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Contents
# encoding: utf-8
module Antelope
module Ace
# Defines a precedence. A precedence has a type, tokens, and a
# level.
class Precedence < Struct.new(:type, :tokens, :level)
# @!attribute [rw] type
# The type of precedence level. This should be one of
# `:left`, `:right`, or `:nonassoc`.
#
# @return [Symbol] the type.
# @!attribute [rw] tokens
# An set of tokens that are on this specific precedence
# level. The tokens are identified as symbols. The special
# symbol, `:_`, represents any token.
#
# @return [Set<Symbol>] the tokens on this level.
# @!attribute [rw] level
# The level we're on. The higher the level, the higher the
# precedence.
include Comparable
# Compares the other object to this object. If the other object
# isn't a {Precedence}, it returns nil. If the other
# precedence isn't on the same level as this one, then the
# levels are compared and the result of that is returned. If
# it is, however, the type is checked; if this precedence is
# left associative, then it returns 1 (it is greater than the
# other); if this precedence is right associative, then it
# returns -1 (it is less than the other); if this precedence is
# nonassociative, it returns 0 (it is equal to the other).
#
# @param other [Object] the object to compare to this one.
# @return [Numeric?]
def <=>(other)
return nil unless other.is_a? Precedence
if level != other.level
level <=> other.level
elsif type == :left
1
elsif type == :right
-1
else
0
end
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems