Querying

Main Helper Classes for Querying

`AstNode`
`CstNode`
`Document`
`Url`	`URL` as described using the Uniform Resource Identifier (URI) specification (RFC3986).
`Heritage`

`ContainerView`	An immutable view into a native random-access container. Implements Sequence protocol.
`ChildrenNodesView`	A view to a container of children nodes.
`ChildrenNodes`	Container that stores a vector of children nodes.
`OwnedChildrenNodes`	Container that stores a vector of potentially owned children nodes.
`ChainedChildrenNodes`	Container that stores a vector of children nodes that may own feature chainings.
`LazyIterator`
`VisitAction`
`SharedMutex`
`WriteLocked`
`Stream`
`QualifiedName`	A sequence of qualified name segments that stringifies with unrestricted names as needed. Unlike string, this allows querying segments in a qualified name without having to parse it again, and is cheaper to construct as string conversion is performed only when needed.
`TypeGuard`	The type used in a type check expression, e.g. `istype`, `hastype`. The actual expression result type is `ScalarValues::Boolean`.

`ExplicitOperator`
`FeatureDirectionKind`	`FeatureDirectionKind` enumerates the possible kinds of `direction` that a `Feature` may be given as a member of a `Type`.
`Operator`
`PortionKind`	`PortionKind` is an enumeration of the specific kinds of `Occurrence` portions that can be represented by an `OccurrenceUsage`.
`RequirementConstraintKind`	A `RequirementConstraintKind` indicates whether a `ConstraintUsage` is an assumption or a requirement in a `RequirementDefinition` or `RequirementUsage`.
`StateSubactionKind`	A `StateSubactionKind` indicates whether the `action` of a StateSubactionMembership is an entry, do or exit action.
`TransitionFeatureKind`	A `TransitionActionKind` indicates whether the `transition_feature` of a `TransitionFeatureMembership` is a trigger, guard or effect.
`TriggerKind`	`TriggerKind` enumerates the kinds of triggers that can be represented by a `TriggerInvocationExpression`.
`VisibilityKind`	`VisibilityKind` is an enumeration whose literals specify the visibility of a `Membership` of an `Element` in a `Namespace` outside of that `Namespace`. Note that “visibility” specifically restricts whether an `Element` in a `Namespace` may be referenced by name from outside the `Namespace` and only otherwise restricts access to an `Element` as provided by specific constraints in the abstract syntax (e.g., preventing the import or inheritance of private `Elements`).
`NameID`

`Url`	`URL` as described using the Uniform Resource Identifier (URI) specification (RFC3986).
`make_file_url`	Construct a Url for a filesystem path with file:// scheme. This correctly handles Windows and Posix paths, and percent escapes Unicode characters.
`decode_path`	Decode a filesystem path from a `Url`. This correctly handles Windows and Posix paths using `file://` scheme and returns other `Urls` as is.
`EncodingOpts`	Percent-encoding options
`HostType`
`IPv4Address`
`IPv6Address`
`Scheme`