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

base_scope_depth[RW]
disabled_tags[W]
environments[R]
errors[RW]
exception_renderer[RW]
filters[W]
global_filter[RW]
partial[RW]
registers[R]
resource_limits[R]
scopes[R]
static_environments[R]
static_registers[R]
strainer[W]
strict_filters[RW]
strict_variables[RW]
template_name[RW]
warnings[W]

Public Class Methods

build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {}, &block) click to toggle source

rubocop:disable Metrics/ParameterLists

# File lib/liquid/context.rb, line 21
def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {}, &block)
  new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments, &block)
end
new(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {}) { |self| ... } click to toggle source
# File lib/liquid/context.rb, line 25
def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {})
  @environments = [environments]
  @environments.flatten!

  @static_environments = [static_environments].flat_map(&:freeze).freeze
  @scopes              = [(outer_scope || {})]
  @registers           = registers.is_a?(Registers) ? registers : Registers.new(registers)
  @errors              = []
  @partial             = false
  @strict_variables    = false
  @resource_limits     = resource_limits || ResourceLimits.new(Template.default_resource_limits)
  @base_scope_depth    = 0
  @interrupts          = []
  @filters             = []
  @global_filter       = nil
  @disabled_tags       = {}

  @registers.static[:cached_partials] ||= {}
  @registers.static[:file_system] ||= Liquid::Template.file_system
  @registers.static[:template_factory] ||= Liquid::TemplateFactory.new

  self.exception_renderer = Template.default_exception_renderer
  if rethrow_errors
    self.exception_renderer = Liquid::RAISE_EXCEPTION_LAMBDA
  end

  yield self if block_given?

  # Do this last, since it could result in this object being passed to a Proc in the environment
  squash_instance_assigns_with_environments
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 176
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 164
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 70
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 76
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 159
def clear_instance_assigns
  @scopes[0] = {}
end
evaluate(object) click to toggle source
# File lib/liquid/context.rb, line 184
def evaluate(object)
  object.respond_to?(:evaluate) ? object.evaluate(self) : object
end
find_variable(key, raise_on_not_found: true) click to toggle source

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

# File lib/liquid/context.rb, line 189
def find_variable(key, raise_on_not_found: true)
  # 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) }

  variable = if index
    lookup_and_evaluate(@scopes[index], key, raise_on_not_found: raise_on_not_found)
  else
    try_variable_find_in_environments(key, raise_on_not_found: raise_on_not_found)
  end

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

  variable
end
handle_error(e, line_number = nil) click to toggle source
# File lib/liquid/context.rb, line 95
def handle_error(e, line_number = 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 81
def interrupt?
  !@interrupts.empty?
end
invoke(method, *args) click to toggle source
# File lib/liquid/context.rb, line 103
def invoke(method, *args)
  strainer.invoke(method, *args).to_liquid
end
key?(key) click to toggle source
# File lib/liquid/context.rb, line 180
def key?(key)
  self[key] != nil
end
lookup_and_evaluate(obj, key, raise_on_not_found: true) click to toggle source
# File lib/liquid/context.rb, line 206
def lookup_and_evaluate(obj, key, raise_on_not_found: true)
  if @strict_variables && raise_on_not_found && 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 114
def merge(new_scopes)
  @scopes[0].merge!(new_scopes)
end
new_isolated_subcontext() click to toggle source

Creates a new context inheriting resource limits, filters, environment etc., but with an isolated scope.

# File lib/liquid/context.rb, line 141
def new_isolated_subcontext
  check_overflow

  self.class.build(
    resource_limits: resource_limits,
    static_environments: static_environments,
    registers: Registers.new(registers)
  ).tap do |subcontext|
    subcontext.base_scope_depth   = base_scope_depth + 1
    subcontext.exception_renderer = exception_renderer
    subcontext.filters  = @filters
    subcontext.strainer = nil
    subcontext.errors   = errors
    subcontext.warnings = warnings
    subcontext.disabled_tags = @disabled_tags
  end
end
pop() click to toggle source

Pop from the stack. use Context#stack instead

# File lib/liquid/context.rb, line 119
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 91
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 108
def push(new_scope = {})
  @scopes.unshift(new_scope)
  check_overflow
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 86
def push_interrupt(e)
  @interrupts.push(e)
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 132
def stack(new_scope = {})
  push(new_scope)
  yield
ensure
  pop
end
strainer() click to toggle source
# File lib/liquid/context.rb, line 62
def strainer
  @strainer ||= StrainerFactory.create(self, @filters)
end
tag_disabled?(tag_name) click to toggle source
# File lib/liquid/context.rb, line 231
def tag_disabled?(tag_name)
  @disabled_tags.fetch(tag_name, 0) > 0
end
warnings() click to toggle source

rubocop:enable Metrics/ParameterLists

# File lib/liquid/context.rb, line 58
def warnings
  @warnings ||= []
end
with_disabled_tags(tag_names) { || ... } click to toggle source
# File lib/liquid/context.rb, line 220
def with_disabled_tags(tag_names)
  tag_names.each do |name|
    @disabled_tags[name] = @disabled_tags.fetch(name, 0) + 1
  end
  yield
ensure
  tag_names.each do |name|
    @disabled_tags[name] -= 1
  end
end

Private Instance Methods

check_overflow() click to toggle source
# File lib/liquid/context.rb, line 259
def check_overflow
  raise StackLevelError, "Nesting too deep" if overflow?
end
internal_error() click to toggle source
# File lib/liquid/context.rb, line 267
def internal_error
  # raise and catch to set backtrace and cause on exception
  raise Liquid::InternalError, 'internal'
rescue Liquid::InternalError => exc
  exc
end
overflow?() click to toggle source
# File lib/liquid/context.rb, line 263
def overflow?
  base_scope_depth + @scopes.length > Block::MAX_DEPTH
end
squash_instance_assigns_with_environments() click to toggle source
# File lib/liquid/context.rb, line 274
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
try_variable_find_in_environments(key, raise_on_not_found:) click to toggle source
# File lib/liquid/context.rb, line 243
def try_variable_find_in_environments(key, raise_on_not_found:)
  @environments.each do |environment|
    found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
    if !found_variable.nil? || @strict_variables && raise_on_not_found
      return found_variable
    end
  end
  @static_environments.each do |environment|
    found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
    if !found_variable.nil? || @strict_variables && raise_on_not_found
      return found_variable
    end
  end
  nil
end