IN: peg.ebnf
: rule ( name word -- parser )
- #! Given an EBNF word produced from EBNF: return the EBNF rule
+ ! Given an EBNF word produced from EBNF: return the EBNF rule
"ebnf-parser" word-prop at ;
ERROR: no-rule rule parser ;
C: <ebnf> ebnf
: filter-hidden ( seq -- seq )
- #! Remove elements that produce no AST from sequence
+ ! Remove elements that produce no AST from sequence
[ ebnf-ensure-not? ] reject [ ebnf-ensure? not ] filter ;
: syntax ( string -- parser )
- #! Parses the string, ignoring white space, and
- #! does not put the result in the AST.
+ ! Parses the string, ignoring white space, and
+ ! does not put the result in the AST.
token sp hide ;
: syntax-pack ( begin parser end -- parser )
- #! Parse parser-parser surrounded by syntax elements
- #! begin and end.
+ ! Parse parser-parser surrounded by syntax elements
+ ! begin and end.
[ syntax ] 2dip syntax pack ;
: insert-escapes ( string -- string )
] choice* replace ;
: identifier-parser ( -- parser )
- #! Return a parser that parses an identifer delimited by
- #! a quotation character. The quotation can be single
- #! or double quotes. The AST produced is the identifier
- #! between the quotes.
+ ! Return a parser that parses an identifer delimited by
+ ! a quotation character. The quotation can be single
+ ! or double quotes. The AST produced is the identifier
+ ! between the quotes.
[
[
[ CHAR: \ = ] satisfy
] choice* [ "" flatten-as unescape-string ] action ;
: non-terminal-parser ( -- parser )
- #! A non-terminal is the name of another rule. It can
- #! be any non-blank character except for characters used
- #! in the EBNF syntax itself.
+ ! A non-terminal is the name of another rule. It can
+ ! be any non-blank character except for characters used
+ ! in the EBNF syntax itself.
[
{
[ blank? ]
] satisfy repeat1 [ >string <ebnf-non-terminal> ] action ;
: terminal-parser ( -- parser )
- #! A terminal is an identifier enclosed in quotations
- #! and it represents the literal value of the identifier.
+ ! A terminal is an identifier enclosed in quotations
+ ! and it represents the literal value of the identifier.
identifier-parser [ <ebnf-terminal> ] action ;
: foreign-name-parser ( -- parser )
- #! Parse a valid foreign parser name
+ ! Parse a valid foreign parser name
[
{
[ blank? ]
] satisfy repeat1 [ >string ] action ;
: foreign-parser ( -- parser )
- #! A foreign call is a call to a rule in another ebnf grammar
+ ! A foreign call is a call to a rule in another ebnf grammar
[
"<foreign" syntax ,
foreign-name-parser sp ,
] seq* [ first2 <ebnf-foreign> ] action ;
: any-character-parser ( -- parser )
- #! A parser to match the symbol for any character match.
+ ! A parser to match the symbol for any character match.
[ CHAR: . = ] satisfy [ drop <ebnf-any-character> ] action ;
: range-parser-parser ( -- parser )
- #! Match the syntax for declaring character ranges
+ ! Match the syntax for declaring character ranges
[
[ "[" syntax , "[" token ensure-not , ] seq* hide ,
[ CHAR: ] = not ] satisfy repeat1 ,
] seq* [ first >string unescape-string <ebnf-range> ] action ;
: (element-parser) ( -- parser )
- #! An element of a rule. It can be a terminal or a
- #! non-terminal but must not be followed by a "=".
- #! The latter indicates that it is the beginning of a
- #! new rule.
+ ! An element of a rule. It can be a terminal or a
+ ! non-terminal but must not be followed by a "=".
+ ! The latter indicates that it is the beginning of a
+ ! new rule.
[
[
[
DEFER: choice-parser
: grouped ( quot suffix -- parser )
- #! Parse a group of choices, with a suffix indicating
- #! the type of group (repeat0, repeat1, etc) and
- #! an quot that is the action that produces the AST.
+ ! Parse a group of choices, with a suffix indicating
+ ! the type of group (repeat0, repeat1, etc) and
+ ! an quot that is the action that produces the AST.
2dup
[
"(" [ choice-parser sp ] delay ")" syntax-pack
] choice* ;
: group-parser ( -- parser )
- #! A grouping with no suffix. Used for precedence.
+ ! A grouping with no suffix. Used for precedence.
[ ] [
"~" token sp ensure-not ,
"*" token sp ensure-not ,
] seq* repeat0 [ "" concat-as ] action ;
: ensure-not-parser ( -- parser )
- #! Parses the '!' syntax to ensure that
- #! something that matches the following elements do
- #! not exist in the parse stream.
+ ! Parses the '!' syntax to ensure that
+ ! something that matches the following elements do
+ ! not exist in the parse stream.
[
"!" syntax ,
group-parser sp ,
] seq* [ first <ebnf-ensure-not> ] action ;
: ensure-parser ( -- parser )
- #! Parses the '&' syntax to ensure that
- #! something that matches the following elements does
- #! exist in the parse stream.
+ ! Parses the '&' syntax to ensure that
+ ! something that matches the following elements does
+ ! exist in the parse stream.
[
"&" syntax ,
group-parser sp ,
] seq* [ first <ebnf-ensure> ] action ;
: (sequence-parser) ( -- parser )
- #! A sequence of terminals and non-terminals, including
- #! groupings of those.
+ ! A sequence of terminals and non-terminals, including
+ ! groupings of those.
[
[
ensure-not-parser sp ,
"?[" factor-code-parser "]?" syntax-pack ;
: sequence-parser ( -- parser )
- #! A sequence of terminals and non-terminals, including
- #! groupings of those.
+ ! A sequence of terminals and non-terminals, including
+ ! groupings of those.
[
[ (sequence-parser) , action-parser , ] seq*
[ first2 <ebnf-action> ] action ,
] keep ;
M: ebnf-sequence (transform) ( ast -- parser )
- #! If ignore-ws is set then each element of the sequence
- #! ignores leading whitespace. This is not inherited by
- #! subelements of the sequence.
+ ! If ignore-ws is set then each element of the sequence
+ ! ignores leading whitespace. This is not inherited by
+ ! subelements of the sequence.
elements>> [
f ignore-ws [ (transform) ] with-variable
ignore-ws get [ sp ] when
pattern>> range-pattern ;
: transform-group ( ast -- parser )
- #! convert a ast node with groups to a parser for that group
+ ! convert a ast node with groups to a parser for that group
group>> (transform) ;
M: ebnf-ensure (transform) ( ast -- parser )
GENERIC: build-locals ( code ast -- code )
M: ebnf-sequence build-locals ( code ast -- code )
- #! Note the need to filter out this ebnf items that
- #! leave nothing in the AST
+ ! Note the need to filter out this ebnf items that
+ ! leave nothing in the AST
elements>> filter-hidden dup length 1 = [
first build-locals
] [
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