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Contents
module Unitwise
module Expression
# Composer creates string expressions for arrays of terms, following
# UCUM's conventions.
class Composer
attr_reader :terms, :mode
def initialize(terms, mode)
@terms = terms
@mode = mode || :primary_code
end
def set
@set ||= terms.reduce(SignedMultiset.new) do |s, t|
identifier = { :f => t.factor,
:p => (t.prefix.to_s(mode) if t.prefix),
:a => (t.atom.to_s(mode) if t.atom) }
s.increment(identifier, t.exponent); s
end
end
def numerator
@numerator ||= set.select{ |_, v| v > 0 }.map do |k, v|
"#{ k[:f] if k[:f] != 1 }#{ k[:p] }#{ k[:a] }#{ v if v != 1 }"
end.select { |t| !t.empty? }.join('.')
end
def denominator
@denominator ||= set.select{ |_, v| v < 0 }.map do |k, v|
"#{ k[:f] if k[:f] != 1 }#{ k[:p] }#{ k[:a] }#{ -v if v != -1 }"
end.select { |t| !t.empty? }.join('.')
end
def expression
@expression = []
@expression << (numerator.empty? ? '1' : numerator)
(@expression << denominator) unless denominator.empty?
@expression.join('/')
end
end
end
end
Version data entries
11 entries across 11 versions & 2 rubygems