Class: ImgToScript::CurrentLinePlaceholder

Inherits:
Object
  • Object
show all
Defined in:
lib/img_to_script/current_line_placeholder.rb

Overview

BASIC known by its widely usage of the GOTO construction. It is a common practice to use statements like N GOTO N + m (i.e. jump m lines away from the current line N).

When a generator generates an abstract token, it doesn’t know anything about the current line or its number yet. It is only when a formatter starts to format the code, this values can be calculated.

Thus, at the generation step a placeholder is being used to mark the current line number.

Placeholder’s job is to tell a formatter that the argument should be replaced with the actual line number value.

The optional attribute ‘shift’ allows to make a relative jump from the current line to a line that is above (a negative value) or to a line that’s behind (a positive value) of the current line.

Shift value is in line steps, i.e. works as a coefficient, so the full form of the expression is: N GOTO N + m * line_step.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(shift = 0) ⇒ CurrentLinePlaceholder

Initialize a placeholder.

Parameters:

  • shift (Integer) (defaults to: 0) —

    A relative shift of the current line number.



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# File 'lib/img_to_script/current_line_placeholder.rb', line 36

def initialize(shift = 0)
  @shift = shift
end

Instance Attribute Details

#shift ⇒ Object (readonly)

Returns the value of attribute shift.



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# File 'lib/img_to_script/current_line_placeholder.rb', line 28

def shift
  @shift
end