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# File 'lib/subtle/evaluator.rb', line 8
def eval(string_or_tree)
if String === string_or_tree
parsed = @parser.parse string_or_tree
t = @transform.apply parsed
else
t = string_or_tree
end
if Hash === t
type = t[:type]
case type
when :monad
verb = t[:verb]
adverb = t[:adverb]
right = try_eval t[:right]
verb = "**" if verb == "^"
if adverb
if Array === right
if right.size < 2
ae! t, "Need Array of size atleast 2 for a monadic adverb." +
" Your Array had #{right.size} items."
end
else
ae! t, "Can only apply monadic adverb on Arrays." +
" You passed in #{right.class}."
end
case adverb
when "/"
right.reduce do |fold, r|
eval type: :dyad, verb: verb, left: fold, right: r
end
end
else
if Array === right
else
ae! t, "Can only apply monadic verb on Arrays." +
" You passed in #{right.class}."
end
case verb
when "&"
[].tap do |ret|
right.each_with_index do |r, i|
r.times { ret << i }
end
end
when "~"
right.map do |r|
r == 0 ? 1 : 0
end
else
nie! "Verb #{verb} without Adverb not implemented as a Monad"
end
end
when :dyad
left = try_eval t[:left]
verb = t[:verb]
adverb = t[:adverb]
right = try_eval t[:right]
verb = "**" if verb == "^"
if adverb
if Array === left && Array === right
else
ae! t, "Adverb `#{adverb}` must have arrays on both left and" +
" right. You passed in #{left.class} and #{right.class}."
end
case adverb
when "/:" right.map do |r|
eval({ type: :dyad, left: left, verb: verb, right: r })
end
when "\\:" left.map do |l|
eval({ type: :dyad, left: l, verb: verb, right: right })
end
else
nie! t, "Invalid Adverb #{adverb}"
end
else
case verb
when "+", "-", "*", "/", "%", "**"
if Numeric === left && Numeric === right
left.send(verb, right)
elsif Array === left && Array === right
if left.size != right.size
ae! t, "Size of left array must be the same as the size of" +
" right one, but #{left.size} != #{right.size}."
end
left.zip(right).map do |x, y|
x.send(verb, y)
end
elsif Array === left && Numeric === right
left.map do |l|
l.send(verb, right)
end
elsif Numeric === left && Array === right
right.map do |r|
left.send(verb, r)
end
else
nie! t
end
when "&", "|"
verb = "min" if verb == "&"
verb = "max" if verb == "|"
if Numeric === left && Numeric === right
[left, right].send(verb)
elsif Array === left && Array === right
if left.size != right.size
ae! t, "Size of left array must be the same as the size of" +
" right one, but #{left.size} != #{right.size}."
end
left.zip(right).map do |x, y|
[x, y].send(verb)
end
elsif Array === left && Numeric === right
left.map do |l|
[l, right].send(verb)
end
elsif Numeric === left && Array === right
right.map do |r|
[left, r].send(verb)
end
else
nie! t
end
else
nie! t, "Invalid verb #{verb}."
end
end
when :enumerate
last = try_eval t[:last]
if Numeric === last
(0...last.floor).to_a
else
nie! t
end
else
nie! t
end
else
t
end
end
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