Enum Event 

#[non_exhaustive]
pub enum Event<'input> {
    StreamStart,
    StreamEnd,
    DocumentStart(bool, Option<YamlVersion>),
    DocumentEnd,
    Alias(usize),
    Comment(Cow<'input, str>, Placement),
    Scalar(Cow<'input, str>, ScalarStyle, usize, Option<Cow<'input, Tag>>),
    SequenceStart(StructureStyle, usize, Option<Cow<'input, Tag>>),
    SequenceEnd,
    MappingStart(StructureStyle, usize, Option<Cow<'input, Tag>>),
    MappingEnd,
}

An event generated by the YAML parser.

Events are used in the low-level event-based API (push parser). The API entrypoint is the EventReceiver trait.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

StreamStart

Event generated at the very beginning of parsing.

StreamEnd

Last event that will be generated by the parser. Signals EOF.

DocumentStart(bool, Option<YamlVersion>)

The start of a YAML document.

Tuple Fields

0: bool

Whether this is an explicit document start marker (---).

When false, the document start is implicit.

1: Option<YamlVersion>

YAML version declared by a preceding %YAML directive, if any.

DocumentEnd

The end of a YAML document.

This event is emitted for both explicit document end markers (...) and implicit document ends.

Alias(usize)

A YAML alias.

Tuple Fields

0: usize

The anchor ID the alias refers to.

Comment(Cow<'input, str>, Placement)

A YAML source comment.

Comments are presentation metadata, not YAML data nodes. The payload is the raw text exactly after #, excluding only the line break. The placement is a best-effort hint for correlating the comment with nearby YAML presentation. The companion parser Span covers the whole source comment, including # and excluding the line break.

Tuple Fields

0: Cow<'input, str>

Raw comment payload exactly after #, excluding only the line break.

1: Placement

Best-effort placement relative to nearby YAML content.

Scalar(Cow<'input, str>, ScalarStyle, usize, Option<Cow<'input, Tag>>)

A YAML scalar value.

Tuple Fields

0: Cow<'input, str>

The scalar value after YAML escape processing.

1: ScalarStyle

The source notation used for the scalar.

2: usize

The anchor ID defined on this scalar, or 0 if it has no anchor.

3: Option<Cow<'input, Tag>>

The resolved tag attached to this scalar, if any.

SequenceStart(StructureStyle, usize, Option<Cow<'input, Tag>>)

The start of a YAML sequence (array).

Tuple Fields

0: StructureStyle

The notation style used for the sequence.

1: usize

The anchor ID defined on this sequence, or 0 if it has no anchor.

2: Option<Cow<'input, Tag>>

The resolved tag attached to this sequence, if any.

SequenceEnd

The end of a YAML sequence (array).

MappingStart(StructureStyle, usize, Option<Cow<'input, Tag>>)

The start of a YAML mapping (object, hash).

Tuple Fields

0: StructureStyle

The notation style used for the mapping (Flow or Block).

1: usize

The anchor ID defined on this mapping, or 0 if it has no anchor.

2: Option<Cow<'input, Tag>>

The resolved tag attached to this mapping, if any.

MappingEnd

The end of a YAML mapping (object, hash).

Implementations

impl<'input> Event<'input>

pub fn anchor_id(&self) -> Option<usize>

Return the anchor ID defined by this event, if any.

Returns Some(id) when this event defines an anchor on a scalar, sequence, or mapping node. Returns None for all other events, including Alias (which references an anchor rather than defining one; use Self::alias_id to obtain the target anchor ID).

pub fn alias_id(&self) -> Option<usize>

Return the target anchor ID referenced by this alias event, if this event is an alias.

pub fn tag(&self) -> Option<&Tag>

Return the resolved tag carried by this node event, if any.

pub fn scalar(&self) -> Option<(&str, ScalarStyle)>

Return the scalar value and style, if this event is a scalar.

pub fn is_node(&self) -> bool

Return whether this event represents a YAML node (value).

Returns true for scalars, collection starts, and aliases — all events that produce a value in the document tree. Returns false for structural events such as StreamStart, DocumentStart, collection ends, etc.

Trait Implementations

impl<'input> Clone for Event<'input>

fn clone(&self) -> Event<'input>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'input> Debug for Event<'input>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'input> Eq for Event<'input>

impl<'input> PartialEq for Event<'input>

fn eq(&self, other: &Event<'input>) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<'input> StructuralPartialEq for Event<'input>