gecko/js/src/jsiter.h

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 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
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 * The Initial Developer of the Original Code is
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#ifndef jsiter_h___
#define jsiter_h___

/*
 * JavaScript iterators.
 */
#include "jscntxt.h"
#include "jsprvtd.h"
#include "jspubtd.h"
#include "jsversion.h"

#include "vm/Stack.h"

/*
 * For cacheable native iterators, whether the iterator is currently active.
 * Not serialized by XDR.
 */
#define JSITER_ACTIVE       0x1000
#define JSITER_UNREUSABLE   0x2000

namespace js {

struct NativeIterator {
    JSObject  *obj;
    jsid      *props_array;
    jsid      *props_cursor;
    jsid      *props_end;
    uint32    *shapes_array;
    uint32    shapes_length;
    uint32    shapes_key;
    uint32    flags;
    JSObject  *next;  /* Forms cx->enumerators list, garbage otherwise. */

    bool isKeyIter() const { return (flags & JSITER_FOREACH) == 0; }

    inline jsid *begin() const {
        return props_array;
    }

    inline jsid *end() const {
        return props_end;
    }

    size_t numKeys() const {
        return end() - begin();
    }

    jsid *current() const {
        JS_ASSERT(props_cursor < props_end);
        return props_cursor;
    }

    void incCursor() {
        props_cursor = props_cursor + 1;
    }

    static NativeIterator *allocateIterator(JSContext *cx, uint32 slength,
                                            const js::AutoIdVector &props);
    void init(JSObject *obj, uintN flags, uint32 slength, uint32 key);

    void mark(JSTracer *trc);
};

bool
VectorToIdArray(JSContext *cx, js::AutoIdVector &props, JSIdArray **idap);

bool
GetIterator(JSContext *cx, JSObject *obj, uintN flags, js::Value *vp);

bool
VectorToKeyIterator(JSContext *cx, JSObject *obj, uintN flags, js::AutoIdVector &props, js::Value *vp);

bool
VectorToValueIterator(JSContext *cx, JSObject *obj, uintN flags, js::AutoIdVector &props, js::Value *vp);

/*
 * Creates either a key or value iterator, depending on flags. For a value
 * iterator, performs value-lookup to convert the given list of jsids.
 */
bool
EnumeratedIdVectorToIterator(JSContext *cx, JSObject *obj, uintN flags, js::AutoIdVector &props, js::Value *vp);

}

/*
 * Convert the value stored in *vp to its iteration object. The flags should
 * contain JSITER_ENUMERATE if js_ValueToIterator is called when enumerating
 * for-in semantics are required, and when the caller can guarantee that the
 * iterator will never be exposed to scripts.
 */
extern JS_FRIEND_API(JSBool)
js_ValueToIterator(JSContext *cx, uintN flags, js::Value *vp);

extern JS_FRIEND_API(JSBool)
js_CloseIterator(JSContext *cx, JSObject *iterObj);

bool
js_SuppressDeletedProperty(JSContext *cx, JSObject *obj, jsid id);

bool
js_SuppressDeletedElement(JSContext *cx, JSObject *obj, uint32 index);

bool
js_SuppressDeletedIndexProperties(JSContext *cx, JSObject *obj, jsint begin, jsint end);

/*
 * IteratorMore() indicates whether another value is available. It might
 * internally call iterobj.next() and then cache the value until its
 * picked up by IteratorNext(). The value is cached in the current context.
 */
extern JSBool
js_IteratorMore(JSContext *cx, JSObject *iterobj, js::Value *rval);

extern JSBool
js_IteratorNext(JSContext *cx, JSObject *iterobj, js::Value *rval);

extern JSBool
js_ThrowStopIteration(JSContext *cx);

#if JS_HAS_GENERATORS

/*
 * Generator state codes.
 */
typedef enum JSGeneratorState {
    JSGEN_NEWBORN,  /* not yet started */
    JSGEN_OPEN,     /* started by a .next() or .send(undefined) call */
    JSGEN_RUNNING,  /* currently executing via .next(), etc., call */
    JSGEN_CLOSING,  /* close method is doing asynchronous return */
    JSGEN_CLOSED    /* closed, cannot be started or closed again */
} JSGeneratorState;

struct JSGenerator {
    JSObject            *obj;
    JSGeneratorState    state;
    js::FrameRegs       regs;
    JSObject            *enumerators;
    js::StackFrame      *floating;
    js::Value           floatingStack[1];

    js::StackFrame *floatingFrame() {
        return floating;
    }

    js::StackFrame *liveFrame() {
        JS_ASSERT((state == JSGEN_RUNNING || state == JSGEN_CLOSING) ==
                  (regs.fp() != floatingFrame()));
        return regs.fp();
    }
};

extern JSObject *
js_NewGenerator(JSContext *cx);

/*
 * Generator stack frames do not have stable pointers since they get copied to
 * and from the generator object and the stack (see SendToGenerator). This is a
 * problem for Block and With objects, which need to store a pointer to the
 * enclosing stack frame. The solution is for Block and With objects to store
 * a pointer to the "floating" stack frame stored in the generator object,
 * since it is stable, and maintain, in the generator object, a pointer to the
 * "live" stack frame (either a copy on the stack or the floating frame). Thus,
 * Block and With objects must "normalize" to and from the floating/live frames
 * in the case of generators using the following functions.
 */
inline js::StackFrame *
js_FloatingFrameIfGenerator(JSContext *cx, js::StackFrame *fp)
{
    if (JS_UNLIKELY(fp->isGeneratorFrame()))
        return cx->generatorFor(fp)->floatingFrame();
    return fp;
}

/* Given a floating frame, given the JSGenerator containing it. */
extern JSGenerator *
js_FloatingFrameToGenerator(js::StackFrame *fp);

inline js::StackFrame *
js_LiveFrameIfGenerator(js::StackFrame *fp)
{
    return fp->isGeneratorFrame() ? js_FloatingFrameToGenerator(fp)->liveFrame() : fp;
}

#endif

namespace js {

static inline bool
IsStopIteration(const js::Value &v)
{
    return v.isObject() && v.toObject().isStopIteration();
}

}  /* namespace js */

extern JSObject *
js_InitIteratorClasses(JSContext *cx, JSObject *obj);

#endif /* jsiter_h___ */