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module Regexp::Expression
class Subexpression < Regexp::Expression::Base
# Traverses the subexpression (depth-first, pre-order) and calls the given
# block for each expression with three arguments; the traversal event,
# the expression, and the index of the expression within its parent.
#
# The event argument is passed as follows:
#
# - For subexpressions, :enter upon entrering the subexpression, and
# :exit upon exiting it.
#
# - For terminal expressions, :visit is called once.
#
# Returns self.
def traverse(include_self = false, &block)
raise 'traverse requires a block' unless block_given?
block.call(:enter, self, 0) if include_self
each_with_index do |exp, index|
if exp.terminal?
block.call(:visit, exp, index)
else
block.call(:enter, exp, index)
exp.traverse(&block)
block.call(:exit, exp, index)
end
end
block.call(:exit, self, 0) if include_self
self
end
alias :walk :traverse
# Iterates over the expressions of this expression as an array, passing
# the expression and its index within its parent to the given block.
def each_expression(include_self = false, &block)
traverse(include_self) do |event, exp, index|
yield(exp, index) unless event == :exit
end
end
# Returns a new array with the results of calling the given block once
# for every expression. If a block is not given, returns an array with
# each expression and its level index as an array.
def map(include_self = false, &block)
result = []
each_expression(include_self) do |exp, index|
if block_given?
result << yield(exp, index)
else
result << [exp, index]
end
end
result
end
end
end
Version data entries
23 entries across 23 versions & 1 rubygems