Class: Janeway::Interpreters::ArraySliceSelectorDeleter

Inherits:
ArraySliceSelectorInterpreter show all
Defined in:
lib/janeway/interpreters/array_slice_selector_deleter.rb

Overview

Interprets array slice selector and deletes matching values

Constant Summary

Constants inherited from Base

Base::NOTHING

Instance Attribute Summary

Attributes inherited from Base

#next, #node

Instance Method Summary collapse

Methods inherited from ArraySliceSelectorInterpreter

#as_json

Methods inherited from Base

#as_json, #initialize, #selector, #to_s, #type

Constructor Details

This class inherits a constructor from Janeway::Interpreters::Base

Instance Method Details

#interpret(input, _parent, _root, _path) ⇒ Array

Delete values at the indices matched by the array slice selector



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# File 'lib/janeway/interpreters/array_slice_selector_deleter.rb', line 16

def interpret(input, _parent, _root, _path)
  return [] unless input.is_a?(Array)
  return [] if selector&.step&.zero? # RFC: When step is 0, no elements are selected.

  # Calculate the upper and lower indices of the target range
  lower = selector.lower_index(input.size)
  upper = selector.upper_index(input.size)

  # Convert bounds and step to index values.
  # Omit the final index, since no value is collected for that.
  # Delete indexes from largest to smallest, so that deleting an index does
  # not change the remaining indexes
  results = []
  if selector.step.positive?
    indexes = lower.step(to: upper - 1, by: selector.step).to_a
    indexes.reverse_each { |i| results << input.delete_at(i) }
    results.reverse
  else
    indexes = upper.step(to: lower + 1, by: selector.step).to_a
    indexes.each { |i| results << input.delete_at(i) }
    results
  end
end