Class: Liquid::For

Inherits:
Block show all
Defined in:
lib/liquid/tags/for.rb

Overview

“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 %}
  <div {% if forloop.first %}class="first"{% endif %}>
    Item {{ forloop.index }}: {{ item.name }}
  </div>
{% 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.

Constant Summary collapse

Syntax = 
/\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o

Constants inherited from Block

Block::ContentOfVariable, Block::FullToken, Block::TAGSTART, Block::VARSTART

Instance Attribute Summary

Attributes inherited from Tag

#line_number, #options, #warnings

Instance Method Summary collapse

Methods inherited from Block

#blank?, #block_delimiter, #block_name, #create_variable, #parse, #render_token_with_profiling, #warnings

Methods inherited from Tag

#blank?, #name, #parse, parse, #raw

Methods included from ParserSwitching

#parse_with_selected_parser

Constructor Details

#initialize(tag_name, markup, options) ⇒ For

Returns a new instance of For.



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# File 'lib/liquid/tags/for.rb', line 49

def initialize(tag_name, markup, options)
  super
  parse_with_selected_parser(markup)
  @nodelist = @for_block = []
end

Instance Method Details

#nodelist ⇒ Object 



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# File 'lib/liquid/tags/for.rb', line 55

def nodelist
  if @else_block
    @for_block + @else_block
  else
    @for_block
  end
end

#render(context) ⇒ Object 



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# File 'lib/liquid/tags/for.rb', line 68

def render(context)
  context.registers[:for] ||= Hash.new(0)

  collection = context[@collection_name]
  collection = collection.to_a if collection.is_a?(Range)

  # Maintains Ruby 1.8.7 String#each behaviour on 1.9
  return render_else(context) unless iterable?(collection)

  from = if @attributes['offset'.freeze] == 'continue'.freeze
    context.registers[:for][@name].to_i
  else
    context[@attributes['offset'.freeze]].to_i
  end

  limit = context[@attributes['limit'.freeze]]
  to    = limit ? limit.to_i + from : nil

  segment = Utils.slice_collection(collection, from, to)

  return render_else(context) if segment.empty?

  segment.reverse! if @reversed

  result = ''

  length = segment.length

  # Store our progress through the collection for the continue flag
  context.registers[:for][@name] = from + segment.length

  context.stack do
    segment.each_with_index do |item, index|
      context[@variable_name] = item
      context['forloop'.freeze] = {
        'name'.freeze    => @name,
        'length'.freeze  => length,
        'index'.freeze   => index + 1,
        'index0'.freeze  => index,
        'rindex'.freeze  => length - index,
        'rindex0'.freeze => length - index - 1,
        'first'.freeze   => (index == 0),
        'last'.freeze    => (index == length - 1)
      }

      result << render_all(@for_block, context)

      # Handle any interrupts if they exist.
      if context.has_interrupt?
        interrupt = context.pop_interrupt
        break if interrupt.is_a? BreakInterrupt
        next if interrupt.is_a? ContinueInterrupt
      end
    end
  end
  result
end

#unknown_tag(tag, markup, tokens) ⇒ Object 



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# File 'lib/liquid/tags/for.rb', line 63

def unknown_tag(tag, markup, tokens)
  return super unless tag == 'else'.freeze
  @nodelist = @else_block = []
end