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
Public Class Methods
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
# 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 @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 = {} 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
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 172 def [](expression) evaluate(Expression.parse(expression)) end
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 66 def add_filters(filters) filters = [filters].flatten.compact @filters += filters @strainer = nil end
# File lib/liquid/context.rb, line 72 def apply_global_filter(obj) global_filter.nil? ? obj : global_filter.call(obj) end
# File lib/liquid/context.rb, line 155 def clear_instance_assigns @scopes[0] = {} end
# File lib/liquid/context.rb, line 180 def evaluate(object) object.respond_to?(:evaluate) ? object.evaluate(self) : object end
Fetches an object starting at the local scope and then moving up the hierachy
# File lib/liquid/context.rb, line 185 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
# File lib/liquid/context.rb, line 91 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
are there any not handled interrupts?
# File lib/liquid/context.rb, line 77 def interrupt? !@interrupts.empty? end
# File lib/liquid/context.rb, line 99 def invoke(method, *args) strainer.invoke(method, *args).to_liquid end
# File lib/liquid/context.rb, line 176 def key?(key) self[key] != nil end
# File lib/liquid/context.rb, line 202 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 a hash of variables in the current local scope
# File lib/liquid/context.rb, line 110 def merge(new_scopes) @scopes[0].merge!(new_scopes) end
Creates a new context inheriting resource limits, filters, environment etc., but with an isolated scope.
# File lib/liquid/context.rb, line 137 def new_isolated_subcontext check_overflow self.class.build( resource_limits: resource_limits, static_environments: static_environments, registers: StaticRegisters.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 from the stack. use Context#stack
instead
# File lib/liquid/context.rb, line 115 def pop raise ContextError if @scopes.size == 1 @scopes.shift end
pop an interrupt from the stack
# File lib/liquid/context.rb, line 87 def pop_interrupt @interrupts.pop end
Push new local scope on the stack. use Context#stack
instead
# File lib/liquid/context.rb, line 104 def push(new_scope = {}) @scopes.unshift(new_scope) check_overflow end
push an interrupt to the stack. this interrupt is considered not handled.
# File lib/liquid/context.rb, line 82 def push_interrupt(e) @interrupts.push(e) end
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 128 def stack(new_scope = {}) push(new_scope) yield ensure pop end
# File lib/liquid/context.rb, line 58 def strainer @strainer ||= StrainerFactory.create(self, @filters) end
# File lib/liquid/context.rb, line 227 def tag_disabled?(tag_name) @disabled_tags.fetch(tag_name, 0) > 0 end
rubocop:enable Metrics/ParameterLists
# File lib/liquid/context.rb, line 54 def warnings @warnings ||= [] end
Private Instance Methods
# File lib/liquid/context.rb, line 255 def check_overflow raise StackLevelError, "Nesting too deep" if overflow? end
# File lib/liquid/context.rb, line 263 def internal_error # raise and catch to set backtrace and cause on exception raise Liquid::InternalError, 'internal' rescue Liquid::InternalError => exc exc end
# File lib/liquid/context.rb, line 259 def overflow? base_scope_depth + @scopes.length > Block::MAX_DEPTH end
# File lib/liquid/context.rb, line 270 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
# File lib/liquid/context.rb, line 239 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