Add cpp-peglib grammar extracted from peglib.h (#222)

grammar/cpp-peglib.peg

@@ -0,0 +1,145 @@
+# Setup PEG syntax parser
+Grammar <-  Spacing  Definition+  EndOfFile
+
+Definition <-
+	Ignore  IdentCont  Parameters  LEFTARROW Expression  Instruction?
+	/ Ignore  Identifier  LEFTARROW  Expression Instruction?
+
+Expression <-  Sequence  (SLASH  Sequence)*
+
+Sequence <-  (CUT /  Prefix)*
+
+Prefix <-  (AND /  NOT)?  SuffixWithLabel
+
+SuffixWithLabel <- Suffix  (LABEL  Identifier)?
+
+Suffix <-  Primary  Loop?
+
+Loop <-  QUESTION /  STAR /  PLUS /  Repetition
+
+Primary <-
+	Ignore  IdentCont  Arguments !LEFTARROW
+	/ Ignore  Identifier !(Parameters?  LEFTARROW)
+	/ OPEN  Expression  CLOSE
+	/ BeginTok  Expression  EndTok
+	/ BeginCapScope  Expression  EndCapScope
+	/ BeginCap  Expression  EndCap
+	/ BackRef
+	/ LiteralI
+	/ Dictionary
+	/ Literal
+	/ NegatedClass
+	/ Class
+	/  DOT
+
+Identifier <-  IdentCont  Spacing
+
+IdentCont <- IdentStart  IdentRest*
+
+IdentStart <-  !"↑"  !"⇑" ([a-zA-Z_%] /  [\u0080-\uFFFF])
+
+IdentRest <-  IdentStart /  [0-9]
+
+Dictionary <-  LiteralD  (PIPE  LiteralD)+
+
+lit_ope <-
+	[']  <(![']  Char)*> [']  Spacing
+	/ ["]  <(!["]  Char)*> ["]  Spacing
+
+Literal <-  lit_ope
+
+LiteralD <-  lit_ope
+
+LiteralI <-
+	[']  <(![']  Char)*>  "'i" Spacing
+	/ ["]  <(!["]  Char)*>  '"i' Spacing
+
+# NOTE: The original Brian Ford's paper uses 'zom' instead of 'oom'.
+Class <-  '['  !'^' <(!']'  Range)+>  ']' Spacing
+NegatedClass <-  "[^" <(!']'  Range)+>  ']' Spacing
+
+Range <-  (Char  '-'  ! ']' Char) /  Char
+
+Char <-
+	'\\'  [nrt'\"[\]\\^]
+	/ '\\'  [0-3]  [0-7]  [0-7]
+	/ '\\'  [0-7]  [0-7]?
+	/ "\\x"  [0-9a-fA-F]  [0-9a-fA-F]?
+	/ "\\u" (((('0' [0-9a-fA-F]) / "10") [0-9a-fA-F]{4,4}) / [0-9a-fA-F]{4,5})
+	/ !'\\'   .
+
+Repetition <- BeginBlacket  RepetitionRange  EndBlacket
+
+RepetitionRange <-
+	Number  COMMA  Number
+	/ Number  COMMA
+	/  Number
+	/ COMMA  Number
+
+Number <-  [0-9]+  Spacing
+
+LEFTARROW <-  ("<-" / "←")  Spacing
+
+~SLASH <-  '/'  Spacing
+~PIPE <-  '|'  Spacing
+AND <-  '&'  Spacing
+NOT <-  '!'  Spacing
+QUESTION <- '?'  Spacing
+STAR <-  '*'  Spacing
+PLUS <-  '+'  Spacing
+~OPEN <-  '('  Spacing
+~CLOSE <- ')'  Spacing
+DOT <-  '.'  Spacing
+
+CUT <-  "↑"  Spacing
+~LABEL <-  ('^' /  "⇑")  Spacing
+
+~Spacing <-  (Space /  Comment)*
+Comment <- '#'  (!EndOfLine   . )*
+Space <-  ' ' /  '\t' /  EndOfLine
+EndOfLine <-  "\r\n" /  '\n' /  '\r'
+EndOfFile <-  ! .
+
+~BeginTok <-  '<'  Spacing
+~EndTok <-  '>'  Spacing
+
+~BeginCapScope <-  '$'  '('  Spacing
+~EndCapScope <-  ')'  Spacing
+
+BeginCap <-  '$'  <IdentCont>  '<'  Spacing
+~EndCap <-  '>'  Spacing
+
+BackRef <-  '$'  <IdentCont>  Spacing
+
+IGNORE <-  '~'
+
+Ignore <-  IGNORE?
+Parameters <-  OPEN  Identifier (COMMA  Identifier)*  CLOSE
+Arguments <-  OPEN  Expression (COMMA  Expression)*  CLOSE
+~COMMA <-  ','  Spacing
+
+# Instruction grammars
+Instruction <-
+	BeginBlacket (InstructionItem  (InstructionItemSeparator InstructionItem)*)? EndBlacket
+InstructionItem <- PrecedenceClimbing /  ErrorMessage /  NoAstOpt
+~InstructionItemSeparator <-  ';'  Spacing
+
+~SpacesZom <-  Space*
+~SpacesOom <-  Space+
+~BeginBlacket <-  '{'  Spacing
+~EndBlacket <-  '}'  Spacing
+
+# PrecedenceClimbing instruction
+PrecedenceClimbing <- "precedence"  SpacesOom  PrecedenceInfo (SpacesOom  PrecedenceInfo)*  SpacesZom
+PrecedenceInfo <- PrecedenceAssoc (~SpacesOom  PrecedenceOpe)+
+PrecedenceOpe <-
+	['] <(!(Space /  ['])  Char)*> [']
+	/ ["] <(!(Space /  ["])  Char)*> ["]
+	/ <(!(PrecedenceAssoc /  Space /  '}')  . )+>
+PrecedenceAssoc <-  [LR]
+
+# Error message instruction
+ErrorMessage <- "message"  SpacesOom  LiteralD  SpacesZom
+
+# No Ast node optimazation instruction
+NoAstOpt <-  "no_ast_opt"  SpacesZom