Class: Unitwise::Expression::Decomposer

Inherits:
Object
  • Object
show all
Defined in:
lib/unitwise/expression/decomposer.rb

Overview

The decomposer is used to turn string expressions into collections of terms. It is responsible for executing the parsing and transformation of a string, as well as caching the results.

Constant Summary

MODES =
[:primary_code, :secondary_code, :names, :slugs, :symbol].freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(expression) ⇒ Decomposer

Returns a new instance of Decomposer



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# File 'lib/unitwise/expression/decomposer.rb', line 51

def initialize(expression)
  @expression = expression.to_s
  if expression.empty? || terms.nil? || terms.empty?
    fail(ExpressionError, "Could not evaluate '#{ expression }'.")
  end
end

Instance Attribute Details

#expressionObject (readonly)

Returns the value of attribute expression



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# File 'lib/unitwise/expression/decomposer.rb', line 49

def expression
  @expression
end

#modeObject (readonly)

Returns the value of attribute mode



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# File 'lib/unitwise/expression/decomposer.rb', line 49

def mode
  @mode
end

Class Method Details

.parse(expression) ⇒ Object

Parse an expression to an array of terms and cache the results



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# File 'lib/unitwise/expression/decomposer.rb', line 13

def parse(expression)
  expression = expression.to_s
  if cache.key?(expression)
    cache[expression]
  elsif decomposer = new(expression)
    cache[expression] = decomposer
  end
end

.parsersObject



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# File 'lib/unitwise/expression/decomposer.rb', line 22

def parsers
  @parsers ||= MODES.reduce({}) do |hash, mode|
    hash[mode] = Parser.new(mode); hash
  end
end

.transformerObject



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# File 'lib/unitwise/expression/decomposer.rb', line 28

def transformer
  @transformer = Transformer.new
end

Instance Method Details

#parseObject



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# File 'lib/unitwise/expression/decomposer.rb', line 58

def parse
  self.class.parsers.reduce(nil) do |_, (mode, parser)|
    parsed = parser.parse(expression) rescue next
    @mode = mode
    break parsed
  end
end

#termsObject



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# File 'lib/unitwise/expression/decomposer.rb', line 70

def terms
  @terms ||= if transform.respond_to?(:terms)
    transform.terms
  else
    Array(transform)
  end
end

#transformObject



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# File 'lib/unitwise/expression/decomposer.rb', line 66

def transform
  @transform ||= self.class.transformer.apply(parse, :mode => mode)
end