Module ast

Expand description

Abstract Syntax Tree for GraphQL documents. An AST Document is more permissive but lower-level than Schema or ExecutableDocument.

This AST aims to faithfully represent documents that conform to the GraphQL syntactic grammar, except that ignored tokens such as whitespace are not preserved. These documents may or may not be valid.

Parsing an input that does not conform to the grammar results in parse errors together with a partial AST.

§Parsing

Start with Document::parse, or Parser to change the parser configuration.

Nodes inside documents are wrapped in Node, a reference-counted smart pointer. This allows sharing nodes between documents without cloning entire subtrees. To modify a node, the make_mut method provides copy-on-write semantics.

§Serialization

Document and its node types implement Display and ToString by serializing to GraphQL syntax with a default configuration. serialize methods return a builder that has chaining methods for setting serialization configuration, and also implements Display and ToString.

§Example

use apollo_compiler::{ast, name};

let source = "{field}";
let mut doc = ast::Document::parse(source, "example.graphql").unwrap();
for def in &mut doc.definitions {
    if let ast::Definition::OperationDefinition(op) = def {
        // `op` has type `&mut Node<ast::OperationDefinition>`
        // `Node` implements `Deref` but not `DeferMut`
        // `make_mut()` clones if necessary and returns `&mut ast::OperationDefinition`
        op.make_mut().directives.push(ast::Directive::new(name!(dir)));
    }
}
assert_eq!(doc.serialize().no_indent().to_string(), "query @dir { field }")

Structs§

Argument: AST for an Argument of a Field selection or Directive application.
Directive: AST for a Directive application.
DirectiveDefinition: Type system AST for a directive @foo DirectiveDefinition.
DirectiveList: AST for the list of Directives applied to some context.
Document: AST for a GraphQL Document that can contain executable definitions, type system (schema) definitions, or both.
EnumTypeDefinition: Type system AST for an enum FooE EnumTypeDefinition.
EnumTypeExtension: Type system AST for an extend enum FooE EnumTypeExtension.
EnumValueDefinition: Type system AST for an EnumValueDefinition in an enum type definition or extension.
Field: Executable AST for a Field selection in a selection set.
FieldDefinition: Type system AST for a FieldDefinition in an object type or interface type defintion or extension.
FloatOverflowError: Error type of IntValue::try_to_f64 an FloatValue::try_to_f64 for conversions that overflow f64 and would be “rounded” to infinity.
FloatValue: An FloatValue, represented as a string in order not to lose range or precision.
FragmentDefinition: Executable AST for a FragmentDefinition.
FragmentSpread: Executable AST for a FragmentSpread selection in a selection set.
InlineFragment: Executable AST for an InlineFragment selection in a selection set.
InputObjectTypeDefinition: Type system AST for an input FooIn InputObjectTypeDefinition.
InputObjectTypeExtension: Type system AST for an extend input FooIn InputObjectTypeExtension.
InputValueDefinition: Type system AST for an InputValueDefinition, a input type field definition or an argument definition.
IntValue: An IntValue, represented as a string in order not to lose range or precision.
InterfaceTypeDefinition: Type system AST for an interface FooI InterfaceTypeDefinition.
InterfaceTypeExtension: Type system AST for an extend interface FooI InterfaceTypeExtension.
ObjectTypeDefinition: Type system AST for a type FooO ObjectTypeDefinition.
ObjectTypeExtension: Type system AST for an extend type FooO ObjectTypeExtension.
OperationDefinition: Executable AST for an OperationDefinition.
ScalarTypeDefinition: Type system AST for a scalar FooS ScalarTypeDefinition.
ScalarTypeExtension: Type system AST for an extend scalar FooS ScalarTypeExtension.
SchemaDefinition: Type system AST for a schema SchemaDefinition.
SchemaExtension: Type system AST for an extend schema SchemaExtension.
Serialize: Builder pattern for GraphQL serialization configuration. Implements Display and ToString.
UnionTypeDefinition: Type system AST for a union FooU UnionTypeDefinition.
UnionTypeExtension: Type system AST for an extend union FooU UnionTypeExtension.
VariableDefinition: Executable AST for a VariableDefinition in an OperationDefinition.

Enums§

ArgumentByNameError: Error type of Directive::argument_by_name and Field::argument_by_name
Definition: AST for a top-level Definition of any kind: executable, type system, or type system extension.
DirectiveLocation: AST for a DirectiveLocation of a DirectiveDefinition.
OperationType: AST for the OperationType of an OperationDefinition or RootOperationDefinition.
Selection: Executable AST for a Selection in a selection set.
Type: Type system AST for a reference to a GraphQL Type
Value: Executable AST for a literal GraphQL Value.

Type Aliases§

NamedType: A NamedType references by name a GraphQL type defined elsewhere.

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