Class: MODL::Parser::Evaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/modl/parser/evaluator.rb

Overview

Evaluate a conditional expression

Class Method Summary collapse

Class Method Details

.evaluate(global, condition) ⇒ Object

Evaluate the given condition



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# File 'lib/modl/parser/evaluator.rb', line 30

def self.evaluate(global, condition)
  return false if global.nil? || !global.is_a?(GlobalParseContext) || !condition.is_a?(MODL::Parser::Parsed::ParsedCondition)

  start = 0
  if condition.text
    value1, success = value(global, condition.text)
  else
    start = 1
    value1, success = value(global, condition.values[0].text)
  end


  # Handle single-value conditions of the form '{x?}'
  if condition.values.length == start
    return false if value1.nil?
    return false if value1.is_a?(FalseClass)
    return true if value1.is_a?(TrueClass)

    return success ? value1 : false
  end

  # Handle the right-hand side, which might have many values and operators, e.g. '{x=a|b|c|d?}'
  i = start
  result = false
  while i < condition.values.length
    item = condition.values[i]
    if item.primitive.constant
      value2 = Substitutions.process(item.text)
    else
      value2, success = value(global, item.text)
    end
    partial = false
    case condition.operator
    when '='
      wild = value2.is_a?(String) && value2.include?('*') ? true : false
      if wild
        regex = '^'.dup
        value2.each_char do |c|
          regex << (c == '*' ? '.*' : c)
        end
        partial |= !value1.match(regex).nil?
      else
        partial |= value1 == value2
      end
    when '>'
      partial |= value1 > value2
    when '<'
      partial |= value1 < value2
    when '>='
      partial |= value1 >= value2
    when '<='
      partial |= value1 <= value2
    end
    i += 1
    result |= partial
  end
  result
end

.value(global, k) ⇒ Object 



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# File 'lib/modl/parser/evaluator.rb', line 89

def self.value(global, k)
  success = false
  if k.is_a?(String) && k.include?('%')
    value1, _ignore = MODL::Parser::RefProcessor.deref(k, global)
    success = true
  elsif k.is_a?(FalseClass)
    value1 = false
    success = true
  elsif k.is_a?(TrueClass)
    value1 = true
    success = true
  elsif k.is_a?(NilClass)
    value1 = nil
  else
    key = k
    ikey = key.to_i
    if ikey.to_s == key
      index_val = global.index[ikey]
      value1 = index_val.respond_to?(:text) ? index_val.text : nil
      value1 = Substitutions.process(value1)
    else
      pair = global.pair(key)
      return Substitutions.process(k) unless pair

      value1 = Substitutions.process(pair.text)
    end
    success = true
  end
  [value1, success]
end