Class: Janeway::Interpreters::ArraySliceSelectorInterpreter

Inherits:
Base
  • Object
show all
Defined in:
lib/janeway/interpreters/array_slice_selector_interpreter.rb

Overview

Interprets array slice selector on the given input

Constant Summary

Constants inherited from Base

Base::NOTHING

Instance Attribute Summary

Attributes inherited from Base

#next, #node

Instance Method Summary collapse

Methods inherited from Base

#initialize

Constructor Details

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

Instance Method Details

#interpret(input, root) ⇒ Array

Filter the input by applying the array slice selector.

Parameters:

  • selector (ArraySliceSelector)
  • input (Array, Hash) —

    the results of processing so far

  • root (Array, Hash) —

    the entire input

Returns:

  • (Array) 


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# File 'lib/janeway/interpreters/array_slice_selector_interpreter.rb', line 17

def interpret(input, root)
  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)

  # Collect values from target indices. Omit the value from the final index.
  results =
    if selector.step.positive?
      lower.step(to: upper - 1, by: selector.step).map { input[_1] }
    else
      upper.step(to: lower + 1, by: selector.step).map { input[_1] }
    end
  return results unless @next

  # Apply child selector to each node in the output node list
  node_list = results
  results = []
  node_list.each do |node|
    results.concat @next.interpret(node, root)
  end
  results
end