Basic string prefix matching functions for tokenization. Based on previous…

Basic string prefix matching functions for tokenization. Based on previous parser-writing experience, I don't think I'll need a general-purpose regexp library.

src/parser/test.c

+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "text_prefix_matchers.h"
+
+int main() {
+  char *s = "'this is a \"string\" now' blah blah blah";
+  int l = text_has_delimited_prefix(s, "'", "'", 1);
+  if (l) {
+    printf("matched a string literal of length %d:\n", l);
+    int i;
+    for (i = 0; i < l; i++) {
+      putchar(s[i]);
+    }
+    putchar('\n');
+  }
+  return 0;
+}
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src/parser/text_prefix_matchers.c

+#include <ctype.h>
+#include <string.h>
+
+#define text_has_ctype_prefix(src, type) (is ## type((src)[0]) ? 1 : 0)
+
+#define DEF_SINGLE_CTYPE_PREFIX_MATCHER(type) \
+size_t text_starts_with_one_ ## type(char *src) \
+  return is ## type(src[0]) ? 1 : 0; \
+}
+
+#define DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(type) \
+size_t text_starts_with_ ## type ## s(char *src) { \
+  int p = 0; \
+  while (is ## type(src[p])) p++; \
+  return p; \
+}
+
+
+size_t text_has_exact_prefix(char *src, char* pre) {
+  int p = 0;
+  while (1) {
+    if (pre[p] == '\0') return p;
+    if (pre[p] != src[p]) return 0;
+    p++;
+  }
+}
+
+size_t text_has_delimited_prefix(char *src, char *beg, char *end, int esc) {
+  int p = 0;
+  size_t len = text_has_exact_prefix(src, beg);
+  if (!len) return 0;
+  p += len;
+  while (1) {
+    if (src[p] == '\0') return 0;
+    len = text_has_exact_prefix(src+p, end);
+    if (len && esc && src[p-1] != '\\') return p + len;
+    p += len || 1;
+  }
+}
+
+DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(space);  /* size_t text_starts_with_spaces(char *)  */
+DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(alpha);  /* size_t text_starts_with_alphas(char *)  */
+DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(digit);  /* size_t text_starts_with_digits(char *)  */
+DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(xdigit); /* size_t text_starts_with_xdigits(char *) */
+DEF_CTYPE_SEQUENCE_PREFIX_MATCHER(alnum);  /* size_t text_starts_with_alnums(char *)  */
+
+size_t text_starts_with_whitespace(char *src) {
+  int p = 0;
+  while (isspace(src[p++])) ;
+  return p;
+}
+
+size_t text_starts_with_block_comment(char *src) {
+  return text_has_delimited_prefix(src, "/*", "*/", 0);
+}
+
+size_t text_starts_with_line_comment(char *src) {
+  int p = text_has_exact_prefix(src, "//");
+  while (src[p] != '\n' && src[p] != '\0') p++;
+  return p;
+}
+
+size_t text_starts_with_string_constant(char *src) {
+  return text_has_delimited_prefix(src, "\"", "\"", 1)
+      || text_has_delimited_prefix(src, "'", "'", 1);
+}
+
+size_t text_starts_with_interpolant(char *src) {
+  return text_has_delimited_prefix(src, "#{", "}", 0);
+}

src/parser/text_prefix_matchers.h

+size_t sass_text_has_exact_prefix(char *, char*);
+
+size_t sass_text_has_delimited_prefix(char *, char *, char *, int);
+
+size_t sass_text_starts_with_delimited(char *src, char d);
+
+size_t sass_text_starts_with_line_comment(char *src);
+
+size_t sass_text_starts_with_block_comment(char *src);
+
+/* more to come */
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