Lua syntax ambiguity

Ahoy list,

Let's say we're writing Lua code generator. He just applies grammar rules.

So let's take parts of Lua grammar and apply them.

   chunk ::= block

   block ::= {stat} [retstat]

   stat ::= varlist ‘=’ explist

   varlist ::= var {‘,’ var}

   var ::=  Name | prefixexp ‘[’ exp ‘]’

   explist ::= exp {‘,’ exp}

   exp ::=  false | true | LiteralString | prefixexp | tableconstructor

   prefixexp ::= var

   tableconstructor ::= ‘{’ [fieldlist] ‘}’

   fieldlist ::= field {fieldsep field} [fieldsep]

   field ::= ‘[’ exp ‘]’ ‘=’ exp

   fieldsep ::= ‘,’ | ‘;’

Problem is that "LiteralString" can start with "[" (long quotes).
And so when writing index in "field" we emit "[", then we go
to "exp" which may be "LiteralString" and we will emit another "[".

So we'll have text like "t={[[[a]]]=true}".

It's generated by perfectly abiding EBNF rules and greedy parser will
miserably fail on it.

I doubt there is a way to fix it by mangling EBNF grammar.
That's just consequence that character to open index is "[",
same character was chosen to start "long quotes", and table
index can be literal string.

-- Martin

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