ref: 74bd921fc755aefb20c8171d83758bc3f5d0877b
dir: /src/peg.peg/
# PE Grammar for PE Grammars
#
# Adapted from [1] by Ian Piumarta <first-name at last-name point com>.
#
# Local modifications (marked '#ikp') to support:
# C text in '{ ... }' copied verbatim to output as 'semantic action'
# input consumed between '<' and '>' is 'char yytext[]' in semantic actions
#
# Best viewed using 140 columns monospaced with tabs every 8.
#
# [1] Bryan Ford. "Parsing Expression Grammars: A Recognition-Based Syntactic
# Foundation." Symposium on Principles of Programming Languages,
# January 14--16, 2004, Venice, Italy.
#
# Last edited: 2007-05-15 10:32:44 by piumarta on emilia
# Hierarchical syntax
Grammar <- Spacing Definition+ EndOfFile
Definition <- Identifier { if (push(beginRule(findRule(yytext)))->rule.expression) fprintf(stderr, "rule '%s' redefined\n", yytext); }
LEFTARROW Expression { Node *e= pop(); Rule_setExpression(pop(), e); } &{ YYACCEPT }
Expression <- Sequence (SLASH Sequence { Node *f= pop(); push(Alternate_append(pop(), f)); }
)*
Sequence <- Prefix (Prefix { Node *f= pop(); push(Sequence_append(pop(), f)); } #ikp expanded from 'Seq <- Prefix*'
)*
/ { push(makePredicate("1")); } #ikp added
Prefix <- AND Action { push(makePredicate(yytext)); } #ikp added
/ AND Suffix { push(makePeekFor(pop())); } #ikp expanded from 'Prefix <- (AND/NOT)? Suffix'
/ NOT Suffix { push(makePeekNot(pop())); }
/ Suffix
Suffix <- Primary (QUESTION { push(makeQuery(pop())); }
/ STAR { push(makeStar (pop())); }
/ PLUS { push(makePlus (pop())); }
)?
Primary <- Identifier !LEFTARROW { push(makeName(findRule(yytext))); }
/ OPEN Expression CLOSE
/ Literal { push(makeString(yytext)); }
/ Class { push(makeClass(yytext)); }
/ DOT { push(makeDot()); }
/ Action { push(makeAction(yytext)); } #ikp added
/ BEGIN { push(makePredicate("YY_BEGIN")); } #ikp added
/ END { push(makePredicate("YY_END")); } #ikp added
# Lexical syntax
Identifier <- < IdentStart IdentCont* > Spacing #ikp inserted < ... >
IdentStart <- [a-zA-Z_]
IdentCont <- IdentStart / [0-9]
Literal <- ['] < (!['] Char )* > ['] Spacing #ikp inserted < ... >
/ ["] < (!["] Char )* > ["] Spacing #ikp inserted < ... >
Class <- '[' < (!']' Range)* > ']' Spacing #ikp inserted < ... >
Range <- Char '-' Char / Char
Char <- '\\' [abefnrtv'"\[\]\\] #ikp added missing ANSI escapes: abefv
/ '\\' [0-3][0-7][0-7]
/ '\\' [0-7][0-7]?
/ '\\' '-' #ikp added
/ !'\\' .
LEFTARROW <- '<-' Spacing
SLASH <- '/' Spacing
AND <- '&' Spacing
NOT <- '!' Spacing
QUESTION <- '?' Spacing
STAR <- '*' Spacing
PLUS <- '+' Spacing
OPEN <- '(' Spacing
CLOSE <- ')' Spacing
DOT <- '.' Spacing
Spacing <- (Space / Comment)*
Comment <- '#' (!EndOfLine .)* EndOfLine
Space <- ' ' / '\t' / EndOfLine
EndOfLine <- '\r\n' / '\n' / '\r'
EndOfFile <- !.
Action <- '{' < [^}]* > '}' Spacing #ikp added
BEGIN <- '<' Spacing #ikp added
END <- '>' Spacing #ikp added