Runtime: optimize re_search_forward and re_search_backward

Author: hhugo

runtime/js/str.js

@@ -70,8 +70,7 @@ var re_match = (function () {
       cpool = caml_js_from_array(re[2]),
       normtable = caml_jsbytes_of_string(re[3]),
       numgroups = re[4] | 0,
-      numregisters = re[5] | 0,
-      startchars = re[6] | 0;
+      numregisters = re[5] | 0;
 
     var s = caml_uint8_array_of_string(s);
 
@@ -293,29 +292,62 @@ var re_match = (function () {
 
 //Provides: re_search_forward
 //Requires: re_match, caml_ml_string_length, caml_invalid_argument
+//Requires: caml_string_get
 function re_search_forward(re, s, pos) {
   if (pos < 0 || pos > caml_ml_string_length(s))
     caml_invalid_argument("Str.search_forward");
-  while (pos <= caml_ml_string_length(s)) {
-    var res = re_match(re, s, pos, 0);
-    if (res) return res;
-    pos++;
+  var startchars = re[6] | 0;
+  var len = caml_ml_string_length(s);
+  if (startchars >= 0) {
+    startchars = re[2][startchars + 1];
+    do {
+      while (
+        pos < len &&
+        caml_string_get(startchars, caml_string_get(s, pos)) === 0
+      )
+        pos++;
+      var res = re_match(re, s, pos, 0);
+      if (res) return res;
+      pos++;
+    } while (pos <= len);
+  } else {
+    do {
+      var res = re_match(re, s, pos, 0);
+      if (res) return res;
+      pos++;
+    } while (pos <= len);
   }
-
   return [0]; /* [||] : int array */
 }
 
 //Provides: re_search_backward
 //Requires: re_match, caml_ml_string_length, caml_invalid_argument
+//Requires: caml_string_get
 function re_search_backward(re, s, pos) {
   if (pos < 0 || pos > caml_ml_string_length(s))
     caml_invalid_argument("Str.search_backward");
-  while (pos >= 0) {
-    var res = re_match(re, s, pos, 0);
-    if (res) return res;
-    pos--;
+  var startchars = re[6] | 0;
+  if (startchars >= 0) {
+    startchars = re[2][startchars + 1];
+    var len = caml_ml_string_length(s);
+    do {
+      while (
+        pos > 0 &&
+        pos < len &&
+        caml_string_get(startchars, caml_string_get(s, pos)) === 0
+      )
+        pos--;
+      var res = re_match(re, s, pos, 0);
+      if (res) return res;
+      pos--;
+    } while (pos >= 0);
+  } else {
+    do {
+      var res = re_match(re, s, pos, 0);
+      if (res) return res;
+      pos--;
+    } while (pos >= 0);
   }
-
   return [0]; /* [||] : int array */
 }