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duktape/src-input/duk_js_var.c

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/*
* Identifier access and function closure handling.
*
* Provides the primitives for slow path identifier accesses: GETVAR,
* PUTVAR, DELVAR, etc. The fast path, direct register accesses, should
* be used for most identifier accesses. Consequently, these slow path
* primitives should be optimized for maximum compactness.
*
* ECMAScript environment records (declarative and object) are represented
* as internal objects with control keys. Environment records have a
* parent record ("outer environment reference") which is represented by
* the implicit prototype for technical reasons (in other words, it is a
* convenient field). The prototype chain is not followed in the ordinary
* sense for variable lookups.
*
* See identifier-handling.rst for more details on the identifier algorithms
* and the internal representation. See function-objects.rst for details on
* what function templates and instances are expected to look like.
*
* Care must be taken to avoid duk_tval pointer invalidation caused by
* e.g. value stack or object resizing.
*
* TODO: properties for function instances could be initialized much more
* efficiently by creating a property allocation for a certain size and
* filling in keys and values directly (and INCREFing both with "bulk incref"
* primitives.
*
* XXX: duk_hobject_getprop() and duk_hobject_putprop() calls are a bit
* awkward (especially because they follow the prototype chain); rework
* if "raw" own property helpers are added.
*/
#include "duk_internal.h"
/*
* Local result type for duk__get_identifier_reference() lookup.
*/
typedef struct {
duk_hobject *env;
duk_hobject *holder; /* for object-bound identifiers */
duk_tval *value; /* for register-bound and declarative env identifiers */
duk_uint_t attrs; /* property attributes for identifier (relevant if value != NULL) */
duk_bool_t has_this; /* for object-bound identifiers: provide 'this' binding */
} duk__id_lookup_result;
/*
* Create a new function object based on a "template function" which contains
* compiled bytecode, constants, etc, but lacks a lexical environment.
*
* ECMAScript requires that each created closure is a separate object, with
* its own set of editable properties. However, structured property values
* (such as the formal arguments list and the variable map) are shared.
* Also the bytecode, constants, and inner functions are shared.
*
* See E5 Section 13.2 for detailed requirements on the function objects;
* there are no similar requirements for function "templates" which are an
* implementation dependent internal feature. Also see function-objects.rst
* for a discussion on the function instance properties provided by this
* implementation.
*
* Notes:
*
* * Order of internal properties should match frequency of use, since the
* properties will be linearly scanned on lookup (functions usually don't
* have enough properties to warrant a hash part).
*
* * The created closure is independent of its template; they do share the
* same 'data' buffer object, but the template object itself can be freed
* even if the closure object remains reachable.
*/
DUK_LOCAL void duk__inc_data_inner_refcounts(duk_hthread *thr, duk_hcompfunc *f) {
duk_tval *tv, *tv_end;
duk_hobject **funcs, **funcs_end;
DUK_UNREF(thr);
/* If function creation fails due to out-of-memory, the data buffer
* pointer may be NULL in some cases. That's actually possible for
* GC code, but shouldn't be possible here because the incomplete
* function will be unwound from the value stack and never instantiated.
*/
DUK_ASSERT(DUK_HCOMPFUNC_GET_DATA(thr->heap, f) != NULL);
tv = DUK_HCOMPFUNC_GET_CONSTS_BASE(thr->heap, f);
tv_end = DUK_HCOMPFUNC_GET_CONSTS_END(thr->heap, f);
while (tv < tv_end) {
DUK_TVAL_INCREF(thr, tv);
tv++;
}
funcs = DUK_HCOMPFUNC_GET_FUNCS_BASE(thr->heap, f);
funcs_end = DUK_HCOMPFUNC_GET_FUNCS_END(thr->heap, f);
while (funcs < funcs_end) {
DUK_HEAPHDR_INCREF(thr, (duk_heaphdr *) *funcs);
funcs++;
}
}
/* Push a new closure on the stack.
*
* Note: if fun_temp has NEWENV, i.e. a new lexical and variable declaration
* is created when the function is called, only outer_lex_env matters
* (outer_var_env is ignored and may or may not be same as outer_lex_env).
*/
DUK_LOCAL const duk_uint16_t duk__closure_copy_proplist[] = {
/* order: most frequent to least frequent */
DUK_STRIDX_INT_VARMAP,
DUK_STRIDX_INT_FORMALS,
#if defined(DUK_USE_PC2LINE)
DUK_STRIDX_INT_PC2LINE,
#endif
#if defined(DUK_USE_FUNC_FILENAME_PROPERTY)
DUK_STRIDX_FILE_NAME,
#endif
#if defined(DUK_USE_NONSTD_FUNC_SOURCE_PROPERTY)
DUK_STRIDX_INT_SOURCE
#endif
};
DUK_INTERNAL
void duk_js_push_closure(duk_hthread *thr,
duk_hcompfunc *fun_temp,
duk_hobject *outer_var_env,
duk_hobject *outer_lex_env,
duk_bool_t add_auto_proto) {
duk_hcompfunc *fun_clos;
duk_harray *formals;
duk_small_uint_t i;
duk_uint_t len_value;
DUK_ASSERT(fun_temp != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_DATA(thr->heap, fun_temp) != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_FUNCS(thr->heap, fun_temp) != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_BYTECODE(thr->heap, fun_temp) != NULL);
DUK_ASSERT(outer_var_env != NULL);
DUK_ASSERT(outer_lex_env != NULL);
DUK_UNREF(len_value);
DUK_STATS_INC(thr->heap, stats_envrec_pushclosure);
fun_clos = duk_push_hcompfunc(thr);
DUK_ASSERT(fun_clos != NULL);
DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, (duk_hobject *) fun_clos) == thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
duk_push_hobject(thr, &fun_temp->obj); /* -> [ ... closure template ] */
DUK_ASSERT(DUK_HOBJECT_IS_COMPFUNC((duk_hobject *) fun_clos));
DUK_ASSERT(DUK_HCOMPFUNC_GET_DATA(thr->heap, fun_clos) == NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_FUNCS(thr->heap, fun_clos) == NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_BYTECODE(thr->heap, fun_clos) == NULL);
DUK_HCOMPFUNC_SET_DATA(thr->heap, fun_clos, DUK_HCOMPFUNC_GET_DATA(thr->heap, fun_temp));
DUK_HCOMPFUNC_SET_FUNCS(thr->heap, fun_clos, DUK_HCOMPFUNC_GET_FUNCS(thr->heap, fun_temp));
DUK_HCOMPFUNC_SET_BYTECODE(thr->heap, fun_clos, DUK_HCOMPFUNC_GET_BYTECODE(thr->heap, fun_temp));
/* Note: all references inside 'data' need to get their refcounts
* upped too. This is the case because refcounts are decreased
* through every function referencing 'data' independently.
*/
DUK_HBUFFER_INCREF(thr, DUK_HCOMPFUNC_GET_DATA(thr->heap, fun_clos));
duk__inc_data_inner_refcounts(thr, fun_temp);
fun_clos->nregs = fun_temp->nregs;
fun_clos->nargs = fun_temp->nargs;
#if defined(DUK_USE_DEBUGGER_SUPPORT)
fun_clos->start_line = fun_temp->start_line;
fun_clos->end_line = fun_temp->end_line;
#endif
DUK_ASSERT(DUK_HCOMPFUNC_GET_DATA(thr->heap, fun_clos) != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_FUNCS(thr->heap, fun_clos) != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_BYTECODE(thr->heap, fun_clos) != NULL);
/* XXX: Could also copy from template, but there's no way to have any
* other value here now (used code has no access to the template).
* Prototype is set by duk_push_hcompfunc().
*/
DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, &fun_clos->obj) == thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
#if 0
DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, &fun_clos->obj, thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
#endif
/* Copy duk_hobject flags as is from the template using a mask.
* Leave out duk_heaphdr owned flags just in case (e.g. if there's
* some GC flag or similar). Some flags can then be adjusted
* separately if necessary.
*/
/* DUK_HEAPHDR_SET_FLAGS() masks changes to non-duk_heaphdr flags only. */
DUK_HEAPHDR_SET_FLAGS((duk_heaphdr *) fun_clos, DUK_HEAPHDR_GET_FLAGS_RAW((duk_heaphdr *) fun_temp));
DUK_DD(DUK_DDPRINT("fun_temp heaphdr flags: 0x%08lx, fun_clos heaphdr flags: 0x%08lx",
(unsigned long) DUK_HEAPHDR_GET_FLAGS_RAW((duk_heaphdr *) fun_temp),
(unsigned long) DUK_HEAPHDR_GET_FLAGS_RAW((duk_heaphdr *) fun_clos)));
DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(&fun_clos->obj));
DUK_ASSERT(!DUK_HOBJECT_HAS_BOUNDFUNC(&fun_clos->obj));
DUK_ASSERT(DUK_HOBJECT_HAS_COMPFUNC(&fun_clos->obj));
DUK_ASSERT(!DUK_HOBJECT_HAS_NATFUNC(&fun_clos->obj));
DUK_ASSERT(!DUK_HOBJECT_IS_THREAD(&fun_clos->obj));
/* DUK_HOBJECT_FLAG_ARRAY_PART: don't care */
/* DUK_HOBJECT_FLAG_NEWENV: handled below */
DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARRAY(&fun_clos->obj));
DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_STRINGOBJ(&fun_clos->obj));
DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARGUMENTS(&fun_clos->obj));
if (!DUK_HOBJECT_HAS_CONSTRUCTABLE(&fun_clos->obj)) {
/* If the template is not constructable don't add an automatic
* .prototype property. This is the case for e.g. ES2015 object
* literal getters/setters and method definitions.
*/
add_auto_proto = 0;
}
/*
* Setup environment record properties based on the template and
* its flags.
*
* If DUK_HOBJECT_HAS_NEWENV(fun_temp) is true, the environment
* records represent identifiers "outside" the function; the
* "inner" environment records are created on demand. Otherwise,
* the environment records are those that will be directly used
* (e.g. for declarations).
*
* _Lexenv is always set; _Varenv defaults to _Lexenv if missing,
* so _Varenv is only set if _Lexenv != _Varenv.
*
* This is relatively complex, see doc/identifier-handling.rst.
*/
if (DUK_HOBJECT_HAS_NEWENV(&fun_clos->obj)) {
#if defined(DUK_USE_FUNC_NAME_PROPERTY)
if (DUK_HOBJECT_HAS_NAMEBINDING(&fun_clos->obj)) {
duk_hobject *proto;
duk_hdecenv *new_env;
/*
* Named function expression, name needs to be bound
* in an intermediate environment record. The "outer"
* lexical/variable environment will thus be:
*
* a) { funcname: <func>, __prototype: outer_lex_env }
* b) { funcname: <func>, __prototype: <globalenv> } (if outer_lex_env missing)
*/
if (outer_lex_env) {
proto = outer_lex_env;
} else {
proto = thr->builtins[DUK_BIDX_GLOBAL_ENV];
}
/* -> [ ... closure template env ] */
new_env = duk_hdecenv_alloc(thr,
DUK_HOBJECT_FLAG_EXTENSIBLE |
DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV));
DUK_ASSERT(new_env != NULL);
duk_push_hobject(thr, (duk_hobject *) new_env);
DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, (duk_hobject *) new_env) == NULL);
DUK_HOBJECT_SET_PROTOTYPE(thr->heap, (duk_hobject *) new_env, proto);
DUK_HOBJECT_INCREF_ALLOWNULL(thr, proto);
DUK_ASSERT(new_env->thread == NULL); /* Closed. */
DUK_ASSERT(new_env->varmap == NULL);
/* It's important that duk_xdef_prop() is a 'raw define' so that any
* properties in an ancestor are never an issue (they should never be
* e.g. non-writable, but just in case).
*
* Because template objects are not visible to user code, the case
* where .name is missing shouldn't happen in practice. It it does,
* the name 'undefined' gets bound and maps to the closure (which is
* a bit odd, but safe).
*/
(void) duk_get_prop_stridx_short(thr, -2, DUK_STRIDX_NAME);
/* -> [ ... closure template env funcname ] */
duk_dup_m4(thr); /* -> [ ... closure template env funcname closure ] */
duk_xdef_prop(thr, -3, DUK_PROPDESC_FLAGS_NONE); /* -> [ ... closure template env ] */
/* env[funcname] = closure */
/* [ ... closure template env ] */
DUK_HCOMPFUNC_SET_LEXENV(thr->heap, fun_clos, (duk_hobject *) new_env);
DUK_HCOMPFUNC_SET_VARENV(thr->heap, fun_clos, (duk_hobject *) new_env);
DUK_HOBJECT_INCREF(thr, (duk_hobject *) new_env);
DUK_HOBJECT_INCREF(thr, (duk_hobject *) new_env);
duk_pop_unsafe(thr);
/* [ ... closure template ] */
}
else
#endif /* DUK_USE_FUNC_NAME_PROPERTY */
{
/*
* Other cases (function declaration, anonymous function expression,
* strict direct eval code). The "outer" environment will be whatever
* the caller gave us.
*/
DUK_HCOMPFUNC_SET_LEXENV(thr->heap, fun_clos, outer_lex_env);
DUK_HCOMPFUNC_SET_VARENV(thr->heap, fun_clos, outer_lex_env);
DUK_HOBJECT_INCREF(thr, outer_lex_env);
DUK_HOBJECT_INCREF(thr, outer_lex_env);
/* [ ... closure template ] */
}
} else {
/*
* Function gets no new environment when called. This is the
* case for global code, indirect eval code, and non-strict
* direct eval code. There is no direct correspondence to the
* E5 specification, as global/eval code is not exposed as a
* function.
*/
DUK_ASSERT(!DUK_HOBJECT_HAS_NAMEBINDING(&fun_temp->obj));
DUK_HCOMPFUNC_SET_LEXENV(thr->heap, fun_clos, outer_lex_env);
DUK_HCOMPFUNC_SET_VARENV(thr->heap, fun_clos, outer_var_env);
DUK_HOBJECT_INCREF(thr, outer_lex_env); /* NULLs not allowed; asserted on entry */
DUK_HOBJECT_INCREF(thr, outer_var_env);
}
DUK_DDD(DUK_DDDPRINT("closure varenv -> %!ipO, lexenv -> %!ipO",
(duk_heaphdr *) fun_clos->var_env,
(duk_heaphdr *) fun_clos->lex_env));
/* Call handling assumes this for all callable closures. */
DUK_ASSERT(DUK_HCOMPFUNC_GET_LEXENV(thr->heap, fun_clos) != NULL);
DUK_ASSERT(DUK_HCOMPFUNC_GET_VARENV(thr->heap, fun_clos) != NULL);
/*
* Copy some internal properties directly
*
* The properties will be non-writable and non-enumerable, but
* configurable.
*
* Function templates are bare objects, so inheritance of internal
* Symbols is not an issue here even when using ordinary property
* reads. The function instance created is not bare, so internal
* Symbols must be defined without inheritance checks.
*/
/* [ ... closure template ] */
DUK_DDD(DUK_DDDPRINT("copying properties: closure=%!iT, template=%!iT",
(duk_tval *) duk_get_tval(thr, -2),
(duk_tval *) duk_get_tval(thr, -1)));
for (i = 0; i < (duk_small_uint_t) (sizeof(duk__closure_copy_proplist) / sizeof(duk_uint16_t)); i++) {
duk_small_int_t stridx = (duk_small_int_t) duk__closure_copy_proplist[i];
if (duk_xget_owndataprop_stridx_short(thr, -1, stridx)) {
/* [ ... closure template val ] */
DUK_DDD(DUK_DDDPRINT("copying property, stridx=%ld -> found", (long) stridx));
duk_xdef_prop_stridx_short(thr, -3, stridx, DUK_PROPDESC_FLAGS_C);
} else {
DUK_DDD(DUK_DDDPRINT("copying property, stridx=%ld -> not found", (long) stridx));
duk_pop_unsafe(thr);
}
}
/*
* "length" maps to number of formals (E5 Section 13.2) for function
* declarations/expressions (non-bound functions). Note that 'nargs'
* is NOT necessarily equal to the number of arguments. Use length
* of _Formals; if missing, assume nargs matches .length.
*/
/* [ ... closure template ] */
formals = duk_hobject_get_formals(thr, (duk_hobject *) fun_temp);
if (formals) {
len_value = (duk_uint_t) formals->length;
DUK_DD(DUK_DDPRINT("closure length from _Formals -> %ld", (long) len_value));
} else {
len_value = fun_temp->nargs;
DUK_DD(DUK_DDPRINT("closure length defaulted from nargs -> %ld", (long) len_value));
}
duk_push_uint(thr, len_value); /* [ ... closure template len_value ] */
duk_xdef_prop_stridx_short(thr, -3, DUK_STRIDX_LENGTH, DUK_PROPDESC_FLAGS_C);
/*
* "prototype" is, by default, a fresh object with the "constructor"
* property.
*
* Note that this creates a circular reference for every function
* instance (closure) which prevents refcount-based collection of
* function instances.
*
* XXX: Try to avoid creating the default prototype object, because
* many functions are not used as constructors and the default
* prototype is unnecessary. Perhaps it could be created on-demand
* when it is first accessed?
*/
/* [ ... closure template ] */
if (add_auto_proto) {
duk_push_object(thr); /* -> [ ... closure template newobj ] */
duk_dup_m3(thr); /* -> [ ... closure template newobj closure ] */
duk_xdef_prop_stridx_short(thr, -2, DUK_STRIDX_CONSTRUCTOR, DUK_PROPDESC_FLAGS_WC); /* -> [ ... closure template newobj ] */
duk_compact(thr, -1); /* compact the prototype */
duk_xdef_prop_stridx_short(thr, -3, DUK_STRIDX_PROTOTYPE, DUK_PROPDESC_FLAGS_W); /* -> [ ... closure template ] */
}
/*
* "arguments" and "caller" must be mapped to throwers for strict
* mode and bound functions (E5 Section 15.3.5).
*
* XXX: This is expensive to have for every strict function instance.
* Try to implement as virtual properties or on-demand created properties.
*/
/* [ ... closure template ] */
if (DUK_HOBJECT_HAS_STRICT(&fun_clos->obj)) {
duk_xdef_prop_stridx_thrower(thr, -2, DUK_STRIDX_CALLER);
duk_xdef_prop_stridx_thrower(thr, -2, DUK_STRIDX_LC_ARGUMENTS);
} else {
#if defined(DUK_USE_NONSTD_FUNC_CALLER_PROPERTY)
DUK_DDD(DUK_DDDPRINT("function is non-strict and non-standard 'caller' property in use, add initial 'null' value"));
duk_push_null(thr);
duk_xdef_prop_stridx_short(thr, -3, DUK_STRIDX_CALLER, DUK_PROPDESC_FLAGS_NONE);
#else
DUK_DDD(DUK_DDDPRINT("function is non-strict and non-standard 'caller' property not used"));
#endif
}
/*
* "name" used to be non-standard but is now defined by ES2015.
* In ES2015/ES2016 the .name property is configurable.
*/
/* [ ... closure template ] */
#if defined(DUK_USE_FUNC_NAME_PROPERTY)
/* XXX: Look for own property only; doesn't matter much because
* templates are bare objects.
*/
if (duk_get_prop_stridx_short(thr, -1, DUK_STRIDX_NAME)) {
/* [ ... closure template name ] */
DUK_ASSERT(duk_is_string(thr, -1));
DUK_DD(DUK_DDPRINT("setting function instance name to %!T", duk_get_tval(thr, -1)));
duk_xdef_prop_stridx_short(thr, -3, DUK_STRIDX_NAME, DUK_PROPDESC_FLAGS_C); /* -> [ ... closure template ] */
} else {
/* Anonymous functions don't have a .name in ES2015, so don't set
* it on the instance either. The instance will then inherit
* it from Function.prototype.name.
*/
DUK_DD(DUK_DDPRINT("not setting function instance .name"));
duk_pop_unsafe(thr);
}
#endif
/*
* Compact the closure, in most cases no properties will be added later.
* Also, without this the closures end up having unused property slots
* (e.g. in Duktape 0.9.0, 8 slots would be allocated and only 7 used).
* A better future solution would be to allocate the closure directly
* to correct size (and setup the properties directly without going
* through the API).
*/
duk_compact(thr, -2);
/*
* Some assertions (E5 Section 13.2).
*/
DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(&fun_clos->obj) == DUK_HOBJECT_CLASS_FUNCTION);
DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, &fun_clos->obj) == thr->builtins[DUK_BIDX_FUNCTION_PROTOTYPE]);
DUK_ASSERT(DUK_HOBJECT_HAS_EXTENSIBLE(&fun_clos->obj));
DUK_ASSERT(duk_has_prop_stridx(thr, -2, DUK_STRIDX_LENGTH) != 0);
DUK_ASSERT(add_auto_proto == 0 || duk_has_prop_stridx(thr, -2, DUK_STRIDX_PROTOTYPE) != 0);
/* May be missing .name */
DUK_ASSERT(!DUK_HOBJECT_HAS_STRICT(&fun_clos->obj) ||
duk_has_prop_stridx(thr, -2, DUK_STRIDX_CALLER) != 0);
DUK_ASSERT(!DUK_HOBJECT_HAS_STRICT(&fun_clos->obj) ||
duk_has_prop_stridx(thr, -2, DUK_STRIDX_LC_ARGUMENTS) != 0);
/*
* Finish
*/
/* [ ... closure template ] */
DUK_DDD(DUK_DDDPRINT("created function instance: template=%!iT -> closure=%!iT",
(duk_tval *) duk_get_tval(thr, -1),
(duk_tval *) duk_get_tval(thr, -2)));
duk_pop_unsafe(thr);
/* [ ... closure ] */
}
/*
* Delayed activation environment record initialization (for functions
* with NEWENV).
*
* The non-delayed initialization is handled by duk_handle_call().
*/
DUK_LOCAL void duk__preallocate_env_entries(duk_hthread *thr, duk_hobject *varmap, duk_hobject *env) {
duk_uint_fast32_t i;
for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(varmap); i++) {
duk_hstring *key;
key = DUK_HOBJECT_E_GET_KEY(thr->heap, varmap, i);
DUK_ASSERT(key != NULL); /* assume keys are compact in _Varmap */
DUK_ASSERT(!DUK_HOBJECT_E_SLOT_IS_ACCESSOR(thr->heap, varmap, i)); /* assume plain values */
/* Predefine as 'undefined' to reserve a property slot.
* This makes the unwind process (where register values
* are copied to the env object) safe against throwing.
*
* XXX: This could be made much faster by creating the
* property table directly.
*/
duk_push_undefined(thr);
DUK_DDD(DUK_DDDPRINT("preallocate env entry for key %!O", key));
duk_hobject_define_property_internal(thr, env, key, DUK_PROPDESC_FLAGS_WE);
}
}
/* shared helper */
DUK_INTERNAL
duk_hobject *duk_create_activation_environment_record(duk_hthread *thr,
duk_hobject *func,
duk_size_t bottom_byteoff) {
duk_hdecenv *env;
duk_hobject *parent;
duk_hcompfunc *f;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(func != NULL);
DUK_STATS_INC(thr->heap, stats_envrec_create);
f = (duk_hcompfunc *) func;
parent = DUK_HCOMPFUNC_GET_LEXENV(thr->heap, f);
if (!parent) {
parent = thr->builtins[DUK_BIDX_GLOBAL_ENV];
}
env = duk_hdecenv_alloc(thr,
DUK_HOBJECT_FLAG_EXTENSIBLE |
DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV));
DUK_ASSERT(env != NULL);
duk_push_hobject(thr, (duk_hobject *) env);
DUK_ASSERT(DUK_HOBJECT_GET_PROTOTYPE(thr->heap, (duk_hobject *) env) == NULL);
DUK_HOBJECT_SET_PROTOTYPE(thr->heap, (duk_hobject *) env, parent);
DUK_HOBJECT_INCREF_ALLOWNULL(thr, parent); /* parent env is the prototype */
/* open scope information, for compiled functions only */
DUK_ASSERT(env->thread == NULL);
DUK_ASSERT(env->varmap == NULL);
DUK_ASSERT(env->regbase_byteoff == 0);
if (DUK_HOBJECT_IS_COMPFUNC(func)) {
duk_hobject *varmap;
varmap = duk_hobject_get_varmap(thr, func);
if (varmap != NULL) {
env->varmap = varmap;
DUK_HOBJECT_INCREF(thr, varmap);
env->thread = thr;
DUK_HTHREAD_INCREF(thr, thr);
env->regbase_byteoff = bottom_byteoff;
/* Preallocate env property table to avoid potential
* for out-of-memory on unwind when the env is closed.
*/
duk__preallocate_env_entries(thr, varmap, (duk_hobject *) env);
} else {
/* If function has no _Varmap, leave the environment closed. */
DUK_ASSERT(env->thread == NULL);
DUK_ASSERT(env->varmap == NULL);
DUK_ASSERT(env->regbase_byteoff == 0);
}
}
return (duk_hobject *) env;
}
DUK_INTERNAL
void duk_js_init_activation_environment_records_delayed(duk_hthread *thr,
duk_activation *act) {
duk_hobject *func;
duk_hobject *env;
DUK_ASSERT(thr != NULL);
func = DUK_ACT_GET_FUNC(act);
DUK_ASSERT(func != NULL);
DUK_ASSERT(!DUK_HOBJECT_HAS_BOUNDFUNC(func)); /* bound functions are never in act 'func' */
/*
* Delayed initialization only occurs for 'NEWENV' functions.
*/
DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
DUK_ASSERT(act->lex_env == NULL);
DUK_ASSERT(act->var_env == NULL);
DUK_STATS_INC(thr->heap, stats_envrec_delayedcreate);
env = duk_create_activation_environment_record(thr, func, act->bottom_byteoff);
DUK_ASSERT(env != NULL);
/* 'act' is a stable pointer, so still OK. */
DUK_DDD(DUK_DDDPRINT("created delayed fresh env: %!ipO", (duk_heaphdr *) env));
#if defined(DUK_USE_DEBUG_LEVEL) && (DUK_USE_DEBUG_LEVEL >= 2)
{
duk_hobject *p = env;
while (p) {
DUK_DDD(DUK_DDDPRINT(" -> %!ipO", (duk_heaphdr *) p));
p = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, p);
}
}
#endif
act->lex_env = env;
act->var_env = env;
DUK_HOBJECT_INCREF(thr, env); /* XXX: incref by count (here 2 times) */
DUK_HOBJECT_INCREF(thr, env);
duk_pop_unsafe(thr);
}
/*
* Closing environment records.
*
* The environment record MUST be closed with the thread where its activation
* is; i.e. if 'env' is open, 'thr' must match env->thread, and the regbase
* and varmap must still be valid. On entry, 'env' must be reachable.
*/
DUK_INTERNAL void duk_js_close_environment_record(duk_hthread *thr, duk_hobject *env) {
duk_uint_fast32_t i;
duk_hobject *varmap;
duk_hstring *key;
duk_tval *tv;
duk_uint_t regnum;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(env != NULL);
if (DUK_UNLIKELY(!DUK_HOBJECT_IS_DECENV(env))) {
DUK_DDD(DUK_DDDPRINT("env not a declarative record: %!iO", (duk_heaphdr *) env));
return;
}
varmap = ((duk_hdecenv *) env)->varmap;
if (varmap == NULL) {
DUK_DDD(DUK_DDDPRINT("env already closed: %!iO", (duk_heaphdr *) env));
return;
}
DUK_ASSERT(((duk_hdecenv *) env)->thread != NULL);
DUK_HDECENV_ASSERT_VALID((duk_hdecenv *) env);
DUK_DDD(DUK_DDDPRINT("closing env: %!iO", (duk_heaphdr *) env));
DUK_DDD(DUK_DDDPRINT("varmap: %!O", (duk_heaphdr *) varmap));
/* Env must be closed in the same thread as where it runs. */
DUK_ASSERT(((duk_hdecenv *) env)->thread == thr);
/* XXX: additional conditions when to close variables? we don't want to do it
* unless the environment may have "escaped" (referenced in a function closure).
* With delayed environments, the existence is probably good enough of a check.
*/
/* Note: we rely on the _Varmap having a bunch of nice properties, like:
* - being compacted and unmodified during this process
* - not containing an array part
* - having correct value types
*/
DUK_DDD(DUK_DDDPRINT("copying bound register values, %ld bound regs", (long) DUK_HOBJECT_GET_ENEXT(varmap)));
/* Copy over current variable values from value stack to the
* environment record. The scope object is empty but may
* inherit from another scope which has conflicting names.
*/
/* XXX: Do this using a once allocated entry area, no side effects.
* Hash part would need special treatment however (maybe copy, and
* then realloc with hash part if large enough).
*/
for (i = 0; i < (duk_uint_fast32_t) DUK_HOBJECT_GET_ENEXT(varmap); i++) {
duk_size_t regbase_byteoff;
key = DUK_HOBJECT_E_GET_KEY(thr->heap, varmap, i);
DUK_ASSERT(key != NULL); /* assume keys are compact in _Varmap */
DUK_ASSERT(!DUK_HOBJECT_E_SLOT_IS_ACCESSOR(thr->heap, varmap, i)); /* assume plain values */
tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, varmap, i);
DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
DUK_ASSERT(DUK_TVAL_GET_NUMBER(tv) <= (duk_double_t) DUK_UINT32_MAX); /* limits */
#if defined(DUK_USE_FASTINT)
DUK_ASSERT(DUK_TVAL_IS_FASTINT(tv));
regnum = (duk_uint_t) DUK_TVAL_GET_FASTINT_U32(tv);
#else
regnum = (duk_uint_t) DUK_TVAL_GET_NUMBER(tv);
#endif
regbase_byteoff = ((duk_hdecenv *) env)->regbase_byteoff;
DUK_ASSERT((duk_uint8_t *) thr->valstack + regbase_byteoff + sizeof(duk_tval) * regnum >= (duk_uint8_t *) thr->valstack);
DUK_ASSERT((duk_uint8_t *) thr->valstack + regbase_byteoff + sizeof(duk_tval) * regnum < (duk_uint8_t *) thr->valstack_top);
/* Write register value into env as named properties.
* If property already exists, overwrites silently.
* Property is writable, but not deletable (not configurable
* in terms of property attributes).
*
* This property write must not throw because we're unwinding
* and unwind code is not allowed to throw at present. The
* call itself has no such guarantees, but we've preallocated
* entries for each property when the env was created, so no
* out-of-memory error should be possible. If this guarantee
* is not provided, problems like GH-476 may happen.
*/
duk_push_tval(thr, (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack + regbase_byteoff + sizeof(duk_tval) * regnum));
DUK_DDD(DUK_DDDPRINT("closing identifier %!O -> reg %ld, value %!T",
(duk_heaphdr *) key,
(long) regnum,
(duk_tval *) duk_get_tval(thr, -1)));
duk_hobject_define_property_internal(thr, env, key, DUK_PROPDESC_FLAGS_WE);
}
/* NULL atomically to avoid inconsistent state + side effects. */
DUK_HOBJECT_DECREF_NORZ(thr, ((duk_hdecenv *) env)->thread);
DUK_HOBJECT_DECREF_NORZ(thr, ((duk_hdecenv *) env)->varmap);
((duk_hdecenv *) env)->thread = NULL;
((duk_hdecenv *) env)->varmap = NULL;
DUK_DDD(DUK_DDDPRINT("env after closing: %!O", (duk_heaphdr *) env));
}
/*
* GETIDREF: a GetIdentifierReference-like helper.
*
* Provides a parent traversing lookup and a single level lookup
* (for HasBinding).
*
* Instead of returning the value, returns a bunch of values allowing
* the caller to read, write, or delete the binding. Value pointers
* are duk_tval pointers which can be mutated directly as long as
* refcounts are properly updated. Note that any operation which may
* reallocate valstacks or compact objects may invalidate the returned
* duk_tval (but not object) pointers, so caller must be very careful.
*
* If starting environment record 'env' is given, 'act' is ignored.
* However, if 'env' is NULL, the caller may identify, in 'act', an
* activation which hasn't had its declarative environment initialized
* yet. The activation registers are then looked up, and its parent
* traversed normally.
*
* The 'out' structure values are only valid if the function returns
* success (non-zero).
*/
/* lookup name from an open declarative record's registers */
DUK_LOCAL
duk_bool_t duk__getid_open_decl_env_regs(duk_hthread *thr,
duk_hstring *name,
duk_hdecenv *env,
duk__id_lookup_result *out) {
duk_tval *tv;
duk_size_t reg_rel;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT(env != NULL);
DUK_ASSERT(out != NULL);
DUK_ASSERT(DUK_HOBJECT_IS_DECENV((duk_hobject *) env));
DUK_HDECENV_ASSERT_VALID(env);
if (env->thread == NULL) {
/* already closed */
return 0;
}
DUK_ASSERT(env->varmap != NULL);
tv = duk_hobject_find_entry_tval_ptr(thr->heap, env->varmap, name);
if (DUK_UNLIKELY(tv == NULL)) {
return 0;
}
DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
DUK_ASSERT(DUK_TVAL_GET_NUMBER(tv) <= (duk_double_t) DUK_UINT32_MAX); /* limits */
#if defined(DUK_USE_FASTINT)
DUK_ASSERT(DUK_TVAL_IS_FASTINT(tv));
reg_rel = (duk_size_t) DUK_TVAL_GET_FASTINT_U32(tv);
#else
reg_rel = (duk_size_t) DUK_TVAL_GET_NUMBER(tv);
#endif
DUK_ASSERT_DISABLE(reg_rel >= 0); /* unsigned */
tv = (duk_tval *) (void *) ((duk_uint8_t *) env->thread->valstack + env->regbase_byteoff + sizeof(duk_tval) * reg_rel);
DUK_ASSERT(tv >= env->thread->valstack && tv < env->thread->valstack_end); /* XXX: more accurate? */
out->value = tv;
out->attrs = DUK_PROPDESC_FLAGS_W; /* registers are mutable, non-deletable */
out->env = (duk_hobject *) env;
out->holder = NULL;
out->has_this = 0;
return 1;
}
/* lookup name from current activation record's functions' registers */
DUK_LOCAL
duk_bool_t duk__getid_activation_regs(duk_hthread *thr,
duk_hstring *name,
duk_activation *act,
duk__id_lookup_result *out) {
duk_tval *tv;
duk_hobject *func;
duk_hobject *varmap;
duk_size_t reg_rel;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT(act != NULL);
DUK_ASSERT(out != NULL);
func = DUK_ACT_GET_FUNC(act);
DUK_ASSERT(func != NULL);
DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
if (!DUK_HOBJECT_IS_COMPFUNC(func)) {
return 0;
}
/* XXX: move varmap to duk_hcompfunc struct field? */
varmap = duk_hobject_get_varmap(thr, func);
if (!varmap) {
return 0;
}
tv = duk_hobject_find_entry_tval_ptr(thr->heap, varmap, name);
if (!tv) {
return 0;
}
DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv));
reg_rel = (duk_size_t) DUK_TVAL_GET_NUMBER(tv);
DUK_ASSERT_DISABLE(reg_rel >= 0);
DUK_ASSERT(reg_rel < ((duk_hcompfunc *) func)->nregs);
tv = (duk_tval *) (void *) ((duk_uint8_t *) thr->valstack + act->bottom_byteoff);
tv += reg_rel;
out->value = tv;
out->attrs = DUK_PROPDESC_FLAGS_W; /* registers are mutable, non-deletable */
out->env = NULL;
out->holder = NULL;
out->has_this = 0;
return 1;
}
DUK_LOCAL
duk_bool_t duk__get_identifier_reference(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name,
duk_activation *act,
duk_bool_t parents,
duk__id_lookup_result *out) {
duk_tval *tv;
duk_uint_t sanity;
DUK_ASSERT(thr != NULL);
DUK_ASSERT(env != NULL || act != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT(out != NULL);
DUK_ASSERT(!env || DUK_HOBJECT_IS_ENV(env));
DUK_ASSERT(!env || !DUK_HOBJECT_HAS_ARRAY_PART(env));
/*
* Conceptually, we look for the identifier binding by starting from
* 'env' and following to chain of environment records (represented
* by the prototype chain).
*
* If 'env' is NULL, the current activation does not yet have an
* allocated declarative environment record; this should be treated
* exactly as if the environment record existed but had no bindings
* other than register bindings.
*
* Note: we assume that with the DUK_HOBJECT_FLAG_NEWENV cleared
* the environment will always be initialized immediately; hence
* a NULL 'env' should only happen with the flag set. This is the
* case for: (1) function calls, and (2) strict, direct eval calls.
*/
if (env == NULL && act != NULL) {
duk_hobject *func;
duk_hcompfunc *f;
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference: env is NULL, activation is non-NULL -> "
"delayed env case, look up activation regs first"));
/*
* Try registers
*/
if (duk__getid_activation_regs(thr, name, act, out)) {
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
"name=%!O -> value=%!T, attrs=%ld, has_this=%ld, env=%!O, holder=%!O "
"(found from register bindings when env=NULL)",
(duk_heaphdr *) name, (duk_tval *) out->value,
(long) out->attrs, (long) out->has_this,
(duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
return 1;
}
DUK_DDD(DUK_DDDPRINT("not found in current activation regs"));
/*
* Not found in registers, proceed to the parent record.
* Here we need to determine what the parent would be,
* if 'env' was not NULL (i.e. same logic as when initializing
* the record).
*
* Note that environment initialization is only deferred when
* DUK_HOBJECT_HAS_NEWENV is set, and this only happens for:
* - Function code
* - Strict eval code
*
* We only need to check _Lexenv here; _Varenv exists only if it
* differs from _Lexenv (and thus _Lexenv will also be present).
*/
if (!parents) {
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference failed, no parent traversal "
"(not found from register bindings when env=NULL)"));
goto fail_not_found;
}
func = DUK_ACT_GET_FUNC(act);
DUK_ASSERT(func != NULL);
DUK_ASSERT(DUK_HOBJECT_HAS_NEWENV(func));
f = (duk_hcompfunc *) func;
env = DUK_HCOMPFUNC_GET_LEXENV(thr->heap, f);
if (!env) {
env = thr->builtins[DUK_BIDX_GLOBAL_ENV];
}
DUK_DDD(DUK_DDDPRINT("continue lookup from env: %!iO",
(duk_heaphdr *) env));
}
/*
* Prototype walking starting from 'env'.
*
* ('act' is not needed anywhere here.)
*/
sanity = DUK_HOBJECT_PROTOTYPE_CHAIN_SANITY;
while (env != NULL) {
duk_small_uint_t cl;
duk_uint_t attrs;
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference, name=%!O, considering env=%p -> %!iO",
(duk_heaphdr *) name,
(void *) env,
(duk_heaphdr *) env));
DUK_ASSERT(env != NULL);
DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(env));
cl = DUK_HOBJECT_GET_CLASS_NUMBER(env);
DUK_ASSERT(cl == DUK_HOBJECT_CLASS_OBJENV || cl == DUK_HOBJECT_CLASS_DECENV);
if (cl == DUK_HOBJECT_CLASS_DECENV) {
/*
* Declarative environment record.
*
* Identifiers can never be stored in ancestors and are
* always plain values, so we can use an internal helper
* and access the value directly with an duk_tval ptr.
*
* A closed environment is only indicated by it missing
* the "book-keeping" properties required for accessing
* register-bound variables.
*/
DUK_HDECENV_ASSERT_VALID((duk_hdecenv *) env);
if (duk__getid_open_decl_env_regs(thr, name, (duk_hdecenv *) env, out)) {
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
"name=%!O -> value=%!T, attrs=%ld, has_this=%ld, env=%!O, holder=%!O "
"(declarative environment record, scope open, found in regs)",
(duk_heaphdr *) name, (duk_tval *) out->value,
(long) out->attrs, (long) out->has_this,
(duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
return 1;
}
tv = duk_hobject_find_entry_tval_ptr_and_attrs(thr->heap, env, name, &attrs);
if (tv) {
out->value = tv;
out->attrs = attrs;
out->env = env;
out->holder = env;
out->has_this = 0;
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
"name=%!O -> value=%!T, attrs=%ld, has_this=%ld, env=%!O, holder=%!O "
"(declarative environment record, found in properties)",
(duk_heaphdr *) name, (duk_tval *) out->value,
(long) out->attrs, (long) out->has_this,
(duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
return 1;
}
} else {
/*
* Object environment record.
*
* Binding (target) object is an external, uncontrolled object.
* Identifier may be bound in an ancestor property, and may be
* an accessor. Target can also be a Proxy which we must support
* here.
*/
/* XXX: we could save space by using _Target OR _This. If _Target, assume
* this binding is undefined. If _This, assumes this binding is _This, and
* target is also _This. One property would then be enough.
*/
duk_hobject *target;
duk_bool_t found;
DUK_ASSERT(cl == DUK_HOBJECT_CLASS_OBJENV);
DUK_HOBJENV_ASSERT_VALID((duk_hobjenv *) env);
target = ((duk_hobjenv *) env)->target;
DUK_ASSERT(target != NULL);
/* Target may be a Proxy or property may be an accessor, so we must
* use an actual, Proxy-aware hasprop check here.
*
* out->holder is NOT set to the actual duk_hobject where the
* property is found, but rather the object binding target object.
*/
#if defined(DUK_USE_ES6_PROXY)
if (DUK_UNLIKELY(DUK_HOBJECT_IS_PROXY(target))) {
duk_tval tv_name;
duk_tval tv_target_tmp;
DUK_ASSERT(name != NULL);
DUK_TVAL_SET_STRING(&tv_name, name);
DUK_TVAL_SET_OBJECT(&tv_target_tmp, target);
found = duk_hobject_hasprop(thr, &tv_target_tmp, &tv_name);
} else
#endif /* DUK_USE_ES6_PROXY */
{
/* XXX: duk_hobject_hasprop() would be correct for
* non-Proxy objects too, but it is about ~20-25%
* slower at present so separate code paths for
* Proxy and non-Proxy now.
*/
found = duk_hobject_hasprop_raw(thr, target, name);
}
if (found) {
out->value = NULL; /* can't get value, may be accessor */
out->attrs = 0; /* irrelevant when out->value == NULL */
out->env = env;
out->holder = target;
out->has_this = ((duk_hobjenv *) env)->has_this;
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference successful: "
"name=%!O -> value=%!T, attrs=%ld, has_this=%ld, env=%!O, holder=%!O "
"(object environment record)",
(duk_heaphdr *) name, (duk_tval *) out->value,
(long) out->attrs, (long) out->has_this,
(duk_heaphdr *) out->env, (duk_heaphdr *) out->holder));
return 1;
}
}
if (!parents) {
DUK_DDD(DUK_DDDPRINT("duk__get_identifier_reference failed, no parent traversal "
"(not found from first traversed env)"));
goto fail_not_found;
}
if (DUK_UNLIKELY(sanity-- == 0)) {
DUK_ERROR_RANGE(thr, DUK_STR_PROTOTYPE_CHAIN_LIMIT);
DUK_WO_NORETURN(return 0;);
}
env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, env);
}
/*
* Not found (even in global object)
*/
fail_not_found:
return 0;
}
/*
* HASVAR: check identifier binding from a given environment record
* without traversing its parents.
*
* This primitive is not exposed to user code as such, but is used
* internally for e.g. declaration binding instantiation.
*
* See E5 Sections:
* 10.2.1.1.1 HasBinding(N)
* 10.2.1.2.1 HasBinding(N)
*
* Note: strictness has no bearing on this check. Hence we don't take
* a 'strict' parameter.
*/
#if 0 /*unused*/
DUK_INTERNAL
duk_bool_t duk_js_hasvar_envrec(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name) {
duk__id_lookup_result ref;
duk_bool_t parents;
DUK_DDD(DUK_DDDPRINT("hasvar: thr=%p, env=%p, name=%!O "
"(env -> %!dO)",
(void *) thr, (void *) env, (duk_heaphdr *) name,
(duk_heaphdr *) env));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(env != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
DUK_ASSERT(!DUK_HOBJECT_HAS_ARRAY_PART(env));
/* lookup results is ignored */
parents = 0;
return duk__get_identifier_reference(thr, env, name, NULL, parents, &ref);
}
#endif
/*
* GETVAR
*
* See E5 Sections:
* 11.1.2 Identifier Reference
* 10.3.1 Identifier Resolution
* 11.13.1 Simple Assignment [example of where the Reference is GetValue'd]
* 8.7.1 GetValue (V)
* 8.12.1 [[GetOwnProperty]] (P)
* 8.12.2 [[GetProperty]] (P)
* 8.12.3 [[Get]] (P)
*
* If 'throw' is true, always leaves two values on top of stack: [val this].
*
* If 'throw' is false, returns 0 if identifier cannot be resolved, and the
* stack will be unaffected in this case. If identifier is resolved, returns
* 1 and leaves [val this] on top of stack.
*
* Note: the 'strict' flag of a reference returned by GetIdentifierReference
* is ignored by GetValue. Hence we don't take a 'strict' parameter.
*
* The 'throw' flag is needed for implementing 'typeof' for an unreferenced
* identifier. An unreference identifier in other contexts generates a
* ReferenceError.
*/
DUK_LOCAL
duk_bool_t duk__getvar_helper(duk_hthread *thr,
duk_hobject *env,
duk_activation *act,
duk_hstring *name,
duk_bool_t throw_flag) {
duk__id_lookup_result ref;
duk_tval tv_tmp_obj;
duk_tval tv_tmp_key;
duk_bool_t parents;
DUK_DDD(DUK_DDDPRINT("getvar: thr=%p, env=%p, act=%p, name=%!O "
"(env -> %!dO)",
(void *) thr, (void *) env, (void *) act,
(duk_heaphdr *) name, (duk_heaphdr *) env));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(name != NULL);
/* env and act may be NULL */
DUK_STATS_INC(thr->heap, stats_getvar_all);
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
parents = 1; /* follow parent chain */
if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
if (ref.value) {
duk_push_tval(thr, ref.value);
duk_push_undefined(thr);
} else {
DUK_ASSERT(ref.holder != NULL);
/* ref.holder is safe across the getprop call (even
* with side effects) because 'env' is reachable and
* ref.holder is a direct heap pointer.
*/
DUK_TVAL_SET_OBJECT(&tv_tmp_obj, ref.holder);
DUK_TVAL_SET_STRING(&tv_tmp_key, name);
(void) duk_hobject_getprop(thr, &tv_tmp_obj, &tv_tmp_key); /* [value] */
if (ref.has_this) {
duk_push_hobject(thr, ref.holder);
} else {
duk_push_undefined(thr);
}
/* [value this] */
}
return 1;
} else {
if (throw_flag) {
DUK_ERROR_FMT1(thr, DUK_ERR_REFERENCE_ERROR,
"identifier '%s' undefined",
(const char *) DUK_HSTRING_GET_DATA(name));
DUK_WO_NORETURN(return 0;);
}
return 0;
}
}
DUK_INTERNAL
duk_bool_t duk_js_getvar_envrec(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name,
duk_bool_t throw_flag) {
return duk__getvar_helper(thr, env, NULL, name, throw_flag);
}
DUK_INTERNAL
duk_bool_t duk_js_getvar_activation(duk_hthread *thr,
duk_activation *act,
duk_hstring *name,
duk_bool_t throw_flag) {
DUK_ASSERT(act != NULL);
return duk__getvar_helper(thr, act->lex_env, act, name, throw_flag);
}
/*
* PUTVAR
*
* See E5 Sections:
* 11.1.2 Identifier Reference
* 10.3.1 Identifier Resolution
* 11.13.1 Simple Assignment [example of where the Reference is PutValue'd]
* 8.7.2 PutValue (V,W) [see especially step 3.b, undefined -> automatic global in non-strict mode]
* 8.12.4 [[CanPut]] (P)
* 8.12.5 [[Put]] (P)
*
* Note: may invalidate any valstack (or object) duk_tval pointers because
* putting a value may reallocate any object or any valstack. Caller beware.
*/
DUK_LOCAL
void duk__putvar_helper(duk_hthread *thr,
duk_hobject *env,
duk_activation *act,
duk_hstring *name,
duk_tval *val,
duk_bool_t strict) {
duk__id_lookup_result ref;
duk_tval tv_tmp_val;
duk_tval tv_tmp_obj;
duk_tval tv_tmp_key;
duk_bool_t parents;
DUK_STATS_INC(thr->heap, stats_putvar_all);
DUK_DDD(DUK_DDDPRINT("putvar: thr=%p, env=%p, act=%p, name=%!O, val=%p, strict=%ld "
"(env -> %!dO, val -> %!T)",
(void *) thr, (void *) env, (void *) act,
(duk_heaphdr *) name, (void *) val, (long) strict,
(duk_heaphdr *) env, (duk_tval *) val));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT(val != NULL);
/* env and act may be NULL */
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(env);
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
DUK_ASSERT_REFCOUNT_NONZERO_TVAL(val);
DUK_TVAL_SET_TVAL(&tv_tmp_val, val); /* Stabilize. */
val = NULL;
/*
* In strict mode E5 protects 'eval' and 'arguments' from being
* assigned to (or even declared anywhere). Attempt to do so
* should result in a compile time SyntaxError. See the internal
* design documentation for details.
*
* Thus, we should never come here, run-time, for strict code,
* and name 'eval' or 'arguments'.
*/
DUK_ASSERT(!strict ||
(name != DUK_HTHREAD_STRING_EVAL(thr) &&
name != DUK_HTHREAD_STRING_LC_ARGUMENTS(thr)));
/*
* Lookup variable and update in-place if found.
*/
parents = 1; /* follow parent chain */
if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
if (ref.value && (ref.attrs & DUK_PROPDESC_FLAG_WRITABLE)) {
/* Update duk_tval in-place if pointer provided and the
* property is writable. If the property is not writable
* (immutable binding), use duk_hobject_putprop() which
* will respect mutability.
*/
duk_tval *tv_val;
tv_val = ref.value;
DUK_ASSERT(tv_val != NULL);
DUK_TVAL_SET_TVAL_UPDREF(thr, tv_val, &tv_tmp_val); /* side effects */
/* ref.value invalidated here */
} else {
DUK_ASSERT(ref.holder != NULL);
DUK_TVAL_SET_OBJECT(&tv_tmp_obj, ref.holder);
DUK_TVAL_SET_STRING(&tv_tmp_key, name);
(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, &tv_tmp_val, strict);
/* ref.value invalidated here */
}
return;
}
/*
* Not found: write to global object (non-strict) or ReferenceError
* (strict); see E5 Section 8.7.2, step 3.
*/
if (strict) {
DUK_DDD(DUK_DDDPRINT("identifier binding not found, strict => reference error"));
DUK_ERROR_FMT1(thr, DUK_ERR_REFERENCE_ERROR,
"identifier '%s' undefined",
(const char *) DUK_HSTRING_GET_DATA(name));
DUK_WO_NORETURN(return;);
}
DUK_DDD(DUK_DDDPRINT("identifier binding not found, not strict => set to global"));
DUK_TVAL_SET_OBJECT(&tv_tmp_obj, thr->builtins[DUK_BIDX_GLOBAL]);
DUK_TVAL_SET_STRING(&tv_tmp_key, name);
(void) duk_hobject_putprop(thr, &tv_tmp_obj, &tv_tmp_key, &tv_tmp_val, 0); /* 0 = no throw */
/* NB: 'val' may be invalidated here because put_value may realloc valstack,
* caller beware.
*/
}
DUK_INTERNAL
void duk_js_putvar_envrec(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name,
duk_tval *val,
duk_bool_t strict) {
duk__putvar_helper(thr, env, NULL, name, val, strict);
}
DUK_INTERNAL
void duk_js_putvar_activation(duk_hthread *thr,
duk_activation *act,
duk_hstring *name,
duk_tval *val,
duk_bool_t strict) {
DUK_ASSERT(act != NULL);
duk__putvar_helper(thr, act->lex_env, act, name, val, strict);
}
/*
* DELVAR
*
* See E5 Sections:
* 11.4.1 The delete operator
* 10.2.1.1.5 DeleteBinding (N) [declarative environment record]
* 10.2.1.2.5 DeleteBinding (N) [object environment record]
*
* Variable bindings established inside eval() are deletable (configurable),
* other bindings are not, including variables declared in global level.
* Registers are always non-deletable, and the deletion of other bindings
* is controlled by the configurable flag.
*
* For strict mode code, the 'delete' operator should fail with a compile
* time SyntaxError if applied to identifiers. Hence, no strict mode
* run-time deletion of identifiers should ever happen. This function
* should never be called from strict mode code!
*/
DUK_LOCAL
duk_bool_t duk__delvar_helper(duk_hthread *thr,
duk_hobject *env,
duk_activation *act,
duk_hstring *name) {
duk__id_lookup_result ref;
duk_bool_t parents;
DUK_DDD(DUK_DDDPRINT("delvar: thr=%p, env=%p, act=%p, name=%!O "
"(env -> %!dO)",
(void *) thr, (void *) env, (void *) act,
(duk_heaphdr *) name, (duk_heaphdr *) env));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(name != NULL);
/* env and act may be NULL */
DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR(name);
parents = 1; /* follow parent chain */
if (duk__get_identifier_reference(thr, env, name, act, parents, &ref)) {
if (ref.value && !(ref.attrs & DUK_PROPDESC_FLAG_CONFIGURABLE)) {
/* Identifier found in registers (always non-deletable)
* or declarative environment record and non-configurable.
*/
return 0;
}
DUK_ASSERT(ref.holder != NULL);
return duk_hobject_delprop_raw(thr, ref.holder, name, 0);
}
/*
* Not found (even in global object).
*
* In non-strict mode this is a silent SUCCESS (!), see E5 Section 11.4.1,
* step 3.b. In strict mode this case is a compile time SyntaxError so
* we should not come here.
*/
DUK_DDD(DUK_DDDPRINT("identifier to be deleted not found: name=%!O "
"(treated as silent success)",
(duk_heaphdr *) name));
return 1;
}
#if 0 /*unused*/
DUK_INTERNAL
duk_bool_t duk_js_delvar_envrec(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name) {
return duk__delvar_helper(thr, env, NULL, name);
}
#endif
DUK_INTERNAL
duk_bool_t duk_js_delvar_activation(duk_hthread *thr,
duk_activation *act,
duk_hstring *name) {
DUK_ASSERT(act != NULL);
return duk__delvar_helper(thr, act->lex_env, act, name);
}
/*
* DECLVAR
*
* See E5 Sections:
* 10.4.3 Entering Function Code
* 10.5 Declaration Binding Instantion
* 12.2 Variable Statement
* 11.1.2 Identifier Reference
* 10.3.1 Identifier Resolution
*
* Variable declaration behavior is mainly discussed in Section 10.5,
* and is not discussed in the execution semantics (Sections 11-13).
*
* Conceptually declarations happen when code (global, eval, function)
* is entered, before any user code is executed. In practice, register-
* bound identifiers are 'declared' automatically (by virtue of being
* allocated to registers with the initial value 'undefined'). Other
* identifiers are declared in the function prologue with this primitive.
*
* Since non-register bindings eventually back to an internal object's
* properties, the 'prop_flags' argument is used to specify binding
* type:
*
* - Immutable binding: set DUK_PROPDESC_FLAG_WRITABLE to false
* - Non-deletable binding: set DUK_PROPDESC_FLAG_CONFIGURABLE to false
* - The flag DUK_PROPDESC_FLAG_ENUMERABLE should be set, although it
* doesn't really matter for internal objects
*
* All bindings are non-deletable mutable bindings except:
*
* - Declarations in eval code (mutable, deletable)
* - 'arguments' binding in strict function code (immutable)
* - Function name binding of a function expression (immutable)
*
* Declarations may go to declarative environment records (always
* so for functions), but may also go to object environment records
* (e.g. global code). The global object environment has special
* behavior when re-declaring a function (but not a variable); see
* E5.1 specification, Section 10.5, step 5.e.
*
* Declarations always go to the 'top-most' environment record, i.e.
* we never check the record chain. It's not an error even if a
* property (even an immutable or non-deletable one) of the same name
* already exists.
*
* If a declared variable already exists, its value needs to be updated
* (if possible). Returns 1 if a PUTVAR needs to be done by the caller;
* otherwise returns 0.
*/
DUK_LOCAL
duk_bool_t duk__declvar_helper(duk_hthread *thr,
duk_hobject *env,
duk_hstring *name,
duk_tval *val,
duk_small_uint_t prop_flags,
duk_bool_t is_func_decl) {
duk_hobject *holder;
duk_bool_t parents;
duk__id_lookup_result ref;
duk_tval *tv;
DUK_DDD(DUK_DDDPRINT("declvar: thr=%p, env=%p, name=%!O, val=%!T, prop_flags=0x%08lx, is_func_decl=%ld "
"(env -> %!iO)",
(void *) thr, (void *) env, (duk_heaphdr *) name,
(duk_tval *) val, (unsigned long) prop_flags,
(unsigned int) is_func_decl, (duk_heaphdr *) env));
DUK_ASSERT(thr != NULL);
DUK_ASSERT(env != NULL);
DUK_ASSERT(name != NULL);
DUK_ASSERT(val != NULL);
/* Note: in strict mode the compiler should reject explicit
* declaration of 'eval' or 'arguments'. However, internal
* bytecode may declare 'arguments' in the function prologue.
* We don't bother checking (or asserting) for these now.
*/
/* Note: val is a stable duk_tval pointer. The caller makes
* a value copy into its stack frame, so 'tv_val' is not subject
* to side effects here.
*/
/*
* Check whether already declared.
*
* We need to check whether the binding exists in the environment
* without walking its parents. However, we still need to check
* register-bound identifiers and the prototype chain of an object
* environment target object.
*/
parents = 0; /* just check 'env' */
if (duk__get_identifier_reference(thr, env, name, NULL, parents, &ref)) {
duk_int_t e_idx;
duk_int_t h_idx;
duk_small_uint_t flags;
/*
* Variable already declared, ignore re-declaration.
* The only exception is the updated behavior of E5.1 for
* global function declarations, E5.1 Section 10.5, step 5.e.
* This behavior does not apply to global variable declarations.
*/
if (!(is_func_decl && env == thr->builtins[DUK_BIDX_GLOBAL_ENV])) {
DUK_DDD(DUK_DDDPRINT("re-declare a binding, ignoring"));
return 1; /* 1 -> needs a PUTVAR */
}
/*
* Special behavior in E5.1.
*
* Note that even though parents == 0, the conflicting property
* may be an inherited property (currently our global object's
* prototype is Object.prototype). Step 5.e first operates on
* the existing property (which is potentially in an ancestor)
* and then defines a new property in the global object (and
* never modifies the ancestor).
*
* Also note that this logic would become even more complicated
* if the conflicting property might be a virtual one. Object
* prototype has no virtual properties, though.
*
* XXX: this is now very awkward, rework.
*/
DUK_DDD(DUK_DDDPRINT("re-declare a function binding in global object, "
"updated E5.1 processing"));
DUK_ASSERT(ref.holder != NULL);
holder = ref.holder;
/* holder will be set to the target object, not the actual object
* where the property was found (see duk__get_identifier_reference()).
*/
DUK_ASSERT(DUK_HOBJECT_GET_CLASS_NUMBER(holder) == DUK_HOBJECT_CLASS_GLOBAL);
DUK_ASSERT(!DUK_HOBJECT_HAS_EXOTIC_ARRAY(holder)); /* global object doesn't have array part */
/* XXX: use a helper for prototype traversal; no loop check here */
/* must be found: was found earlier, and cannot be inherited */
for (;;) {
DUK_ASSERT(holder != NULL);
if (duk_hobject_find_entry(thr->heap, holder, name, &e_idx, &h_idx)) {
DUK_ASSERT(e_idx >= 0);
break;
}
/* SCANBUILD: NULL pointer dereference, doesn't actually trigger,
* asserted above.
*/
holder = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, holder);
}
DUK_ASSERT(holder != NULL);
DUK_ASSERT(e_idx >= 0);
/* SCANBUILD: scan-build produces a NULL pointer dereference warning
* below; it never actually triggers because holder is actually never
* NULL.
*/
/* ref.holder is global object, holder is the object with the
* conflicting property.
*/
flags = DUK_HOBJECT_E_GET_FLAGS(thr->heap, holder, e_idx);
if (!(flags & DUK_PROPDESC_FLAG_CONFIGURABLE)) {
if (flags & DUK_PROPDESC_FLAG_ACCESSOR) {
DUK_DDD(DUK_DDDPRINT("existing property is a non-configurable "
"accessor -> reject"));
goto fail_existing_attributes;
}
if (!((flags & DUK_PROPDESC_FLAG_WRITABLE) &&
(flags & DUK_PROPDESC_FLAG_ENUMERABLE))) {
DUK_DDD(DUK_DDDPRINT("existing property is a non-configurable "
"plain property which is not writable and "
"enumerable -> reject"));
goto fail_existing_attributes;
}
DUK_DDD(DUK_DDDPRINT("existing property is not configurable but "
"is plain, enumerable, and writable -> "
"allow redeclaration"));
}
if (holder == ref.holder) {
/* XXX: if duk_hobject_define_property_internal() was updated
* to handle a pre-existing accessor property, this would be
* a simple call (like for the ancestor case).
*/
DUK_DDD(DUK_DDDPRINT("redefine, offending property in global object itself"));
if (flags & DUK_PROPDESC_FLAG_ACCESSOR) {
duk_hobject *tmp;
tmp = DUK_HOBJECT_E_GET_VALUE_GETTER(thr->heap, holder, e_idx);
DUK_HOBJECT_E_SET_VALUE_GETTER(thr->heap, holder, e_idx, NULL);
DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
DUK_UNREF(tmp);
tmp = DUK_HOBJECT_E_GET_VALUE_SETTER(thr->heap, holder, e_idx);
DUK_HOBJECT_E_SET_VALUE_SETTER(thr->heap, holder, e_idx, NULL);
DUK_HOBJECT_DECREF_ALLOWNULL(thr, tmp);
DUK_UNREF(tmp);
} else {
tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx);
DUK_TVAL_SET_UNDEFINED_UPDREF(thr, tv);
}
/* Here val would be potentially invalid if we didn't make
* a value copy at the caller.
*/
tv = DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx);
DUK_TVAL_SET_TVAL(tv, val);
DUK_TVAL_INCREF(thr, tv);
DUK_HOBJECT_E_SET_FLAGS(thr->heap, holder, e_idx, prop_flags);
DUK_DDD(DUK_DDDPRINT("updated global binding, final result: "
"value -> %!T, prop_flags=0x%08lx",
(duk_tval *) DUK_HOBJECT_E_GET_VALUE_TVAL_PTR(thr->heap, holder, e_idx),
(unsigned long) prop_flags));
} else {
DUK_DDD(DUK_DDDPRINT("redefine, offending property in ancestor"));
DUK_ASSERT(ref.holder == thr->builtins[DUK_BIDX_GLOBAL]);
duk_push_tval(thr, val);
duk_hobject_define_property_internal(thr, ref.holder, name, prop_flags);
}
return 0;
}
/*
* Not found (in registers or record objects). Declare
* to current variable environment.
*/
/*
* Get holder object
*/
if (DUK_HOBJECT_IS_DECENV(env)) {
DUK_HDECENV_ASSERT_VALID((duk_hdecenv *) env);
holder = env;
} else {
DUK_HOBJENV_ASSERT_VALID((duk_hobjenv *) env);
holder = ((duk_hobjenv *) env)->target;
DUK_ASSERT(holder != NULL);
}
/*
* Define new property
*
* Note: this may fail if the holder is not extensible.
*/
/* XXX: this is awkward as we use an internal method which doesn't handle
* extensibility etc correctly. Basically we'd want to do a [[DefineOwnProperty]]
* or Object.defineProperty() here.
*/
if (!DUK_HOBJECT_HAS_EXTENSIBLE(holder)) {
goto fail_not_extensible;
}
duk_push_hobject(thr, holder);
duk_push_hstring(thr, name);
duk_push_tval(thr, val);
duk_xdef_prop(thr, -3, prop_flags); /* [holder name val] -> [holder] */
duk_pop_unsafe(thr);
return 0;
fail_existing_attributes:
fail_not_extensible:
DUK_ERROR_TYPE(thr, "declaration failed");
DUK_WO_NORETURN(return 0;);
}
DUK_INTERNAL
duk_bool_t duk_js_declvar_activation(duk_hthread *thr,
duk_activation *act,
duk_hstring *name,
duk_tval *val,
duk_small_uint_t prop_flags,
duk_bool_t is_func_decl) {
duk_hobject *env;
duk_tval tv_val_copy;
DUK_ASSERT(act != NULL);
/*
* Make a value copy of the input val. This ensures that
* side effects cannot invalidate the pointer.
*/
DUK_TVAL_SET_TVAL(&tv_val_copy, val);
val = &tv_val_copy;
/*
* Delayed env creation check
*/
if (!act->var_env) {
DUK_ASSERT(act->lex_env == NULL);
duk_js_init_activation_environment_records_delayed(thr, act);
/* 'act' is a stable pointer, so still OK. */
}
DUK_ASSERT(act->lex_env != NULL);
DUK_ASSERT(act->var_env != NULL);
env = act->var_env;
DUK_ASSERT(env != NULL);
DUK_ASSERT(DUK_HOBJECT_IS_ENV(env));
return duk__declvar_helper(thr, env, name, val, prop_flags, is_func_decl);
}