[gentoo-soc] libbash weekly report #10

[gentoo-soc] libbash weekly report #10

[Mu Qiao]

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Finally I have done with the backtracking removal. Now doing semantic
predicate is much easier. With this change, I successfully supported
here document, which was the biggest blocker before I started this work.
In addition, the performance is better. I used valgrind to get
performance comparison. Here is the output of ms_print (post-processing
tool for Massif) before and after backtracking removal: before[1],
after[2]. I reduced about 38% memory usage and got the library run 20%
faster.

What I have done in the past week:

    Completed the work on the new parser and incorporated it to our project
    Improved parameter expansion parsing and its runtime
    Improved built-in and keyword test
    Improved the runtime for case statement
    Improved arithmetic expansion
    Improved the local built-in
    Fixed some minor problems in compound statement and parameter expansion
    Reimplemented the export built-in
    Removed several tokens to avoid conflicts
    Improved here document and here string
    Fixed single quoted string in command substitution

In the following week, I will:

    Get backtracking removal pushed
    Fix our instruo implementation (now it crashes with the new grammar)
    Improve process substitution
    Support redirection without any command
    Reimplement the local built-in
    Fix some minor problems in variable expansion and bash test
    Remove some composite tokens

I started working on this project early and I will start seeking a job
soon (I’ll soon graduate from my university). So Petteri and I agreed to
end the GSoC on 08.06. As a result, this is the last iteration of this
year’s GSoC. I’ll write one more regular report and a final report
before the end. I’ll continue my work on this project as soon as I get a
job :).

[1] http://dev.gentoo.org/~qiaomuf/massif.before
[2] http://dev.gentoo.org/~qiaomuf/massif.after

-- 
Best wishes,
Mu Qiao
GnuPG fingerprint: 92B1 B0C4 8D14 F8C4 EFA5  3ACC 30B3 0DE4 17B1 57E9


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