! Copyright (C) 2009 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: peg peg.ebnf smalltalk.ast sequences sequences.deep strings
math.parser kernel arrays byte-arrays math assocs ;
IN: testing

EBNF: parse-smalltalk

WhitespaceCharacter = (" " | "\t" | "\n" | "\r" )
Letter = [A-Za-z]

OptionalWhiteSpace = (WhitespaceCharacter)*
Whitespace = (WhitespaceCharacter)+

Identifier = Letter*

UnaryMessageSelector = Identifier
Keyword = Identifier:i ":"
BinarySelectorChar =   "~" | "!" | "@" | "%" | "&" | "*" | "-" | "+"
                     | "=" | "|" | "\" | "<" | ">" | "," | "?" | "/"
BinaryMessageSelector = BinarySelectorChar+

Operand =       "(" Expression ")" | Identifier

UnaryMessage = UnaryMessageSelector
UnaryMessageOperand = UnaryMessageSend | Operand
UnaryMessageSend = UnaryMessageOperand:receiver
                   OptionalWhiteSpace UnaryMessageSelector:selector !(":")

BinaryMessage = BinaryMessageSelector OptionalWhiteSpace BinaryMessageOperand
BinaryMessageOperand = BinaryMessageSend | UnaryMessageSend | Operand
BinaryMessageSend-1 = BinaryMessageOperand:lhs
                    OptionalWhiteSpace
                    BinaryMessageSelector:selector
                    OptionalWhiteSpace
                    UnaryMessageOperand:rhs
BinaryMessageSend = (BinaryMessageSend:lhs
                    OptionalWhiteSpace
                    BinaryMessageSelector:selector
                    OptionalWhiteSpace
                    UnaryMessageOperand:rhs)
                    | BinaryMessageSend-1

KeywordMessageSegment = Keyword:k OptionalWhiteSpace BinaryMessageOperand:arg
KeywordMessageSend = BinaryMessageOperand:receiver
                     OptionalWhiteSpace
                     KeywordMessageSegment:h
                     (OptionalWhiteSpace KeywordMessageSegment:s)*:t

Expression = KeywordMessageSend | BinaryMessageSend | UnaryMessageSend | Operand

End = !(.)

Program = Expression End
;EBNF

"(a x + b) x" parse-smalltalk