speedup descriptors parsing, avoid using regexp split

src/org/jetbrains/java/decompiler/struct/consts/LinkConstant.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2014 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -135,31 +135,32 @@ public class LinkConstant extends PooledConstant {
   }
 
   private void resolveDescriptor(String descr) {
+    int parenth = descr.indexOf(')');
+    if (descr.length() < 2 || parenth < 0 || descr.charAt(0) != '(') {
+      throw new IllegalArgumentException("Invalid descriptor: " + descr);
+    }
 
-    String[] arr = descr.split("[()]");
+    int counter = 0;
-    String par = arr[1];
+    if (parenth > 1) { // params
-
+      int index = 1;
-    int index = 0, counter = 0;
+      while (index < parenth) {
-    int len = par.length();
+        char c = descr.charAt(index);
-
-    while (index < len) {
-
-      char c = par.charAt(index);
         if (c == 'L') {
-        index = par.indexOf(";", index);
+          index = descr.indexOf(";", index);
         }
         else if (c == '[') {
           index++;
           continue;
         }
-
         counter++;
         index++;
       }
+    }
 
     paramCount = counter;
-    isVoid = "V".equals(arr[2]);
+    char retChar = descr.charAt(parenth + 1);
-    returnCategory2 = ("D".equals(arr[2]) || "J".equals(arr[2]));
+    isVoid = retChar == 'V';
+    returnCategory2 = (retChar == 'D') || (retChar == 'J');
    }
 }