Class: Liquid::VariableLookup

Inherits:
Object
  • Object
show all
Defined in:
lib/liquid/variable_lookup.rb

Defined Under Namespace

Classes: ParseTreeVisitor

Constant Summary collapse

SQUARE_BRACKETED = 
/\A\[(.*)\]\z/m
COMMAND_METHODS = 
['size', 'first', 'last'].freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(markup) ⇒ VariableLookup

Returns a new instance of VariableLookup.



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# File 'lib/liquid/variable_lookup.rb', line 14

def initialize(markup)
  lookups = markup.scan(VariableParser)

  name = lookups.shift
  if name =~ SQUARE_BRACKETED
    name = Expression.parse(Regexp.last_match(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(Regexp.last_match(1))
    elsif COMMAND_METHODS.include?(lookup)
      @command_flags |= 1 << i
    end
  end
end

Instance Attribute Details

#lookups ⇒ Object (readonly)

Returns the value of attribute lookups.



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# File 'lib/liquid/variable_lookup.rb', line 8

def lookups
  @lookups
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/liquid/variable_lookup.rb', line 8

def name
  @name
end

Class Method Details

.parse(markup) ⇒ Object 



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# File 'lib/liquid/variable_lookup.rb', line 10

def self.parse(markup)
  new(markup)
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/liquid/variable_lookup.rb', line 77

def ==(other)
  self.class == other.class && state == other.state
end

#evaluate(context) ⇒ Object 



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# File 'lib/liquid/variable_lookup.rb', line 36

def evaluate(context)
  name   = context.evaluate(@name)
  object = context.find_variable(name)

  @lookups.each_index do |i|
    key = context.evaluate(@lookups[i])

    # Cast "key" to its liquid value to enable it to act as a primitive value
    key = Liquid::Utils.to_liquid_value(key)

    # 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