module OpPrec
class TreeOutput
def initialize
reset
end
@@dont_rewrite = false
def self.dont_rewrite
@@dont_rewrite = true
end
def reset
@vstack = []
end
def flatten(r)
return r if !r.is_a?(Array)
return r if r[0] != :comma
return r[1..2] if !r[2].is_a?(Array) or r[2][0] == :array
return [r[1], flatten(r[2])] if r[2][0] != :comma
return [r[1]] + flatten(r[2])
end
def oper(o)
raise "Missing value in expression / #{o.inspect}" if @vstack.empty? && o.minarity > 0
rightv = @vstack.pop if o.arity > 0
raise "Missing value in expression / op: #{o.inspect} / vstack: #{@vstack.inspect} / rightv: #{rightv.inspect}" if @vstack.empty? and o.minarity > 1
leftv = @vstack.pop if o.arity > 1
leftv = [] if !leftv && o.sym == :flatten # Empty argument list. :flatten is badly named
la = leftv.is_a?(Array)
ra = rightv.is_a?(Array)
# Debug option: Output the tree without rewriting.
return @vstack << [o.sym, leftv, rightv] if @@dont_rewrite
# Rewrite rules to simplify the tree
if ra and rightv[0] == :flatten
@vstack << [o.sym, leftv] + flatten(rightv[1..-1])
elsif ra and rightv[0] == :call and o.sym == :callm
@vstack << [o.sym, leftv] + flatten(rightv[1..-1])
elsif la and leftv[0] == :callm and o.sym == :call
@vstack << leftv + [flatten(rightv)]
elsif la and leftv[0] == :callm and o.sym == :assign and leftv[2] == :[]
# FIXME: Will need rewrite for things like self.foo = bar too, but in that case *without
# arguments
rightv = [rightv] if !ra
@vstack << [:callm, leftv[1], "[]=".to_sym,leftv[3]+rightv]
elsif o.sym == :index
if ra and rightv[0] == :array
@vstack << [:callm, leftv, :[], flatten(rightv[1..-1])]
else
@vstack << [:callm, leftv, :[], [rightv]]
end
elsif ra and rightv[0] == :comma and o.sym == :array || o.sym == :hash
@vstack << [o.sym, leftv].compact + flatten(rightv)
elsif ra and rightv[0] == :comma and o.sym != :comma
@vstack << [o.sym, leftv, flatten(rightv)].compact
else
@vstack << [o.sym, flatten(leftv), rightv].compact
end
return
end
def value(v)
@vstack << v
end
def result
raise "Incomplete expression - #{@vstack.inspect}" if @vstack.length > 1
return @vstack[0]
end
end
end
