[Issue 18336] New: Add std.algorithm.untilClosingParens

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18336

          Issue ID: 18336
           Summary: Add std.algorithm.untilClosingParens
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: greensunny12 at gmail.com

Similar to balancedParens, but returning a range (i.e. it's a generalization of
it and balancedParens should be able to use it)

See also:

https://github.com/dlang/dlang.org/pull/2060#discussion_r163830331
https://github.com/dlang/phobos/pull/6098

A naive, non-efficient implementation:

```
// a range until the next ')', nested () are ignored
auto untilClosingParentheses(R)(R rs)
{
    return rs.cumulativeFold!((count, r){
        switch(r)
        {
            case '(':
                count++;
                break;
            case ')':
                count--;
                break;
            default:
        }
        return count;
    })(1).zip(rs).until!(e => e[0] == 0).map!(e => e[1]);
}

unittest
{
    import std.algorithm.comparison : equal;
    assert("aa $(foo $(bar)foobar)".untilClosingParentheses.equal("aa $(foo
$(bar)foobar)"));
    assert("$(FOO a, b, $(ARGS e, f)))".untilClosingParentheses.equal("$(FOO a,
b, $(ARGS e, f))"));
}
```

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