Class: GraphQL::InternalRepresentation::Rewrite

Inherits:
Object
  • Object
show all
Includes:
Language
Defined in:
lib/graphql/internal_representation/rewrite.rb

Overview

Convert an AST into a tree of Nodes

This rides along with StaticValidation, building a tree of nodes.

However, if any errors occurred during validation, the resulting tree is bogus. (For example, nil could have been pushed instead of a type.)

Defined Under Namespace

Classes: InlineFragmentDirectives

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initializeRewrite


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# File 'lib/graphql/internal_representation/rewrite.rb', line 15

def initialize
  # { String => Node } Tracks the roots of the query
  @operations = {}
  @fragments = {}
  # [String...] fragments which don't have fragments inside them
  @independent_fragments = []
  # Tracks the current node during traversal
  # Stack<InternalRepresentation::Node>
  @nodes = []
  # This tracks dependencies from fragment to Node where it was used
  # { frag_name => [dependent_node, dependent_node]}
  @fragment_spreads = Hash.new { |h, k| h[k] = []}
  # [[Nodes::Directive ...]] directive affecting the current scope
  @parent_directives = []
end

Instance Attribute Details

#operationsHash<String => InternalRepresentation::Node> (readonly)


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# File 'lib/graphql/internal_representation/rewrite.rb', line 13

def operations
  @operations
end

Instance Method Details

#validate(context) ⇒ Object


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# File 'lib/graphql/internal_representation/rewrite.rb', line 31

def validate(context)
  visitor = context.visitor

  visitor[Nodes::OperationDefinition].enter << ->(ast_node, prev_ast_node) {
    node = Node.new(
      return_type: context.type_definition && context.type_definition.unwrap,
      ast_node: ast_node,
      name: ast_node.name,
      parent: nil,
    )
    @nodes.push(node)
    @operations[ast_node.name] = node
  }

  visitor[Nodes::Field].enter << ->(ast_node, prev_ast_node) {
    parent_node = @nodes.last
    node_name = ast_node.alias || ast_node.name
    owner_type = context.parent_type_definition.unwrap
    # This node might not be novel, eg inside an inline fragment
    node = parent_node.typed_children[owner_type][node_name] ||= Node.new(
      return_type: context.type_definition && context.type_definition.unwrap,
      ast_node: ast_node,
      name: node_name,
      definition_name: ast_node.name,
      definition: context.field_definition,
      parent: parent_node,
      owner_type: owner_type,
      included: false, # may be set to true on leaving the node
    )
    parent_node.children[node_name] ||= node
    node.definitions[owner_type] = context.field_definition
    @nodes.push(node)
    @parent_directives.push([])
  }

  visitor[Nodes::InlineFragment].enter << ->(ast_node, prev_ast_node) {
    @parent_directives.push(InlineFragmentDirectives.new)
  }

  visitor[Nodes::Directive].enter << ->(ast_node, prev_ast_node) {
    # It could be a query error where a directive is somewhere it shouldn't be
    if @parent_directives.any?
      directive_irep_node = Node.new(
        name: ast_node.name,
        definition_name: ast_node.name,
        ast_node: ast_node,
        definition: context.directive_definition,
        definitions: {context.directive_definition => context.directive_definition},
        # This isn't used, the directive may have many parents in the case of inline fragment
        parent: nil,
      )
      @parent_directives.last.push(directive_irep_node)
    end
  }

  visitor[Nodes::FragmentSpread].enter << ->(ast_node, prev_ast_node) {
    parent_node = @nodes.last
    # Record _both sides_ of the dependency
    spread_node = Node.new(
      parent: parent_node,
      name: ast_node.name,
      ast_node: ast_node,
      included: false, # this may be set to true on leaving the node
    )
    # The parent node has a reference to the fragment
    parent_node.spreads.push(spread_node)
    # And keep a reference from the fragment to the parent node
    @fragment_spreads[ast_node.name].push(parent_node)
    @nodes.push(spread_node)
    @parent_directives.push([])
  }

  visitor[Nodes::FragmentDefinition].enter << ->(ast_node, prev_ast_node) {
    node = Node.new(
      parent: nil,
      name: ast_node.name,
      return_type: context.type_definition,
      ast_node: ast_node,
    )
    @nodes.push(node)
    @fragments[ast_node.name] = node
  }

  visitor[Nodes::InlineFragment].leave  << ->(ast_node, prev_ast_node) {
    @parent_directives.pop
  }

  visitor[Nodes::FragmentSpread].leave  << ->(ast_node, prev_ast_node) {
    # Capture any directives that apply to this spread
    # so that they can be applied to fields when
    # the fragment is merged in later
    spread_node = @nodes.pop
    applicable_directives = pop_applicable_directives(@parent_directives)
    spread_node.included ||= GraphQL::Execution::DirectiveChecks.include?(applicable_directives, context.query)
    spread_node.directives.merge(applicable_directives)
  }

  visitor[Nodes::FragmentDefinition].leave << ->(ast_node, prev_ast_node) {
    # This fragment doesn't depend on any others,
    # we should save it as the starting point for dependency resolution
    frag_node = @nodes.pop
    if !any_fragment_spreads?(frag_node)
      @independent_fragments << frag_node
    end
  }

  visitor[Nodes::OperationDefinition].leave << ->(ast_node, prev_ast_node) {
    @nodes.pop
  }

  visitor[Nodes::Field].leave << ->(ast_node, prev_ast_node) {
    # Pop this field's node
    # and record any directives that were visited
    # during this field & before it (eg, inline fragments)
    field_node = @nodes.pop
    applicable_directives = pop_applicable_directives(@parent_directives)
    field_node.directives.merge(applicable_directives)
    field_node.included ||= GraphQL::Execution::DirectiveChecks.include?(applicable_directives, context.query)
  }

  visitor[Nodes::Document].leave << ->(ast_node, prev_ast_node) {
    # Resolve fragment dependencies. Start with fragments with no
    # dependencies and work along the spreads.
    while fragment_node = @independent_fragments.pop
      fragment_usages = @fragment_spreads[fragment_node.name]
      while dependent_node = fragment_usages.pop
        # Find the spreads for this reference
        resolved_spread_nodes = dependent_node.spreads.select { |spr| spr.name == fragment_node.name }
        spread_is_included = resolved_spread_nodes.any?(&:included?)
        # Since we're going to resolve them, remove them from the dependcies
        resolved_spread_nodes.each { |r_node| dependent_node.spreads.delete(r_node) }

        # resolve the dependency (merge into dependent node)
        deep_merge(dependent_node, fragment_node, spread_is_included)
        owner = dependent_node.owner
        if owner.ast_node.is_a?(Nodes::FragmentDefinition) && !any_fragment_spreads?(owner)
          @independent_fragments.push(owner)
        end
      end
    end
  }
end