Class: Rewrite::ByExample::LengthOne

Inherits:
Sequence
  • Object
show all
Defined in:
lib/rewrite/by_example/length_one.rb

Overview

Natches a sequence containing one item. Wraps an entity matcher, with the wrapped matcher matching the one item.

Confusing? Consider SymbolEntity.new(:foo). It matches a single entity, :foo. Whereas LengthOne.new(SymbolEntity.new(:foo)) matches a sequence of length one where that one thing happens to match :foo.

This distinction is important because sequences can only consist of collections of other sequences. So the LengthOnes are leaves of the sequence trees.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(entity_matcher) ⇒ LengthOne

Returns a new instance of LengthOne.



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# File 'lib/rewrite/by_example/length_one.rb', line 21

def initialize(entity_matcher)
  @matcher = entity_matcher
  @lambda = lambda { |arr| entity_matcher.unfold(arr.first) }
end

Instance Attribute Details

#matcher ⇒ Object (readonly)

Returns the value of attribute matcher.



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# File 'lib/rewrite/by_example/length_one.rb', line 19

def matcher
  @matcher
end

Instance Method Details

#fold(enum_of_bindings) ⇒ Object 



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# File 'lib/rewrite/by_example/length_one.rb', line 42

def fold(enum_of_bindings)
  matcher.fold(enum_of_bindings)
end

#length_range ⇒ Object 



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# File 'lib/rewrite/by_example/length_one.rb', line 34

def length_range
  1..1
end

#to_s ⇒ Object 



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# File 'lib/rewrite/by_example/length_one.rb', line 38

def to_s
  "<#{matcher.to_s}>"
end

#unfolders_by_length(length) ⇒ Object 



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# File 'lib/rewrite/by_example/length_one.rb', line 26

def unfolders_by_length(length)
  if length == 1
    [ @lambda ]
  else
    []
  end
end