Class: SyntaxTree::YARV::ExpandArray

Inherits:
Instruction show all
Defined in:
lib/syntax_tree/yarv/instructions.rb

Overview

### Summary

‘expandarray` looks at the top of the stack, and if the value is an array it replaces it on the stack with `number` elements of the array, or `nil` if the elements are missing.

### Usage

~~~ruby x, = [true, false, nil] ~~~

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Instruction

#branch_targets, #canonical, #falls_through?, #leaves?, #side_effects?

Constructor Details

#initialize(number, flags) ⇒ ExpandArray

Returns a new instance of ExpandArray.



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1448

def initialize(number, flags)
  @number = number
  @flags = flags
end

Instance Attribute Details

#flags ⇒ Object (readonly)

Returns the value of attribute flags.



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1446

def flags
  @flags
end

#number ⇒ Object (readonly)

Returns the value of attribute number.



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1446

def number
  @number
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1465

def ==(other)
  other.is_a?(ExpandArray) && other.number == number &&
    other.flags == flags
end

#call(vm) ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1482

def call(vm)
  object = vm.pop
  object =
    if Array === object
      object.dup
    elsif object.respond_to?(:to_ary, true)
      object.to_ary
    else
      [object]
    end

  splat_flag = flags & 0x01 > 0
  postarg_flag = flags & 0x02 > 0

  if number == 0 && splat_flag == 0
    # no space left on stack
  elsif postarg_flag
    values = []

    if number > object.size
      (number - object.size).times { values.push(nil) }
    end
    [number, object.size].min.times { values.push(object.pop) }
    values.push(object.to_a) if splat_flag

    values.each { |item| vm.push(item) }
  else
    values = []

    [number, object.size].min.times { values.push(object.shift) }
    if number > values.size
      (number - values.size).times { values.push(nil) }
    end
    values.push(object.to_a) if splat_flag

    values.reverse_each { |item| vm.push(item) }
  end
end

#deconstruct_keys(_keys) ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1461

def deconstruct_keys(_keys)
  { number: number, flags: flags }
end

#disasm(fmt) ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1453

def disasm(fmt)
  fmt.instruction("expandarray", [fmt.object(number), fmt.object(flags)])
end

#length ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1470

def length
  3
end

#pops ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1474

def pops
  1
end

#pushes ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1478

def pushes
  number
end

#to_a(_iseq) ⇒ Object 



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# File 'lib/syntax_tree/yarv/instructions.rb', line 1457

def to_a(_iseq)
  [:expandarray, number, flags]
end