module Liquid # "For" iterates over an array or collection. # Several useful variables are available to you within the loop. # # == Basic usage: # {% for item in collection %} # {{ forloop.index }}: {{ item.name }} # {% endfor %} # # == Advanced usage: # {% for item in collection %} #
# Item {{ forloop.index }}: {{ item.name }} #
# {% else %} # There is nothing in the collection. # {% endfor %} # # You can also define a limit and offset much like SQL. Remember # that offset starts at 0 for the first item. # # {% for item in collection limit:5 offset:10 %} # {{ item.name }} # {% end %} # # To reverse the for loop simply use {% for item in collection reversed %} # # == Available variables: # # forloop.name:: 'item-collection' # forloop.length:: Length of the loop # forloop.index:: The current item's position in the collection; # forloop.index starts at 1. # This is helpful for non-programmers who start believe # the first item in an array is 1, not 0. # forloop.index0:: The current item's position in the collection # where the first item is 0 # forloop.rindex:: Number of items remaining in the loop # (length - index) where 1 is the last item. # forloop.rindex0:: Number of items remaining in the loop # where 0 is the last item. # forloop.first:: Returns true if the item is the first item. # forloop.last:: Returns true if the item is the last item. # forloop.parentloop:: Provides access to the parent loop, if present. # class For < Block Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o def initialize(tag_name, markup, options) super parse_with_selected_parser(markup) @for_block = BlockBody.new end def parse(tokens) return unless parse_body(@for_block, tokens) parse_body(@else_block, tokens) end def nodelist @else_block ? [@for_block, @else_block] : [@for_block] end def unknown_tag(tag, markup, tokens) return super unless tag == 'else'.freeze @else_block = BlockBody.new end def render(context) segment = collection_segment(context) if segment.empty? render_else(context) else render_segment(context, segment) end end protected def lax_parse(markup) if markup =~ Syntax @variable_name = $1 collection_name = $2 @reversed = !!$3 @name = "#{@variable_name}-#{collection_name}" @collection_name = Expression.parse(collection_name) markup.scan(TagAttributes) do |key, value| set_attribute(key, value) end else raise SyntaxError.new(options[:locale].t("errors.syntax.for".freeze)) end end def strict_parse(markup) p = Parser.new(markup) @variable_name = p.consume(:id) raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_in".freeze)) unless p.id?('in'.freeze) collection_name = p.expression @name = "#{@variable_name}-#{collection_name}" @collection_name = Expression.parse(collection_name) @reversed = p.id?('reversed'.freeze) while p.look(:id) && p.look(:colon, 1) unless attribute = p.id?('limit'.freeze) || p.id?('offset'.freeze) raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_attribute".freeze)) end p.consume set_attribute(attribute, p.expression) end p.consume(:end_of_string) end private def collection_segment(context) offsets = context.registers[:for] ||= Hash.new(0) from = if @from == :continue offsets[@name].to_i else context.evaluate(@from).to_i end collection = context.evaluate(@collection_name) collection = collection.to_a if collection.is_a?(Range) limit = context.evaluate(@limit) to = limit ? limit.to_i + from : nil segment = Utils.slice_collection(collection, from, to) segment.reverse! if @reversed offsets[@name] = from + segment.length segment end def render_segment(context, segment) for_stack = context.registers[:for_stack] ||= [] length = segment.length result = '' context.stack do loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1]) for_stack.push(loop_vars) begin context['forloop'.freeze] = loop_vars segment.each_with_index do |item, index| context[@variable_name] = item result << @for_block.render(context) loop_vars.send(:increment!) # Handle any interrupts if they exist. if context.interrupt? interrupt = context.pop_interrupt break if interrupt.is_a? BreakInterrupt next if interrupt.is_a? ContinueInterrupt end end ensure for_stack.pop end end result end def set_attribute(key, expr) case key when 'offset'.freeze @from = if expr == 'continue'.freeze :continue else Expression.parse(expr) end when 'limit'.freeze @limit = Expression.parse(expr) end end def render_else(context) @else_block ? @else_block.render(context) : ''.freeze end end Template.register_tag('for'.freeze, For) end