Presentation of IWST16, Prag Video: https://youtu.be/wI5g1RN4cF8

1. 1
PetitParser Compiler
Jan Kurš & Jan Vraný
Mohammad Ghafari, Mircea Lungu and
Oscar Nierstrasz

2. 2

3. 3
Parsing
Contexts
Bounded
Seas
Furthest
Failure
Layout-
senstivity

4. 4

5. 5

6. 6
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

7. 7
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

8. 8
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

9. 9
id ← #letter #word*
expr ← term /
‘(‘ expr ‘)’ /
…

10. 10
id ← #letter #word*
expr ← term /
‘(‘ expr ‘)’ /
…

11. 11
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

12. 12
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

13. 13
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

14. 14
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

15. 15
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

16. 16

17. 17
id ← #letter #word*
block ← #INDENT
expr /
block /
…
#DEDENT
expr ← term /
‘(‘ expr ‘)’ /
…

18. 18
PetitParser
Compiler

19. 19
10k methods of Pharo code
3 parsers
Compared to Compiled PetitParser
Speedup

20. 20
PetitParser SmaCC RBParser
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5

21. 21
Expressions Python Smalltalk Java Ruby
0
2
4
6
8
10
12
14

22. 22
PetitParser SmaCC RBParser
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Compiler

23. 23
map:
Plus
program
Token
classToken
Token
idToken
Sequence
body
Action
class
Sequence
identifier
Sequence
ClassNode new
id: idToken value
body: body
CharClass
#letter
Choice
letterOrDigit
CharClass
#digit
Star
… Indent
indent
Star Dedent
dedent
Choice
Action
method
…

24. 24
0
0.2
0.4
0.6
0.8
1
1.2
Time[microseconds]
Time per Character of Smalltalk
Compiled Parser
GC time