Doubt about ebnf parser using lpeg.

[Cleverton Hentz <cleverton_hentz@...>]

Hi,

I'm trying describe EBNF parser with lpeg library but my implementation of parser don't recognize some sentences. 

The grammar defined by me is show below:

local function t(s) return (P(s) * Space1) end

-- Lexical Elements

local Space = S(" \n\t")^0

local idSafe = R('AZ', 'az')

local DecimalDigit = R('09')

local MetaID = idSafe * (idSafe + P('_') + DecimalDigit)^0 * Space

local string = (P('"') * (P('\\') * P(1) + (1 - P('"')))^0 * P('"') +

               P("'") * (P("\\")* P(1) + (1 - P("'")))^0 * P("'")) * Space

local SyntaxRule, Def, SingleDef = V('SyntaxRule'), V('Def'), V('SingleDef')

local Term, Primary = V('Term'), V('Primary')

local OptionalSequence, RepeatedSequence, RepeatedSequenceP, GroupedSequence,

    TerminalString, Empty = V('OptionalSequence'), V('RepeatedSequence'), V('RepeatedSequenceP'), V('GroupedSequence'),

    V('TerminalString'), V('Empty')

local G4 = P{"Syntax";

  Syntax = SyntaxRule^1,

  SyntaxRule = MetaID * t('=') * Def * t(';'),

  Def = SingleDef * (t('|') * SingleDef)^0,

  SingleDef = Term * (t(',') * Term)^0,

  Term = Primary,

  Primary = TerminalString +  

    OptionalSequence +

    RepeatedSequence +

    GroupedSequence +

    MetaID +

    Empty,

  TerminalString = string,

  Empty = Space,

  OptionalSequence = t('[') * Def * t(']'),

  RepeatedSequence = t('{') * Def * t('}') * RepeatedSequenceP + --ZeroOrMore 

    MetaID * t('+') * RepeatedSequenceP +

    string * t('+') * RepeatedSequenceP +  

    t('[') * Def * t(']') * t('+') * RepeatedSequenceP +    

    GroupedSequence * t('+') * RepeatedSequenceP +

    Space * t('+') * RepeatedSequenceP + --OneOrMore

    

    MetaID * t('+') * TerminalString * RepeatedSequenceP +

    string * t('+') * TerminalString * RepeatedSequenceP +  

    t('[') * Def * t(']') * t('+') * TerminalString * RepeatedSequenceP +    

    GroupedSequence * t('+') * TerminalString * RepeatedSequenceP +

    Space * t('+') * TerminalString * RepeatedSequenceP, --OneOrMoreSeparation

    

  RepeatedSequenceP =  t('') +

    t('+') * RepeatedSequenceP + 

    t('+') * TerminalString * RepeatedSequenceP,

    

  GroupedSequence = t('(') * Def * t(')')

}

G4 = G4 * -1 / '%0'

But with this grammar, I don't recognize the sentence "A = 'a'+;". The code I use for this is 

print(lpeg.match(G4, "A = 'a'+;"))

Any idea why this problem happens ?

Thanks in advice,

Cleverton Hentz