JavaScriptCore/pcre/pcre_ucp_searchfuncs.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 Apple Inc. All rights reserved.

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      this software without specific prior written permission.

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*/


/* This module contains code for searching the table of Unicode character
properties. */

#include "pcre_internal.h"

#include "ucpinternal.h"       /* Internal table details */
#include "ucptable.cpp"        /* The table itself */

/*************************************************
*       Search table and return other case       *
*************************************************/

/* If the given character is a letter, and there is another case for the
letter, return the other case. Otherwise, return -1.

Arguments:
  c           the character value

Returns:      the other case or -1 if none
*/

int kjs_pcre_ucp_othercase(unsigned c)
{
    int bot = 0;
    int top = sizeof(ucp_table) / sizeof(cnode);
    int mid;
    
    /* The table is searched using a binary chop. You might think that using
     intermediate variables to hold some of the common expressions would speed
     things up, but tests with gcc 3.4.4 on Linux showed that, on the contrary, it
     makes things a lot slower. */
    
    for (;;) {
        if (top <= bot)
            return -1;
        mid = (bot + top) >> 1;
        if (c == (ucp_table[mid].f0 & f0_charmask))
            break;
        if (c < (ucp_table[mid].f0 & f0_charmask))
            top = mid;
        else {
            if ((ucp_table[mid].f0 & f0_rangeflag) && (c <= (ucp_table[mid].f0 & f0_charmask) + (ucp_table[mid].f1 & f1_rangemask)))
                break;
            bot = mid + 1;
        }
    }
    
    /* Found an entry in the table. Return -1 for a range entry. Otherwise return
     the other case if there is one, else -1. */
    
    if (ucp_table[mid].f0 & f0_rangeflag)
        return -1;
    
    int offset = ucp_table[mid].f1 & f1_casemask;
    if (offset & f1_caseneg)
        offset |= f1_caseneg;
    return !offset ? -1 : c + offset;
}