Compile expression failed with string escape sequence \" in List and Map

[gaox0326]

version: 2.4.14.Final

// compile string literals a\"b
MVEL.compileExpression("\"a\\\"b\""); // success
MVEL.compileExpression("[\"a\\\"b\"]"); // failed
MVEL.compileExpression("[\"key\":\"a\\\"b\"]"); // failed

It seems that CollectionParser don't handle string escape

[Error: unterminated string literal]
[Near : {... ["key":"a"b"] ....}]
^
[Line: 1, Column: 14]
at org.mvel2.util.ParseTools.balancedCapture(ParseTools.java:1413)
at org.mvel2.util.CollectionParser.parseCollection(CollectionParser.java:170)
at org.mvel2.util.CollectionParser.parseCollection(CollectionParser.java:93)
at org.mvel2.util.CollectionParser.parseCollection(CollectionParser.java:140)
at org.mvel2.util.CollectionParser.parseCollection(CollectionParser.java:76)
at org.mvel2.ast.InlineCollectionNode.parseGraph(InlineCollectionNode.java:111)
at org.mvel2.ast.InlineCollectionNode.(InlineCollectionNode.java:49)
at org.mvel2.compiler.AbstractParser.nextToken(AbstractParser.java:1268)
at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:127)
at org.mvel2.compiler.ExpressionCompiler.compile(ExpressionCompiler.java:68)
at org.mvel2.MVEL.compileExpression(MVEL.java:827)
at org.mvel2.MVEL.compileExpression(MVEL.java:836)
at org.mvel2.MVEL.compileExpression(MVEL.java:740)

[ruoyangryan]

I've taken a look at the method balancedCapture(char[] chars, int start, int end, char type) in ParseTools class, there is a code block like this:

if (type == term) {
  for (start++; start < end; start++) {
    if (chars[start] == type) {
      return start;
    }
  }
}

What it was trying to do is basically finding out the terminate of a String literal. But since it is reading the whole char[] element by element, it cannot identify the '\' and '"' as a combination but rather treats them separately. So it thinks the String "a/"b" terminated as "a/".

I've opened a pull request to fix this problem. Check #317