Add JavaCodeParser.SkipToIfBalanced with unit tests

CodeStatistics/Handling/Languages/Java/JavaCodeParser.cs

@@ -17,6 +17,39 @@ namespace CodeStatistics.Handling.Languages.Java{
             return new JavaCodeParser(newCode ?? string.Empty);
         }
 
+        /// <summary>
+        /// Skips to the next matching character where the brackets ([{ }]) are balanced, and returns itself.
+        /// If the skip fails, the cursor will not move.
+        /// </summary>
+        public JavaCodeParser SkipToIfBalanced(char chr){
+            int prevCursor = cursor;
+            Stack<char> bracketStack = new Stack<char>(4);
+
+            while(cursor < length){
+                if (bracketStack.Count == 0 && Char == chr)break;
+
+                switch(Char){
+                    case '(': bracketStack.Push(')'); break;
+                    case '[': bracketStack.Push(']'); break;
+                    case '{': bracketStack.Push('}'); break;
+
+                    case ')': case ']': case '}':
+                        if (bracketStack.Count == 0 || bracketStack.Pop() != Char){
+                            cursor = prevCursor;
+                            return this;
+                        }
+
+                        break;
+                }
+
+                ++cursor;
+            }
+
+            if (Char != chr || bracketStack.Count > 0)cursor = prevCursor;
+
+            return this;
+        }
+
         /// <summary>
         /// Reads the entire full type name, which consists of one or more identifiers separated by the dot character. <para/>
         /// https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#d5e7695

CodeStatisticsTests/Languages/Java/JavaCodeParserTests.cs

@@ -36,5 +36,31 @@ namespace CodeStatisticsTests.Languages.Java{
             Annotation? annotation8 = new JavaCodeParser("@123").ReadAnnotation();
             Assert.IsFalse(annotation8.HasValue);
         }
+
+        [TestMethod]
+        public void TestBalanceSkip(){
+            JavaCodeParser parser1 = new JavaCodeParser("simple;D");
+            parser1.SkipToIfBalanced(';');
+            Assert.AreEqual(';',parser1.Char);
+            Assert.AreEqual('D',parser1.Next());
+
+            JavaCodeParser parser2 = new JavaCodeParser("find ( ;semicolon {[ ( ; ) ; ]} ; keep looking ) ;-)");
+            parser2.SkipToIfBalanced(';');
+            Assert.AreEqual(';',parser2.Char);
+            Assert.AreEqual('-',parser2.Next());
+            Assert.AreEqual(')',parser2.Next());
+
+            JavaCodeParser parser3 = new JavaCodeParser("nope");
+            parser3.SkipToIfBalanced(';');
+            Assert.AreEqual('n',parser3.Char);
+
+            JavaCodeParser parser4 = new JavaCodeParser("cannot find (;;;)");
+            parser4.SkipToIfBalanced(';');
+            Assert.AreEqual('c',parser4.Char);
+
+            JavaCodeParser parser5 = new JavaCodeParser("( invalid [ balance ) ] ;");
+            parser5.SkipToIfBalanced(';');
+            Assert.AreEqual('(',parser5.Char);
+        }
     }
 }