Why isn't this expression being parsed correctly?

Why isn't this expression being parsed correctly?

References

Reference NO 1

http://stackoverflow.com/questions/15188625/why-isnt-this-expression-being-parsed-correctly

Reference NO 2

http://stackoverflow.com/questions/14504726/antlr-parsing-literals-and-quoted-ids

Reference NO 3

http://www.codinghorror.com/blog/2009/11/parsing-html-the-cthulhu-way.html

Reference NO 4

https://forums.oracle.com/thread/1661948

Reference NO 5

http://compilers.iecc.com/crenshaw/tutor2.txt

Reference NO 6

http://kore-nordmann.de/blog/do_NOT_parse_using_regexp.html

Reference NO 7

https://github.com/jsdoc3/jsdoc/issues/152

Reference NO 8

http://johndwells.com/blog/expressionengine-parse-order-advanced-conditionals-as-tag-parameters