I would like to come up with a regex for the following:
<action>::=Action(<entity><entity><Asset>)
I would like to have tokens such as :
Action(
<entity>
<entity>
<Asset>
)
entity and asset have <> around them and Action is followed by "(". However, ")" is an independent token. I am using the following:
([a-zA-Z]+\\()|((<.*?>)|([a-zA-Z]*))|(\\))?
but it fails to show the ")" as token? What am I doing wrong?
Try this regex :
([a-zA-Z]*\\()|(<[a-zA-Z]*>)|(\\))
Something is actually wrong with your regular expression, or at least it makes the expression behave in an unexpected manner (to me).
The expression can be decomposed as such:
([a-zA-Z]+\\()| (?# matches alphabetical characters and an opening round-bracket)
((<.*?>)| (?# non-greedily matches anything between brackets)
([a-zA-Z]*))| (?# 3rd pattern: may match an empty string)
(\\))? (?# 4th pattern: optionally matches a closing round bracket)
Since the | operator is never greedy, the third pattern is triggered (matching an empty string) before the 4th pattern you actually want is.
Proof of this is that the tokens you actually get with your regular expression are:
''
''
''
'Action('
'<entity>'
'<entity>'
'<Asset>'
''
''
Therefore what you want is probably something like this:
([a-zA-Z]+\\()| (?# matches alphabetical characters and an opening round-bracket)
(<.*?>)| (?# non-greedily matches anything between brackets)
(\\)) (?# matches a closing round bracket)
Please note I removed the ? operator from the 4th pattern which was weirdly put outside the brackets and which also captured empty string.
