jsregexp.c

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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** 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):
 *
 * 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 regular expressions, after Perl.
 */
#include "jsstddef.h"
#include <stdlib.h>
#include <string.h>
#include "jstypes.h"
#include "jsarena.h" /* Added by JSIFY */
#include "jsutil.h" /* Added by JSIFY */
#include "jsapi.h"
#include "jsarray.h"
#include "jsatom.h"
#include "jscntxt.h"
#include "jsconfig.h"
#include "jsfun.h"
#include "jsgc.h"
#include "jsinterp.h"
#include "jslock.h"
#include "jsnum.h"
#include "jsobj.h"
#include "jsopcode.h"
#include "jsregexp.h"
#include "jsscan.h"
#include "jsstr.h"

#ifdef XP_MAC
#include <MacMemory.h>
#endif

#if JS_HAS_REGEXPS

/* Note : contiguity of 'simple opcodes' is important for simpleMatch() */
typedef enum REOp {
    REOP_EMPTY         = 0,  /* match rest of input against rest of r.e. */
    REOP_ALT           = 1,  /* alternative subexpressions in kid and next */
    REOP_SIMPLE_START  = 2,  /* start of 'simple opcodes' */
    REOP_BOL           = 2,  /* beginning of input (or line if multiline) */
    REOP_EOL           = 3,  /* end of input (or line if multiline) */
    REOP_WBDRY         = 4,  /* match "" at word boundary */
    REOP_WNONBDRY      = 5,  /* match "" at word non-boundary */
    REOP_DOT           = 6,  /* stands for any character */
    REOP_DIGIT         = 7,  /* match a digit char: [0-9] */
    REOP_NONDIGIT      = 8,  /* match a non-digit char: [^0-9] */
    REOP_ALNUM         = 9,  /* match an alphanumeric char: [0-9a-z_A-Z] */
    REOP_NONALNUM      = 10, /* match a non-alphanumeric char: [^0-9a-z_A-Z] */
    REOP_SPACE         = 11, /* match a whitespace char */
    REOP_NONSPACE      = 12, /* match a non-whitespace char */
    REOP_BACKREF       = 13, /* back-reference (e.g., \1) to a parenthetical */
    REOP_FLAT          = 14, /* match a flat string */
    REOP_FLAT1         = 15, /* match a single char */
    REOP_FLATi         = 16, /* case-independent REOP_FLAT */
    REOP_FLAT1i        = 17, /* case-independent REOP_FLAT1 */
    REOP_UCFLAT1       = 18, /* single Unicode char */
    REOP_UCFLAT1i      = 19, /* case-independent REOP_UCFLAT1 */
    REOP_UCFLAT        = 20, /* flat Unicode string; len immediate counts chars */
    REOP_UCFLATi       = 21, /* case-independent REOP_UCFLAT */
    REOP_CLASS         = 22, /* character class with index */
    REOP_NCLASS        = 23, /* negated character class with index */
    REOP_SIMPLE_END    = 23, /* end of 'simple opcodes' */
    REOP_QUANT         = 25, /* quantified atom: atom{1,2} */
    REOP_STAR          = 26, /* zero or more occurrences of kid */
    REOP_PLUS          = 27, /* one or more occurrences of kid */
    REOP_OPT           = 28, /* optional subexpression in kid */
    REOP_LPAREN        = 29, /* left paren bytecode: kid is u.num'th sub-regexp */
    REOP_RPAREN        = 30, /* right paren bytecode */
    REOP_JUMP          = 31, /* for deoptimized closure loops */
    REOP_DOTSTAR       = 32, /* optimize .* to use a single opcode */
    REOP_ANCHOR        = 33, /* like .* but skips left context to unanchored r.e. */
    REOP_EOLONLY       = 34, /* $ not preceded by any pattern */
    REOP_BACKREFi      = 37, /* case-independent REOP_BACKREF */
    REOP_LPARENNON     = 41, /* non-capturing version of REOP_LPAREN */
    REOP_ASSERT        = 43, /* zero width positive lookahead assertion */
    REOP_ASSERT_NOT    = 44, /* zero width negative lookahead assertion */
    REOP_ASSERTTEST    = 45, /* sentinel at end of assertion child */
    REOP_ASSERTNOTTEST = 46, /* sentinel at end of !assertion child */
    REOP_MINIMALSTAR   = 47, /* non-greedy version of * */
    REOP_MINIMALPLUS   = 48, /* non-greedy version of + */
    REOP_MINIMALOPT    = 49, /* non-greedy version of ? */
    REOP_MINIMALQUANT  = 50, /* non-greedy version of {} */
    REOP_ENDCHILD      = 51, /* sentinel at end of quantifier child */
    REOP_REPEAT        = 52, /* directs execution of greedy quantifier */
    REOP_MINIMALREPEAT = 53, /* directs execution of non-greedy quantifier */
    REOP_ALTPREREQ     = 54, /* prerequisite for ALT, either of two chars */
    REOP_ALTPREREQ2    = 55, /* prerequisite for ALT, a char or a class */
    REOP_ENDALT        = 56, /* end of final alternate */
    REOP_CONCAT        = 57, /* concatenation of terms (parse time only) */

    REOP_END
} REOp;

#define REOP_IS_SIMPLE(op)  (((op) >= REOP_SIMPLE_START) && ((op) <= REOP_SIMPLE_END))

struct RENode {
    REOp            op;         /* r.e. op bytecode */
    RENode          *next;      /* next in concatenation order */
    void            *kid;       /* first operand */
    union {
        void        *kid2;      /* second operand */
        jsint       num;        /* could be a number */
        jsint       parenIndex; /* or a parenthesis index */
        struct {                /* or a quantifier range */
            uint16  min;
            uint16  max;
            JSBool  greedy;
        } range;
        struct {                /* or a character class */
            uint16  startIndex;
            uint16  kidlen;     /* length of string at kid, in jschars */
            uint16  bmsize;     /* bitmap size, based on max char code */
            uint16  index;      /* index into class list */
            JSBool  sense;
        } ucclass;
        struct {                /* or a literal sequence */
            jschar  chr;        /* of one character */
            uint16  length;     /* or many (via the kid) */      
        } flat;
        struct {
            RENode  *kid2;      /* second operand from ALT */
            jschar  ch1;        /* match char for ALTPREREQ */
            jschar  ch2;        /* ditto, or class index for ALTPREREQ2 */
        } altprereq;
    } u;
};

#define RE_IS_LETTER(c)      ( ((c >= 'A') && (c <= 'Z')) ||               \
                                ((c >= 'a') && (c <= 'z')) )
#define RE_IS_LINE_TERM(c)  ( (c == '\n') || (c == '\r') ||               \
                                (c == LINE_SEPARATOR) || (c == PARA_SEPARATOR))

#define CLASS_CACHE_SIZE (4)
typedef struct CompilerState {
    JSContext       *context;
    JSTokenStream   *tokenStream; /* For reporting errors */
    const jschar    *cpbegin;
    const jschar    *cpend;
    const jschar    *cp;
    uintN           flags;
    uint16          parenCount;
    uint16          classCount;   /* number of [] encountered */
    size_t          progLength;   /* estimated bytecode length */
    uintN           treeDepth;    /* maximum depth of parse tree */
    RENode          *result;    
    struct {
        const jschar *start;        /* small cache of class strings */
        uint16 length;              /* since they're often the same */
        uint16 index;
    } classCache[CLASS_CACHE_SIZE];
} CompilerState;

typedef struct RECapture {
    int32 index;               /* start of contents, -1 for empty  */
    uint16 length;             /* length of capture */
} RECapture;

typedef struct REMatchState {
    const jschar *cp;
    RECapture parens[1];      /* first of 're->parenCount' captures, 
                               * allocated at end of this struct.
                               */
} REMatchState;

struct REBackTrackData;

typedef struct REProgState {
    jsbytecode *continue_pc;        /* current continuation data */
    jsbytecode continue_op;                  
    uint16 index;                   /* progress in text */
    uintN parenSoFar;               /* highest indexed paren started */
    union {
        struct {
            uint16 min;             /* current quantifier limits */
            uint16 max;
        } quantifier;
        struct {
            size_t top;             /* backtrack stack state */
            size_t sz;
        } assertion;
    } u;
} REProgState;

typedef struct REBackTrackData {
    size_t sz;                      /* size of previous stack entry */
    jsbytecode *backtrack_pc;       /* where to backtrack to */
    jsbytecode backtrack_op;
    const jschar *cp;               /* index in text of match at backtrack */
    intN parenIndex;                /* start index of saved paren contents */
    uint16 parenCount;              /* # of saved paren contents */
    uint16 precedingStateTop;       /* number of parent states */
    /* saved parent states follow */
    /* saved paren contents follow */
} REBackTrackData;

#define INITIAL_STATESTACK (100)
#define INITIAL_BACKTRACK (8000)

typedef struct REGlobalData {
    JSContext *cx;
    JSRegExp *regexp;               /* the RE in execution */   
    JSBool ok;                      /* runtime error (out_of_memory only?) */
    size_t start;                   /* offset to start at */
    ptrdiff_t skipped;              /* chars skipped anchoring this r.e. */
    const jschar *cpbegin, *cpend;  /* text base address and limit */

    REProgState *stateStack;        /* stack of state of current parents */
    uint16 stateStackTop;
    uint16 maxStateStack;

    REBackTrackData *backTrackStack;/* stack of matched-so-far positions */
    REBackTrackData *backTrackSP;
    size_t maxBackTrack;
    size_t cursz;                   /* size of current stack entry */

    JSArenaPool pool;               /* I don't understand but it's faster to
                                     * use this than to malloc/free the three
                                     * items that are allocated from this pool
                                     */

} REGlobalData;


/*
 * 1. If IgnoreCase is false, return ch.
 * 2. Let u be ch converted to upper case as if by calling 
 *    String.prototype.toUpperCase on the one-character string ch.
 * 3. If u does not consist of a single character, return ch.
 * 4. Let cu be u's character.
 * 5. If ch's code point value is greater than or equal to decimal 128 and cu's
 *    code point value is less than decimal 128, then return ch.
 * 6. Return cu.
 */
static jschar
upcase(jschar ch)
{
    jschar cu = JS_TOUPPER(ch);
    if ((ch >= 128) && (cu < 128)) return ch;
    return cu;
}

static jschar
downcase(jschar ch)
{
    jschar cl = JS_TOLOWER(ch);
    if ((cl >= 128) && (ch < 128)) return ch;
    return cl;
}

/* Construct and initialize an RENode, returning NULL for out-of-memory */
static RENode *
NewRENode(CompilerState *state, REOp op)
{
    JSContext *cx;
    RENode *ren;

    cx = state->context;
    JS_ARENA_ALLOCATE_CAST(ren, RENode *, &cx->tempPool, sizeof *ren);
    if (!ren) {
        JS_ReportOutOfMemory(cx);
        return NULL;
    }
    ren->op = op;
    ren->next = NULL;
    ren->kid = NULL;
    return ren;
}

/*
 * Validates and converts hex ascii value.
 */
static JSBool
isASCIIHexDigit(jschar c, uintN *digit)
{
    uintN cv = c;

    if (cv < '0')
        return JS_FALSE;
    if (cv <= '9') {
        *digit = cv - '0';
        return JS_TRUE;
    }
    cv |= 0x20;
    if (cv >= 'a' && cv <= 'f') {
        *digit = cv - 'a' + 10;
        return JS_TRUE;
    }
    return JS_FALSE;
}


typedef struct {
    REOp op;
    const jschar *errPos;
    uint16 parenIndex;
} REOpData;


/* 
 * Process the op against the two top operands, reducing them to a single
 * operand in the penultimate slot. Update progLength and treeDepth.
 */
static JSBool 
processOp(CompilerState *state, REOpData *opData, RENode **operandStack, intN operandSP)
{
    RENode *result;

    switch (opData->op) {
    case REOP_ALT:
        result = NewRENode(state, REOP_ALT);
        if (!result) 
            return JS_FALSE;
        result->kid = operandStack[operandSP - 2];
        result->u.kid2 = operandStack[operandSP - 1];
        operandStack[operandSP - 2] = result;
        /* 
         * look at both alternates to see if there's a FLAT or a CLASS at
         * the start of each. If so, use a prerequisite match
         */
        ++state->treeDepth;