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1 office 1 /* source: nestlex.c */
2 /* Copyright Gerhard Rieger 2006-2010 */
3 /* Published under the GNU General Public License V.2, see file COPYING */
4  
5 /* a function for lexical scanning of nested character patterns */
6  
7 #include "config.h"
8 #include "mytypes.h"
9  
10 #include "sysincludes.h"
11  
12  
13 /* sub: scan a string and copy its value to output string
14 end scanning when an unescaped, unnested string from ends array is found
15 does not copy the end pattern
16 does not write a trailing \0 to token
17 allows escaping with \ and quoting (\ and quotes are removed)
18 allows nesting with div. parens
19 returns -1 if out string was too small
20 returns 1 if addr ended unexpectedly
21 returns 0 if token could be extracted successfully
22 */
23 int nestlex(const char **addr, /* input string; aft points to end token */
24 char **token, /* output token; aft points to first unwritten
25 char (caller might want to set it to \0) */
26 size_t *len, /* remaining bytes in token space (incl. \0) */
27 const char *ends[], /* list of end strings */
28 const char *hquotes[],/* list of strings that quote (hard qu.) */
29 const char *squotes[],/* list of strings that quote softly */
30 const char *nests[],/* list of strings that start nesting;
31 every second one is matching end */
32 bool dropspace, /* drop trailing space before end token */
33 bool dropquotes, /* drop the outermost quotes */
34 bool c_esc, /* solve C char escapes: \n \t \0 etc */
35 bool html_esc /* solve HTML char escapes: %0d %08 etc */
36 ) {
37 const char *in = *addr; /* pointer into input string */
38 const char **endx; /* loops over end patterns */
39 const char **quotx; /* loops over quote patterns */
40 const char **nestx; /* loops over nest patterns */
41 char *out = *token; /* pointer into output token */
42 char *lastnonspace = out;
43 char c;
44 int i;
45 int result;
46  
47 while (true) {
48  
49 /* is this end of input string? */
50 if (*in == 0) {
51 if (dropspace) {
52 out = lastnonspace;
53 }
54 break; /* end of string */
55 }
56  
57 /* first check the end patterns (e.g. for ']') */
58 endx = ends; i = 0;
59 while (*endx) {
60 if (!strncmp(in, *endx, strlen(*endx))) {
61 /* this end pattern matches */
62 if (dropspace) {
63 out = lastnonspace;
64 }
65 *addr = in;
66 *token = out;
67 return 0;
68 }
69 ++endx;
70 }
71  
72 /* check for hard quoting pattern */
73 quotx = hquotes;
74 while (hquotes && *quotx) {
75 if (!strncmp(in, *quotx, strlen(*quotx))) {
76 /* this quote pattern matches */
77 const char *endnest[2];
78 if (dropquotes) {
79 /* we strip this quote */
80 in += strlen(*quotx);
81 } else {
82 for (i = strlen(*quotx); i > 0; --i) {
83 *out++ = *in++;
84 if (--*len <= 0) { *addr = in; *token = out; return -1; }
85 }
86 }
87 /* we call nestlex recursively */
88 endnest[0] = *quotx;
89 endnest[1] = NULL;
90 result =
91 nestlex(&in, &out, len, endnest, NULL/*hquotes*/,
92 NULL/*squotes*/, NULL/*nests*/,
93 false, false, c_esc, html_esc);
94 if (result == 0 && dropquotes) {
95 /* we strip this quote */
96 in += strlen(*quotx);
97 } else {
98 /* we copy the trailing quote */
99 for (i = strlen(*quotx); i > 0; --i) {
100 *out++ = *in++;
101 if (--*len <= 0) { *addr = in; *token = out; return -1; }
102 }
103 }
104  
105 break;
106 }
107 ++quotx;
108 }
109 if (hquotes && *quotx != NULL) {
110 /* there was a quote; string might continue with hard quote */
111 lastnonspace = out;
112 continue;
113 }
114  
115 /* check for soft quoting pattern */
116 quotx = squotes;
117 while (squotes && *quotx) {
118 if (!strncmp(in, *quotx, strlen(*quotx))) {
119 /* this quote pattern matches */
120 /* we strip this quote */
121 /* we call nestlex recursively */
122 const char *endnest[2];
123 if (dropquotes) {
124 /* we strip this quote */
125 in += strlen(*quotx);
126 } else {
127 for (i = strlen(*quotx); i > 0; --i) {
128 *out++ = *in++;
129 if (--*len <= 0) { *addr = in; *token = out; return -1; }
130 }
131 }
132 endnest[0] = *quotx;
133 endnest[1] = NULL;
134 result =
135 nestlex(&in, &out, len, endnest, hquotes,
136 squotes, nests,
137 false, false, c_esc, html_esc);
138  
139 if (result == 0 && dropquotes) {
140 /* we strip the trailing quote */
141 in += strlen(*quotx);
142 } else {
143 /* we copy the trailing quote */
144 for (i = strlen(*quotx); i > 0; --i) {
145 *out++ = *in++;
146 if (--*len <= 0) { *addr = in; *token = out; return -1; }
147 }
148 }
149 break;
150 }
151 ++quotx;
152 }
153 if (squotes && *quotx != NULL) {
154 /* there was a soft quote; string might continue with any quote */
155 lastnonspace = out;
156 continue;
157 }
158  
159 /* check patterns that start a nested clause */
160 nestx = nests; i = 0;
161 while (nests && *nestx) {
162 if (!strncmp(in, *nestx, strlen(*nestx))) {
163 /* this nest pattern matches */
164 const char *endnest[2];
165 endnest[0] = nestx[1];
166 endnest[1] = NULL;
167  
168 for (i = strlen(nestx[1]); i > 0; --i) {
169 *out++ = *in++;
170 if (--*len <= 0) { *addr = in; *token = out; return -1; }
171 }
172  
173 result =
174 nestlex(&in, &out, len, endnest, hquotes, squotes, nests,
175 false, false, c_esc, html_esc);
176 if (result == 0) {
177 /* copy endnest */
178 i = strlen(nestx[1]); while (i > 0) {
179 *out++ = *in++;
180 if (--*len <= 0) {
181 *addr = in;
182 *token = out;
183 return -1;
184 }
185 --i;
186 }
187 }
188 break;
189 }
190 nestx += 2; /* skip matching end pattern in table */
191 }
192 if (nests && *nestx) {
193 /* we handled a nested expression, continue loop */
194 lastnonspace = out;
195 continue;
196 }
197  
198 /* "normal" data, possibly escaped */
199 c = *in++;
200 if (c == '\\') {
201 /* found a plain \ escaped part */
202 c = *in++;
203 if (c == 0) { /* Warn("trailing '\\'");*/ break; }
204 if (c_esc) { /* solve C char escapes: \n \t \0 etc */
205 switch (c) {
206 case '0': c = '\0'; break;
207 case 'a': c = '\a'; break;
208 case 'b': c = '\b'; break;
209 case 'f': c = '\f'; break;
210 case 'n': c = '\n'; break;
211 case 'r': c = '\r'; break;
212 case 't': c = '\t'; break;
213 case 'v': c = '\v'; break;
214 #if LATER
215 case 'x': !!! 1 to 2 hex digits; break;
216 case 'u': !!! 4 hex digits?; break;
217 case 'U': !!! 8 hex digits?; break;
218 #endif
219 default: break;
220 }
221 }
222 *out++ = c;
223 --*len;
224 if (*len == 0) {
225 *addr = in;
226 *token = out;
227 return -1; /* output overflow */
228 }
229 lastnonspace = out;
230 continue;
231 }
232  
233 /* just a simple char */
234 *out++ = c;
235 --*len;
236 if (*len == 0) {
237 *addr = in;
238 *token = out;
239 return -1; /* output overflow */
240 }
241 if (!isspace(c)) {
242 lastnonspace = out;
243 }
244  
245 }
246 /* never come here? */
247  
248 *addr = in;
249 *token = out;
250 return 0; /* OK */
251 }
252  
253 int skipsp(const char **text) {
254 while (isspace(**text)) {
255 ++(*text);
256 }
257 return 0;
258 }