New line as whitespace and terminator
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I am parsing javascript ES6, however I can't get it to work without semicolons. I used Tin's grammar from ES5 as base , ( https://github.com/usethesource/rascal/blob/master/src/org/rascalmpl/library/lang/javascript/saner/Syntax.rsc ) and already got most of the new features from ES6, but I still can't remove the need for semicolons
Take for example:
lexical Whitespace
= [t-nr ];
lexical LAYOUT
= Whitespace
| Comment
;
layout LAYOUTLIST
= LAYOUT*
!>> [t n]
!>> "/*"
!>> "//" ;
syntax Variable
= VariableIdentifier {VariableDeclaration ","}+ declarations ";"
syntax Statement
= varDecl: Variable varDecl;
I get parsing error replacing ";" to "n" on Syntax Variable , or even creating a new rule for end of statement:
syntax EOS
= ";" | "n";
The parsing error goes to the next line after the newline.
Removing from whitespaces or from the layoutlist gives me parsing error on comments at the start of the file.
And removing on the layoutlist gives me ambiguity.
javascript grammar rascal
asked 2 days ago
Adriano Torres
133
add a comment |
up vote
1
down vote
favorite
I am parsing javascript ES6, however I can't get it to work without semicolons. I used Tin's grammar from ES5 as base , ( https://github.com/usethesource/rascal/blob/master/src/org/rascalmpl/library/lang/javascript/saner/Syntax.rsc ) and already got most of the new features from ES6, but I still can't remove the need for semicolons
Take for example:
lexical Whitespace
= [t-nr ];
lexical LAYOUT
= Whitespace
| Comment
;
layout LAYOUTLIST
= LAYOUT*
!>> [t n]
!>> "/*"
!>> "//" ;
syntax Variable
= VariableIdentifier {VariableDeclaration ","}+ declarations ";"
syntax Statement
= varDecl: Variable varDecl;
I get parsing error replacing ";" to "n" on Syntax Variable , or even creating a new rule for end of statement:
syntax EOS
= ";" | "n";
The parsing error goes to the next line after the newline.
Removing from whitespaces or from the layoutlist gives me parsing error on comments at the start of the file.
And removing on the layoutlist gives me ambiguity.
javascript grammar rascal
asked 2 days ago
Adriano Torres
133
This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I am parsing javascript ES6, however I can't get it to work without semicolons. I used Tin's grammar from ES5 as base , ( https://github.com/usethesource/rascal/blob/master/src/org/rascalmpl/library/lang/javascript/saner/Syntax.rsc ) and already got most of the new features from ES6, but I still can't remove the need for semicolons
Take for example:
lexical Whitespace
= [t-nr ];
lexical LAYOUT
= Whitespace
| Comment
;
layout LAYOUTLIST
= LAYOUT*
!>> [t n]
!>> "/*"
!>> "//" ;
syntax Variable
= VariableIdentifier {VariableDeclaration ","}+ declarations ";"
syntax Statement
= varDecl: Variable varDecl;
I get parsing error replacing ";" to "n" on Syntax Variable , or even creating a new rule for end of statement:
syntax EOS
= ";" | "n";
The parsing error goes to the next line after the newline.
Removing from whitespaces or from the layoutlist gives me parsing error on comments at the start of the file.
And removing on the layoutlist gives me ambiguity.
javascript grammar rascal
asked 2 days ago
Adriano Torres
133
I am parsing javascript ES6, however I can't get it to work without semicolons. I used Tin's grammar from ES5 as base , ( https://github.com/usethesource/rascal/blob/master/src/org/rascalmpl/library/lang/javascript/saner/Syntax.rsc ) and already got most of the new features from ES6, but I still can't remove the need for semicolons
Take for example:
lexical Whitespace
= [t-nr ];
lexical LAYOUT
= Whitespace
| Comment
;
layout LAYOUTLIST
= LAYOUT*
!>> [t n]
!>> "/*"
!>> "//" ;
syntax Variable
= VariableIdentifier {VariableDeclaration ","}+ declarations ";"
syntax Statement
= varDecl: Variable varDecl;
I get parsing error replacing ";" to "n" on Syntax Variable , or even creating a new rule for end of statement:
syntax EOS
= ";" | "n";
The parsing error goes to the next line after the newline.
Removing from whitespaces or from the layoutlist gives me parsing error on comments at the start of the file.
And removing on the layoutlist gives me ambiguity.
javascript grammar rascal
javascript grammar rascal
asked 2 days ago
Adriano Torres
133
asked 2 days ago
Adriano Torres
133
asked 2 days ago
Adriano Torres
133
asked 2 days ago
Adriano Torres
133
asked 2 days ago
Adriano Torres
133
133
This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago
add a comment |
This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago
This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago
This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago
add a comment |
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This is tricky stuff! You need a number of advanced features and a lot of thinking and debugging you get this right. I'll try and list the useful features in an answer tomorrow if I feel well enough. For now it's best to go for an ambiguous grammar first, which exactly describes js syntax input but is an over-approximation (too many) for its syntax trees. Using step-by-step grammar changes, and adding disambiguation constructs you can filter the superfluous trees. Better make a regression test set using rascals test function feature as well, to help in trusting the changes.
– jurgenv
2 days ago