/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jsfun_h___
#define jsfun_h___
/*
 * JS function definitions.
 */
#include "jsprvtd.h"
#include "jspubtd.h"
#include "jsobj.h"
#include "jsatom.h"
#include "jsscript.h"
#include "jsstr.h"

#include "gc/Barrier.h"

/*
 * The high two bits of JSFunction.flags encode whether the function is native
 * or interpreted, and if interpreted, what kind of optimized closure form (if
 * any) it might be.
 *
 *   00   not interpreted
 *   01   interpreted, not null closure
 *   11   interpreted, null closure
 *
 * NB: JSFUN_EXPR_CLOSURE reuses JSFUN_STUB_GSOPS, which is an API request flag
 * bit only, never stored in fun->flags.
 *
 * If we need more bits in the future, all flags for interpreted functions can
 * move to u.i.script->flags. For now we use function flag bits to minimize
 * pointer-chasing.
 */
#define JSFUN_PROTOTYPE     0x0800  /* function is Function.prototype for some
                                       global object */

#define JSFUN_EXPR_CLOSURE  0x1000  /* expression closure: function(x) x*x */
#define JSFUN_EXTENDED      0x2000  /* structure is FunctionExtended */
#define JSFUN_INTERPRETED   0x4000  /* use u.i if kind >= this value else u.native */
#define JSFUN_NULL_CLOSURE  0x8000  /* null closure entrains no scope chain */
#define JSFUN_KINDMASK      0xc000  /* encode interp vs. native and closure
                                       optimization level -- see above */

namespace js { class FunctionExtended; }

struct JSFunction : public JSObject
{
    uint16_t        nargs;        /* maximum number of specified arguments,
                                     reflected as f.length/f.arity */
    uint16_t        flags;        /* flags, see JSFUN_* below and in jsapi.h */
    union U {
        js::Native  native;       /* native method pointer or null */
        struct Scripted {
            JSScript    *script_; /* interpreted bytecode descriptor or null;
                                     use the accessor! */
            JSObject    *env_;    /* environment for new activations;
                                     use the accessor! */
        } i;
        void            *nativeOrScript;
    } u;
    js::HeapPtrAtom  atom;        /* name for diagnostics and decompiling */

    bool hasDefaults()       const { return flags & JSFUN_HAS_DEFAULTS; }
    bool hasRest()           const { return flags & JSFUN_HAS_REST; }
    bool isInterpreted()     const { return kind() >= JSFUN_INTERPRETED; }
    bool isNative()          const { return !isInterpreted(); }
    bool isNativeConstructor() const { return flags & JSFUN_CONSTRUCTOR; }
    bool isHeavyweight()     const { return JSFUN_HEAVYWEIGHT_TEST(flags); }
    bool isNullClosure()     const { return kind() == JSFUN_NULL_CLOSURE; }
    bool isFunctionPrototype() const { return flags & JSFUN_PROTOTYPE; }
    bool isInterpretedConstructor() const { return isInterpreted() && !isFunctionPrototype(); }
    bool isNamedLambda()     const { return (flags & JSFUN_LAMBDA) && atom; }

    uint16_t kind()          const { return flags & JSFUN_KINDMASK; }
    void setKind(uint16_t k) {
        JS_ASSERT(!(k & ~JSFUN_KINDMASK));
        flags = (flags & ~JSFUN_KINDMASK) | k;
    }

    /* Returns the strictness of this function, which must be interpreted. */
    inline bool inStrictMode() const;

    void setArgCount(uint16_t nargs) {
        JS_ASSERT(this->nargs == 0);
        this->nargs = nargs;
    }

    void setHasRest() {
        JS_ASSERT(!hasRest());
        this->flags |= JSFUN_HAS_REST;
    }

    void setHasDefaults() {
        JS_ASSERT(!hasDefaults());
        this->flags |= JSFUN_HAS_DEFAULTS;
    }

    /* uint16_t representation bounds number of call object dynamic slots. */
    enum { MAX_ARGS_AND_VARS = 2 * ((1U << 16) - 1) };

    /*
     * For an interpreted function, accessors for the initial scope object of
     * activations (stack frames) of the function.
     */
    inline JSObject *environment() const;
    inline void setEnvironment(JSObject *obj);
    inline void initEnvironment(JSObject *obj);

    static inline size_t offsetOfEnvironment() { return offsetof(JSFunction, u.i.env_); }

    JSScript *script() const {
        JS_ASSERT(isInterpreted());
        return *(js::HeapPtrScript *)&u.i.script_;
    }

    js::HeapPtrScript &mutableScript() {
        JS_ASSERT(isInterpreted());
        return *(js::HeapPtrScript *)&u.i.script_;
    }

    inline void setScript(JSScript *script_);
    inline void initScript(JSScript *script_);

    JSScript *maybeScript() const {
        return isInterpreted() ? script() : NULL;
    }

    JSNative native() const {
        JS_ASSERT(isNative());
        return u.native;
    }

    JSNative maybeNative() const {
        return isInterpreted() ? NULL : native();
    }

    static unsigned offsetOfNativeOrScript() {
        JS_STATIC_ASSERT(offsetof(U, native) == offsetof(U, i.script_));
        JS_STATIC_ASSERT(offsetof(U, native) == offsetof(U, nativeOrScript));
        return offsetof(JSFunction, u.nativeOrScript);
    }

#if JS_BITS_PER_WORD == 32
    static const js::gc::AllocKind FinalizeKind = js::gc::FINALIZE_OBJECT2_BACKGROUND;
    static const js::gc::AllocKind ExtendedFinalizeKind = js::gc::FINALIZE_OBJECT4_BACKGROUND;
#else
    static const js::gc::AllocKind FinalizeKind = js::gc::FINALIZE_OBJECT4_BACKGROUND;
    static const js::gc::AllocKind ExtendedFinalizeKind = js::gc::FINALIZE_OBJECT8_BACKGROUND;
#endif

    inline void trace(JSTracer *trc);

    /* Bound function accessors. */

    inline bool initBoundFunction(JSContext *cx, js::HandleValue thisArg,
                                  const js::Value *args, unsigned argslen);

    inline JSObject *getBoundFunctionTarget() const;
    inline const js::Value &getBoundFunctionThis() const;
    inline const js::Value &getBoundFunctionArgument(unsigned which) const;
    inline size_t getBoundFunctionArgumentCount() const;

  private:
    inline js::FunctionExtended *toExtended();
    inline const js::FunctionExtended *toExtended() const;

    inline bool isExtended() const {
        JS_STATIC_ASSERT(FinalizeKind != ExtendedFinalizeKind);
        JS_ASSERT(!!(flags & JSFUN_EXTENDED) == (getAllocKind() == ExtendedFinalizeKind));
        return !!(flags & JSFUN_EXTENDED);
    }

  public:
    /* Accessors for data stored in extended functions. */
    inline void initializeExtended();
    inline void setExtendedSlot(size_t which, const js::Value &val);
    inline const js::Value &getExtendedSlot(size_t which) const;

    /* Constructs a new type for the function if necessary. */
    bool setTypeForScriptedFunction(JSContext *cx, bool singleton = false);

  private:
    /*
     * These member functions are inherited from JSObject, but should never be applied to
     * a value statically known to be a JSFunction.
     */
    inline JSFunction *toFunction() MOZ_DELETE;
    inline const JSFunction *toFunction() const MOZ_DELETE;
};

inline JSFunction *
JSObject::toFunction()
{
    JS_ASSERT(JS_ObjectIsFunction(NULL, this));
    return static_cast<JSFunction *>(this);
}

inline const JSFunction *
JSObject::toFunction() const
{
    JS_ASSERT(JS_ObjectIsFunction(NULL, const_cast<JSObject *>(this)));
    return static_cast<const JSFunction *>(this);
}

extern JSString *
fun_toStringHelper(JSContext *cx, JSObject *obj, unsigned indent);

extern JSFunction *
js_NewFunction(JSContext *cx, JSObject *funobj, JSNative native, unsigned nargs,
               unsigned flags, js::HandleObject parent, JSAtom *atom,
               js::gc::AllocKind kind = JSFunction::FinalizeKind);

extern JSFunction * JS_FASTCALL
js_CloneFunctionObject(JSContext *cx, js::HandleFunction fun,
                       js::HandleObject parent, js::HandleObject proto,
                       js::gc::AllocKind kind = JSFunction::FinalizeKind);

extern JSFunction *
js_DefineFunction(JSContext *cx, js::HandleObject obj, js::HandleId id, JSNative native,
                  unsigned nargs, unsigned flags,
                  js::gc::AllocKind kind = JSFunction::FinalizeKind);

namespace js {

/*
 * Function extended with reserved slots for use by various kinds of functions.
 * Most functions do not have these extensions, but enough are that efficient
 * storage is required (no malloc'ed reserved slots).
 */
class FunctionExtended : public JSFunction
{
    friend struct JSFunction;

    /* Reserved slots available for storage by particular native functions. */
    HeapValue extendedSlots[2];
};

} // namespace js

inline js::FunctionExtended *
JSFunction::toExtended()
{
    JS_ASSERT(isExtended());
    return static_cast<js::FunctionExtended *>(this);
}

inline const js::FunctionExtended *
JSFunction::toExtended() const
{
    JS_ASSERT(isExtended());
    return static_cast<const js::FunctionExtended *>(this);
}

namespace js {

template<XDRMode mode>
bool
XDRInterpretedFunction(XDRState<mode> *xdr, HandleObject enclosingScope,
                       HandleScript enclosingScript, JSObject **objp);

extern JSObject *
CloneInterpretedFunction(JSContext *cx, HandleObject enclosingScope, HandleFunction fun);

} /* namespace js */

extern JSBool
js_fun_apply(JSContext *cx, unsigned argc, js::Value *vp);

extern JSBool
js_fun_call(JSContext *cx, unsigned argc, js::Value *vp);

extern JSObject*
js_fun_bind(JSContext *cx, js::HandleObject target, js::HandleValue thisArg,
            js::Value *boundArgs, unsigned argslen);

#endif /* jsfun_h___ */