class Liquid::Context

Context keeps the variable stack and resolves variables, as well as keywords

context['variable'] = 'testing'
context['variable'] #=> 'testing'
context['true']     #=> true
context['10.2232']  #=> 10.2232

context.stack do
   context['bob'] = 'bobsen'
end

context['bob']  #=> nil  class Context

Constants

LITERALS

Attributes

environments[R]
errors[R]
registers[R]
resource_limits[R]
scopes[R]

Public Class Methods

new(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = {}) click to toggle source
# File lib/liquid/context.rb, line 18
def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = {})
  @environments    = [environments].flatten
  @scopes          = [(outer_scope || {})]
  @registers       = registers
  @errors          = []
  @rethrow_errors  = rethrow_errors
  @resource_limits = (resource_limits || {}).merge!({ :render_score_current => 0, :assign_score_current => 0 })
  squash_instance_assigns_with_environments

  @interrupts = []
end

Public Instance Methods

[](key) click to toggle source
# File lib/liquid/context.rb, line 126
def [](key)
  resolve(key)
end
[]=(key, value) click to toggle source

Only allow String, Numeric, Hash, Array, Proc, Boolean or Liquid::Drop

# File lib/liquid/context.rb, line 122
def []=(key, value)
  @scopes[0][key] = value
end
add_filters(filters) click to toggle source

Adds filters to this context.

Note that this does not register the filters with the main Template object. see Template.register_filter for that

# File lib/liquid/context.rb, line 44
def add_filters(filters)
  filters = [filters].flatten.compact

  filters.each do |f|
    raise ArgumentError, "Expected module but got: #{f.class}" unless f.is_a?(Module)
    Strainer.add_known_filter(f)
    strainer.extend(f)
  end
end
clear_instance_assigns() click to toggle source
# File lib/liquid/context.rb, line 117
def clear_instance_assigns
  @scopes[0] = {}
end
handle_error(e) click to toggle source
# File lib/liquid/context.rb, line 69
def handle_error(e)
  errors.push(e)
  raise if @rethrow_errors

  case e
  when SyntaxError
    "Liquid syntax error: #{e.message}"
  else
    "Liquid error: #{e.message}"
  end
end
has_interrupt?() click to toggle source

are there any not handled interrupts?

# File lib/liquid/context.rb, line 55
def has_interrupt?
  @interrupts.any?
end
has_key?(key) click to toggle source
# File lib/liquid/context.rb, line 130
def has_key?(key)
  resolve(key) != nil
end
invoke(method, *args) click to toggle source
# File lib/liquid/context.rb, line 81
def invoke(method, *args)
  strainer.invoke(method, *args)
end
merge(new_scopes) click to toggle source

Merge a hash of variables in the current local scope

# File lib/liquid/context.rb, line 92
def merge(new_scopes)
  @scopes[0].merge!(new_scopes)
end
pop() click to toggle source

Pop from the stack. use Context#stack instead

# File lib/liquid/context.rb, line 97
def pop
  raise ContextError if @scopes.size == 1
  @scopes.shift
end
pop_interrupt() click to toggle source

pop an interrupt from the stack

# File lib/liquid/context.rb, line 65
def pop_interrupt
  @interrupts.pop
end
push(new_scope={}) click to toggle source

Push new local scope on the stack. use Context#stack instead

# File lib/liquid/context.rb, line 86
def push(new_scope={})
  @scopes.unshift(new_scope)
  raise StackLevelError, "Nesting too deep" if @scopes.length > 100
end
push_interrupt(e) click to toggle source

push an interrupt to the stack. this interrupt is considered not handled.

# File lib/liquid/context.rb, line 60
def push_interrupt(e)
  @interrupts.push(e)
end
resource_limits_reached?() click to toggle source
# File lib/liquid/context.rb, line 30
def resource_limits_reached?
  (@resource_limits[:render_length_limit] && @resource_limits[:render_length_current] > @resource_limits[:render_length_limit]) ||
  (@resource_limits[:render_score_limit]  && @resource_limits[:render_score_current]  > @resource_limits[:render_score_limit] ) ||
  (@resource_limits[:assign_score_limit]  && @resource_limits[:assign_score_current]  > @resource_limits[:assign_score_limit] )
end
stack(new_scope={}) { || ... } click to toggle source

Pushes a new local scope on the stack, pops it at the end of the block

Example:

context.stack do
   context['var'] = 'hi'
end

context['var]  #=> nil
# File lib/liquid/context.rb, line 110
def stack(new_scope={})
  push(new_scope)
  yield
ensure
  pop
end
strainer() click to toggle source
# File lib/liquid/context.rb, line 36
def strainer
  @strainer ||= Strainer.create(self)
end

Private Instance Methods

find_variable(key) click to toggle source

Fetches an object starting at the local scope and then moving up the hierachy

# File lib/liquid/context.rb, line 173
def find_variable(key)
  scope = @scopes.find { |s| s.has_key?(key) }
  variable = nil

  if scope.nil?
    @environments.each do |e|
      if variable = lookup_and_evaluate(e, key)
        scope = e
        break
      end
    end
  end

  scope     ||= @environments.last || @scopes.last
  variable  ||= lookup_and_evaluate(scope, key)

  variable = variable.to_liquid
  variable.context = self if variable.respond_to?(:context=)

  return variable
end
lookup_and_evaluate(obj, key) click to toggle source
# File lib/liquid/context.rb, line 247
def lookup_and_evaluate(obj, key)
  if (value = obj[key]).is_a?(Proc) && obj.respond_to?(:[]=)
    obj[key] = (value.arity == 0) ? value.call : value.call(self)
  else
    value
  end
end
resolve(key) click to toggle source

Look up variable, either resolve directly after considering the name. We can directly handle Strings, digits, floats and booleans (true,false). If no match is made we lookup the variable in the current scope and later move up to the parent blocks to see if we can resolve the variable somewhere up the tree. Some special keywords return symbols. Those symbols are to be called on the rhs object in expressions

Example:

products == empty #=> products.empty?
# File lib/liquid/context.rb, line 151
def resolve(key)
  if LITERALS.key?(key)
    LITERALS[key]
  else
    case key
    when /^'(.*)'$/ # Single quoted strings
      $1
    when /^"(.*)"$/ # Double quoted strings
      $1
    when /^(-?\d+)$/ # Integer and floats
      $1.to_i
    when /^\((\S+)\.\.(\S+)\)$/ # Ranges
      (resolve($1).to_i..resolve($2).to_i)
    when /^(-?\d[\d\.]+)$/ # Floats
      $1.to_f
    else
      variable(key)
    end
  end
end
squash_instance_assigns_with_environments() click to toggle source
# File lib/liquid/context.rb, line 255
def squash_instance_assigns_with_environments
  @scopes.last.each_key do |k|
    @environments.each do |env|
      if env.has_key?(k)
        scopes.last[k] = lookup_and_evaluate(env, k)
        break
      end
    end
  end
end
variable(markup) click to toggle source

Resolves namespaced queries gracefully.

Example

@context['hash'] = {"name" => 'tobi'}
assert_equal 'tobi', @context['hash.name']
assert_equal 'tobi', @context['hash["name"]']
# File lib/liquid/context.rb, line 201
def variable(markup)
  parts = markup.scan(VariableParser)
  square_bracketed = /^\[(.*)\]$/

  first_part = parts.shift

  if first_part =~ square_bracketed
    first_part = resolve($1)
  end

  if object = find_variable(first_part)

    parts.each do |part|
      part = resolve($1) if part_resolved = (part =~ square_bracketed)

      # 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?(:[]) and
        ((object.respond_to?(:has_key?) and object.has_key?(part)) or
         (object.respond_to?(:fetch) and part.is_a?(Integer)))

        # if its a proc we will replace the entry with the proc
        res = lookup_and_evaluate(object, part)
        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 !part_resolved and object.respond_to?(part) and ['size', 'first', 'last'].include?(part)

        object = object.send(part.intern).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
      else
        return nil
      end

      # If we are dealing with a drop here we have to
      object.context = self if object.respond_to?(:context=)
    end
  end

  object
end