optimizing parser combinators
TRANSCRIPT
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PetitParser CompilerJan Kurš & Jan Vraný
Mohammad Ghafari, Mircea Lungu and
Oscar Nierstrasz
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Parsing Contexts
Bounded Seas
Furthest Failure
Layout-senstivity
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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id ← #letter #word*
block ← #INDENT expr / block /
… #DEDENT
expr ← term /‘(‘ expr ‘)’ /…
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PetitParserCompiler
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10k methods of Pharo code
3 parsers
Compared to Compiled PetitParser
Speedup
20PetitParser SmaCC RBParser
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
21Expressions Python Smalltalk Java Ruby
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PetitParser SmaCC RBParser0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Compiler
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map:
Plusprogram
TokenclassToken
TokenidToken
Sequencebody
Actionclass
Sequenceidentifier
Sequence
ClassNode new id: idToken value body: body
CharClass#letter
ChoiceletterOrDigit
CharClass#digit
Star
… Indentindent
Star Dedentdedent
Choice
Actionmethod
…
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0
0.2
0.4
0.6
0.8
1
1.2Ti
me [
mic
rose
conds]
Time per Character of Smalltalk
Compiled ParserGC time