optimizations and fixes for friday

regex.c

@@ -7,11 +7,13 @@
 
 // Checks if the first char in needle matches on c
 // needle may begin with a plain character or a character class
-bool char_match(char c, char *needle)
+bool char_match(char c, char *needle, char **nneedl)
 {
 	// depth of brackets
 	int db;
 	bool neg;
+	bool m;
+	m = false;
 	if (*needle == '[')
 	{
 		needle++;
@@ -21,7 +23,7 @@ bool char_match(char c, char *needle)
 		for (db = 1; *needle && (*needle != ']' || db); needle++)
 		{
 			if (db > 1 && ((*needle == c) != neg))
-				return true;
+				m = true;
 			else if (db > 1)
 				db--;
 			else if (*needle == '\\')
@@ -29,15 +31,18 @@ bool char_match(char c, char *needle)
 			else if (*needle == ']')
 				db--;
 			else if ((*needle == c) != neg)
-				return true;
+				m = true;
 		}
-		return false;
 	}
-	if (*needle == '$')
+	else if (*needle == '$')
-		return c == 0;
+		m = (c == 0);
 	else if (*needle == '.')
-		return true;
+		m = true;
-	return *needle == c;
+	else
+		m = (*needle == c);
+	if (*needle && nneedl)
+		*nneedl = needle + 1;
+	return m;
 }
 
 // Find next variant, or closing parenthesis of open group, or end of string
@@ -100,6 +105,8 @@ char *end_of_group(char *needle)
 // Returns opening parenthesis, or needle0
 char *start_of_group(char *needle0, char *needle)
 {
+	if (*needle == ')' && needle0 < needle)
+		needle--;
 	for (int dp = 0, db = 0;
 			needle > needle0 && (*needle != '(' || dp > 0 || db > 0 || *needle == ')');
 			needle--)
@@ -118,20 +125,14 @@ char *start_of_group(char *needle0, char *needle)
 	return needle;
 }
 
-// Determine quantifier for group, character class, or character
+char quant(char c)
-// Returns quantifier character, or 0 if absent.
-char quant(char *needle)
 {
-	if (*needle == '(')
+	switch (c)
-		needle = end_of_group(needle + 1);
-	else
-		needle = next_char(needle);
-	switch (*needle)
 	{
 		case '*':
 		case '+':
 		case '?':
-			return *needle;
+			return c;
 	}
 	return 0;
 }
@@ -166,7 +167,7 @@ bool regex_match(char *haystack, char *needle)
 	}
 
 	// iterate over the haystack until accepting
-	for (; !bv[accept] && !na; haystack++) {
+	do {
 		// handle groups, variants, and quantifier
 		for (size_t st = 0; st < states - 1; st++)
 		{
@@ -186,7 +187,7 @@ bool regex_match(char *haystack, char *needle)
 			{
 				// at end of group, look for quantifier
 				bv[st] = false;
-				q = quant(needle + st);
+				q = quant(needle[st+1]);
 				// first, activate subsequent state after group
 				bv[q ? st + 2 : st + 1] = true;
 				// then, handle quantifiers
@@ -205,23 +206,23 @@ bool regex_match(char *haystack, char *needle)
 			{
 				// at start of group, look at variants and quantifier
 				bv[st] = false;
-				for (var = needle + 1; *var && *var != ')'; var = next_var(var))
+				for (var = needle + st + 1; *var && *var != ')'; var = next_var(var))
 					bv[var - needle] = true;
-				q = quant(var);
 				if (*var == ')')
 					var++;
+				q = quant(*var);
 				if (q == '*' || q == '?')
 					bv[var + 1 - needle] = true;
 			}
-			else if ((q = quant(needle + st)) && (q == '*' || q == '?'))
+			else
 			{
-				// current needle has quantifier
+				// check if current needle is optional
-				bv[next_char(needle + st) + 1 - needle] = true;
+				nneedl = next_char(needle + st);
+				q = *nneedl;
+				if (q == '*' || q == '?')
+					bv[nneedl + 1 - needle] = true;
 			}
 		}
-		// check if we are only tidying up
-		if (!*haystack)
-			break;
 		memcpy(bvtmp, bv, sizeof(bv));
 		// actual match, backwards
 		na = true;
@@ -233,22 +234,23 @@ bool regex_match(char *haystack, char *needle)
 			// perform match for active state
 			fprintf(stderr, "state %lu: \"%s\" ~ \"%s\"\n", st-1, haystack, needle + st - 1);
 			bvtmp[st-1] = false;
-			char q = quant(needle + st-1);
+			m = char_match(*haystack, needle + st-1, &nneedl);
-			q = quant(needle + st-1);
+			q = quant(*nneedl);
-			m = char_match(*haystack, needle + st-1);
 			if (m || q == '*' || q == '?')
 			{
-				if (q == '*' || q == '+')
-					bvtmp[st-1] = true;
-				nneedl = next_char(needle + st-1);
 				if (q)
 					nneedl++;
+				if (q == '*' || q == '+')
+					bvtmp[st-1] = true;
 				bvtmp[nneedl - needle] = true;
 			}
 		}
 		memcpy(bv, bvtmp, sizeof(bv));
 		putc('\n', stderr);
-	}
+		// check if we have reached the end of haystack, and advance
+		if (!*(haystack++))
+			break;
+	} while (!bv[accept] && !na);
 
 	return bv[accept];
 }