JavaScriptCore/pcre/pcre_xclass.cpp

/* This is JavaScriptCore's variant of the PCRE library. While this library
started out as a copy of PCRE, many of the features of PCRE have been
removed. This library now supports only the regular expression features
required by the JavaScript language specification, and has only the functions
needed by JavaScriptCore and the rest of WebKit.

                 Originally written by Philip Hazel
           Copyright (c) 1997-2006 University of Cambridge
    Copyright (C) 2002, 2004, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.

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*/

/* This module contains an internal function that is used to match an extended
class (one that contains characters whose values are > 255). */

#include "config.h"
#include "pcre_internal.h"

/*************************************************
*       Match character against an XCLASS        *
*************************************************/

/* This function is called to match a character against an extended class that
might contain values > 255.

Arguments:
  c           the character
  data        points to the flag byte of the XCLASS data

Returns:      true if character matches, else false
*/

/* Get the next UTF-8 character, advancing the pointer. This is called when we
 know we are in UTF-8 mode. */

static inline void getUTF8CharAndAdvancePointer(int& c, const unsigned char*& subjectPtr)
{
    c = *subjectPtr++;
    if ((c & 0xc0) == 0xc0) {
        int gcaa = jsc_pcre_utf8_table4[c & 0x3f];  /* Number of additional bytes */
        int gcss = 6 * gcaa;
        c = (c & jsc_pcre_utf8_table3[gcaa]) << gcss;
        while (gcaa-- > 0) {
            gcss -= 6;
            c |= (*subjectPtr++ & 0x3f) << gcss;
        }
    }
}

bool jsc_pcre_xclass(int c, const unsigned char* data)
{
    bool negated = (*data & XCL_NOT);
    
    /* Character values < 256 are matched against a bitmap, if one is present. If
     not, we still carry on, because there may be ranges that start below 256 in the
     additional data. */
    
    if (c < 256) {
        if ((*data & XCL_MAP) != 0 && (data[1 + c/8] & (1 << (c&7))) != 0)
            return !negated;   /* char found */
    }
    
    /* First skip the bit map if present. Then match against the list of Unicode
     properties or large chars or ranges that end with a large char. We won't ever
     encounter XCL_PROP or XCL_NOTPROP when UCP support is not compiled. */
    
    if ((*data++ & XCL_MAP) != 0)
        data += 32;
    
    int t;
    while ((t = *data++) != XCL_END) {
        if (t == XCL_SINGLE) {
            int x;
            getUTF8CharAndAdvancePointer(x, data);
            if (c == x)
                return !negated;
        }
        else if (t == XCL_RANGE) {
            int x, y;
            getUTF8CharAndAdvancePointer(x, data);
            getUTF8CharAndAdvancePointer(y, data);
            if (c >= x && c <= y)
                return !negated;
        }
    }
    
    return negated;   /* char did not match */
}