56 lines
1.6 KiB
C
56 lines
1.6 KiB
C
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/* qindex.c
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This program works just like "index()", but it recognizes Prospero quoting.
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Looks for first unquoted instance of "c" in string s.
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Returns NULL if none found.
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If it finds a mis-quoted string, returns NULL and sets perrno to
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PARSE_ERROR.
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Author: swa@isi.edu, 8/17/92
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*/
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#include <pfs.h> /* to make sure we match definition. */
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#include <perrno.h>
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char *
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qindex(const char *s, char c)
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{
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enum { OUTSIDE_QUOTATION, IN_QUOTATION,
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SEEN_POSSIBLE_CLOSING_QUOTE } state;
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const char *start = s;
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state = OUTSIDE_QUOTATION;
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for (; *s; ++s) {
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switch (state) {
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case OUTSIDE_QUOTATION:
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if (*s == '\'')
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state = IN_QUOTATION;
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else if (*s == c)
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return (char *) s; /* flush CONST */
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break;
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case IN_QUOTATION:
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if (*s == '\'')
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state = SEEN_POSSIBLE_CLOSING_QUOTE;
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break;
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case SEEN_POSSIBLE_CLOSING_QUOTE:
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if (*s == '\'') {
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if (c == '\'')
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return (char *) s; /* flush CONST */
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state = IN_QUOTATION;
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} else {
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state = OUTSIDE_QUOTATION;
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if (*s == c)
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return (char *) s; /* flush CONST */
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}
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break;
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default:
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internal_error("qindex(): impossible state!");
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}
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}
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if (state == IN_QUOTATION) {
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perrno = PARSE_ERROR;
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p_err_string = qsprintf_stcopyr(p_err_string,
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"qindex(): encountered text with unbalanced quoting: %'s", start);
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}
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return NULL;
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}
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