indexed substrings (prefixes only, for now), and untested AND and OR

support.

matchprefix.c

@@ -0,0 +1,18 @@
+#include "byte.h"
+#include "ldif.h"
+
+/* behave like strcmp, but also return 0 if s is a prefix of c. */
+int matchprefix(struct string* s,const char* c) {
+  unsigned int l,l1,i;
+  if (!c) return -1;
+  l1=l=strlen(c);
+  if (s->l<l1) l1=s->l;
+  i=byte_diff(s->s,l1,c);
+  if (i) return i;
+  /* one is a prefix of the other */
+  if (l==s->l) return 0;
+  if (c[l1]) /* is c the longer string? */
+    return 0;
+  return -(int)(s->s[l1]);
+}
+