238 lines
6.4 KiB
C
238 lines
6.4 KiB
C
/* source: nestlex.c */
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/* Copyright Gerhard Rieger 2006-2010 */
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/* Published under the GNU General Public License V.2, see file COPYING */
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/* a function for lexical scanning of nested character patterns */
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#include "config.h"
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#include "mytypes.h"
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#include "sysincludes.h"
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/* sub: scan a string and copy its value to output string
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end scanning when an unescaped, unnested string from ends array is found
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does not copy the end pattern
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does not write a trailing \0 to token
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allows escaping with \ and quoting (\ and quotes are removed)
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allows nesting with div. parens
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returns -1 if out string was too small
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returns 1 if addr ended unexpectedly
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returns 0 if token could be extracted successfully
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*/
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int nestlex(const char **addr, /* input string; aft points to end token */
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char **token, /* output token; aft points to first unwritten
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char (caller might want to set it to \0) */
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size_t *len, /* remaining bytes in token space (incl. \0) */
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const char *ends[], /* list of end strings */
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const char *hquotes[],/* list of strings that quote (hard qu.) */
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const char *squotes[],/* list of strings that quote softly */
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const char *nests[],/* list of strings that start nesting;
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every second one is matching end */
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bool dropquotes, /* drop the outermost quotes */
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bool c_esc, /* solve C char escapes: \n \t \0 etc */
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bool html_esc /* solve HTML char escapes: %0d %08 etc */
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) {
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const char *in = *addr; /* pointer into input string */
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const char **endx; /* loops over end patterns */
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const char **quotx; /* loops over quote patterns */
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const char **nestx; /* loops over nest patterns */
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char *out = *token; /* pointer into output token */
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char c;
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int i;
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int result;
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while (true) {
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/* is this end of input string? */
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if (*in == 0) {
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break; /* end of string */
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}
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/* first check the end patterns (e.g. for ']') */
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endx = ends; i = 0;
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while (*endx) {
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if (!strncmp(in, *endx, strlen(*endx))) {
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/* this end pattern matches */
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*addr = in;
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*token = out;
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return 0;
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}
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++endx;
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}
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/* check for hard quoting pattern */
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quotx = hquotes;
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while (hquotes && *quotx) {
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if (!strncmp(in, *quotx, strlen(*quotx))) {
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/* this quote pattern matches */
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const char *endnest[2];
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if (dropquotes) {
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/* we strip this quote */
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in += strlen(*quotx);
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} else {
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for (i = strlen(*quotx); i > 0; --i) {
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*out++ = *in++;
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if (--*len <= 0) { *addr = in; *token = out; return -1; }
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}
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}
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/* we call nestlex recursively */
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endnest[0] = *quotx;
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endnest[1] = NULL;
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result =
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nestlex(&in, &out, len, endnest, NULL/*hquotes*/,
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NULL/*squotes*/, NULL/*nests*/,
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false, c_esc, html_esc);
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if (result == 0 && dropquotes) {
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/* we strip this quote */
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in += strlen(*quotx);
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} else {
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/* we copy the trailing quote */
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for (i = strlen(*quotx); i > 0; --i) {
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*out++ = *in++;
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if (--*len <= 0) { *addr = in; *token = out; return -1; }
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}
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}
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break;
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}
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++quotx;
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}
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if (hquotes && *quotx != NULL) {
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/* there was a quote; string might continue with hard quote */
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continue;
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}
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/* check for soft quoting pattern */
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quotx = squotes;
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while (squotes && *quotx) {
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if (!strncmp(in, *quotx, strlen(*quotx))) {
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/* this quote pattern matches */
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/* we strip this quote */
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/* we call nestlex recursively */
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const char *endnest[2];
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if (dropquotes) {
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/* we strip this quote */
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in += strlen(*quotx);
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} else {
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for (i = strlen(*quotx); i > 0; --i) {
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*out++ = *in++;
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if (--*len <= 0) { *addr = in; *token = out; return -1; }
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}
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}
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endnest[0] = *quotx;
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endnest[1] = NULL;
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result =
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nestlex(&in, &out, len, endnest, hquotes,
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squotes, nests,
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false, c_esc, html_esc);
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if (result == 0 && dropquotes) {
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/* we strip the trailing quote */
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in += strlen(*quotx);
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} else {
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/* we copy the trailing quote */
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for (i = strlen(*quotx); i > 0; --i) {
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*out++ = *in++;
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if (--*len <= 0) { *addr = in; *token = out; return -1; }
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}
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}
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break;
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}
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++quotx;
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}
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if (squotes && *quotx != NULL) {
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/* there was a soft quote; string might continue with any quote */
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continue;
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}
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/* check patterns that start a nested clause */
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nestx = nests; i = 0;
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while (nests && *nestx) {
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if (!strncmp(in, *nestx, strlen(*nestx))) {
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/* this nest pattern matches */
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const char *endnest[2];
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endnest[0] = nestx[1];
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endnest[1] = NULL;
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for (i = strlen(nestx[1]); i > 0; --i) {
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*out++ = *in++;
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if (--*len <= 0) { *addr = in; *token = out; return -1; }
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}
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result =
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nestlex(&in, &out, len, endnest, hquotes, squotes, nests,
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false, c_esc, html_esc);
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if (result == 0) {
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/* copy endnest */
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i = strlen(nestx[1]); while (i > 0) {
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*out++ = *in++;
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if (--*len <= 0) {
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*addr = in;
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*token = out;
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return -1;
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}
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--i;
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}
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}
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break;
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}
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nestx += 2; /* skip matching end pattern in table */
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}
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if (nests && *nestx) {
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/* we handled a nested expression, continue loop */
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continue;
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}
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/* "normal" data, possibly escaped */
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c = *in++;
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if (c == '\\') {
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/* found a plain \ escaped part */
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c = *in++;
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if (c == 0) { /* Warn("trailing '\\'");*/ break; }
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if (c_esc) { /* solve C char escapes: \n \t \0 etc */
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switch (c) {
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case '0': c = '\0'; break;
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case 'a': c = '\a'; break;
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case 'b': c = '\b'; break;
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case 'f': c = '\f'; break;
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case 'n': c = '\n'; break;
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case 'r': c = '\r'; break;
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case 't': c = '\t'; break;
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case 'v': c = '\v'; break;
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#if LATER
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case 'x': !!! 1 to 2 hex digits; break;
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case 'u': !!! 4 hex digits?; break;
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case 'U': !!! 8 hex digits?; break;
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#endif
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default: break;
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}
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}
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*out++ = c;
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--*len;
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if (*len == 0) {
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*addr = in;
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*token = out;
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return -1; /* output overflow */
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}
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continue;
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}
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/* just a simple char */
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*out++ = c;
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--*len;
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if (*len == 0) {
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*addr = in;
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*token = out;
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return -1; /* output overflow */
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}
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}
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/* never come here? */
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*addr = in;
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*token = out;
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return 0; /* OK */
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}
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