Pattern matching

Steve

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Nov 6, 2012, 4:42:03 AM11/6/12

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Hi

I am trying the following code, which should return a list of html tags.

My thinking is to:

check for '</' to find an end tag, which I ignore since there should also be a start tag, just recurse upon the rest following the '>'

check for '<' to find a start tag, which I add to the list, then recurse upon the rest following the '>'

and (currently) ignore everything else.

When run the code just prints and empty list, rather than [html].

#returns lists of tags
test_html(input) =>
('</':etag:'>':rest) : test_html(rest)
('<':tag:'>':rest) : [tag] + test_html(rest)
* : []

main ->
print(test_html(content))
where content: '<html>123</html>'

Even using '<html>' or '</html>' as content yields the same result: []

Any ideas? It would appear to execute the wildcard case, rather than matching the previous rule.

But I would expect the patterns to be check in the order (top to bottom) they appear in the code.

Thanks for any help!

Steve

Dhanji R. Prasanna

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Nov 8, 2012, 1:55:26 AM11/8/12

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Hi, let me investigate--seems odd. Did you look at the test case for pattern matching? It does a similar thing with parsing new lines.

Steve

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Nov 8, 2012, 3:23:48 AM11/8/12

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Hi

I think it has to do with using '>' in both patterns. When I remove one of the pattern matching lines I get the expected result.

I used the flag to dump the generated byte code and not being familar with byte code used a tool to decompile.