Class: GraphQL::Language::Visitor
- Inherits:
-
Object
- Object
- GraphQL::Language::Visitor
- Defined in:
- lib/graphql/language/visitor.rb
Overview
Depth-first traversal through the tree, calling hooks at each stop.
Direct Known Subclasses
Analysis::AST::Visitor, DefinitionSlice::DependencyVisitor, StaticValidation::BaseVisitor
Defined Under Namespace
Classes: DeleteNode, NodeVisitor
Constant Summary collapse
- SKIP =
Deprecated.
Use
super
to continue the visit; or don’t call it to halt.If any hook returns this value, the GraphQL::Language::Visitor stops visiting this node right away
:_skip
- DELETE_NODE =
When this is returned from a visitor method, Then the
node
passed into the method is removed fromparent
’s children. DeleteNode.new
Instance Attribute Summary collapse
-
#result ⇒ GraphQL::Language::Nodes::Document
readonly
The document with any modifications applied.
Class Method Summary collapse
-
.make_visit_method(node_method) ⇒ Object
We don’t use
alias
here because it breakssuper
.
Instance Method Summary collapse
-
#[](node_class) ⇒ NodeVisitor
deprecated
Deprecated.
see
on_
methods, like #on_field -
#initialize(document) ⇒ Visitor
constructor
A new instance of Visitor.
-
#on_abstract_node(node, parent) ⇒ Array?
The default implementation for visiting an AST node.
-
#visit ⇒ void
Visit
document
and all children, applying hooks as you go. -
#visit_node(node, parent) ⇒ Object
Call the user-defined handler for
node
.
Constructor Details
#initialize(document) ⇒ Visitor
Returns a new instance of Visitor.
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# File 'lib/graphql/language/visitor.rb', line 45 def initialize(document) @document = document @visitors = {} @result = nil end |
Instance Attribute Details
#result ⇒ GraphQL::Language::Nodes::Document (readonly)
Returns The document with any modifications applied.
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# File 'lib/graphql/language/visitor.rb', line 52 def result @result end |
Class Method Details
.make_visit_method(node_method) ⇒ Object
We don’t use alias
here because it breaks super
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# File 'lib/graphql/language/visitor.rb', line 120 def self.make_visit_method(node_method) class_eval(<<-RUBY, __FILE__, __LINE__ + 1) def #{node_method}(node, parent) child_mod = on_abstract_node(node, parent) # If visiting the children returned changes, continue passing those. child_mod || [node, parent] end RUBY end |
Instance Method Details
#[](node_class) ⇒ NodeVisitor
see on_
methods, like #on_field
Get a NodeVisitor for node_class
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# File 'lib/graphql/language/visitor.rb', line 61 def [](node_class) @visitors[node_class] ||= NodeVisitor.new end |
#on_abstract_node(node, parent) ⇒ Array?
The default implementation for visiting an AST node. It doesn’t do anything, but it continues to visiting the node’s children. To customize this hook, override one of its make_visit_methodes (or the base method?) in your subclasses.
For compatibility, it calls hook procs, too.
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# File 'lib/graphql/language/visitor.rb', line 91 def on_abstract_node(node, parent) if node == DELETE_NODE # This might be passed to `super(DELETE_NODE, ...)` # by a user hook, don't want to keep visiting in that case. nil else # Run hooks if there are any new_node = node no_hooks = !@visitors.key?(node.class) if no_hooks || begin_visit(new_node, parent) node.children.each do |child_node| new_child_and_node = on_node_with_modifications(child_node, new_node) # Reassign `node` in case the child hook makes a modification if new_child_and_node.is_a?(Array) new_node = new_child_and_node[1] end end end end_visit(new_node, parent) unless no_hooks if new_node.equal?(node) nil else [new_node, parent] end end end |
#visit ⇒ void
This method returns an undefined value.
Visit document
and all children, applying hooks as you go
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# File 'lib/graphql/language/visitor.rb', line 67 def visit result = on_node_with_modifications(@document, nil) @result = if result.is_a?(Array) result.first else # The node wasn't modified @document end end |
#visit_node(node, parent) ⇒ Object
Call the user-defined handler for node
.
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# File 'lib/graphql/language/visitor.rb', line 78 def visit_node(node, parent) public_send(node.visit_method, node, parent) end |