Class: GraphQL::InternalRepresentation::Rewrite

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

Overview

While visiting an AST, build a normalized, flattened tree of Nodes.

No unions or interfaces are present in this tree, only object types.

Selections from the AST are attached to the object types they apply to.

Inline fragments and fragment spreads are preserved in InternalRepresentation::Node#ast_spreads, where they can be used to check for the presence of directives. This might not be sufficient for future directives, since the selections' grouping is lost.

The rewritten query tree serves as the basis for the FieldsWillMerge validation.

Defined Under Namespace

Classes: VisitDefinition

Constant Summary collapse

NO_DIRECTIVES =
[].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Language

serialize

Constructor Details

#initializeRewrite

Returns a new instance of Rewrite


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# File 'lib/graphql/internal_representation/rewrite.rb', line 24

def initialize
  @document = InternalRepresentation::Document.new
end

Instance Attribute Details

#documentObject (readonly)

Returns InternalRepresentation::Document

Returns:

  • InternalRepresentation::Document


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# File 'lib/graphql/internal_representation/rewrite.rb', line 22

def document
  @document
end

Instance Method Details

#operationsHash<String, Node>

Returns Roots of this query

Returns:

  • (Hash<String, Node>)

    Roots of this query


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# File 'lib/graphql/internal_representation/rewrite.rb', line 29

def operations
  warn "#{self.class}#operations is deprecated; use `document.operation_definitions` instead"
  document.operation_definitions
end

#skip?(ast_node, query) ⇒ Boolean

Returns:

  • (Boolean)

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# File 'lib/graphql/internal_representation/rewrite.rb', line 159

def skip?(ast_node, query)
  dir = ast_node.directives
  dir.any? && !GraphQL::Execution::DirectiveChecks.include?(dir, query)
end

#validate(context) ⇒ Object


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# File 'lib/graphql/internal_representation/rewrite.rb', line 34

def validate(context)
  visitor = context.visitor
  query = context.query
  # Hash<Nodes::FragmentSpread => Set<InternalRepresentation::Node>>
  # A record of fragment spreads and the irep nodes that used them
  spread_parents = Hash.new { |h, k| h[k] = Set.new }
  # Hash<Nodes::FragmentSpread => Scope>
  spread_scopes = {}
  # Array<Set<InternalRepresentation::Node>>
  # The current point of the irep_tree during visitation
  nodes_stack = []
  # Array<Scope>
  scopes_stack = []

  skip_nodes = Set.new

  visit_op = VisitDefinition.new(context, @document.operation_definitions, nodes_stack, scopes_stack)
  visitor[Nodes::OperationDefinition].enter << visit_op.method(:enter)
  visitor[Nodes::OperationDefinition].leave << visit_op.method(:leave)

  visit_frag = VisitDefinition.new(context, @document.fragment_definitions, nodes_stack, scopes_stack)
  visitor[Nodes::FragmentDefinition].enter << visit_frag.method(:enter)
  visitor[Nodes::FragmentDefinition].leave << visit_frag.method(:leave)

  visitor[Nodes::InlineFragment].enter << ->(ast_node, ast_parent) {
    # Inline fragments provide two things to the rewritten tree:
    # - They _may_ narrow the scope by their type condition
    # - They _may_ apply their directives to their children
    if skip?(ast_node, query)
      skip_nodes.add(ast_node)
    end

    if skip_nodes.none?
      scopes_stack.push(scopes_stack.last.enter(context.type_definition))
    end
  }

  visitor[Nodes::InlineFragment].leave << ->(ast_node, ast_parent) {
    if skip_nodes.none?
      scopes_stack.pop
    end

    if skip_nodes.include?(ast_node)
      skip_nodes.delete(ast_node)
    end
  }

  visitor[Nodes::Field].enter << ->(ast_node, ast_parent) {
    if skip?(ast_node, query)
      skip_nodes.add(ast_node)
    end

    if skip_nodes.none?
      node_name = ast_node.alias || ast_node.name
      parent_nodes = nodes_stack.last
      next_nodes = []

      field_defn = context.field_definition
      if field_defn.nil?
        # It's a non-existent field
        new_scope = nil
      else
        field_return_type = field_defn.type
        scopes_stack.last.each do |scope_type|
          parent_nodes.each do |parent_node|
            node = parent_node.scoped_children[scope_type][node_name] ||= Node.new(
              parent: parent_node,
              name: node_name,
              owner_type: scope_type,
              query: query,
              return_type: field_return_type,
            )
            node.ast_nodes << ast_node
            node.definitions << field_defn
            next_nodes << node
          end
        end
        new_scope = Scope.new(query, field_return_type.unwrap)
      end

      nodes_stack.push(next_nodes)
      scopes_stack.push(new_scope)
    end
  }

  visitor[Nodes::Field].leave << ->(ast_node, ast_parent) {
    if skip_nodes.none?
      nodes_stack.pop
      scopes_stack.pop
    end

    if skip_nodes.include?(ast_node)
      skip_nodes.delete(ast_node)
    end
  }

  visitor[Nodes::FragmentSpread].enter << ->(ast_node, ast_parent) {
    if skip_nodes.none? && !skip?(ast_node, query)
      # Register the irep nodes that depend on this AST node:
      spread_parents[ast_node].merge(nodes_stack.last)
      spread_scopes[ast_node] = scopes_stack.last
    end
  }

  # Resolve fragment spreads.
  # Fragment definitions got their own irep trees during visitation.
  # Those nodes are spliced in verbatim (not copied), but this is OK
  # because fragments are resolved from the "bottom up", each fragment
  # can be shared between its usages.
  context.on_dependency_resolve do |defn_ast_node, spread_ast_nodes, frag_ast_node|
    frag_name = frag_ast_node.name
    fragment_node = @document.fragment_definitions[frag_name]

    if fragment_node
      spread_ast_nodes.each do |spread_ast_node|
        parent_nodes = spread_parents[spread_ast_node]
        parent_scope = spread_scopes[spread_ast_node]
        parent_nodes.each do |parent_node|
          parent_node.deep_merge_node(fragment_node, scope: parent_scope, merge_self: false)
        end
      end
    end
  end
end