Enum Element 

pub enum Element<K> {
    Node(Node<K>),
    Token(Token<K>),
}

One child of a Node: either a nested node or a leaf token.

A concrete syntax tree alternates between the two — a node groups a run of children under a kind, and a Token is a leaf carrying a classified span of source. Trivia (whitespace, comments) is not special: it rides as an ordinary leaf token, which is what makes the tree lossless.

Examples

use syntax_lang::{Element, Node, Span, Token};

let leaf: Element<&str> = Element::Token(Token::new("ident", Span::new(0, 3)));
assert!(leaf.is_token());
assert_eq!(leaf.kind(), &"ident");
assert_eq!(leaf.span(), Span::new(0, 3));

let group = Element::Node(Node::new("expr", vec![leaf]));
assert!(group.is_node());
assert_eq!(group.span(), Span::new(0, 3));

Variants

Node(Node<K>)

A nested interior node.

Token(Token<K>)

A leaf token: a classified span of source.

Implementations

impl<K> Element<K>

pub fn span(&self) -> Span

The span of source this child covers — the node’s covering span or the token’s own span.

Examples

use syntax_lang::{Element, Span, Token};

let e = Element::Token(Token::new('x', Span::new(4, 5)));
assert_eq!(e.span(), Span::new(4, 5));

pub fn kind(&self) -> &K

Borrows the kind of this child — the node’s kind or the token’s kind.

Node kinds and token kinds share one type K (the rowan model), so a caller can read a child’s kind without first knowing whether it is a node or a leaf.

Examples

use syntax_lang::{Element, Span, Token};

let e = Element::Token(Token::new("plus", Span::new(1, 2)));
assert_eq!(e.kind(), &"plus");

pub fn as_node(&self) -> Option<&Node<K>>

Returns the nested node if this child is one, otherwise None.

Examples

use syntax_lang::{Element, Node, Span, Token};

let node = Element::Node(Node::new("n", vec![Element::Token(Token::new("t", Span::new(0, 1)))]));
assert!(node.as_node().is_some());
assert!(node.as_token().is_none());

pub fn as_token(&self) -> Option<&Token<K>>

Returns the leaf token if this child is one, otherwise None.

Examples

use syntax_lang::{Element, Span, Token};

let e = Element::Token(Token::new("t", Span::new(0, 1)));
assert_eq!(e.as_token().map(|t| *t.kind()), Some("t"));

pub fn is_node(&self) -> bool

Whether this child is a nested node.

Examples

use syntax_lang::{Element, Span, Token};

assert!(!Element::Token(Token::new(0u8, Span::new(0, 1))).is_node());

pub fn is_token(&self) -> bool

Whether this child is a leaf token.

Examples

use syntax_lang::{Element, Span, Token};

assert!(Element::Token(Token::new(0u8, Span::new(0, 1))).is_token());

Trait Implementations

impl<K: Clone> Clone for Element<K>

fn clone(&self) -> Element<K>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K: Debug> Debug for Element<K>

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

Formats the value using the given formatter.

impl<K: Eq> Eq for Element<K>

impl<K: PartialEq> PartialEq for Element<K>

fn eq(&self, other: &Element<K>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K: PartialEq> StructuralPartialEq for Element<K>