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# encoding: UTF-8
# Copyright 2012 Twitter, Inc
# http://www.apache.org/licenses/LICENSE-2.0
module TwitterCldr
module Collation
# Trie that delegates all not found keys to the fallback.
#
# Note: methods #get and #find_prefix have a bit different behavior. The first one, #get, delegates to the fallback
# any key that was not found. On the other hand, #find_refix delegates the key only if none of its prefixes was
# found.
#
# E.g., if the fallback contains key [1, 2] with value '12' and the trie itself contains only key [1] with value '1'
# results will be the following:
#
# trie.get([1, 2]) #=> '12' - key [1, 2] wasn't found in the trie, so it was delegated to the fallback where the
# value '12' was found.
#
# trie.find_prefix([1, 2]) #=> ['1', 1, suffixes] - key [1, 2] is not present in the trie, but its prefix [1] was
# found, so the fallback wasn't used.
#
# trie.find_prefix([3, 2]) - the trie itself includes neither key [3, 2] nor its prefix [3], so this call is
# delegated to the fallback.
#
# This special behavior of the #find_prefix method allows 'hiding' fallback keys that contain more than one element
# by adding their one element prefixes to the trie itself. This feature is useful for some applications, e.g., for
# suppressing contractions in a tailored fractional collation elements trie.
#
class TrieWithFallback < TwitterCldr::Collation::Trie
attr_accessor :fallback
def initialize(fallback)
super()
self.fallback = fallback
end
def get(key)
super || fallback.get(key)
end
def find_prefix(key)
value, prefix_size, suffixes = super
if prefix_size > 0
[value, prefix_size, suffixes]
else
fallback.find_prefix(key)
end
end
end
end
end
Version data entries
40 entries across 40 versions & 2 rubygems