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