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|
//! Syntax tree traversal.
use super::*;
macro_rules! visit {
($(fn $name:ident($v:ident, $node:ident: &$ty:ty) $body:block)*) => {
/// Traverses the syntax tree.
pub trait Visit<'ast> {
$(fn $name(&mut self, $node: &'ast $ty) {
$name(self, $node);
})*
}
$(visit! {
@concat!("Walk a node of type [`", stringify!($ty), "`]."),
pub fn $name<'ast, V>($v: &mut V, $node: &'ast $ty)
where
V: Visit<'ast> + ?Sized
$body
})*
};
(@$doc:expr, $($tts:tt)*) => {
#[doc = $doc]
$($tts)*
}
}
visit! {
fn visit_tree(v, node: &Tree) {
for node in node {
v.visit_node(&node);
}
}
fn visit_node(v, node: &Node) {
match node {
Node::Strong => {}
Node::Emph => {}
Node::Space => {}
Node::Linebreak => {}
Node::Parbreak => {}
Node::Text(_) => {}
Node::Heading(n) => v.visit_tree(&n.contents),
Node::Raw(_) => {}
Node::Expr(expr) => v.visit_expr(expr),
}
}
fn visit_expr(v, node: &Expr) {
match node {
Expr::Lit(_) => {}
Expr::Ident(_) => {}
Expr::Array(e) => v.visit_array(e),
Expr::Dict(e) => v.visit_dict(e),
Expr::Template(e) => v.visit_template(e),
Expr::Group(e) => v.visit_group(e),
Expr::Block(e) => v.visit_block(e),
Expr::Unary(e) => v.visit_unary(e),
Expr::Binary(e) => v.visit_binary(e),
Expr::Call(e) => v.visit_call(e),
Expr::Let(e) => v.visit_let(e),
Expr::If(e) => v.visit_if(e),
Expr::For(e) => v.visit_for(e),
}
}
fn visit_array(v, node: &ExprArray) {
for expr in &node.items {
v.visit_expr(&expr);
}
}
fn visit_dict(v, node: &ExprDict) {
for named in &node.items {
v.visit_expr(&named.expr);
}
}
fn visit_template(v, node: &ExprTemplate) {
v.visit_tree(&node.tree);
}
fn visit_group(v, node: &ExprGroup) {
v.visit_expr(&node.expr);
}
fn visit_block(v, node: &ExprBlock) {
for expr in &node.exprs {
v.visit_expr(&expr);
}
}
fn visit_binary(v, node: &ExprBinary) {
v.visit_expr(&node.lhs);
v.visit_expr(&node.rhs);
}
fn visit_unary(v, node: &ExprUnary) {
v.visit_expr(&node.expr);
}
fn visit_call(v, node: &ExprCall) {
v.visit_expr(&node.callee);
v.visit_args(&node.args);
}
fn visit_args(v, node: &ExprArgs) {
for arg in &node.items {
v.visit_arg(arg);
}
}
fn visit_arg(v, node: &ExprArg) {
match node {
ExprArg::Pos(expr) => v.visit_expr(&expr),
ExprArg::Named(named) => v.visit_expr(&named.expr),
}
}
fn visit_let(v, node: &ExprLet) {
if let Some(init) = &node.init {
v.visit_expr(&init);
}
}
fn visit_if(v, node: &ExprIf) {
v.visit_expr(&node.condition);
v.visit_expr(&node.if_body);
if let Some(body) = &node.else_body {
v.visit_expr(&body);
}
}
fn visit_for(v, node: &ExprFor) {
v.visit_expr(&node.iter);
v.visit_expr(&node.body);
}
}
|
