Class: Daedalus::DependencyGrapher::ExpressionEvaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/daedalus/dependency_grapher.rb

Instance Method Summary collapse

Constructor Details

#initialize(expression) ⇒ ExpressionEvaluator

Returns a new instance of ExpressionEvaluator.



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# File 'lib/daedalus/dependency_grapher.rb', line 27

def initialize(expression)
  @expression = expression.strip
end

Instance Method Details

#evaluate(defines) ⇒ Object 



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# File 'lib/daedalus/dependency_grapher.rb', line 31

def evaluate(defines)
  # Stage1: find 'defined's and evaluate
  #         replace defined with boolean evaluation value
  @expression.gsub!(/(defined\(.+?\))/) { |expr|
    defkey = expr.match(/\((.+?)\)/)[1]
    if defines.include?(defkey)
      'true'
    else
      'false'
    end
  }
  # Stage2: scan macro-defined keywords
  #         replace with actual value (true or false)
  # this covers patterns like __clang__ and __x86_64__
  @expression.gsub!(/__[A-Za-z0-9_]+__/) { |expr|
    if defines.include?(expr)
      defines[expr].to_s
    elsif integer?(expr)
      expr
    else
      '0'
    end
  }

  # this covers other patters.
  @expression.gsub!(/[A-Z0-9_]{4,}/) { |expr|
    if defines.include?(expr)
      defines[expr].to_s
    elsif integer?(expr)
      expr
    else
      '0'
    end
  }
  # Stage3: Evaluate with ruby eval()
  eval(@expression)
end