parsing contexts for petitparser

Parsing Contextsfor PetitParser

Jan Kurškurs@iam.unibe.chSoftware Composition Group

2

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

3

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

4

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

ifKeyword := 'if' asParser.

5

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

6

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

identifier := #letter, (#letter / #digit) star.

7

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

8

print “Hello!”

if (outOf(milk)):

print “We are out of milk!”

order(milk)

if (outOf(eggs)):

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

9

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

10

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

indent := ???

dedent := ???

11Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

12

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

13

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

14

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

15

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

16

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

17

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Lan

gu

age

sC

on

text

-Fre

eLa

ng

uag

es

State of the ArtC

on

text

-Se

nsi

tive

Lan

gu

age

s

18

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

Goal

19

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

Goal

20

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

Goal

21

PetitParser uses Parser Combinators

22

#letter, (#letter / #digit) star

PetitParser uses Parser Combinators

23

#letter, (#letter / #digit) star

PetitParser uses Parser Combinators

24

#letter, (#letter / #digit) star

,,

#letter

#digit #letter

//

PetitParser uses Parser Combinators

star

25

String

String

26

String

String

27

String

String

“Hello”

“ello”

#letter #letter

28

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

29

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

indent := ???

dedent := ???

30

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

▼

31

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

block := indent, command plus, dedent.

indent := ???

dedent := ???

▼

32

String

String

33

String

String

34

String

String

String&

Indentation Stack

String&

Indentation Stack

35

String

String

ParsingParsingContextsContexts

ParsingParsingContextsContexts

36

String

String

ParsingParsingContextsContexts

ParsingParsingContextsContexts

String

Other Data

37

print “Hello!”

if (outOf(milk))

print “We are out of milk!”

order(milk)

if (outOf(eggs))

…

if keyword

block of commands

eggs identifier

Indentation Example

▼

block := , command plus,

[:context | | column indentation stack |

(context isBeginOfLine) ifFalse: [ ^ Failure ]. context consumeLeadingWhitespace. " Save the current column " column := context stream column. stack := (context propertyAt: #indent). indentation := stack top.

(column > indentation) ifTrue: [ stack push: column. ^ #indent ]. ^ Failure]

[:context | | column referenceIndentation stack |

(context isBeginOfLine) ifFalse: [ ^ Failure ]. context consumeLeadingWhitespace. column := context stream column. " Restore previous column from the " " stack and compare with current " stack := (context propertyAt: #indent). stack pop. referenceIndentation := stack top.

(column == referenceIndentation) ifTrue: [ ^ #dedent ]. ^ Failure]

38

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

39

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

40

GrammarImplementors

41

FrameworkImplementors

GrammarImplementors

42

FrameworkImplementors

GrammarImplementors

N (N ← ∪ T)*

43

FrameworkImplementors

GrammarImplementors

N (N ← ∪ T)*

indent, command plus, dedent

44

FrameworkImplementors

GrammarImplementors

N (N ← ∪ T)*

indent, command plus, dedent

, command plus,

[:context | | column indentation stack |

(context isBeginOfLine) ifFalse: [ ^ Failure ]. context consumeLeadingWhitespace. " Save the current column " column := context stream column. stack := (context propertyAt: #indent). indentation := stack top.

(column > indentation) ifTrue: [ stack push: column. ^ #indent ]. ^ Failure]

[:context | | column referenceIndentation stack |

(context isBeginOfLine) ifFalse: [ ^ Failure ]. context consumeLeadingWhitespace. column := context stream column. " Restore previous column from the " " stack and compare with current " stack := (context propertyAt: #indent). stack pop. referenceIndentation := stack top.

(column == referenceIndentation) ifTrue: [ ^ #dedent ]. ^ Failure]

45

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

ParsingParsingContextsContexts

46

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

47

TuringMachine

RegularExpression

Simple Complex

Re

gu

lar

Co

nte

xt-F

ree

Co

nte

xt-S

en

siti

ve

ParsingParsingContextsContexts

48

indentation

49

indentation

50

indentation

tolerant parsing

51

indentation

tolerant parsing

52

indentation

typedef

tolerant parsing

53

indentation

typedef

tolerant parsing

54

indentation

typedef

recursion

tolerant parsing

55

indentation

typedef

recursion

tolerant parsing

56

indentation

typedef

recursion

ParsingParsingContextsContexts

tolerant parsing

57

http://smalltalkhub.com/#!/~JanKurs/PetitParser

58

TuringMachine

RegularExpression

ParsingParsingContextsContexts

59

String

String

ParsingContext

Parsing Context

TuringMachine

RegularExpression

ParsingParsingContextsContexts

60

String

String

ParsingContext

Parsing Context

Framework Implementors

Grammar Implementor

N (N T)*← ∪

TuringMachine

RegularExpression

ParsingParsingContextsContexts

61

String

String

ParsingContext

Parsing Context

indentation

typedef

tolerant parsing

recursion

ParsingParsingContextsContexts

Framework Implementors

Grammar Implementor

N (N T)*← ∪

TuringMachine

RegularExpression

ParsingParsingContextsContexts