Updated integer regexp to allow for negatives #40
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| @@ -73,8 +73,7 @@ def _unescape_string(s): | |||
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| class JavaScriptLexer(purplex.Lexer): | |||
| """Lexer for a subset of JavaScript.""" | |||
| # TODO: Negative integers | |||
| INTEGER = purplex.TokenDef(r'\d+') | |||
| INTEGER = purplex.TokenDef(r'[+-]?(?<!\.)\b[0-9]+\b(?!\.[0-9])') | |||
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Can you explain what the regular expression is doing? Why not just [-+]?\d+?
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No, I can't explain it : ) I'm not the best with these. I was going off of the SO link I found + the unit test. I linked it in the PR. There is an explation there.
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[+-]?
one of +, -, or nothing
(?<!\.)
Negative lookbehind, makes sure that a literal dot will not be matched at this position
\b
“the boundary between a word char (\w) and something that is not a word char”
[0-9]+
One or more digit
\b
-''-
(?!\.[0-9])
Negative lookahead, will make sure a literal dot followed by a digit is not matched
All in all, it means that it will match things like 42, +42, and -42, but not floats like 42.6 or .42
Found this while looking for TODOs
Implemented this pattern instead. Added a unit test and it seems to be working.