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

Attributes

environments[R]
errors[R]
exception_renderer[RW]
global_filter[RW]
partial[RW]
registers[R]
resource_limits[R]
scopes[R]
strict_filters[RW]
strict_variables[RW]
template_name[RW]

Public Class Methods

new(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil) click to toggle source
# File lib/liquid/context.rb, line 18
def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
  @environments     = [environments].flatten
  @scopes           = [(outer_scope || {})]
  @registers        = registers
  @errors           = []
  @partial          = false
  @strict_variables = false
  @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
  squash_instance_assigns_with_environments

  @this_stack_used = false

  self.exception_renderer = Template.default_exception_renderer
  if rethrow_errors
    self.exception_renderer = ->(e) { raise }
  end

  @interrupts = []
  @filters = []
  @global_filter = nil
end

Public Instance Methods

[](expression) 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 150
def [](expression)
  evaluate(Expression.parse(expression))
end
[]=(key, value) click to toggle source

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

# File lib/liquid/context.rb, line 134
def []=(key, value)
  unless @this_stack_used
    @this_stack_used = true
    push({})
  end
  @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 52
def add_filters(filters)
  filters = [filters].flatten.compact
  @filters += filters
  @strainer = nil
end
apply_global_filter(obj) click to toggle source
# File lib/liquid/context.rb, line 58
def apply_global_filter(obj)
  global_filter.nil? ? obj : global_filter.call(obj)
end
clear_instance_assigns() click to toggle source
# File lib/liquid/context.rb, line 129
def clear_instance_assigns
  @scopes[0] = {}
end
evaluate(object) click to toggle source
# File lib/liquid/context.rb, line 158
def evaluate(object)
  object.respond_to?(:evaluate) ? object.evaluate(self) : object
end
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 163
def find_variable(key)
  # This was changed from find() to find_index() because this is a very hot
  # path and find_index() is optimized in MRI to reduce object allocation
  index = @scopes.find_index { |s| s.key?(key) }
  scope = @scopes[index] if index

  variable = nil

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

  variable
end
handle_error(e, line_number = nil, raw_token = nil) click to toggle source
# File lib/liquid/context.rb, line 77
def handle_error(e, line_number = nil, raw_token = nil)
  e = internal_error unless e.is_a?(Liquid::Error)
  e.template_name ||= template_name
  e.line_number ||= line_number
  errors.push(e)
  exception_renderer.call(e).to_s
end
interrupt?() click to toggle source

are there any not handled interrupts?

# File lib/liquid/context.rb, line 63
def interrupt?
  !@interrupts.empty?
end
invoke(method, *args) click to toggle source
# File lib/liquid/context.rb, line 85
def invoke(method, *args)
  strainer.invoke(method, *args).to_liquid
end
key?(key) click to toggle source
# File lib/liquid/context.rb, line 154
def key?(key)
  self[key] != nil
end
lookup_and_evaluate(obj, key) click to toggle source
# File lib/liquid/context.rb, line 190
def lookup_and_evaluate(obj, key)
  if @strict_variables && obj.respond_to?(:key?) && !obj.key?(key)
    raise Liquid::UndefinedVariable, "undefined variable #{key}"
  end

  value = obj[key]

  if value.is_a?(Proc) && obj.respond_to?(:[]=)
    obj[key] = (value.arity == 0) ? value.call : value.call(self)
  else
    value
  end
end
merge(new_scopes) click to toggle source

Merge a hash of variables in the current local scope

# File lib/liquid/context.rb, line 96
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 101
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 73
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 90
def push(new_scope = {})
  @scopes.unshift(new_scope)
  raise StackLevelError, "Nesting too deep".freeze 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 68
def push_interrupt(e)
  @interrupts.push(e)
end
stack(new_scope = nil) { || ... } 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 114
def stack(new_scope = nil)
  old_stack_used = @this_stack_used
  if new_scope
    push(new_scope)
    @this_stack_used = true
  else
    @this_stack_used = false
  end

  yield
ensure
  pop if @this_stack_used
  @this_stack_used = old_stack_used
end
strainer() click to toggle source
# File lib/liquid/context.rb, line 44
def strainer
  @strainer ||= Strainer.create(self, @filters)
end
warnings() click to toggle source
# File lib/liquid/context.rb, line 40
def warnings
  @warnings ||= []
end

Private Instance Methods

internal_error() click to toggle source
# File lib/liquid/context.rb, line 206
def internal_error
  # raise and catch to set backtrace and cause on exception
  raise Liquid::InternalError, 'internal'
rescue Liquid::InternalError => exc
  exc
end
squash_instance_assigns_with_environments() click to toggle source
# File lib/liquid/context.rb, line 213
def squash_instance_assigns_with_environments
  @scopes.last.each_key do |k|
    @environments.each do |env|
      if env.key?(k)
        scopes.last[k] = lookup_and_evaluate(env, k)
        break
      end
    end
  end
end