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|
//! Example that takes the input
//! 1 + 2 * 3 + 4
//! and builds the tree
//! - Marker(Root)
//! - Marker(Operation)
//! - Marker(Operation)
//! - "1" Token(Number)
//! - "+" Token(Add)
//! - Marker(Operation)
//! - "2" Token(Number)
//! - "*" Token(Mul)
//! - "3" Token(Number)
//! - "+" Token(Add)
//! - "4" Token(Number)
use rowan::{GreenNodeBuilder, NodeOrToken};
use std::iter::Peekable;
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[allow(non_camel_case_types)]
#[repr(u16)]
enum SyntaxKind {
WHITESPACE = 0,
ADD,
SUB,
MUL,
DIV,
NUMBER,
ERROR,
OPERATION,
ROOT,
}
use SyntaxKind::*;
impl From<SyntaxKind> for rowan::SyntaxKind {
fn from(kind: SyntaxKind) -> Self {
Self(kind as u16)
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
enum Lang {}
impl rowan::Language for Lang {
type Kind = SyntaxKind;
fn kind_from_raw(raw: rowan::SyntaxKind) -> Self::Kind {
assert!(raw.0 <= ROOT as u16);
unsafe { std::mem::transmute::<u16, SyntaxKind>(raw.0) }
}
fn kind_to_raw(kind: Self::Kind) -> rowan::SyntaxKind {
kind.into()
}
}
type SyntaxNode = rowan::SyntaxNode<Lang>;
#[allow(unused)]
type SyntaxToken = rowan::SyntaxToken<Lang>;
#[allow(unused)]
type SyntaxElement = rowan::NodeOrToken<SyntaxNode, SyntaxToken>;
struct Parser<I: Iterator<Item = (SyntaxKind, String)>> {
builder: GreenNodeBuilder<'static>,
iter: Peekable<I>,
}
impl<I: Iterator<Item = (SyntaxKind, String)>> Parser<I> {
fn peek(&mut self) -> Option<SyntaxKind> {
while self.iter.peek().map(|&(t, _)| t == WHITESPACE).unwrap_or(false) {
self.bump();
}
self.iter.peek().map(|&(t, _)| t)
}
fn bump(&mut self) {
if let Some((token, string)) = self.iter.next() {
self.builder.token(token.into(), string.as_str());
}
}
fn parse_val(&mut self) {
match self.peek() {
Some(NUMBER) => self.bump(),
_ => {
self.builder.start_node(ERROR.into());
self.bump();
self.builder.finish_node();
}
}
}
fn handle_operation(&mut self, tokens: &[SyntaxKind], next: fn(&mut Self)) {
let checkpoint = self.builder.checkpoint();
next(self);
while self.peek().map(|t| tokens.contains(&t)).unwrap_or(false) {
self.builder.start_node_at(checkpoint, OPERATION.into());
self.bump();
next(self);
self.builder.finish_node();
}
}
fn parse_mul(&mut self) {
self.handle_operation(&[MUL, DIV], Self::parse_val)
}
fn parse_add(&mut self) {
self.handle_operation(&[ADD, SUB], Self::parse_mul)
}
fn parse(mut self) -> SyntaxNode {
self.builder.start_node(ROOT.into());
self.parse_add();
self.builder.finish_node();
SyntaxNode::new_root(self.builder.finish())
}
}
fn print(indent: usize, element: SyntaxElement) {
let kind: SyntaxKind = element.kind().into();
print!("{:indent$}", "", indent = indent);
match element {
NodeOrToken::Node(node) => {
println!("- {:?}", kind);
for child in node.children_with_tokens() {
print(indent + 2, child);
}
}
NodeOrToken::Token(token) => println!("- {:?} {:?}", token.text(), kind),
}
}
fn main() {
let ast = Parser {
builder: GreenNodeBuilder::new(),
iter: vec![
// 1 + 2 * 3 + 4
(NUMBER, "1".into()),
(WHITESPACE, " ".into()),
(ADD, "+".into()),
(WHITESPACE, " ".into()),
(NUMBER, "2".into()),
(WHITESPACE, " ".into()),
(MUL, "*".into()),
(WHITESPACE, " ".into()),
(NUMBER, "3".into()),
(WHITESPACE, " ".into()),
(ADD, "+".into()),
(WHITESPACE, " ".into()),
(NUMBER, "4".into()),
]
.into_iter()
.peekable(),
}
.parse();
print(0, ast.into());
}
|
