/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set sw=4 ts=8 et tw=78:
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Nick Fitzgerald <nfitzgerald@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*
 * JS lexical scanner.
 */
#include <stdio.h>      /* first to avoid trouble on some systems */
#include <errno.h>
#include <limits.h>
#include <math.h>
#ifdef HAVE_MEMORY_H
#include <memory.h>
#endif
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsstdint.h"
#include "jsbit.h"
#include "jsutil.h"
#include "jsprf.h"
#include "jsapi.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsversion.h"
#include "jsemit.h"
#include "jsexn.h"
#include "jsnum.h"
#include "jsopcode.h"
#include "jsparse.h"
#include "jsregexp.h"
#include "jsscan.h"
#include "jsscript.h"
#include "jsstaticcheck.h"
#include "jsvector.h"

#include "jsscriptinlines.h"

#if JS_HAS_XML_SUPPORT
#include "jsxml.h"
#endif

using namespace js;
using namespace js::unicode;

#define JS_KEYWORD(keyword, type, op, version) \
    const char js_##keyword##_str[] = #keyword;
#include "jskeyword.tbl"
#undef JS_KEYWORD

static const KeywordInfo keywords[] = {
#define JS_KEYWORD(keyword, type, op, version) \
    {js_##keyword##_str, type, op, version},
#include "jskeyword.tbl"
#undef JS_KEYWORD
};

namespace js {

const KeywordInfo *
FindKeyword(const jschar *s, size_t length)
{
    JS_ASSERT(length != 0);

    register size_t i;
    const struct KeywordInfo *kw;
    const char *chars;

#define JSKW_LENGTH()           length
#define JSKW_AT(column)         s[column]
#define JSKW_GOT_MATCH(index)   i = (index); goto got_match;
#define JSKW_TEST_GUESS(index)  i = (index); goto test_guess;
#define JSKW_NO_MATCH()         goto no_match;
#include "jsautokw.h"
#undef JSKW_NO_MATCH
#undef JSKW_TEST_GUESS
#undef JSKW_GOT_MATCH
#undef JSKW_AT
#undef JSKW_LENGTH

  got_match:
    return &keywords[i];

  test_guess:
    kw = &keywords[i];
    chars = kw->chars;
    do {
        if (*s++ != (unsigned char)(*chars++))
            goto no_match;
    } while (--length != 0);
    return kw;

  no_match:
    return NULL;
}

} // namespace js

JSBool
js_IsIdentifier(JSLinearString *str)
{
    const jschar *chars = str->chars();
    size_t length = str->length();

    if (length == 0)
        return JS_FALSE;
    jschar c = *chars;
    if (!IsIdentifierStart(c))
        return JS_FALSE;
    const jschar *end = chars + length;
    while (++chars != end) {
        c = *chars;
        if (!IsIdentifierPart(c))
            return JS_FALSE;
    }
    return JS_TRUE;
}

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable:4351)
#endif

/* Initialize members that aren't initialized in |init|. */
TokenStream::TokenStream(JSContext *cx)
  : cx(cx), tokens(), cursor(), lookahead(), flags(), listenerTSData(), tokenbuf(cx)
{}

#ifdef _MSC_VER
#pragma warning(pop)
#endif

bool
TokenStream::init(const jschar *base, size_t length, const char *fn, uintN ln, JSVersion v)
{
    filename = fn;
    lineno = ln;
    version = v;
    xml = VersionHasXML(v);

    userbuf.init(base, length);
    linebase = base;
    prevLinebase = NULL;
    sourceMap = NULL;

    JSSourceHandler listener = cx->debugHooks->sourceHandler;
    void *listenerData = cx->debugHooks->sourceHandlerData;

    if (listener)
        listener(fn, ln, base, length, &listenerTSData, listenerData);

    /*
     * This table holds all the token kinds that satisfy these properties:
     * - A single char long.
     * - Cannot be a prefix of any longer token (eg. '+' is excluded because
     *   '+=' is a valid token).
     * - Doesn't need tp->t_op set (eg. this excludes '~').
     *
     * The few token kinds satisfying these properties cover roughly 35--45%
     * of the tokens seen in practice.
     *
     * Nb: oneCharTokens, maybeEOL and maybeStrSpecial could be static, but
     * initializing them this way is a bit easier.  Don't worry, the time to
     * initialize them for each TokenStream is trivial.  See bug 639420.
     */
    memset(oneCharTokens, 0, sizeof(oneCharTokens));
    oneCharTokens[unsigned(';')] = TOK_SEMI;
    oneCharTokens[unsigned(',')] = TOK_COMMA;
    oneCharTokens[unsigned('?')] = TOK_HOOK;
    oneCharTokens[unsigned('[')] = TOK_LB;
    oneCharTokens[unsigned(']')] = TOK_RB;
    oneCharTokens[unsigned('{')] = TOK_LC;
    oneCharTokens[unsigned('}')] = TOK_RC;
    oneCharTokens[unsigned('(')] = TOK_LP;
    oneCharTokens[unsigned(')')] = TOK_RP;

    /* See getChar() for an explanation of maybeEOL[]. */
    memset(maybeEOL, 0, sizeof(maybeEOL));
    maybeEOL[unsigned('\n')] = true;
    maybeEOL[unsigned('\r')] = true;
    maybeEOL[unsigned(LINE_SEPARATOR & 0xff)] = true;
    maybeEOL[unsigned(PARA_SEPARATOR & 0xff)] = true;

    /* See getTokenInternal() for an explanation of maybeStrSpecial[]. */
    memset(maybeStrSpecial, 0, sizeof(maybeStrSpecial));
    maybeStrSpecial[unsigned('"')] = true;
    maybeStrSpecial[unsigned('\'')] = true;
    maybeStrSpecial[unsigned('\\')] = true;
    maybeStrSpecial[unsigned('\n')] = true;
    maybeStrSpecial[unsigned('\r')] = true;
    maybeStrSpecial[unsigned(LINE_SEPARATOR & 0xff)] = true;
    maybeStrSpecial[unsigned(PARA_SEPARATOR & 0xff)] = true;
    maybeStrSpecial[unsigned(EOF & 0xff)] = true;

    /*
     * Set |ln| as the beginning line number of the ungot "current token", so
     * that js::Parser::statements (and potentially other such methods, in the
     * future) can create parse nodes with good source coordinates before they
     * explicitly get any tokens.
     *
     * Switching the parser/lexer so we always get the next token ahead of the
     * parser needing it (the so-called "pump-priming" model) might be a better
     * way to address the dependency from statements on the current token.
     */
    tokens[0].pos.begin.lineno = tokens[0].pos.end.lineno = ln;
    return true;
}

TokenStream::~TokenStream()
{
    if (flags & TSF_OWNFILENAME)
        cx->free_((void *) filename);
    if (sourceMap)
        cx->free_(sourceMap);
}

/* Use the fastest available getc. */
#if defined(HAVE_GETC_UNLOCKED)
# define fast_getc getc_unlocked
#elif defined(HAVE__GETC_NOLOCK)
# define fast_getc _getc_nolock
#else
# define fast_getc getc
#endif

JS_FRIEND_API(int)
js_fgets(char *buf, int size, FILE *file)
{
    int n, i, c;
    JSBool crflag;

    n = size - 1;
    if (n < 0)
        return -1;

    crflag = JS_FALSE;
    for (i = 0; i < n && (c = fast_getc(file)) != EOF; i++) {
        buf[i] = c;
        if (c == '\n') {        /* any \n ends a line */
            i++;                /* keep the \n; we know there is room for \0 */
            break;
        }
        if (crflag) {           /* \r not followed by \n ends line at the \r */
            ungetc(c, file);
            break;              /* and overwrite c in buf with \0 */
        }
        crflag = (c == '\r');
    }

    buf[i] = '\0';
    return i;
}

JS_ALWAYS_INLINE void
TokenStream::updateLineInfoForEOL()
{
    prevLinebase = linebase;
    linebase = userbuf.addressOfNextRawChar();
    lineno++;
}

JS_ALWAYS_INLINE void
TokenStream::updateFlagsForEOL()
{
    flags &= ~TSF_DIRTYLINE;
    flags |= TSF_EOL;
}

/* This gets the next char, normalizing all EOL sequences to '\n' as it goes. */
int32
TokenStream::getChar()
{
    int32 c;
    if (JS_LIKELY(userbuf.hasRawChars())) {
        c = userbuf.getRawChar();

        /*
         * Normalize the jschar if it was a newline.  We need to detect any of
         * these four characters:  '\n' (0x000a), '\r' (0x000d),
         * LINE_SEPARATOR (0x2028), PARA_SEPARATOR (0x2029).  Testing for each
         * one in turn is slow, so we use a single probabilistic check, and if
         * that succeeds, test for them individually.
         *
         * We use the bottom 8 bits to index into a lookup table, succeeding
         * when d&0xff is 0xa, 0xd, 0x28 or 0x29.  Among ASCII chars (which
         * are by the far the most common) this gives false positives for '('
         * (0x0028) and ')' (0x0029).  We could avoid those by incorporating
         * the 13th bit of d into the lookup, but that requires extra shifting
         * and masking and isn't worthwhile.  See TokenStream::init() for the
         * initialization of the relevant entries in the table.
         */
        if (JS_UNLIKELY(maybeEOL[c & 0xff])) {
            if (c == '\n')
                goto eol;
            if (c == '\r') {
                /* if it's a \r\n sequence: treat as a single EOL, skip over the \n */
                if (userbuf.hasRawChars())
                    userbuf.matchRawChar('\n');
                goto eol;
            }
            if (c == LINE_SEPARATOR || c == PARA_SEPARATOR)
                goto eol;
        }
        return c;
    }

    flags |= TSF_EOF;
    return EOF;

  eol:
    updateLineInfoForEOL();
    return '\n';
}

/*
 * This gets the next char. It does nothing special with EOL sequences, not
 * even updating the line counters.  It can be used safely if (a) the
 * resulting char is guaranteed to be ungotten (by ungetCharIgnoreEOL()) if
 * it's an EOL, and (b) the line-related state (lineno, linebase) is not used
 * before it's ungotten.
 */
int32
TokenStream::getCharIgnoreEOL()
{
    if (JS_LIKELY(userbuf.hasRawChars()))
        return userbuf.getRawChar();

    flags |= TSF_EOF;
    return EOF;
}

void
TokenStream::ungetChar(int32 c)
{
    if (c == EOF)
        return;
    JS_ASSERT(!userbuf.atStart());
    userbuf.ungetRawChar();
    if (c == '\n') {
#ifdef DEBUG
        int32 c2 = userbuf.peekRawChar();
        JS_ASSERT(TokenBuf::isRawEOLChar(c2));
#endif

        /* if it's a \r\n sequence, also unget the \r */
        if (!userbuf.atStart())
            userbuf.matchRawCharBackwards('\r');

        JS_ASSERT(prevLinebase);    /* we should never get more than one EOL char */
        linebase = prevLinebase;
        prevLinebase = NULL;
        lineno--;
    } else {
        JS_ASSERT(userbuf.peekRawChar() == c);
    }
}

void
TokenStream::ungetCharIgnoreEOL(int32 c)
{
    if (c == EOF)
        return;
    JS_ASSERT(!userbuf.atStart());
    userbuf.ungetRawChar();
}

/*
 * Return true iff |n| raw characters can be read from this without reading past
 * EOF or a newline, and copy those characters into |cp| if so.  The characters
 * are not consumed: use skipChars(n) to do so after checking that the consumed
 * characters had appropriate values.
 */
bool
TokenStream::peekChars(intN n, jschar *cp)
{
    intN i, j;
    int32 c;

    for (i = 0; i < n; i++) {
        c = getCharIgnoreEOL();
        if (c == EOF)
            break;
        if (c == '\n') {
            ungetCharIgnoreEOL(c);
            break;
        }
        cp[i] = (jschar)c;
    }
    for (j = i - 1; j >= 0; j--)
        ungetCharIgnoreEOL(cp[j]);
    return i == n;
}

const jschar *
TokenStream::TokenBuf::findEOL()
{
    const jschar *tmp = ptr;
#ifdef DEBUG
    /*
     * This is the one exception to the "TokenBuf isn't accessed after
     * poisoning" rule -- we may end up calling findEOL() in order to set up
     * an error.
     */
    if (!tmp)
        tmp = ptrWhenPoisoned;
#endif

    while (true) {
        if (tmp >= limit)
            break;
        if (TokenBuf::isRawEOLChar(*tmp++))
            break;
    }
    return tmp;
}

bool
TokenStream::reportCompileErrorNumberVA(JSParseNode *pn, uintN flags, uintN errorNumber,
                                        va_list ap)
{
    JSErrorReport report;
    char *message;
    jschar *linechars;
    char *linebytes;
    bool warning;
    JSBool ok;
    const TokenPos *tp;
    uintN i;

    if (JSREPORT_IS_STRICT(flags) && !cx->hasStrictOption())
        return true;

    warning = JSREPORT_IS_WARNING(flags);
    if (warning && cx->hasWErrorOption()) {
        flags &= ~JSREPORT_WARNING;
        warning = false;
    }

    PodZero(&report);
    report.flags = flags;
    report.errorNumber = errorNumber;
    message = NULL;
    linechars = NULL;
    linebytes = NULL;

    MUST_FLOW_THROUGH("out");
    ok = js_ExpandErrorArguments(cx, js_GetErrorMessage, NULL,
                                 errorNumber, &message, &report,
                                 !(flags & JSREPORT_UC), ap);
    if (!ok) {
        warning = false;
        goto out;
    }

    report.filename = filename;

    tp = pn ? &pn->pn_pos : &currentToken().pos;
    report.lineno = tp->begin.lineno;

    /*
     * Given a token, T, that we want to complain about: if T's (starting)
     * lineno doesn't match TokenStream's lineno, that means we've scanned past
     * the line that T starts on, which makes it hard to print some or all of
     * T's (starting) line for context.
     *
     * So we don't even try, leaving report.linebuf and friends zeroed.  This
     * means that any error involving a multi-line token (eg. an unterminated
     * multi-line string literal) won't have a context printed.
     */
    if (report.lineno == lineno) {
        size_t linelength = userbuf.findEOL() - linebase;

        linechars = (jschar *)cx->malloc_((linelength + 1) * sizeof(jschar));
        if (!linechars) {
            warning = false;
            goto out;
        }
        memcpy(linechars, linebase, linelength * sizeof(jschar));
        linechars[linelength] = 0;
        linebytes = DeflateString(cx, linechars, linelength);
        if (!linebytes) {
            warning = false;
            goto out;
        }

        /* Unicode and char versions of the offending source line, without final \n */
        report.linebuf = linebytes;
        report.uclinebuf = linechars;

        /* The lineno check above means we should only see single-line tokens here. */
        JS_ASSERT(tp->begin.lineno == tp->end.lineno);
        report.tokenptr = report.linebuf + tp->begin.index;
        report.uctokenptr = report.uclinebuf + tp->begin.index;
    }

    /*
     * If there's a runtime exception type associated with this error
     * number, set that as the pending exception.  For errors occuring at
     * compile time, this is very likely to be a JSEXN_SYNTAXERR.
     *
     * If an exception is thrown but not caught, the JSREPORT_EXCEPTION
     * flag will be set in report.flags.  Proper behavior for an error
     * reporter is to ignore a report with this flag for all but top-level
     * compilation errors.  The exception will remain pending, and so long
     * as the non-top-level "load", "eval", or "compile" native function
     * returns false, the top-level reporter will eventually receive the
     * uncaught exception report.
     */
    if (!js_ErrorToException(cx, message, &report, NULL, NULL)) {
        /*
         * If debugErrorHook is present then we give it a chance to veto
         * sending the error on to the regular error reporter.
         */
        bool reportError = true;
        if (JSDebugErrorHook hook = cx->debugHooks->debugErrorHook)
            reportError = hook(cx, message, &report, cx->debugHooks->debugErrorHookData);

        /* Report the error */
        if (reportError && cx->errorReporter)
            cx->errorReporter(cx, message, &report);
    }

  out:
    if (linebytes)
        cx->free_(linebytes);
    if (linechars)
        cx->free_(linechars);
    if (message)
        cx->free_(message);
    if (report.ucmessage)
        cx->free_((void *)report.ucmessage);

    if (report.messageArgs) {
        if (!(flags & JSREPORT_UC)) {
            i = 0;
            while (report.messageArgs[i])
                cx->free_((void *)report.messageArgs[i++]);
        }
        cx->free_((void *)report.messageArgs);
    }

    return warning;
}

bool
js::ReportStrictModeError(JSContext *cx, TokenStream *ts, JSTreeContext *tc, JSParseNode *pn,
                          uintN errorNumber, ...)
{
    JS_ASSERT(ts || tc);
    JS_ASSERT(cx == ts->getContext());

    /* In strict mode code, this is an error, not merely a warning. */
    uintN flags;
    if ((ts && ts->isStrictMode()) || (tc && (tc->flags & TCF_STRICT_MODE_CODE))) {
        flags = JSREPORT_ERROR;
    } else {
        if (!cx->hasStrictOption())
            return true;
        flags = JSREPORT_WARNING;
    }

    va_list ap;
    va_start(ap, errorNumber);
    bool result = ts->reportCompileErrorNumberVA(pn, flags, errorNumber, ap);
    va_end(ap);

    return result;
}

bool
js::ReportCompileErrorNumber(JSContext *cx, TokenStream *ts, JSParseNode *pn,
                             uintN flags, uintN errorNumber, ...)
{
    va_list ap;

    /*
     * We don't accept a JSTreeContext argument, so we can't implement
     * JSREPORT_STRICT_MODE_ERROR here.  Use ReportStrictModeError instead,
     * or do the checks in the caller and pass plain old JSREPORT_ERROR.
     */
    JS_ASSERT(!(flags & JSREPORT_STRICT_MODE_ERROR));

    va_start(ap, errorNumber);
    JS_ASSERT(cx == ts->getContext());
    bool result = ts->reportCompileErrorNumberVA(pn, flags, errorNumber, ap);
    va_end(ap);

    return result;
}

#if JS_HAS_XML_SUPPORT

bool
TokenStream::getXMLEntity()
{
    ptrdiff_t offset, length, i;
    int c, d;
    JSBool ispair;
    jschar *bp, digit;
    char *bytes;
    JSErrNum msg;

    CharBuffer &tb = tokenbuf;

    /* Put the entity, including the '&' already scanned, in tokenbuf. */
    offset = tb.length();
    if (!tb.append('&'))
        return false;
    while ((c = getChar()) != ';') {
        if (c == EOF || c == '\n') {
            ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_END_OF_XML_ENTITY);
            return false;
        }
        if (!tb.append(c))
            return false;
    }

    /* Let length be the number of jschars after the '&', including the ';'. */
    length = tb.length() - offset;
    bp = tb.begin() + offset;
    c = d = 0;
    ispair = false;
    if (length > 2 && bp[1] == '#') {
        /* Match a well-formed XML Character Reference. */
        i = 2;
        if (length > 3 && (bp[i] == 'x' || bp[i] == 'X')) {
            if (length > 9)     /* at most 6 hex digits allowed */
                goto badncr;
            while (++i < length) {
                digit = bp[i];
                if (!JS7_ISHEX(digit))
                    goto badncr;
                c = (c << 4) + JS7_UNHEX(digit);
            }
        } else {
            while (i < length) {
                digit = bp[i++];
                if (!JS7_ISDEC(digit))
                    goto badncr;
                c = (c * 10) + JS7_UNDEC(digit);
                if (c < 0)
                    goto badncr;
            }
        }

        if (0x10000 <= c && c <= 0x10FFFF) {
            /* Form a surrogate pair (c, d) -- c is the high surrogate. */
            d = 0xDC00 + (c & 0x3FF);
            c = 0xD7C0 + (c >> 10);
            ispair = true;
        } else {
            /* Enforce the http://www.w3.org/TR/REC-xml/#wf-Legalchar WFC. */
            if (c != 0x9 && c != 0xA && c != 0xD &&
                !(0x20 <= c && c <= 0xD7FF) &&
                !(0xE000 <= c && c <= 0xFFFD)) {
                goto badncr;
            }
        }
    } else {
        /* Try to match one of the five XML 1.0 predefined entities. */
        switch (length) {
          case 3:
            if (bp[2] == 't') {
                if (bp[1] == 'l')
                    c = '<';
                else if (bp[1] == 'g')
                    c = '>';
            }
            break;
          case 4:
            if (bp[1] == 'a' && bp[2] == 'm' && bp[3] == 'p')
                c = '&';
            break;
          case 5:
            if (bp[3] == 'o') {
                if (bp[1] == 'a' && bp[2] == 'p' && bp[4] == 's')
                    c = '\'';
                else if (bp[1] == 'q' && bp[2] == 'u' && bp[4] == 't')
                    c = '"';
            }
            break;
        }
        if (c == 0) {
            msg = JSMSG_UNKNOWN_XML_ENTITY;
            goto bad;
        }
    }

    /* If we matched, retract tokenbuf and store the entity's value. */
    *bp++ = (jschar) c;
    if (ispair)
        *bp++ = (jschar) d;
    tb.shrinkBy(tb.end() - bp);
    return true;

  badncr:
    msg = JSMSG_BAD_XML_NCR;
  bad:
    /* No match: throw a TypeError per ECMA-357 10.3.2.1 step 8(a). */
    JS_ASSERT((tb.end() - bp) >= 1);
    bytes = DeflateString(cx, bp + 1, (tb.end() - bp) - 1);
    if (bytes) {
        ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, msg, bytes);
        cx->free_(bytes);
    }
    return false;
}

bool
TokenStream::getXMLTextOrTag(TokenKind *ttp, Token **tpp)
{
    TokenKind tt;
    int c, qc;
    Token *tp;
    JSAtom *atom;

    /*
     * Look for XML text.
     */
    if (flags & TSF_XMLTEXTMODE) {
        tt = TOK_XMLSPACE;      /* veto if non-space, return TOK_XMLTEXT */
        tp = newToken(0);
        tokenbuf.clear();
        qc = (flags & TSF_XMLONLYMODE) ? '<' : '{';

        while ((c = getChar()) != qc && c != '<' && c != EOF) {
            if (c == '&' && qc == '<') {
                if (!getXMLEntity())
                    goto error;
                tt = TOK_XMLTEXT;
                continue;
            }

            if (!IsXMLSpace(c))
                tt = TOK_XMLTEXT;
            if (!tokenbuf.append(c))
                goto error;
        }
        ungetChar(c);

        if (tokenbuf.empty()) {
            atom = NULL;
        } else {
            atom = atomize(cx, tokenbuf);
            if (!atom)
                goto error;
        }
        tp->pos.end.lineno = lineno;
        tp->t_op = JSOP_STRING;
        tp->t_atom = atom;
        goto out;
    }

    /*
     * XML tags.
     */
    else {
        JS_ASSERT(flags & TSF_XMLTAGMODE);
        tp = newToken(0);
        c = getChar();
        if (c != EOF && IsXMLSpace(c)) {
            do {
                c = getChar();
                if (c == EOF)
                    break;
            } while (IsXMLSpace(c));
            ungetChar(c);
            tp->pos.end.lineno = lineno;
            tt = TOK_XMLSPACE;
            goto out;
        }

        if (c == EOF) {
            tt = TOK_EOF;
            goto out;
        }

        tokenbuf.clear();
        if (IsXMLNamespaceStart(c)) {
            JSBool sawColon = JS_FALSE;

            if (!tokenbuf.append(c))
                goto error;
            while ((c = getChar()) != EOF && IsXMLNamePart(c)) {
                if (c == ':') {
                    int nextc;

                    if (sawColon ||
                        (nextc = peekChar(),
                         ((flags & TSF_XMLONLYMODE) || nextc != '{') &&
                         !IsXMLNamePart(nextc))) {
                        ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                                 JSMSG_BAD_XML_QNAME);
                        goto error;
                    }
                    sawColon = JS_TRUE;
                }

                if (!tokenbuf.append(c))
                    goto error;
            }

            ungetChar(c);
            atom = atomize(cx, tokenbuf);
            if (!atom)
                goto error;
            tp->t_op = JSOP_STRING;
            tp->t_atom = atom;
            tt = TOK_XMLNAME;
            goto out;
        }

        switch (c) {
          case '{':
            if (flags & TSF_XMLONLYMODE)
                goto bad_xml_char;
            tt = TOK_LC;
            goto out;

          case '=':
            tt = TOK_ASSIGN;
            goto out;

          case '"':
          case '\'':
            qc = c;
            while ((c = getChar()) != qc) {
                if (c == EOF) {
                    ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                             JSMSG_UNTERMINATED_STRING);
                    goto error;
                }

                /*
                 * XML attribute values are double-quoted when pretty-printed,
                 * so escape " if it is expressed directly in a single-quoted
                 * attribute value.
                 */
                if (c == '"' && !(flags & TSF_XMLONLYMODE)) {
                    JS_ASSERT(qc == '\'');
                    if (!tokenbuf.append(js_quot_entity_str,
                                     strlen(js_quot_entity_str)))
                        goto error;
                    continue;
                }

                if (c == '&' && (flags & TSF_XMLONLYMODE)) {
                    if (!getXMLEntity())
                        goto error;
                    continue;
                }

                if (!tokenbuf.append(c))
                    goto error;
            }
            atom = atomize(cx, tokenbuf);
            if (!atom)
                goto error;
            tp->pos.end.lineno = lineno;
            tp->t_op = JSOP_STRING;
            tp->t_atom = atom;
            tt = TOK_XMLATTR;
            goto out;

          case '>':
            tt = TOK_XMLTAGC;
            goto out;

          case '/':
            if (matchChar('>')) {
                tt = TOK_XMLPTAGC;
                goto out;
            }
            /* FALL THROUGH */

          bad_xml_char:
          default:
            ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_BAD_XML_CHARACTER);
            goto error;
        }
        JS_NOT_REACHED("getXMLTextOrTag 1");
    }
    JS_NOT_REACHED("getXMLTextOrTag 2");

  out:
    *ttp = tt;
    *tpp = tp;
    return true;

  error:
    *ttp = TOK_ERROR;
    *tpp = tp;
    return false;
}

/*
 * After much testing, it's clear that Postel's advice to protocol designers
 * ("be liberal in what you accept, and conservative in what you send") invites
 * a natural-law repercussion for JS as "protocol":
 *
 * "If you are liberal in what you accept, others will utterly fail to be
 *  conservative in what they send."
 *
 * Which means you will get <!-- comments to end of line in the middle of .js
 * files, and after if conditions whose then statements are on the next line,
 * and other wonders.  See at least the following bugs:
 * - https://bugzilla.mozilla.org/show_bug.cgi?id=309242
 * - https://bugzilla.mozilla.org/show_bug.cgi?id=309712
 * - https://bugzilla.mozilla.org/show_bug.cgi?id=310993
 *
 * So without JSOPTION_XML, we changed around Firefox 1.5 never to scan an XML
 * comment or CDATA literal.  Instead, we always scan <! as the start of an
 * HTML comment hack to end of line, used since Netscape 2 to hide script tag
 * content from script-unaware browsers.
 *
 * But this still leaves XML resources with certain internal structure
 * vulnerable to being loaded as script cross-origin, and some internal data
 * stolen, so for Firefox 3.5 and beyond, we reject programs whose source
 * consists only of XML literals. See:
 *
 * https://bugzilla.mozilla.org/show_bug.cgi?id=336551
 *
 * The check for this is in jsparse.cpp, Compiler::compileScript.
 */
bool
TokenStream::getXMLMarkup(TokenKind *ttp, Token **tpp)
{
    TokenKind tt;
    int c;
    Token *tp = *tpp;
    JSAtom *atom;
    JSBool inTarget;
    size_t targetLength;
    ptrdiff_t contentIndex;

    /* Check for XML comment or CDATA section. */
    if (matchChar('!')) {
        tokenbuf.clear();

        /* Scan XML comment. */
        if (matchChar('-')) {
            if (!matchChar('-'))
                goto bad_xml_markup;
            while ((c = getChar()) != '-' || !matchChar('-')) {
                if (c == EOF)
                    goto bad_xml_markup;
                if (!tokenbuf.append(c))
                    goto error;
            }
            tt = TOK_XMLCOMMENT;
            tp->t_op = JSOP_XMLCOMMENT;
            goto finish_xml_markup;
        }

        /* Scan CDATA section. */
        if (matchChar('[')) {
            jschar cp[6];
            if (peekChars(6, cp) &&
                cp[0] == 'C' &&
                cp[1] == 'D' &&
                cp[2] == 'A' &&
                cp[3] == 'T' &&
                cp[4] == 'A' &&
                cp[5] == '[') {
                skipChars(6);
                while ((c = getChar()) != ']' ||
                       !peekChars(2, cp) ||
                       cp[0] != ']' ||
                       cp[1] != '>') {
                    if (c == EOF)
                        goto bad_xml_markup;
                    if (!tokenbuf.append(c))
                        goto error;
                }
                getChar();            /* discard ] but not > */
                tt = TOK_XMLCDATA;
                tp->t_op = JSOP_XMLCDATA;
                goto finish_xml_markup;
            }
            goto bad_xml_markup;
        }
    }

    /* Check for processing instruction. */
    if (matchChar('?')) {
        inTarget = JS_TRUE;
        targetLength = 0;
        contentIndex = -1;

        tokenbuf.clear();
        while ((c = getChar()) != '?' || peekChar() != '>') {
            if (c == EOF)
                goto bad_xml_markup;
            if (inTarget) {
                if (IsXMLSpace(c)) {
                    if (tokenbuf.empty())
                        goto bad_xml_markup;
                    inTarget = JS_FALSE;
                } else {
                    if (!(tokenbuf.empty()
                          ? IsXMLNamespaceStart(c)
                          : IsXMLNamespacePart(c))) {
                        goto bad_xml_markup;
                    }
                    ++targetLength;
                }
            } else {
                if (contentIndex < 0 && !IsXMLSpace(c))
                    contentIndex = tokenbuf.length();
            }
            if (!tokenbuf.append(c))
                goto error;
        }
        if (targetLength == 0)
            goto bad_xml_markup;
        if (contentIndex < 0) {
            atom = cx->runtime->atomState.emptyAtom;
        } else {
            atom = js_AtomizeChars(cx, tokenbuf.begin() + contentIndex,
                                   tokenbuf.length() - contentIndex);
            if (!atom)
                goto error;
        }
        tokenbuf.shrinkBy(tokenbuf.length() - targetLength);
        tp->t_atom2 = atom;
        tt = TOK_XMLPI;

  finish_xml_markup:
        if (!matchChar('>'))
            goto bad_xml_markup;
        atom = atomize(cx, tokenbuf);
        if (!atom)
            goto error;
        tp->t_atom = atom;
        tp->pos.end.lineno = lineno;
        goto out;
    }

    /* An XML start-of-tag character. */
    tt = matchChar('/') ? TOK_XMLETAGO : TOK_XMLSTAGO;

  out:
    *ttp = tt;
    *tpp = tp;
    return true;

  bad_xml_markup:
    ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_BAD_XML_MARKUP);
  error:
    *ttp = TOK_ERROR;
    *tpp = tp;
    return false;
}
#endif /* JS_HAS_XML_SUPPORT */

/*
 * We have encountered a '\': check for a Unicode escape sequence after it.
 * Return 'true' and the character code value (by value) if we found a
 * Unicode escape sequence.  Otherwise, return 'false'.  In both cases, do not
 * advance along the buffer.
 */
bool
TokenStream::peekUnicodeEscape(int *result)
{
    jschar cp[5];

    if (peekChars(5, cp) && cp[0] == 'u' &&
        JS7_ISHEX(cp[1]) && JS7_ISHEX(cp[2]) &&
        JS7_ISHEX(cp[3]) && JS7_ISHEX(cp[4]))
    {
        *result = (((((JS7_UNHEX(cp[1]) << 4)
                + JS7_UNHEX(cp[2])) << 4)
              + JS7_UNHEX(cp[3])) << 4)
            + JS7_UNHEX(cp[4]);
        return true;
    }
    return false;
}

bool
TokenStream::matchUnicodeEscapeIdStart(int32 *cp)
{
    if (peekUnicodeEscape(cp) && IsIdentifierStart(*cp)) {
        skipChars(5);
        return true;
    }
    return false;
}

bool
TokenStream::matchUnicodeEscapeIdent(int32 *cp)
{
    if (peekUnicodeEscape(cp) && IsIdentifierPart(*cp)) {
        skipChars(5);
        return true;
    }
    return false;
}

/*
 * Helper function which returns true if the first length(q) characters in p are
 * the same as the characters in q.
 */
static bool
CharsMatch(const jschar *p, const char *q) {
    while (*q) {
        if (*p++ != *q++)
            return false;
    }
    return true;
}

bool
TokenStream::getAtLine()
{
    int c;
    jschar cp[5];
    uintN i, line, temp;
    char filenameBuf[1024];

    /*
     * Hack for source filters such as the Mozilla XUL preprocessor:
     * "//@line 123\n" sets the number of the *next* line after the
     * comment to 123.  If we reach here, we've already seen "//".
     */
    if (peekChars(5, cp) && CharsMatch(cp, "@line")) {
        skipChars(5);
        while ((c = getChar()) != '\n' && c != EOF && IsSpaceOrBOM2(c))
            continue;
        if (JS7_ISDEC(c)) {
            line = JS7_UNDEC(c);
            while ((c = getChar()) != EOF && JS7_ISDEC(c)) {
                temp = 10 * line + JS7_UNDEC(c);
                if (temp < line) {
                    /* Ignore overlarge line numbers. */
                    return true;
                }
                line = temp;
            }
            while (c != '\n' && c != EOF && IsSpaceOrBOM2(c))
                c = getChar();
            i = 0;
            if (c == '"') {
                while ((c = getChar()) != EOF && c != '"') {
                    if (c == '\n') {
                        ungetChar(c);
                        return true;
                    }
                    if ((c >> 8) != 0 || i >= sizeof filenameBuf - 1)
                        return true;
                    filenameBuf[i++] = (char) c;
                }
                if (c == '"') {
                    while ((c = getChar()) != '\n' && c != EOF && IsSpaceOrBOM2(c))
                        continue;
                }
            }
            filenameBuf[i] = '\0';
            if (c == EOF || c == '\n') {
                if (i > 0) {
                    if (flags & TSF_OWNFILENAME)
                        cx->free_((void *) filename);
                    filename = JS_strdup(cx, filenameBuf);
                    if (!filename)
                        return false;
                    flags |= TSF_OWNFILENAME;
                }
                lineno = line;
            }
        }
        ungetChar(c);
    }
    return true;
}

bool
TokenStream::getAtSourceMappingURL()
{
    jschar peeked[18];

    /* Match comments of the form @sourceMappingURL=<url> */
    if (peekChars(18, peeked) && CharsMatch(peeked, "@sourceMappingURL=")) {
        skipChars(18);
        tokenbuf.clear();

        jschar c;
        while (!IsSpaceOrBOM2((c = getChar())) &&
               ((char) c) != '\0' &&
               ((char) c) != EOF)
            tokenbuf.append(c);

        if (tokenbuf.empty())
            /* The source map's URL was missing, but not quite an exception that
             * we should stop and drop everything for, though. */
            return true;

        int len = tokenbuf.length();

        if (sourceMap)
            cx->free_(sourceMap);
        sourceMap = (jschar *) cx->malloc_(sizeof(jschar) * (len + 1));
        if (!sourceMap)
            return false;

        for (int i = 0; i < len; i++)
            sourceMap[i] = tokenbuf[i];
        sourceMap[len] = '\0';
    }
    return true;
}

Token *
TokenStream::newToken(ptrdiff_t adjust)
{
    cursor = (cursor + 1) & ntokensMask;
    Token *tp = &tokens[cursor];
    tp->ptr = userbuf.addressOfNextRawChar() + adjust;
    tp->pos.begin.index = tp->ptr - linebase;
    tp->pos.begin.lineno = tp->pos.end.lineno = lineno;
    return tp;
}

JS_ALWAYS_INLINE JSAtom *
TokenStream::atomize(JSContext *cx, CharBuffer &cb)
{
    return js_AtomizeChars(cx, cb.begin(), cb.length());
}

#ifdef DEBUG
bool
IsTokenSane(Token *tp)
{
    /*
     * Nb: TOK_EOL should never be used in an actual Token;  it should only be
     * returned as a TokenKind from peekTokenSameLine().
     */
    if (tp->type < TOK_ERROR || tp->type >= TOK_LIMIT || tp->type == TOK_EOL)
        return false;

    if (tp->pos.begin.lineno == tp->pos.end.lineno) {
        if (tp->pos.begin.index > tp->pos.end.index)
            return false;
    } else {
        /* Only certain token kinds can be multi-line. */
        switch (tp->type) {
          case TOK_STRING:
          case TOK_XMLATTR:
          case TOK_XMLSPACE:
          case TOK_XMLTEXT:
          case TOK_XMLCOMMENT:
          case TOK_XMLCDATA:
          case TOK_XMLPI:
            break;
          default:
            return false;
        }
    }
    return true;
}
#endif

bool
TokenStream::putIdentInTokenbuf(const jschar *identStart)
{
    int32 c, qc;
    const jschar *tmp = userbuf.addressOfNextRawChar();
    userbuf.setAddressOfNextRawChar(identStart);

    tokenbuf.clear();
    for (;;) {
        c = getCharIgnoreEOL();
        if (!IsIdentifierPart(c)) {
            if (c != '\\' || !matchUnicodeEscapeIdent(&qc))
                break;
            c = qc;
        }
        if (!tokenbuf.append(c)) {
            userbuf.setAddressOfNextRawChar(tmp);
            return false;
        }
    }
    userbuf.setAddressOfNextRawChar(tmp);
    return true;
}

enum FirstCharKind {
    Other,
    OneChar,
    Ident,
    Dot,
    Equals,
    String,
    Dec,
    Colon,
    Plus,
    HexOct,

    /* These two must be last, so that |c >= Space| matches both. */
    Space,
    EOL
};

#define _______ Other

/*
 * OneChar: 40, 41, 44, 59, 63, 91, 93, 123, 125: '(', ')', ',', ';', '?', '[', ']', '{', '}'
 * Ident:   36, 65..90, 95, 97..122: '$', 'A'..'Z', '_', 'a'..'z'
 * Dot:     46: '.'
 * Equals:  61: '='
 * String:  34, 39: '"', '\''
 * Dec:     49..57: '1'..'9'
 * Colon:   58: ':'
 * Plus:    43: '+'
 * HexOct:  48: '0'
 * Space:   9, 11, 12: '\t', '\v', '\f'
 * EOL:     10, 13: '\n', '\r'
 */
static const uint8 firstCharKinds[] = {
/*         0        1        2        3        4        5        6        7        8        9    */
/*   0+ */ _______, _______, _______, _______, _______, _______, _______, _______, _______,   Space,
/*  10+ */     EOL,   Space,   Space,     EOL, _______, _______, _______, _______, _______, _______,
/*  20+ */ _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,
/*  30+ */ _______, _______,   Space, _______,  String, _______,   Ident, _______, _______,  String,
/*  40+ */ OneChar, OneChar, _______,    Plus, OneChar, _______,     Dot, _______,  HexOct,     Dec,
/*  50+ */     Dec,     Dec,     Dec,     Dec,     Dec,     Dec,     Dec,     Dec,   Colon, OneChar,
/*  60+ */ _______,  Equals, _______, OneChar, _______,   Ident,   Ident,   Ident,   Ident,   Ident,
/*  70+ */   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,
/*  80+ */   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,
/*  90+ */   Ident, OneChar, _______, OneChar, _______,   Ident, _______,   Ident,   Ident,   Ident,
/* 100+ */   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,
/* 110+ */   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,   Ident,
/* 120+ */   Ident,   Ident,   Ident, OneChar, _______, OneChar, _______, _______
};

#undef _______

TokenKind
TokenStream::getTokenInternal()
{
    TokenKind tt;
    int c, qc;
    Token *tp;
    FirstCharKind c1kind;
    const jschar *numStart;
    bool hasFracOrExp;
    const jschar *identStart;
    bool hadUnicodeEscape;

#if JS_HAS_XML_SUPPORT
    /*
     * Look for XML text and tags.
     */
    if (flags & (TSF_XMLTEXTMODE|TSF_XMLTAGMODE)) {
        if (!getXMLTextOrTag(&tt, &tp))
            goto error;
        goto out;
    }
#endif

  retry:
    if (JS_UNLIKELY(!userbuf.hasRawChars())) {
        tp = newToken(0);
        tt = TOK_EOF;
        flags |= TSF_EOF;
        goto out;
    }

    c = userbuf.getRawChar();
    JS_ASSERT(c != EOF);

    /*
     * Chars not in the range 0..127 are rare.  Getting them out of the way
     * early allows subsequent checking to be faster.
     */
    if (JS_UNLIKELY(c >= 128)) {
        if (IsSpaceOrBOM2(c)) {
            if (c == LINE_SEPARATOR || c == PARA_SEPARATOR) {
                updateLineInfoForEOL();
                updateFlagsForEOL();
            }

            goto retry;
        }

        tp = newToken(-1);

        /* '$' and '_' don't pass IsLetter, but they're < 128 so never appear here. */
        JS_STATIC_ASSERT('$' < 128 && '_' < 128);
        if (IsLetter(c)) {
            identStart = userbuf.addressOfNextRawChar() - 1;
            hadUnicodeEscape = false;
            goto identifier;
        }

        goto badchar;
    }

    /*
     * Get the token kind, based on the first char.  The ordering of c1kind
     * comparison is based on the frequency of tokens in real code.  Minified
     * and non-minified code have different characteristics, mostly in that
     * whitespace occurs much less in minified code.  Token kinds that fall in
     * the 'Other' category typically account for less than 2% of all tokens,
     * so their order doesn't matter much.
     */
    c1kind = FirstCharKind(firstCharKinds[c]);

    /*
     * Skip over whitespace chars;  update line state on EOLs.  Even though
     * whitespace isn't very common in minified code we have to handle it first
     * (and jump back to 'retry') before calling newToken().
     */
    if (c1kind >= Space) {
        if (c1kind == EOL) {
            /* If it's a \r\n sequence: treat as a single EOL, skip over the \n. */
            if (c == '\r' && userbuf.hasRawChars())
                userbuf.matchRawChar('\n');
            updateLineInfoForEOL();
            updateFlagsForEOL();
        }
        goto retry;
    }

    tp = newToken(-1);

    /*
     * Look for an unambiguous single-char token.
     */
    if (c1kind == OneChar) {
        tt = (TokenKind)oneCharTokens[c];
        goto out;
    }

    /*
     * Look for an identifier.
     */
    if (c1kind == Ident) {
        identStart = userbuf.addressOfNextRawChar() - 1;
        hadUnicodeEscape = false;

      identifier:
        for (;;) {
            c = getCharIgnoreEOL();
            if (c == EOF)
                break;
            if (!IsIdentifierPart(c)) {
                if (c != '\\' || !matchUnicodeEscapeIdent(&qc))
                    break;
                hadUnicodeEscape = true;
            }
        }
        ungetCharIgnoreEOL(c);

        /*
         * Check for keywords unless we saw Unicode escape or parser asks
         * to ignore keywords.
         */
        const KeywordInfo *kw;
        if (!hadUnicodeEscape &&
            !(flags & TSF_KEYWORD_IS_NAME) &&
            (kw = FindKeyword(identStart, userbuf.addressOfNextRawChar() - identStart))) {
            if (kw->tokentype == TOK_RESERVED) {
                if (!ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                              JSMSG_RESERVED_ID, kw->chars)) {
                    goto error;
                }
            } else if (kw->tokentype == TOK_STRICT_RESERVED) {
                if (isStrictMode()
                    ? !ReportStrictModeError(cx, this, NULL, NULL, JSMSG_RESERVED_ID, kw->chars)
                    : !ReportCompileErrorNumber(cx, this, NULL,
                                                JSREPORT_STRICT | JSREPORT_WARNING,
                                                JSMSG_RESERVED_ID, kw->chars)) {
                    goto error;
                }
            } else {
                if (kw->version <= versionNumber()) {
                    tt = kw->tokentype;
                    tp->t_op = (JSOp) kw->op;
                    goto out;
                }

                /*
                 * let/yield are a Mozilla extension starting in JS1.7. If we
                 * aren't parsing for a version supporting these extensions,
                 * conform to ES5 and forbid these names in strict mode.
                 */
                if ((kw->tokentype == TOK_LET || kw->tokentype == TOK_YIELD) &&
                    !ReportStrictModeError(cx, this, NULL, NULL, JSMSG_RESERVED_ID, kw->chars))
                {
                    goto error;
                }
            }
        }

        /*
         * Identifiers containing no Unicode escapes can be atomized directly
         * from userbuf.  The rest must have the escapes converted via
         * tokenbuf before atomizing.
         */
        JSAtom *atom;
        if (!hadUnicodeEscape)
            atom = js_AtomizeChars(cx, identStart, userbuf.addressOfNextRawChar() - identStart);
        else if (putIdentInTokenbuf(identStart))
            atom = atomize(cx, tokenbuf);
        else
            atom = NULL;
        if (!atom)
            goto error;
        tp->t_op = JSOP_NAME;
        tp->t_atom = atom;
        tt = TOK_NAME;
        goto out;
    }

    if (c1kind == Dot) {
        c = getCharIgnoreEOL();
        if (JS7_ISDEC(c)) {
            numStart = userbuf.addressOfNextRawChar() - 2;
            goto decimal_dot;
        }
#if JS_HAS_XML_SUPPORT
        if (c == '.') {
            tt = TOK_DBLDOT;
            goto out;
        }
#endif
        ungetCharIgnoreEOL(c);
        tt = TOK_DOT;
        goto out;
    }

    if (c1kind == Equals) {
        if (matchChar('=')) {
            tp->t_op = matchChar('=') ? JSOP_STRICTEQ : JSOP_EQ;
            tt = TOK_EQOP;
        } else {
            tp->t_op = JSOP_NOP;
            tt = TOK_ASSIGN;
        }
        goto out;
    }

    /*
     * Look for a string.
     */
    if (c1kind == String) {
        qc = c;
        tokenbuf.clear();
        while (true) {
            /*
             * We need to detect any of these chars:  " or ', \n (or its
             * equivalents), \\, EOF.  We use maybeStrSpecial[] in a manner
             * similar to maybeEOL[], see above.  Because we detect EOL
             * sequences here and put them back immediately, we can use
             * getCharIgnoreEOL().
             */
            c = getCharIgnoreEOL();
            if (maybeStrSpecial[c & 0xff]) {
                if (c == qc)
                    break;
                if (c == '\\') {
                    switch (c = getChar()) {
                      case 'b': c = '\b'; break;
                      case 'f': c = '\f'; break;
                      case 'n': c = '\n'; break;
                      case 'r': c = '\r'; break;
                      case 't': c = '\t'; break;
                      case 'v': c = '\v'; break;

                      default:
                        if ('0' <= c && c < '8') {
                            int32 val = JS7_UNDEC(c);

                            c = peekChar();
                            /* Strict mode code allows only \0, then a non-digit. */
                            if (val != 0 || JS7_ISDEC(c)) {
                                if (!ReportStrictModeError(cx, this, NULL, NULL,
                                                           JSMSG_DEPRECATED_OCTAL)) {
                                    goto error;
                                }
                                setOctalCharacterEscape();
                            }
                            if ('0' <= c && c < '8') {
                                val = 8 * val + JS7_UNDEC(c);
                                getChar();
                                c = peekChar();
                                if ('0' <= c && c < '8') {
                                    int32 save = val;
                                    val = 8 * val + JS7_UNDEC(c);
                                    if (val <= 0377)
                                        getChar();
                                    else
                                        val = save;
                                }
                            }

                            c = (jschar)val;
                        } else if (c == 'u') {
                            jschar cp[4];
                            if (peekChars(4, cp) &&
                                JS7_ISHEX(cp[0]) && JS7_ISHEX(cp[1]) &&
                                JS7_ISHEX(cp[2]) && JS7_ISHEX(cp[3])) {
                                c = (((((JS7_UNHEX(cp[0]) << 4)
                                        + JS7_UNHEX(cp[1])) << 4)
                                      + JS7_UNHEX(cp[2])) << 4)
                                    + JS7_UNHEX(cp[3]);
                                skipChars(4);
                            } else {
                                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                                         JSMSG_MALFORMED_ESCAPE, "Unicode");
                                goto error;
                            }
                        } else if (c == 'x') {
                            jschar cp[2];
                            if (peekChars(2, cp) &&
                                JS7_ISHEX(cp[0]) && JS7_ISHEX(cp[1])) {
                                c = (JS7_UNHEX(cp[0]) << 4) + JS7_UNHEX(cp[1]);
                                skipChars(2);
                            } else {
                                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                                         JSMSG_MALFORMED_ESCAPE, "hexadecimal");
                                goto error;
                            }
                        } else if (c == '\n') {
                            /*
                             * ES5 7.8.4: an escaped line terminator represents
                             * no character.
                             */
                            continue;
                        }
                        break;
                    }
                } else if (TokenBuf::isRawEOLChar(c) || c == EOF) {
                    ungetCharIgnoreEOL(c);
                    ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                             JSMSG_UNTERMINATED_STRING);
                    goto error;
                }
            }
            if (!tokenbuf.append(c))
                goto error;
        }
        JSAtom *atom = atomize(cx, tokenbuf);
        if (!atom)
            goto error;
        tp->pos.end.lineno = lineno;
        tp->t_op = JSOP_STRING;
        tp->t_atom = atom;
        tt = TOK_STRING;
        goto out;
    }

    /*
     * Look for a decimal number.
     */
    if (c1kind == Dec) {
        numStart = userbuf.addressOfNextRawChar() - 1;

      decimal:
        hasFracOrExp = false;
        while (JS7_ISDEC(c))
            c = getCharIgnoreEOL();

        if (c == '.') {
          decimal_dot:
            hasFracOrExp = true;
            do {
                c = getCharIgnoreEOL();
            } while (JS7_ISDEC(c));
        }
        if (c == 'e' || c == 'E') {
            hasFracOrExp = true;
            c = getCharIgnoreEOL();
            if (c == '+' || c == '-')
                c = getCharIgnoreEOL();
            if (!JS7_ISDEC(c)) {
                ungetCharIgnoreEOL(c);
                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                         JSMSG_MISSING_EXPONENT);
                goto error;
            }
            do {
                c = getCharIgnoreEOL();
            } while (JS7_ISDEC(c));
        }
        ungetCharIgnoreEOL(c);

        if (c != EOF && IsIdentifierStart(c)) {
            ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_IDSTART_AFTER_NUMBER);
            goto error;
        }

        /*
         * Unlike identifiers and strings, numbers cannot contain escaped
         * chars, so we don't need to use tokenbuf.  Instead we can just
         * convert the jschars in userbuf directly to the numeric value.
         */
        jsdouble dval;
        const jschar *dummy;
        if (!hasFracOrExp) {
            if (!GetPrefixInteger(cx, numStart, userbuf.addressOfNextRawChar(), 10, &dummy, &dval))
                goto error;
        } else {
            if (!js_strtod(cx, numStart, userbuf.addressOfNextRawChar(), &dummy, &dval))
                goto error;
        }
        tp->t_dval = dval;
        tt = TOK_NUMBER;
        goto out;
    }

    if (c1kind == Colon) {
#if JS_HAS_XML_SUPPORT
        if (matchChar(':')) {
            tt = TOK_DBLCOLON;
            goto out;
        }
#endif
        tp->t_op = JSOP_NOP;
        tt = TOK_COLON;
        goto out;
    }

    if (c1kind == Plus) {
        if (matchChar('=')) {
            tp->t_op = JSOP_ADD;
            tt = TOK_ASSIGN;
        } else if (matchChar('+')) {
            tt = TOK_INC;
        } else {
            tp->t_op = JSOP_POS;
            tt = TOK_PLUS;
        }
        goto out;
    }

    /*
     * Look for a hexadecimal or octal number.
     */
    if (c1kind == HexOct) {
        int radix;
        c = getCharIgnoreEOL();
        if (c == 'x' || c == 'X') {
            radix = 16;
            c = getCharIgnoreEOL();
            if (!JS7_ISHEX(c)) {
                ungetCharIgnoreEOL(c);
                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_MISSING_HEXDIGITS);
                goto error;
            }
            numStart = userbuf.addressOfNextRawChar() - 1;  /* one past the '0x' */
            while (JS7_ISHEX(c))
                c = getCharIgnoreEOL();
        } else if (JS7_ISDEC(c)) {
            radix = 8;
            numStart = userbuf.addressOfNextRawChar() - 1;  /* one past the '0' */
            while (JS7_ISDEC(c)) {
                /* Octal integer literals are not permitted in strict mode code. */
                if (!ReportStrictModeError(cx, this, NULL, NULL, JSMSG_DEPRECATED_OCTAL))
                    goto error;

                /*
                 * Outside strict mode, we permit 08 and 09 as decimal numbers,
                 * which makes our behaviour a superset of the ECMA numeric
                 * grammar. We might not always be so permissive, so we warn
                 * about it.
                 */
                if (c >= '8') {
                    if (!ReportCompileErrorNumber(cx, this, NULL, JSREPORT_WARNING,
                                                  JSMSG_BAD_OCTAL, c == '8' ? "08" : "09")) {
                        goto error;
                    }
                    goto decimal;   /* use the decimal scanner for the rest of the number */
                }
                c = getCharIgnoreEOL();
            }
        } else {
            /* '0' not followed by 'x', 'X' or a digit;  scan as a decimal number. */
            numStart = userbuf.addressOfNextRawChar() - 1;
            goto decimal;
        }
        ungetCharIgnoreEOL(c);

        if (c != EOF && IsIdentifierStart(c)) {
            ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_IDSTART_AFTER_NUMBER);
            goto error;
        }

        jsdouble dval;
        const jschar *dummy;
        if (!GetPrefixInteger(cx, numStart, userbuf.addressOfNextRawChar(), radix, &dummy, &dval))
            goto error;
        tp->t_dval = dval;
        tt = TOK_NUMBER;
        goto out;
    }

    /*
     * This handles everything else.
     */
    JS_ASSERT(c1kind == Other);
    switch (c) {
      case '\\':
        hadUnicodeEscape = matchUnicodeEscapeIdStart(&qc);
        if (hadUnicodeEscape) {
            c = qc;
            identStart = userbuf.addressOfNextRawChar() - 6;
            goto identifier;
        }
        goto badchar;

      case '|':
        if (matchChar(c)) {
            tt = TOK_OR;
        } else if (matchChar('=')) {
            tp->t_op = JSOP_BITOR;
            tt = TOK_ASSIGN;
        } else {
            tt = TOK_BITOR;
        }
        break;

      case '^':
        if (matchChar('=')) {
            tp->t_op = JSOP_BITXOR;
            tt = TOK_ASSIGN;
        } else {
            tt = TOK_BITXOR;
        }
        break;

      case '&':
        if (matchChar(c)) {
            tt = TOK_AND;
        } else if (matchChar('=')) {
            tp->t_op = JSOP_BITAND;
            tt = TOK_ASSIGN;
        } else {
            tt = TOK_BITAND;
        }
        break;

      case '!':
        if (matchChar('=')) {
            tp->t_op = matchChar('=') ? JSOP_STRICTNE : JSOP_NE;
            tt = TOK_EQOP;
        } else {
            tp->t_op = JSOP_NOT;
            tt = TOK_UNARYOP;
        }
        break;

#if JS_HAS_XML_SUPPORT
      case '@':
        tt = TOK_AT;
        break;
#endif

      case '<':
#if JS_HAS_XML_SUPPORT
        if ((flags & TSF_OPERAND) && (hasXML() || peekChar() != '!')) {
            if (!getXMLMarkup(&tt, &tp))
                goto error;
            goto out;
        }
#endif

        /* NB: treat HTML begin-comment as comment-till-end-of-line */
        if (matchChar('!')) {
            if (matchChar('-')) {
                if (matchChar('-')) {
                    flags |= TSF_IN_HTML_COMMENT;
                    goto skipline;
                }
                ungetChar('-');
            }
            ungetChar('!');
        }
        if (matchChar(c)) {
            tp->t_op = JSOP_LSH;
            tt = matchChar('=') ? TOK_ASSIGN : TOK_SHOP;
        } else {
            tp->t_op = matchChar('=') ? JSOP_LE : JSOP_LT;
            tt = TOK_RELOP;
        }
        break;

      case '>':
        if (matchChar(c)) {
            tp->t_op = matchChar(c) ? JSOP_URSH : JSOP_RSH;
            tt = matchChar('=') ? TOK_ASSIGN : TOK_SHOP;
        } else {
            tp->t_op = matchChar('=') ? JSOP_GE : JSOP_GT;
            tt = TOK_RELOP;
        }
        break;

      case '*':
        tp->t_op = JSOP_MUL;
        tt = matchChar('=') ? TOK_ASSIGN : TOK_STAR;
        break;

      case '/':
        /*
         * Look for a single-line comment.
         */
        if (matchChar('/')) {
            if (cx->hasAtLineOption() && !getAtLine())
                goto error;

            if (!getAtSourceMappingURL())
                goto error;

  skipline:
            /* Optimize line skipping if we are not in an HTML comment. */
            if (flags & TSF_IN_HTML_COMMENT) {
                while ((c = getChar()) != EOF && c != '\n') {
                    if (c == '-' && matchChar('-') && matchChar('>'))
                        flags &= ~TSF_IN_HTML_COMMENT;
                }
            } else {
                while ((c = getChar()) != EOF && c != '\n')
                    continue;
            }
            ungetChar(c);
            cursor = (cursor - 1) & ntokensMask;
            goto retry;
        }

        /*
         * Look for a multi-line comment.
         */
        if (matchChar('*')) {
            uintN linenoBefore = lineno;
            while ((c = getChar()) != EOF &&
                   !(c == '*' && matchChar('/'))) {
                /* Ignore all characters until comment close. */
            }
            if (c == EOF) {
                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                         JSMSG_UNTERMINATED_COMMENT);
                goto error;
            }
            if (linenoBefore != lineno)
                updateFlagsForEOL();
            cursor = (cursor - 1) & ntokensMask;
            goto retry;
        }

        /*
         * Look for a regexp.
         */
        if (flags & TSF_OPERAND) {
            uintN reflags, length;
            JSBool inCharClass = JS_FALSE;

            tokenbuf.clear();
            for (;;) {
                c = getChar();
                if (c == '\\') {
                    if (!tokenbuf.append(c))
                        goto error;
                    c = getChar();
                } else if (c == '[') {
                    inCharClass = JS_TRUE;
                } else if (c == ']') {
                    inCharClass = JS_FALSE;
                } else if (c == '/' && !inCharClass) {
                    /* For compat with IE, allow unescaped / in char classes. */
                    break;
                }
                if (c == '\n' || c == EOF) {
                    ungetChar(c);
                    ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR,
                                             JSMSG_UNTERMINATED_REGEXP);
                    goto error;
                }
                if (!tokenbuf.append(c))
                    goto error;
            }
            for (reflags = 0, length = tokenbuf.length() + 1; ; length++) {
                c = peekChar();
                if (c == 'g' && !(reflags & JSREG_GLOB))
                    reflags |= JSREG_GLOB;
                else if (c == 'i' && !(reflags & JSREG_FOLD))
                    reflags |= JSREG_FOLD;
                else if (c == 'm' && !(reflags & JSREG_MULTILINE))
                    reflags |= JSREG_MULTILINE;
                else if (c == 'y' && !(reflags & JSREG_STICKY))
                    reflags |= JSREG_STICKY;
                else
                    break;
                getChar();
            }
            c = peekChar();
            if (JS7_ISLET(c)) {
                char buf[2] = { '\0' };
                tp->pos.begin.index += length + 1;
                buf[0] = (char)c;
                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_BAD_REGEXP_FLAG,
                                         buf);
                (void) getChar();
                goto error;
            }
            tp->t_reflags = reflags;
            tt = TOK_REGEXP;
            break;
        }

        tp->t_op = JSOP_DIV;
        tt = matchChar('=') ? TOK_ASSIGN : TOK_DIVOP;
        break;

      case '%':
        tp->t_op = JSOP_MOD;
        tt = matchChar('=') ? TOK_ASSIGN : TOK_DIVOP;
        break;

      case '~':
        tp->t_op = JSOP_BITNOT;
        tt = TOK_UNARYOP;
        break;

      case '-':
        if (matchChar('=')) {
            tp->t_op = JSOP_SUB;
            tt = TOK_ASSIGN;
        } else if (matchChar(c)) {
            if (peekChar() == '>' && !(flags & TSF_DIRTYLINE)) {
                flags &= ~TSF_IN_HTML_COMMENT;
                goto skipline;
            }
            tt = TOK_DEC;
        } else {
            tp->t_op = JSOP_NEG;
            tt = TOK_MINUS;
        }
        break;

#if JS_HAS_SHARP_VARS
      case '#':
      {
        uint32 n;

        c = getCharIgnoreEOL();
        if (!JS7_ISDEC(c)) {
            ungetCharIgnoreEOL(c);
            goto badchar;
        }
        n = (uint32)JS7_UNDEC(c);
        for (;;) {
            c = getChar();
            if (!JS7_ISDEC(c))
                break;
            n = 10 * n + JS7_UNDEC(c);
            if (n >= UINT16_LIMIT) {
                ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_SHARPVAR_TOO_BIG);
                goto error;
            }
        }
        tp->t_dval = (jsdouble) n;
        if (cx->hasStrictOption() &&
            (c == '=' || c == '#')) {
            char buf[20];
            JS_snprintf(buf, sizeof buf, "#%u%c", n, c);
            if (!ReportCompileErrorNumber(cx, this, NULL, JSREPORT_WARNING | JSREPORT_STRICT,
                                          JSMSG_DEPRECATED_USAGE, buf)) {
                goto error;
            }
        }
        if (c == '=')
            tt = TOK_DEFSHARP;
        else if (c == '#')
            tt = TOK_USESHARP;
        else
            goto badchar;
        break;
      }
#endif /* JS_HAS_SHARP_VARS */

      badchar:
      default:
        ReportCompileErrorNumber(cx, this, NULL, JSREPORT_ERROR, JSMSG_ILLEGAL_CHARACTER);
        goto error;
    }

  out:
    flags |= TSF_DIRTYLINE;
    tp->pos.end.index = userbuf.addressOfNextRawChar() - linebase;
    tp->type = tt;
    JS_ASSERT(IsTokenSane(tp));
    return tt;

  error:
    /*
     * For erroneous multi-line tokens we won't have changed end.lineno (it'll
     * still be equal to begin.lineno) so we revert end.index to be equal to
     * begin.index + 1 (as if it's a 1-char token) to avoid having inconsistent
     * begin/end positions.  end.index isn't used in error messages anyway.
     */
    flags |= TSF_DIRTYLINE;
    tp->pos.end.index = tp->pos.begin.index + 1;
    tp->type = TOK_ERROR;
    JS_ASSERT(IsTokenSane(tp));
#ifdef DEBUG
    /*
     * Poisoning userbuf on error establishes an invariant: once an erroneous
     * token has been seen, userbuf will not be consulted again.  This is true
     * because the parser will either (a) deal with the TOK_ERROR token by
     * aborting parsing immediately; or (b) if the TOK_ERROR token doesn't
     * match what it expected, it will unget the token, and the next getToken()
     * call will immediately return the just-gotten TOK_ERROR token again
     * without consulting userbuf, thanks to the lookahead buffer.
     */
    userbuf.poison();
#endif
    return TOK_ERROR;
}

