StringIndexOutOfBoundException in NativeRegExp.appendReplacement

[Chris Pettitt]

Hello,

I believe I have found a bug in NativeRegExp.appendReplacement around handling of '$'. Per [1], A '$' in newstring that does not match one of the forms in Table 22 should be left as is. The appendReplacement function handles this correctly for most cases, but breaks with the following input:

    jjs> "a".replace("a", "$")
    java.lang.StringIndexOutOfBoundsException: String index out of range: 1

The problem is that appendReplacement assumes that a character will follow the '$' character:

        int cursor = 0;
        Object[] groups = null;

        while (cursor < replacement.length()) {
            char nextChar = replacement.charAt(cursor);
            if (nextChar == '$') {
                // Skip past $
                cursor++;
                nextChar = replacement.charAt(cursor);    // This line fails for the above input, there is no character as index 1.

While the code should be using "$$" as a replacement text, the spec seems to indicate that "$" should work if no characters follow. I tested this with a few JS engines (node, chrome, firefox) and all handle this by replacing "a" with "$", which conforms to my reading of the spec.

Thanks,
Chris


[1]: http://www.ecma-international.org/ecma-262/5.1/#sec-15.5.4.11