Class: Obtuse::Evaluator

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initializeEvaluator

Returns a new instance of Evaluator.



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# File 'lib/obtuse/evaluator.rb', line 6

def initialize
  @stack     = []
  @stash     = []
  @stdin     = $stdin
  @parser    = Parser.new
  @transform = Transform.new
end

Instance Attribute Details

#stackObject (readonly)

Returns the value of attribute stack.



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# File 'lib/obtuse/evaluator.rb', line 4

def stack
  @stack
end

#stashObject (readonly)

Returns the value of attribute stash.



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# File 'lib/obtuse/evaluator.rb', line 4

def stash
  @stash
end

#stdinObject

Returns the value of attribute stdin.



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# File 'lib/obtuse/evaluator.rb', line 3

def stdin
  @stdin
end

Instance Method Details

#eval(input, parsed = false) ⇒ Object



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# File 'lib/obtuse/evaluator.rb', line 14

def eval(input, parsed = false)
  if parsed == false
    input = @transform.apply(@parser.parse(input))
  end

  input.each do |atom|
    case atom
    when Integer, String, Array, AST::Lambda
      push atom
    when :+, :-, :*, :/, :%, :^
      atom = :** if atom == :^
      x, y = pop 2
      if Integer === x && Integer === y
        push x.send(atom, y)
      elsif String === x && Integer === y
        case atom
        when :+
          push x + y.to_s
        when :*
          push x * y
        when :%
          push x % y
        end
      elsif String === x && String === y
        case atom
        when :+
          push x + y
        when :-
          push (x.chars.to_a - y.chars.to_a).join
        when :*
          push x.chars.to_a.join(y)
        end
      elsif String === x && Array === y
        case atom
        when :%
          push x % y
        end
      elsif Array === x
        case atom
        when :+
          push x + Array(y)
        when :-
          push x - Array(y)
        when :*
          if Integer === y
            push x * y
          elsif String === y
            push x.join(y)
          elsif Array === y
            first = x.shift
            push x.reduce([first]) {|fold, el| fold + y + [el] }
          elsif AST::Lambda === y
            push x.shift
            x.each do |el|
              push el
              eval y.expression, true
            end
          end
        when :%
          if AST::Lambda === y
            stash
            x.each do |el|
              push el
              eval y.expression, true
            end
            stack = @stack
            unstash
            push stack
          end
        end
      else
      end
    when :"#"
      x = pop
      if Integer === x
        push [*0...x]
      elsif String === x || Array === x
        push x.length
      end
    when :"$"
      x = pop
      if Integer === x
        push @stack[-x - 1] if @stack[-x - 1]
      elsif String === x
        push x.chars.sort.join
      elsif Array === x
        push x.sort
      elsif AST::Lambda === x
        y = x
        x = pop
        case x
        when String, Array
          stash
          array = String === x ? x.chars.to_a : x
          array.sort_by! do |el|
            @stack = []
            push el
            eval y.expression, true
            @stack
          end
          unstash
          push String === x ? array.join : array
        end
      end
    when :~
      x = pop
      case x
      when String
        eval x
      when Array
        @stack += x
      when AST::Lambda
        eval x.expression, true
      end
    when :!
      push truthy?(pop) ? 0 : 1
    when :"@"
      x, y, z = pop 3
      push y; push z; push x
    when :"."
      x = peek
      push x if x
    when :";"
      pop
    when :"["
      stash
    when :"]"
      stack = @stack
      unstash
      push stack
    when :"=", :<, :>
      atom = :== if atom == :"="
      x, y = pop 2
      if Integer === x && Integer === y ||
          String === x && String === y ||
           Array === x && Array === y
        push x.send(atom, y) ? 1 : 0
      end
    when :"\\"
      x, y = pop 2
      push y; push x;
    when :I
      x, y, z = pop 3
      if AST::Lambda === x
        eval x.expression, true
        if truthy?(pop)
          AST::Lambda === y ? eval(y.expression, true) : push(y)
        else
          AST::Lambda === z ? eval(z.expression, true) : push(z)
        end
      else
        if truthy?(x)
          AST::Lambda === y ? eval(y.expression, true) : push(y)
        else
          AST::Lambda === z ? eval(z.expression, true) : push(z)
        end
      end
    when :W
      x, y = pop 2
      if AST::Lambda === x && AST::Lambda === y
        loop do
          eval x.expression, true
          break unless truthy?(pop)
          eval y.expression, true
        end
      end
    when :Ic
      push pop.to_i.chr
    when :Sg
      x, y, z = pop 3
      if (Integer === x || String === x) &&
         (Integer === y || String === y) &&
         (Integer === z || String === z)
        push x.to_s.gsub(y.to_s, z.to_s)
      end
    when :Sl
      push pop.to_s.downcase
    when :Su
      push pop.to_s.upcase
    when :Sc
      push pop.to_s.capitalize
    when :So
      push pop.to_s.ord
    when :Si
      x, y = pop 2
      push x.to_s.include?(y.to_s) ? 1 : 0
    when :St
      x, y, z = pop 3
      push x.to_s.tr(y.to_s, z.to_s)
    when :Ra
      push stdin.read.chomp
    when :Rl
      push stdin.gets.chomp
    end
  end
end

#peekObject



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# File 'lib/obtuse/evaluator.rb', line 219

def peek
  @stack.last
end

#pop(n = nil) ⇒ Object



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# File 'lib/obtuse/evaluator.rb', line 215

def pop(n = nil)
  n ? @stack.pop(n) : @stack.pop
end

#push(object) ⇒ Object



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# File 'lib/obtuse/evaluator.rb', line 211

def push(object)
  @stack << object
end

#truthy?(x) ⇒ Boolean

Returns:

  • (Boolean)


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# File 'lib/obtuse/evaluator.rb', line 232

def truthy?(x)
  !(x.nil? || x == 0 || x == "" || x == [])
end

#unstashObject



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# File 'lib/obtuse/evaluator.rb', line 228

def unstash
  @stack = @stash.pop
end