jsopcode.c

java script test programing source code

        }

        str = js_DecompileValueGenerator(ss->sprinter.context, off,
                                         JSVAL_NULL, NULL);
        if (!str)
            return 0;
        off = SprintCString(&ss->sprinter, JS_GetStringBytes(str));
        if (off < 0)
            off = 0;
        ss->offsets[i] = off;
    }
    return off;
}

static const char *
GetStr(SprintStack *ss, uintN i)
{
    ptrdiff_t off;

    /*
     * Must call GetOff before using ss->sprinter.base, since it may be null
     * until bootstrapped by GetOff.
     */
    off = GetOff(ss, i);
    return OFF2STR(&ss->sprinter, off);
}

/* Gap between stacked strings to allow for insertion of parens and commas. */
#define PAREN_SLOP      (2 + 1)

/*
 * These pseudo-ops help js_DecompileValueGenerator decompile JSOP_SETNAME,
 * JSOP_SETPROP, and JSOP_SETELEM, respectively.  They are never stored in
 * bytecode, so they don't preempt valid opcodes.
 */
#define JSOP_GETPROP2   256
#define JSOP_GETELEM2   257

static JSBool
PushOff(SprintStack *ss, ptrdiff_t off, JSOp op)
{
    uintN top;

    if (!SprintAlloc(&ss->sprinter, PAREN_SLOP))
        return JS_FALSE;

    /* ss->top points to the next free slot; be paranoid about overflow. */
    top = ss->top;
    JS_ASSERT(top < ss->printer->script->depth);
    if (top >= ss->printer->script->depth) {
        JS_ReportOutOfMemory(ss->sprinter.context);
        return JS_FALSE;
    }

    /* The opcodes stack must contain real bytecodes that index js_CodeSpec. */
    ss->offsets[top] = off;
    ss->opcodes[top] = (op == JSOP_GETPROP2) ? JSOP_GETPROP
                     : (op == JSOP_GETELEM2) ? JSOP_GETELEM
                     : (jsbytecode) op;
    ss->top = ++top;
    memset(OFF2STR(&ss->sprinter, ss->sprinter.offset), 0, PAREN_SLOP);
    ss->sprinter.offset += PAREN_SLOP;
    return JS_TRUE;
}

static ptrdiff_t
PopOff(SprintStack *ss, JSOp op)
{
    uintN top;
    const JSCodeSpec *cs, *topcs;
    ptrdiff_t off;

    /* ss->top points to the next free slot; be paranoid about underflow. */
    top = ss->top;
    JS_ASSERT(top != 0);
    if (top == 0)
        return 0;

    ss->top = --top;
    off = GetOff(ss, top);
    topcs = &js_CodeSpec[ss->opcodes[top]];
    cs = &js_CodeSpec[op];
    if (topcs->prec != 0 && topcs->prec < cs->prec) {
        ss->sprinter.offset = ss->offsets[top] = off - 2;
        off = Sprint(&ss->sprinter, "(%s)", OFF2STR(&ss->sprinter, off));
    } else {
        ss->sprinter.offset = off;
    }
    return off;
}

static const char *
PopStr(SprintStack *ss, JSOp op)
{
    ptrdiff_t off;

    off = PopOff(ss, op);
    return OFF2STR(&ss->sprinter, off);
}

typedef struct TableEntry {
    jsval       key;
    ptrdiff_t   offset;
    JSAtom      *label;
    jsint       order;          /* source order for stable tableswitch sort */
} TableEntry;

static JSBool
CompareOffsets(void *arg, const void *v1, const void *v2, int *result)
{
    ptrdiff_t offset_diff;
    const TableEntry *te1 = (const TableEntry *) v1,
                     *te2 = (const TableEntry *) v2;

    offset_diff = te1->offset - te2->offset;
    *result = (offset_diff == 0 ? te1->order - te2->order
               : offset_diff < 0 ? -1
               : 1);
    return JS_TRUE;
}

static jsbytecode *
Decompile(SprintStack *ss, jsbytecode *pc, intN nb);

static JSBool
DecompileSwitch(SprintStack *ss, TableEntry *table, uintN tableLength,
                jsbytecode *pc, ptrdiff_t switchLength,
                ptrdiff_t defaultOffset, JSBool isCondSwitch)
{
    JSContext *cx;
    JSPrinter *jp;
    ptrdiff_t off, off2, diff, caseExprOff;
    char *lval, *rval;
    uintN i;
    jsval key;
    JSString *str;

    cx = ss->sprinter.context;
    jp = ss->printer;

    /* JSOP_CONDSWITCH doesn't pop, unlike JSOP_{LOOKUP,TABLE}SWITCH. */
    off = isCondSwitch ? GetOff(ss, ss->top-1) : PopOff(ss, JSOP_NOP);
    lval = OFF2STR(&ss->sprinter, off);

    js_printf(CLEAR_MAYBE_BRACE(jp), "\tswitch (%s) {\n", lval);

    if (tableLength) {
        diff = table[0].offset - defaultOffset;
        if (diff > 0) {
            jp->indent += 2;
            js_printf(jp, "\t%s:\n", js_default_str);
            jp->indent += 2;
            if (!Decompile(ss, pc + defaultOffset, diff))
                return JS_FALSE;
            jp->indent -= 4;
        }

        caseExprOff = isCondSwitch ? JSOP_CONDSWITCH_LENGTH : 0;

        for (i = 0; i < tableLength; i++) {
            off = table[i].offset;
            off2 = (i + 1 < tableLength) ? table[i + 1].offset : switchLength;

            key = table[i].key;
            if (isCondSwitch) {
                ptrdiff_t nextCaseExprOff;

                /*
                 * key encodes the JSOP_CASE bytecode's offset from switchtop.
                 * The next case expression follows immediately, unless we are
                 * at the last case.
                 */
                nextCaseExprOff = (ptrdiff_t)JSVAL_TO_INT(key);
                nextCaseExprOff += js_CodeSpec[pc[nextCaseExprOff]].length;
                jp->indent += 2;
                if (!Decompile(ss, pc + caseExprOff,
                               nextCaseExprOff - caseExprOff)) {
                    return JS_FALSE;
                }
                caseExprOff = nextCaseExprOff;

                /* Balance the stack as if this JSOP_CASE matched. */
                --ss->top;
            } else {
                /*
                 * key comes from an atom, not the decompiler, so we need to
                 * quote it if it's a string literal.  But if table[i].label
                 * is non-null, key was constant-propagated and label is the
                 * name of the const we should show as the case label.  We set
                 * key to undefined so this identifier is escaped, if required
                 * by non-ASCII characters, but not quoted, by QuoteString.
                 */
                if (table[i].label) {
                    str = ATOM_TO_STRING(table[i].label);
                    key = JSVAL_VOID;
                } else {
                    str = js_ValueToString(cx, key);
                    if (!str)
                        return JS_FALSE;
                }
                rval = QuoteString(&ss->sprinter, str,
                                   (jschar)(JSVAL_IS_STRING(key) ? '"' : 0));
                if (!rval)
                    return JS_FALSE;
                RETRACT(&ss->sprinter, rval);
                jp->indent += 2;
                js_printf(jp, "\tcase %s:\n", rval);
            }

            jp->indent += 2;
            if (off <= defaultOffset && defaultOffset < off2) {
                diff = defaultOffset - off;
                if (diff != 0) {
                    if (!Decompile(ss, pc + off, diff))
                        return JS_FALSE;
                    off = defaultOffset;
                }
                jp->indent -= 2;
                js_printf(jp, "\t%s:\n", js_default_str);
                jp->indent += 2;
            }
            if (!Decompile(ss, pc + off, off2 - off))
                return JS_FALSE;
            jp->indent -= 4;

            /* Re-balance as if last JSOP_CASE or JSOP_DEFAULT mismatched. */
            if (isCondSwitch)
                ++ss->top;
        }
    }

    if (defaultOffset == switchLength) {
        jp->indent += 2;
        js_printf(jp, "\t%s:;\n", js_default_str);
        jp->indent -= 2;
    }
    js_printf(jp, "\t}\n");

    /* By the end of a JSOP_CONDSWITCH, the discriminant has been popped. */
    if (isCondSwitch)
        --ss->top;
    return JS_TRUE;
}

static JSAtom *
GetSlotAtom(JSPrinter *jp, JSPropertyOp getter, uintN slot)
{
    JSScope *scope;
    JSScopeProperty *sprop;
    JSObject *obj, *proto;

    scope = jp->scope;
    while (scope) {
        for (sprop = SCOPE_LAST_PROP(scope); sprop; sprop = sprop->parent) {
            if (sprop->getter != getter)
                continue;
            JS_ASSERT(sprop->flags & SPROP_HAS_SHORTID);
            JS_ASSERT(JSID_IS_ATOM(sprop->id));
            if ((uintN) sprop->shortid == slot)
                return JSID_TO_ATOM(sprop->id);
        }
        obj = scope->object;
        if (!obj)
            break;
        proto = OBJ_GET_PROTO(jp->sprinter.context, obj);
        if (!proto)
            break;
        scope = OBJ_SCOPE(proto);
    }
    return NULL;
}

/*
 * NB: Indexed by SRC_DECL_* defines from jsemit.h.
 */
static const char * const var_prefix[] = {"var ", "const ", "let "};

static const char *
VarPrefix(jssrcnote *sn)
{
    if (sn && (SN_TYPE(sn) == SRC_DECL || SN_TYPE(sn) == SRC_GROUPASSIGN)) {
        ptrdiff_t type = js_GetSrcNoteOffset(sn, 0);
        if ((uintN)type <= SRC_DECL_LET)
            return var_prefix[type];
    }
    return "";
}
#define LOCAL_ASSERT_RV(expr, rv)                                             \
    JS_BEGIN_MACRO                                                            \
        JS_ASSERT(expr);                                                      \
        if (!(expr)) return (rv);                                             \
    JS_END_MACRO

const char *
GetLocal(SprintStack *ss, jsint i)
{
    ptrdiff_t off;
    JSContext *cx;
    JSScript *script;
    jsatomid j, n;
    JSAtom *atom;
    JSObject *obj;
    jsint depth, count;
    JSScopeProperty *sprop;
    const char *rval;

#define LOCAL_ASSERT(expr)      LOCAL_ASSERT_RV(expr, "")

    off = ss->offsets[i];
    if (off >= 0)
        return OFF2STR(&ss->sprinter, off);

    /*
     * We must be called from js_DecompileValueGenerator (via Decompile) when
     * dereferencing a local that's undefined or null.  Search script->atomMap
     * for the block containing this local by its stack index, i.
     */
    cx = ss->sprinter.context;
    script = ss->printer->script;
    for (j = 0, n = script->atomMap.length; j < n; j++) {
        atom = script->atomMap.vector[j];
        if (ATOM_IS_OBJECT(atom)) {
            obj = ATOM_TO_OBJECT(atom);
            if (OBJ_GET_CLASS(cx, obj) == &js_BlockClass) {
                depth = OBJ_BLOCK_DEPTH(cx, obj);
                count = OBJ_BLOCK_COUNT(cx, obj);
                if ((jsuint)(i - depth) < (jsuint)count)
                    break;
            }
        }
    }

    LOCAL_ASSERT(j < n);
    i -= depth;
    for (sprop = OBJ_SCOPE(obj)->lastProp; sprop; sprop = sprop->parent) {
        if (sprop->shortid == i)
            break;
    }

    LOCAL_ASSERT(sprop && JSID_IS_ATOM(sprop->id));
    atom = JSID_TO_ATOM(sprop->id);
    rval = QuoteString(&ss->sprinter, ATOM_TO_STRING(atom), 0);
    if (!rval)
        return NULL;
    RETRACT(&ss->sprinter, rval);
    return rval;

#undef LOCAL_ASSERT
}

#if JS_HAS_DESTRUCTURING

#define LOCAL_ASSERT(expr)  LOCAL_ASSERT_RV(expr, NULL)
#define LOAD_OP_DATA(pc)    (oplen = (cs = &js_CodeSpec[op = *pc])->length)

static jsbytecode *
DecompileDestructuring(SprintStack *ss, jsbytecode *pc, jsbytecode *endpc);

static jsbytecode *
DecompileDestructuringLHS(SprintStack *ss, jsbytecode *pc, jsbytecode *endpc,
                          JSBool *hole)
{
    JSContext *cx;
    JSPrinter *jp;
    JSOp op;
    const JSCodeSpec *cs;
    uintN oplen, i;
    const char *lval, *xval;
    ptrdiff_t todo;
    JSAtom *atom;

    *hole = JS_FALSE;
    cx = ss->sprinter.context;
    jp = ss->printer;
    LOAD_OP_DATA(pc);

    switch (op) {
      case JSOP_POP:
        *hole = JS_TRUE;
        todo = SprintPut(&ss->sprinter, ", ", 2);
        break;

      case JSOP_DUP:
        pc = DecompileDestructuring(ss, pc, endpc);
        if (!pc)
            return NULL;
        if (pc == endpc)
            return pc;
        LOAD_OP_DATA(pc);
        lval = PopStr(ss, JSOP_NOP);
        todo = SprintCString(&ss->sprinter, lval);
        if (op == JSOP_SETSP)
            return pc;
        LOCAL_ASSERT(*pc == JSOP_POP);
        break;

      case JSOP_SETARG:
      case JSOP_SETVAR:
      case JSOP_SETGVAR:
      case JSOP_SETLOCAL:
        LOCAL_ASSERT(pc[oplen] == JSOP_POP || pc[oplen] == JSOP_SETSP);
        /* FALL THROUGH */