jsopcode.c

一个基于alice开发的机器人

    '\v', 'v',
    '"',  '"',
    '\'', '\'',
    '\\', '\\',
    0
};

static char *
QuoteString(Sprinter *sp, JSString *str, jschar quote)
{
    ptrdiff_t off, len, nb;
    const jschar *s, *t, *u, *z;
    char *bp;
    jschar c;
    JSBool ok;

    /* Sample off first for later return value pointer computation. */
    off = sp->offset;
    if (quote && Sprint(sp, "%c", (char)quote) < 0)
        return NULL;

    /* Loop control variables: z points at end of string sentinel. */
    s = JSSTRING_CHARS(str);
    z = s + JSSTRING_LENGTH(str);
    for (t = s; t < z; s = ++t) {
        /* Move t forward from s past un-quote-worthy characters. */
        c = *t;
        while (JS_ISPRINT(c) && c != quote && c != '\\' && !(c >> 8)) {
            c = *++t;
            if (t == z)
                break;
        }
        len = PTRDIFF(t, s, jschar);

        /* Allocate space for s, including the '\0' at the end. */
        nb = (sp->offset + len + 1) - sp->size;
        if (nb > 0 && !SprintAlloc(sp, nb))
            return NULL;

        /* Advance sp->offset and copy s into sp's buffer. */
        bp = sp->base + sp->offset;
        sp->offset += len;
        while (--len >= 0)
            *bp++ = (char) *s++;
        *bp = '\0';

        if (t == z)
            break;

        /* Use js_EscapeMap, \u, or \x only if necessary. */
        if ((u = js_strchr(js_EscapeMap, c)) != NULL)
            ok = Sprint(sp, "\\%c", (char)u[1]) >= 0;
        else
            ok = Sprint(sp, (c >> 8) ? "\\u%04X" : "\\x%02X", c) >= 0;
        if (!ok)
            return NULL;
    }

    /* Sprint the closing quote and return the quoted string. */
    if (quote && Sprint(sp, "%c", (char)quote) < 0)
        return NULL;
    return OFF2STR(sp, off);
}

JSString *
js_QuoteString(JSContext *cx, JSString *str, jschar quote)
{
    void *mark;
    Sprinter sprinter;
    char *bytes;
    JSString *escstr;

    mark = JS_ARENA_MARK(&cx->tempPool);
    INIT_SPRINTER(cx, &sprinter, &cx->tempPool, 0);
    bytes = QuoteString(&sprinter, str, quote);
    escstr = bytes ? JS_NewStringCopyZ(cx, bytes) : NULL;
    JS_ARENA_RELEASE(&cx->tempPool, mark);
    return escstr;
}

/************************************************************************/

struct JSPrinter {
    Sprinter        sprinter;       /* base class state */
    JSArenaPool     pool;           /* string allocation pool */
    uintN           indent;         /* indentation in spaces */
    JSBool          pretty;         /* pretty-print: indent, use newlines */
    JSScript        *script;        /* script being printed */
    JSScope         *scope;         /* script function scope */
};

JSPrinter *
js_NewPrinter(JSContext *cx, const char *name, uintN indent, JSBool pretty)
{
    JSPrinter *jp;
    JSStackFrame *fp;
    JSObjectMap *map;

    jp = (JSPrinter *) JS_malloc(cx, sizeof(JSPrinter));
    if (!jp)
        return NULL;
    INIT_SPRINTER(cx, &jp->sprinter, &jp->pool, 0);
    JS_InitArenaPool(&jp->pool, name, 256, 1);
    jp->indent = indent;
    jp->pretty = pretty;
    jp->script = NULL;
    jp->scope = NULL;
    fp = cx->fp;
    if (fp && fp->fun && fp->fun->object) {
        map = fp->fun->object->map;
        if (MAP_IS_NATIVE(map))
            jp->scope = (JSScope *)map;
    }
    return jp;
}

void
js_DestroyPrinter(JSPrinter *jp)
{
    JS_FinishArenaPool(&jp->pool);
    JS_free(jp->sprinter.context, jp);
}

JSString *
js_GetPrinterOutput(JSPrinter *jp)
{
    JSContext *cx;
    JSString *str;

    cx = jp->sprinter.context;
    if (!jp->sprinter.base)
        return cx->runtime->emptyString;
    str = JS_NewStringCopyZ(cx, jp->sprinter.base);
    if (!str)
        return NULL;
    JS_FreeArenaPool(&jp->pool);
    INIT_SPRINTER(cx, &jp->sprinter, &jp->pool, 0);
    return str;
}

int
js_printf(JSPrinter *jp, const char *format, ...)
{
    va_list ap;
    char *bp, *fp;
    int cc;

    if (*format == '\0')
        return 0;

    va_start(ap, format);

    /* If pretty-printing, expand magic tab into a run of jp->indent spaces. */
    if (*format == '\t') {
        if (jp->pretty && Sprint(&jp->sprinter, "%*s", jp->indent, "") < 0)
            return -1;
        format++;
    }

    /* Suppress newlines (must be once per format, at the end) if not pretty. */
    fp = NULL;
    if (!jp->pretty && format[cc = strlen(format)-1] == '\n') {
        fp = JS_strdup(jp->sprinter.context, format);
        if (!fp)
            return -1;
        fp[cc] = '\0';
        format = fp;
    }

    /* Allocate temp space, convert format, and put. */
    bp = JS_vsmprintf(format, ap);	/* XXX vsaprintf */
    if (fp) {
        JS_free(jp->sprinter.context, fp);
        format = NULL;
    }
    if (!bp) {
        JS_ReportOutOfMemory(jp->sprinter.context);
        return -1;
    }

    cc = strlen(bp);
    if (SprintPut(&jp->sprinter, bp, (size_t)cc) < 0)
        cc = -1;
    free(bp);

    va_end(ap);
    return cc;
}

JSBool
js_puts(JSPrinter *jp, const char *s)
{
    return SprintPut(&jp->sprinter, s, strlen(s)) >= 0;
}

/************************************************************************/

typedef struct SprintStack {
    Sprinter    sprinter;       /* sprinter for postfix to infix buffering */
    ptrdiff_t   *offsets;       /* stack of postfix string offsets */
    jsbytecode  *opcodes;       /* parallel stack of JS opcodes */
    uintN       top;            /* top of stack index */
    JSPrinter   *printer;       /* permanent output goes here */
} SprintStack;

/* 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.  See the first assertion in
 * PushOff.
 */
#define JSOP_GETPROP2   254
#define JSOP_GETELEM2   255

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

#if JSOP_LIMIT > JSOP_GETPROP2
#error JSOP_LIMIT must be <= JSOP_GETPROP2
#endif
    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;
    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;
    topcs = &js_CodeSpec[ss->opcodes[top]];
    cs = &js_CodeSpec[op];
    if (topcs->prec != 0 && topcs->prec < cs->prec) {
        ss->offsets[top] -= 2;
        ss->sprinter.offset = ss->offsets[top];
        off = Sprint(&ss->sprinter, "(%s)",
                     OFF2STR(&ss->sprinter, ss->sprinter.offset + 2));
    } else {
        off = ss->sprinter.offset = ss->offsets[top];
    }
    return off;
}

#if JS_HAS_SWITCH_STATEMENT
typedef struct TableEntry {
    jsval       key;
    ptrdiff_t   offset;
} TableEntry;

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

    return te1->offset - te2->offset;
}

static JSBool
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;
    char *lval, *rval;
    uintN i;
    ptrdiff_t diff, off, off2, caseExprOff;
    jsval key;
    JSString *str;

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

    lval = OFF2STR(&ss->sprinter, PopOff(ss, JSOP_NOP));
    js_printf(jp, "\tswitch (%s) {\n", lval);

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

        caseExprOff = isCondSwitch
                      ? (ptrdiff_t) js_CodeSpec[JSOP_CONDSWITCH].length
                      : 0;

        for (i = 0; i < tableLength; i++) {
            off = table[i].offset;
            if (i + 1 < tableLength)
                off2 = table[i + 1].offset;
            else
                off2 = 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;
           } else {
                /*
                 * key comes from an atom, not the decompiler, so we need to
                 * quote it if it's a string literal.
                 */
                str = js_ValueToString(cx, key);
                if (!str)
                    return JS_FALSE;
                jp->indent += 2;
                if (JSVAL_IS_STRING(key)) {
                    rval = QuoteString(&ss->sprinter, str, (jschar)'"');
                    if (!rval)
                        return JS_FALSE;
                    RETRACT(&ss->sprinter, rval);
                } else {
                    rval = JS_GetStringBytes(str);
                }
                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;