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| Author |
Message |
< Erlang ~ string pattern matching |
| casper |
 Posted: Thu Aug 16, 2012 5:29 pm |
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Joined: 16 Aug 2012
Posts: 1
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Let's say I have such a string: "<key1="value1" key2="value2">" and I gonna gather value1 and value2 by its keys accordingly.
I write the following code:
Code: gather_value1() ->
Fun = fun("key1=\"" ++ T, F) -> gather_body(T, []);
([_|T], F) -> F(T, F);
([], _) -> not_found
end,
Fun(?Data, Fun).
gather_value2() ->
Fun = fun("key2=\"" ++ T, F) -> gather_body(T, []);
([_|T], F) -> F(T, F);
([], _) -> not_found
end,
Fun(?Data, Fun).
gather_body("\"" ++ _, L) -> reverse(L);
gather_body([H|T], L) -> gather_body(T, [H|L]);
gather_body([], _) -> not_found.
As we can see from here, gather_value1 and gather_value2 differs just by that string which contains the key, so it is obvious to write something like:
Code: gather_value(Key) ->
Fun = fun(Key ++ T, F) -> gather_body(T, []);
([_|T], F) -> F(T, F);
([], _) -> not_found
end,
Fun(?Data, Fun).
but unfortunately "Key ++ T" is illegal pattern.
So, how can I avoid duplicating the code here? |
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| dongdongwu |
| Posted: Thu Sep 20, 2012 5:22 am |
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User
Joined: 19 Sep 2012
Posts: 236
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