In http://pharobooks.gforge.inria.fr/PharoByExampleTwo-Eng/latest/, an ExpressionGrammar is defined. However, it is right-associative
parser parse: '1 + 2 + 6'. ======> #(1 $+ #(2 $+ 6))
How can I make it left-associative so that
parser parse: '1 + 2 + 6'.
results in
#(#(1 $+ 2) $+ 6)
?
For left associative grammars use:
term := (prod sepratedBy: $+ asParser trim) foldLeft: [ :a :op :b |
...]
For right associative grammars use:
raise := (prod sepratedBy: $^ asParser trim) foldRight: [ :a :op :b |
...]
Alternatively you might want to look at PPExpressionParser, that handles all the details automatically for you. You just tell it what operators are left-associative, right-associative, prefix, or postfix operators. Have a look at the class comment for a in-depth discussion.
look at PPExpressionParser class.
it's designed for that and you have a great example in the class comment
