1 /*************************************************
2 *      Perl-Compatible Regular Expressions       *
3 *************************************************/
4 
5 /* PCRE is a library of functions to support regular expressions whose syntax
6 and semantics are as close as possible to those of the Perl 5 language.
7 
8                        Written by Philip Hazel
9      Original API code Copyright (c) 1997-2012 University of Cambridge
10           New API code Copyright (c) 2016-2019 University of Cambridge
11 
12 -----------------------------------------------------------------------------
13 Redistribution and use in source and binary forms, with or without
14 modification, are permitted provided that the following conditions are met:
15 
16     * Redistributions of source code must retain the above copyright notice,
17       this list of conditions and the following disclaimer.
18 
19     * Redistributions in binary form must reproduce the above copyright
20       notice, this list of conditions and the following disclaimer in the
21       documentation and/or other materials provided with the distribution.
22 
23     * Neither the name of the University of Cambridge nor the names of its
24       contributors may be used to endorse or promote products derived from
25       this software without specific prior written permission.
26 
27 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
28 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
31 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 POSSIBILITY OF SUCH DAMAGE.
38 -----------------------------------------------------------------------------
39 */
40 
41 /* This module contains an internal function that is used to match a Unicode
42 extended grapheme sequence. It is used by both pcre2_match() and
43 pcre2_def_match(). However, it is called only when Unicode support is being
44 compiled. Nevertheless, we provide a dummy function when there is no Unicode
45 support, because some compilers do not like functionless source files. */
46 
47 
48 #ifdef HAVE_CONFIG_H
49 #include "config.h"
50 #endif
51 
52 
53 #include "pcre2_internal.h"
54 
55 
56 /* Dummy function */
57 
58 #ifndef SUPPORT_UNICODE
59 PCRE2_SPTR
PRIV(extuni)60 PRIV(extuni)(uint32_t c, PCRE2_SPTR eptr, PCRE2_SPTR start_subject,
61   PCRE2_SPTR end_subject, BOOL utf, int *xcount)
62 {
63 (void)c;
64 (void)eptr;
65 (void)start_subject;
66 (void)end_subject;
67 (void)utf;
68 (void)xcount;
69 return NULL;
70 }
71 #else
72 
73 
74 /*************************************************
75 *      Match an extended grapheme sequence       *
76 *************************************************/
77 
78 /*
79 Arguments:
80   c              the first character
81   eptr           pointer to next character
82   start_subject  pointer to start of subject
83   end_subject    pointer to end of subject
84   utf            TRUE if in UTF mode
85   xcount         pointer to count of additional characters,
86                    or NULL if count not needed
87 
88 Returns:         pointer after the end of the sequence
89 */
90 
91 PCRE2_SPTR
PRIV(extuni)92 PRIV(extuni)(uint32_t c, PCRE2_SPTR eptr, PCRE2_SPTR start_subject,
93   PCRE2_SPTR end_subject, BOOL utf, int *xcount)
94 {
95 int lgb = UCD_GRAPHBREAK(c);
96 
97 while (eptr < end_subject)
98   {
99   int rgb;
100   int len = 1;
101   if (!utf) c = *eptr; else { GETCHARLEN(c, eptr, len); }
102   rgb = UCD_GRAPHBREAK(c);
103   if ((PRIV(ucp_gbtable)[lgb] & (1u << rgb)) == 0) break;
104 
105   /* Not breaking between Regional Indicators is allowed only if there
106   are an even number of preceding RIs. */
107 
108   if (lgb == ucp_gbRegionalIndicator && rgb == ucp_gbRegionalIndicator)
109     {
110     int ricount = 0;
111     PCRE2_SPTR bptr = eptr - 1;
112     if (utf) BACKCHAR(bptr);
113 
114     /* bptr is pointing to the left-hand character */
115 
116     while (bptr > start_subject)
117       {
118       bptr--;
119       if (utf)
120         {
121         BACKCHAR(bptr);
122         GETCHAR(c, bptr);
123         }
124       else
125       c = *bptr;
126       if (UCD_GRAPHBREAK(c) != ucp_gbRegionalIndicator) break;
127       ricount++;
128       }
129     if ((ricount & 1) != 0) break;  /* Grapheme break required */
130     }
131 
132   /* If Extend or ZWJ follows Extended_Pictographic, do not update lgb; this
133   allows any number of them before a following Extended_Pictographic. */
134 
135   if ((rgb != ucp_gbExtend && rgb != ucp_gbZWJ) ||
136        lgb != ucp_gbExtended_Pictographic)
137     lgb = rgb;
138 
139   eptr += len;
140   if (xcount != NULL) *xcount += 1;
141   }
142 
143 return eptr;
144 }
145 
146 #endif  /* SUPPORT_UNICODE */
147 
148 /* End of pcre2_extuni.c */
149