Fixes for two problems

[frederik-h]

Hi,
these changes fix two problems.

1. --invert-match is broken
   $ cat <<END | stack exec cgrep -- -v foo
   foo
   bar
   END
   Using 'cgreprc' configuration file...
   cgrep: Prelude.head: empty list

With my change, I get the expected result:
$cat <<END | stack exec cgrep -- -v foo
foo
bar
END
Using 'cgreprc' configuration file...
:2:bar

2. Output.getOffset2d has a memory leak

When run on a long file with many matching lines,
cgrep becomes very slow. For instance,
I used a list of english-words and searched for the word
"house" which matches many lines:

$ git clone https://github.com/dwyl/english-words
$ time stack exec cgrep -- house english-words/words.txt
Using 'cgreprc' configuration file...
english-words/words.txt:7345:4:alehouse
english-words/words.txt:7346:4:alehouses
english-words/words.txt:8584:5:almshouse
english-words/words.txt:8585:5:almshouses
(...)
english-words/words.txt:351557:5:workhouse
english-words/words.txt:351558:5:workhoused
english-words/words.txt:351559:5:workhouses

real 1m29.212s
user 0m26.680s
sys 0m10.784s

The problem is a memory leak in Output.getOffset2d caused by the sharing of the
list prc defined in this function.
Doing the same search with my change to Output.getOffset2d yields the following statistics:

real 0m3.212s
user 0m3.116s
sys 0m0.260s

Frederik

[awgn]

Thanks for the fixes!

[frederik-h]

You're welcome. I also have a more efficient implementation of Output.mkOutput.
If you are interested, I can also file a pull request for this.
For the example above, it yields a running time of about 0.6s on my computer.

[awgn]

Thanks for your contribution! I'll merge it as soon as I come back home. I'm out for a week. Best, N,

…

On Thu, Jan 26, 2017 at 6:58 AM, frederik-h ***@***.***> wrote: You're welcome. I also have a more efficient implementation of Output.mkOutput. If you are interested, I can also file a pull request for this. For the example above, it yields a running time of about 0.6s on my computer. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#38 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAB6v0W6TRWxbzNUB2QOQk1j821hXaAFks5rWDYYgaJpZM4LtfKj> .

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