{
#ifdef TYPE_DEPENDENT_DISPATCH
	return selector_identical(k, value);
#else
	SEL key = (SEL)k;
	return string_compare(sel_getName(key), sel_getName(value));
#endif
}

/**
 * Hash a selector.
 */
static inline uint32_t hash_selector(const void *s)
{
	SEL sel = (SEL)s;
	uint32_t hash = 5381;
	const char *str = sel_getName(sel);
	uint32_t c;
	while((c = (uint32_t)*str++))
	{
		hash = hash * 33 + c;
	}
	// FIXME: We might want to make the hash dependent on the types, since not
	// doing so increases the number of potential hash collisions.
	return hash;
}

#define MAP_TABLE_NAME selector
#define MAP_TABLE_COMPARE_FUNCTION selector_identical
#define MAP_TABLE_HASH_KEY hash_selector
#define MAP_TABLE_HASH_VALUE hash_selector
#include "hash_table.h"
/**
 * Table of registered selector.  Maps from selector to selector.
 */
static selector_table *sel_table;

/**
 * Lock protecting the selector table.
 */
mutex_t selector_table_lock;


/**
 * Resizes the dtables to ensure that they can store as many selectors as
 * exist.
 */
void objc_resize_dtables(uint32_t);

/**
 * Create data structures to store selectors.
 */
void __objc_init_selector_tables()
{
	selector_list = SparseArrayNew();
	INIT_LOCK(selector_table_lock);
	sel_table = selector_create(4096);
}

static SEL selector_lookup(const char *name, const char *types)
{
	struct objc_selector sel = {name, types};
	return selector_table_get(sel_table, &sel);
}
static inline void add_selector_to_table(SEL aSel, int32_t uid, uint32_t idx)
{
	//fprintf(stderr, "Sel %s uid: %d, idx: %d, hash: %d\n", sel_getName(aSel), uid, idx, hash_selector(aSel));
	struct sel_type_list *typeList =
		(struct sel_type_list *)selector_pool_alloc();
	typeList->value = aSel->name;
	typeList->next = 0;
	// Store the name.
	SparseArrayInsert(selector_list, idx, typeList);
	// Store the selector.
	selector_insert(sel_table, aSel);
	// Set the selector's name to the uid.
	aSel->name = (const char*)(uintptr_t)uid;
}
/**
 * Really registers a selector.  Must be called with the selector table locked.
 */
static inline void register_selector_locked(SEL aSel)
{
	uintptr_t idx = selector_count++;
	if (NULL == aSel->types)
	{
		fprintf(stderr, "Registering selector %d %s\n", idx, sel_getName(aSel));
		add_selector_to_table(aSel, idx, idx);
		objc_resize_dtables(selector_count);
		return;
	}
	SEL untyped = selector_lookup(aSel->name, 0);
	// If this has a type encoding, store the untyped version too.
	if (untyped == NULL)
	{
		untyped = selector_pool_alloc();
		untyped->name = aSel->name;
		untyped->types = 0;
		fprintf(stderr, "Registering selector %d %s\n", idx, sel_getName(aSel));
		add_selector_to_table(untyped, idx, idx);
		// If we are in type dependent dispatch mode, the uid for the typed
		// and untyped versions will be different
		idx++; selector_count++;
	}
	uintptr_t uid = (uintptr_t)untyped->name;
	TDD(uid = idx);
	fprintf(stderr, "Registering typed selector %d %s %s\n", uid, sel_getName(aSel), sel_getType_np(aSel));
	add_selector_to_table(aSel, uid, idx);

	// Add this set of types to the list.
	// This is quite horrible.  Most selectors will only have one type
	// encoding, so we're wasting a lot of memory like this.
	struct sel_type_list *typeListHead =
		SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)untyped->name);
	struct sel_type_list *typeList =
		(struct sel_type_list *)selector_pool_alloc();
	typeList->value = aSel->types;
	typeList->next = typeListHead->next;
	typeListHead->next = typeList;
	objc_resize_dtables(selector_count);
}
/**
 * Registers a selector.  This assumes that the argument is never deallocated.
 */
SEL objc_register_selector(SEL aSel)
{
	if (isSelRegistered(aSel))
	{
		return aSel;
	}
	// Check that this isn't already registered, before we try
	SEL registered = selector_lookup(aSel->name, aSel->types);
	if (NULL != registered && selector_equal(aSel, registered))
	{
		aSel->name = registered->name;
		return registered;
	}
	LOCK(&selector_table_lock);
	register_selector_locked(aSel);
	UNLOCK(&selector_table_lock);
	return aSel;
}

/**
 * Registers a selector by copying the argument.
 */
static SEL objc_register_selector_copy(SEL aSel)
{
	// If an identical selector is already registered, return it.
	SEL copy = selector_lookup(aSel->name, aSel->types);
	//fprintf(stderr, "Checking if old selector is registered: %d (%d)\n", NULL != copy ? selector_equal(aSel, copy) : 0, ((NULL != copy) && selector_equal(aSel, copy)));
	if ((NULL != copy) && selector_identical(aSel, copy))
	{
	//fprintf(stderr, "Not adding new copy\n");
		return copy;
	}
	LOCK_UNTIL_RETURN(&selector_table_lock);
	copy = selector_lookup(aSel->name, aSel->types);
	if (NULL != copy && selector_identical(aSel, copy))
	{
		return copy;
	}
	// Create a copy of this selector.
	copy = selector_pool_alloc();
	copy->name = strdup(aSel->name);
	copy->types = (NULL == aSel->types) ? NULL : strdup(aSel->types);
	// Try to register the copy as the authoritative version
	register_selector_locked(copy);
	return copy;
}

/**
 * Public API functions.
 */

const char *sel_getName(SEL sel)
{
	const char *name = sel->name;
	if (isSelRegistered(sel))
	{
		struct sel_type_list * list =
			SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)sel->name);
		name = (list == NULL) ? NULL : list->value;
	}
	if (NULL == name)
	{
		name = "";
	}
	return name;
}

SEL sel_getUid(const char *selName)
{
	return selector_lookup(selName, 0);
}

BOOL sel_isEqual(SEL sel1, SEL sel2)
{
	if (sel1->name == sel2->name)
	{
		return YES;
	}
	// Otherwise, do a slow compare
	return string_compare(sel_getName(sel1), sel_getName(sel2)) TDD(&&
			(sel1->types == NULL || sel2->types == NULL ||
		selector_types_equivalent(sel_getType_np(sel1), sel_getType_np(sel2))));
}

SEL sel_registerName(const char *selName)
{
	struct objc_selector sel = {selName, 0};
	return objc_register_selector_copy(&sel);
}

SEL sel_registerTypedName_np(const char *selName, const char *types)
{
	struct objc_selector sel = {selName, types};
	return objc_register_selector_copy(&sel);
}

const char *sel_getType_np(SEL aSel)
{
	return aSel->types;
}


unsigned sel_copyTypes_np(const char *selName, const char **types, unsigned count)
{
	SEL untyped = selector_lookup(selName, 0);
	if (untyped == NULL) { return 0; }

	struct sel_type_list *l =
		SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)untyped->name);
	// Skip the head, which just contains the name, not the types.
	l = l->next;

	if (count == 0)
	{
		while (NULL != l)
		{
			count++;
			l = l->next;
		}
		return count;
	}

	unsigned found = 0;
	while (NULL != l && found<count)
	{
		types[found++] = l->value;
		l = l->next;
	}
	return found;
}

unsigned sel_copyTypedSelectors_np(const char *selName, SEL *const sels, unsigned count)
{
	SEL untyped = selector_lookup(selName, 0);
	if (untyped == NULL) { return 0; }

	struct sel_type_list *l =
		SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)untyped->name);
	// Skip the head, which just contains the name, not the types.
	l = l->next;

	if (count == 0)
	{
		while (NULL != l)
		{
			count++;
			l = l->next;
		}
		return count;
	}

	unsigned found = 0;
	while (NULL != l && found<count)
	{
		sels[found++] = selector_lookup(selName, l->value);
		l = l->next;
	}
	return found;
}

void objc_register_selectors_from_list(struct objc_method_list *l)
{
	for (int i=0 ; i<l->count ; i++)
	{
		Method m = &l->methods[i];
		struct objc_selector sel = { (const char*)m->selector, m->types };
		m->selector = objc_register_selector_copy(&sel);
	}
}
/**
 * Register all of the (unregistered) selectors that are used in a class.
 */
void objc_register_selectors_from_class(Class class)
{
	for (struct objc_method_list *l=class->methods ; NULL!=l ; l=l->next)
	{
		objc_register_selectors_from_list(l);
	}
}
void objc_register_selector_array(SEL selectors, unsigned long count)
{
	// GCC is broken and always sets the count to 0, so we ignore count until
	// we can throw stupid and buggy compilers in the bin.
	for (unsigned long i=0 ;  (NULL != selectors[i].name) ; i++)
	{
		objc_register_selector(&selectors[i]);
	}
}


/**
 * Legacy GNU runtime compatibility.
 *
 * All of the functions in this section are deprecated and should not be used
 * in new code.
 */

SEL sel_get_typed_uid (const char *name, const char *types)
{
	SEL sel = selector_lookup(name, types);
	if (NULL == sel) { return sel_registerTypedName_np(name, types); }

	struct sel_type_list *l =
		SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)sel->name);
	// Skip the head, which just contains the name, not the types.
	l = l->next;
	if (NULL != l)
	{
		sel = selector_lookup(name, l->value);
	}
	return sel;
}

SEL sel_get_any_typed_uid (const char *name)
{
	SEL sel = selector_lookup(name, 0);
	if (NULL == sel) { return sel_registerName(name); }

	struct sel_type_list *l =
		SparseArrayLookup(selector_list, (uint32_t)(uintptr_t)sel->name);
	// Skip the head, which just contains the name, not the types.
	l = l->next;
	if (NULL != l)
	{
		sel = selector_lookup(name, l->value);
	}
	return sel;
}

SEL sel_get_any_uid (const char *name)
{
	return selector_lookup(name, 0);
}

SEL sel_get_uid(const char *name)
{
	return selector_lookup(name, 0);
}

const char *sel_get_name(SEL selector)
{
	return sel_getName(selector);
}

BOOL sel_is_mapped(SEL selector)
{
	return isSelRegistered(selector);
}

const char *sel_get_type(SEL selector)
{
	return sel_getType_np(selector);
}

SEL sel_register_name(const char *name)
{
	return sel_registerName(name);
}

SEL sel_register_typed_name(const char *name, const char *type)
{
	return sel_registerTypedName_np(name, type);
}

/*
 * Some simple sanity tests.
 */
#ifdef SEL_TEST
static void logSelector(SEL sel)
{
	fprintf(stderr, "%s = {%p, %s}\n", sel_getName(sel), sel->name, sel_getType_np(sel));
}
void objc_resize_dtables(uint32_t ignored) {}

int main(void)
{
	__objc_init_selector_tables();
	SEL a = sel_registerTypedName_np("foo:", "1234");
	logSelector(a);
	a = sel_registerName("bar:");
	a = sel_registerName("foo:");
	logSelector(a);
	logSelector(sel_get_any_typed_uid("foo:"));
	a = sel_registerTypedName_np("foo:", "1234");
	logSelector(a);
	logSelector(sel_get_any_typed_uid("foo:"));
	a = sel_registerTypedName_np("foo:", "456");
	logSelector(a);
	unsigned count = sel_copyTypes("foo:", NULL, 0);
	const char *types[count];
	sel_copyTypes("foo:", types, count);
	for (unsigned i=0 ; i<count ; i++)
	{
		fprintf(stderr, "Found type %s\n", types[i]);
	}
	uint32_t idx=0;
	struct sel_type_list *type;
	while ((type= SparseArrayNext(selector_list, &idx)))
	{
		fprintf(stderr, "Idx: %d, sel: %s (%s)\n", idx, type->value, ((struct sel_type_list *)SparseArrayLookup(selector_list, idx))->value);
	}
	fprintf(stderr, "Number of types: %d\n", count);
	SEL sel;
}
#endif