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module Liquid
class VariableLookup
SQUARE_BRACKETED = /\A\[(.*)\]\z/m
COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze].freeze
attr_reader :name, :lookups
def self.parse(markup)
new(markup)
end
def initialize(markup)
lookups = markup.scan(VariableParser)
name = lookups.shift
if name =~ SQUARE_BRACKETED
name = Expression.parse($1)
end
@name = name
@lookups = lookups
@command_flags = 0
@lookups.each_index do |i|
lookup = lookups[i]
if lookup =~ SQUARE_BRACKETED
lookups[i] = Expression.parse($1)
elsif COMMAND_METHODS.include?(lookup)
@command_flags |= 1 << i
end
end
end
def evaluate(context)
name = context.evaluate(@name)
object = context.find_variable(name)
@lookups.each_index do |i|
key = context.evaluate(@lookups[i])
# If object is a hash- or array-like object we look for the
# presence of the key and if its available we return it
if object.respond_to?(:[]) &&
((object.respond_to?(:key?) && object.key?(key)) ||
(object.respond_to?(:fetch) && key.is_a?(Integer)))
# if its a proc we will replace the entry with the proc
res = context.lookup_and_evaluate(object, key)
object = res.to_liquid
# Some special cases. If the part wasn't in square brackets and
# no key with the same name was found we interpret following calls
# as commands and call them on the current object
elsif @command_flags & (1 << i) != 0 && object.respond_to?(key)
object = object.send(key).to_liquid
# No key was present with the desired value and it wasn't one of the directly supported
# keywords either. The only thing we got left is to return nil or
# raise an exception if `strict_variables` option is set to true
else
return nil unless context.strict_variables
raise Liquid::UndefinedVariable, "undefined variable #{key}"
end
# If we are dealing with a drop here we have to
object.context = context if object.respond_to?(:context=)
end
object
end
def ==(other)
self.class == other.class && state == other.state
end
protected
def state
[@name, @lookups, @command_flags]
end
class ParseTreeVisitor < Liquid::ParseTreeVisitor
def children
@node.lookups
end
end
end
end
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