Struct ChildCursor 

pub struct ChildCursor<N> { /* private fields */ }

Single-pass field selection used only by generated migration code.

Implementations

impl<N: ExternalCstNode> ChildCursor<N>

pub fn new(parent: &N) -> Self

Collects the children of parent for single-pass field selection.

pub fn required_field(&mut self, field: &'static str) -> Result<N, MigrateError>

Takes the child in required named field.

Errors

Returns MigrateError::MissingField when no child occupies it.

pub fn optional_field(&mut self, field: &'static str) -> Option<N>

Takes the child in optional named field.

pub fn repeated_field(&mut self, field: &'static str) -> Vec<N>

Takes every child in repeated named field.

pub fn required_matching<T>(&mut self) -> Result<N, MigrateError>

where T: Migrate<N>,

Takes a required positional child migrateible as T.

Errors

Returns MigrateError::MissingChild when no remaining positional child can migrate T.

pub fn optional_matching<T>(&mut self) -> Option<N>

where T: Migrate<N>,

Takes an optional positional child migrateible as T.

pub fn repeated_matching<T>(&mut self) -> Vec<N>

where T: Migrate<N>,

Takes every positional child migrateible as T.

pub fn required_anonymous( &mut self, spelling: &'static str, ) -> Result<N, MigrateError>

Takes a required anonymous delimiter or punctuation child.

Errors

Returns MigrateError::MissingChild when the child is absent.

pub fn optional_anonymous(&mut self, spelling: &'static str) -> Option<N>

Takes an optional anonymous delimiter or punctuation child.

pub fn required_delimiter(&mut self) -> Result<Delimiter, MigrateError>

Migrates and consumes one of the supported delimiter pairs.

Errors

Returns MigrateError::MissingChild when no opening delimiter or its matching closing delimiter remains.

pub fn punctuated( &mut self, values: Vec<N>, spelling: &'static str, ) -> Result<(N, Vec<(N, N)>), MigrateError>

Pairs a nonempty list of migrated value nodes with the anonymous punctuation nodes separating them.

Errors

Returns MigrateError::InvalidPunctuated when there is no first value or the parent does not contain exactly one separator between each adjacent value.

pub fn optional_punctuated( &mut self, values: Vec<N>, spelling: &'static str, ) -> Result<Option<(N, Vec<(N, N)>)>, MigrateError>

Pairs an optional punctuated field without inventing a value or a separator when the field is absent.

Errors

Returns MigrateError::InvalidPunctuated when separators remain without values or their count does not match the present values.