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# frozen_string_literal: true
module JMESPath
# @api private
module Nodes
class Slice < Node
def initialize(start, stop, step)
@start = start
@stop = stop
@step = step
raise Errors::InvalidValueError, 'slice step cannot be 0' if @step == 0
end
def visit(value)
if (value = value.respond_to?(:to_str) ? value.to_str : value.respond_to?(:to_ary) ? value.to_ary : nil)
start, stop, step = adjust_slice(value.size, @start, @stop, @step)
result = []
if step > 0
i = start
while i < stop
result << value[i]
i += step
end
else
i = start
while i > stop
result << value[i]
i += step
end
end
value.respond_to?(:to_str) ? result.join : result
end
end
def optimize
if (@step.nil? || @step == 1) && @start && @stop && @start > 0 && @stop > @start
SimpleSlice.new(@start, @stop)
else
self
end
end
private
def adjust_slice(length, start, stop, step)
step = 1 if step.nil?
start = if start.nil?
step < 0 ? length - 1 : 0
else
adjust_endpoint(length, start, step)
end
stop = if stop.nil?
step < 0 ? -1 : length
else
adjust_endpoint(length, stop, step)
end
[start, stop, step]
end
def adjust_endpoint(length, endpoint, step)
if endpoint < 0
endpoint += length
endpoint = step < 0 ? -1 : 0 if endpoint < 0
endpoint
elsif endpoint >= length
step < 0 ? length - 1 : length
else
endpoint
end
end
end
class SimpleSlice < Slice
def initialize(start, stop)
super(start, stop, 1)
end
def visit(value)
if (value = value.respond_to?(:to_str) ? value.to_str : value.respond_to?(:to_ary) ? value.to_ary : nil)
value[@start, @stop - @start]
end
end
end
end
end
|
