Optimize dispstring parsing

Author: tatsuhiro-t

sfparse.c

@@ -856,27 +856,30 @@ static int parser_dispstring(sfparse_parser *sfp, sfparse_value *dest) {
     case 0:
       return SFPARSE_ERR_PARSE;
     case 1:
-      if (utf8state != UTF8_ACCEPT) {
-        return SFPARSE_ERR_PARSE;
-      }
-
       ++sfp->pos;
 
       break;
     case 2:
-      ++sfp->pos;
+      for (;;) {
+        ++sfp->pos;
 
-      if (sfp->pos + 2 > sfp->end) {
-        return SFPARSE_ERR_PARSE;
-      }
+        if (sfp->pos + 2 > sfp->end || pctdecode(&c, &sfp->pos) != 0) {
+          return SFPARSE_ERR_PARSE;
+        }
 
-      if (pctdecode(&c, &sfp->pos) != 0) {
-        return SFPARSE_ERR_PARSE;
-      }
+        utf8_decode(&utf8state, c);
+        if (utf8state == UTF8_ACCEPT) {
+          if (sfp->pos != sfp->end && *sfp->pos == '%') {
+            continue;
+          }
 
-      utf8_decode(&utf8state, c);
-      if (utf8state == UTF8_REJECT) {
-        return SFPARSE_ERR_PARSE;
+          break;
+        }
+
+        if (utf8state == UTF8_REJECT || sfp->pos + 1 > sfp->end ||
+            *sfp->pos != '%') {
+          return SFPARSE_ERR_PARSE;
+        }
       }
 
       break;
@@ -885,20 +888,23 @@ static int parser_dispstring(sfparse_parser *sfp, sfparse_value *dest) {
         return SFPARSE_ERR_PARSE;
       }
 
-      if (dest) {
-        dest->type = SFPARSE_TYPE_DISPSTRING;
-        dest->flags = SFPARSE_VALUE_FLAG_NONE;
-        dest->vec.len = (size_t)(sfp->pos - base);
-        dest->vec.base = dest->vec.len == 0 ? NULL : (uint8_t *)base;
-      }
-
-      ++sfp->pos;
-
-      return 0;
+      goto fin;
     }
   }
 
   return SFPARSE_ERR_PARSE;
+
+fin:
+  if (dest) {
+    dest->type = SFPARSE_TYPE_DISPSTRING;
+    dest->flags = SFPARSE_VALUE_FLAG_NONE;
+    dest->vec.len = (size_t)(sfp->pos - base);
+    dest->vec.base = dest->vec.len == 0 ? NULL : (uint8_t *)base;
+  }
+
+  ++sfp->pos;
+
+  return 0;
 }
 
 static const uint8_t bare_item_tbl[256] = {