rust/crates/ide/src/expand_macro.rs

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use std::iter;
use hir::Semantics;
use ide_db::{helpers::pick_best_token, RootDatabase};
use itertools::Itertools;
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use syntax::{ast, ted, AstNode, NodeOrToken, SyntaxKind, SyntaxNode, WalkEvent, T};
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use crate::FilePosition;
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pub struct ExpandedMacro {
pub name: String,
pub expansion: String,
}
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// Feature: Expand Macro Recursively
//
// Shows the full macro expansion of the macro at current cursor.
//
// |===
// | Editor | Action Name
//
// | VS Code | **Rust Analyzer: Expand macro recursively**
// |===
//
// image::https://user-images.githubusercontent.com/48062697/113020648-b3973180-917a-11eb-84a9-ecb921293dc5.gif[]
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pub(crate) fn expand_macro(db: &RootDatabase, position: FilePosition) -> Option<ExpandedMacro> {
let sema = Semantics::new(db);
let file = sema.parse(position.file_id);
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let tok = pick_best_token(file.syntax().token_at_offset(position.offset), |kind| match kind {
SyntaxKind::IDENT => 1,
_ => 0,
})?;
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let descended = sema.descend_into_macros(tok.clone());
if let Some(attr) = descended.ancestors().find_map(ast::Attr::cast) {
if let Some((path, tt)) = attr.as_simple_call() {
if path == "derive" {
let mut tt = tt.syntax().children_with_tokens().skip(1).join("");
tt.pop();
return sema
.expand_derive_macro(&attr)
.map(insert_whitespaces)
.map(|expansion| ExpandedMacro { name: tt, expansion });
}
}
}
let mut expanded = None;
let mut name = None;
for node in tok.ancestors() {
if let Some(item) = ast::Item::cast(node.clone()) {
if let Some(def) = sema.resolve_attr_macro_call(&item) {
name = def.name(db).map(|name| name.to_string());
expanded = expand_attr_macro_recur(&sema, &item);
break;
}
}
if let Some(mac) = ast::MacroCall::cast(node) {
name = Some(mac.path()?.segment()?.name_ref()?.to_string());
expanded = expand_macro_recur(&sema, &mac);
break;
}
}
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// FIXME:
// macro expansion may lose all white space information
// But we hope someday we can use ra_fmt for that
let expansion = insert_whitespaces(expanded?);
Some(ExpandedMacro { name: name.unwrap_or_else(|| "???".to_owned()), expansion })
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}
fn expand_macro_recur(
sema: &Semantics<RootDatabase>,
macro_call: &ast::MacroCall,
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) -> Option<SyntaxNode> {
let expanded = sema.expand(macro_call)?.clone_for_update();
expand(sema, expanded, ast::MacroCall::cast, expand_macro_recur)
}
fn expand_attr_macro_recur(sema: &Semantics<RootDatabase>, item: &ast::Item) -> Option<SyntaxNode> {
let expanded = sema.expand_attr_macro(item)?.clone_for_update();
expand(sema, expanded, ast::Item::cast, expand_attr_macro_recur)
}
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fn expand<T: AstNode>(
sema: &Semantics<RootDatabase>,
expanded: SyntaxNode,
f: impl FnMut(SyntaxNode) -> Option<T>,
exp: impl Fn(&Semantics<RootDatabase>, &T) -> Option<SyntaxNode>,
) -> Option<SyntaxNode> {
let children = expanded.descendants().filter_map(f);
let mut replacements = Vec::new();
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for child in children {
if let Some(new_node) = exp(sema, &child) {
// check if the whole original syntax is replaced
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if expanded == *child.syntax() {
return Some(new_node);
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}
replacements.push((child, new_node));
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}
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}
replacements.into_iter().rev().for_each(|(old, new)| ted::replace(old.syntax(), new));
Some(expanded)
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}
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// FIXME: It would also be cool to share logic here and in the mbe tests,
// which are pretty unreadable at the moment.
fn insert_whitespaces(syn: SyntaxNode) -> String {
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use SyntaxKind::*;
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let mut res = String::new();
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let mut indent = 0;
let mut last: Option<SyntaxKind> = None;
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for event in syn.preorder_with_tokens() {
let token = match event {
WalkEvent::Enter(NodeOrToken::Token(token)) => token,
WalkEvent::Leave(NodeOrToken::Node(node))
if matches!(node.kind(), ATTR | MATCH_ARM | STRUCT | ENUM | UNION | FN | IMPL) =>
{
res.push('\n');
res.extend(iter::repeat(" ").take(2 * indent));
continue;
}
_ => continue,
};
let is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
token.next_token().map(|it| f(it.kind())).unwrap_or(default)
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};
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let is_last =
|f: fn(SyntaxKind) -> bool, default| -> bool { last.map(f).unwrap_or(default) };
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match token.kind() {
k if is_text(k) && is_next(|it| !it.is_punct(), true) => {
res.push_str(token.text());
res.push(' ');
}
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L_CURLY if is_next(|it| it != R_CURLY, true) => {
indent += 1;
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if is_last(is_text, false) {
res.push(' ');
}
res.push_str("{\n");
res.extend(iter::repeat(" ").take(2 * indent));
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}
R_CURLY if is_last(|it| it != L_CURLY, true) => {
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indent = indent.saturating_sub(1);
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res.push('\n');
res.extend(iter::repeat(" ").take(2 * indent));
res.push_str("}");
}
R_CURLY => {
res.push_str("}\n");
res.extend(iter::repeat(" ").take(2 * indent));
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}
LIFETIME_IDENT if is_next(|it| it == IDENT, true) => {
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res.push_str(token.text());
res.push(' ');
}
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T![;] => {
res.push_str(";\n");
res.extend(iter::repeat(" ").take(2 * indent));
}
T![->] => res.push_str(" -> "),
T![=] => res.push_str(" = "),
T![=>] => res.push_str(" => "),
_ => res.push_str(token.text()),
}
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last = Some(token.kind());
}
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return res;
fn is_text(k: SyntaxKind) -> bool {
k.is_keyword() || k.is_literal() || k == IDENT
}
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}
#[cfg(test)]
mod tests {
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use expect_test::{expect, Expect};
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use crate::fixture;
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#[track_caller]
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fn check(ra_fixture: &str, expect: Expect) {
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let (analysis, pos) = fixture::position(ra_fixture);
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let expansion = analysis.expand_macro(pos).unwrap().unwrap();
let actual = format!("{}\n{}", expansion.name, expansion.expansion);
expect.assert_eq(&actual);
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}
#[test]
fn macro_expand_recursive_expansion() {
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check(
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r#"
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macro_rules! bar {
() => { fn b() {} }
}
macro_rules! foo {
() => { bar!(); }
}
macro_rules! baz {
() => { foo!(); }
}
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f$0oo!();
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"#,
expect![[r#"
foo
fn b(){}
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"#]],
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);
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}
#[test]
fn macro_expand_multiple_lines() {
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check(
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r#"
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macro_rules! foo {
() => {
fn some_thing() -> u32 {
let a = 0;
a + 10
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}
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}
}
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f$0oo!();
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"#,
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expect![[r#"
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foo
fn some_thing() -> u32 {
let a = 0;
a+10
}
"#]],
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);
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}
#[test]
fn macro_expand_match_ast() {
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check(
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r#"
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macro_rules! match_ast {
(match $node:ident { $($tt:tt)* }) => { match_ast!(match ($node) { $($tt)* }) };
(match ($node:expr) {
$( ast::$ast:ident($it:ident) => $res:block, )*
_ => $catch_all:expr $(,)?
}) => {{
$( if let Some($it) = ast::$ast::cast($node.clone()) $res else )*
{ $catch_all }
}};
}
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fn main() {
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mat$0ch_ast! {
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match container {
ast::TraitDef(it) => {},
ast::ImplDef(it) => {},
_ => { continue },
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}
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}
}
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"#,
expect![[r#"
match_ast
{
if let Some(it) = ast::TraitDef::cast(container.clone()){}
else if let Some(it) = ast::ImplDef::cast(container.clone()){}
else {
{
continue
}
}
}"#]],
);
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}
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#[test]
fn macro_expand_match_ast_inside_let_statement() {
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check(
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r#"
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macro_rules! match_ast {
(match $node:ident { $($tt:tt)* }) => { match_ast!(match ($node) { $($tt)* }) };
(match ($node:expr) {}) => {{}};
}
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fn main() {
let p = f(|it| {
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let res = mat$0ch_ast! { match c {}};
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Some(res)
})?;
}
"#,
expect![[r#"
match_ast
{}
"#]],
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);
}
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#[test]
fn macro_expand_inner_macro_fail_to_expand() {
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check(
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r#"
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macro_rules! bar {
(BAD) => {};
}
macro_rules! foo {
() => {bar!()};
}
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fn main() {
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let res = fo$0o!();
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}
"#,
expect![[r#"
foo
"#]],
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);
}
#[test]
fn macro_expand_with_dollar_crate() {
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check(
r#"
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#[macro_export]
macro_rules! bar {
() => {0};
}
macro_rules! foo {
() => {$crate::bar!()};
}
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fn main() {
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let res = fo$0o!();
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}
"#,
expect![[r#"
foo
0 "#]],
);
}
#[test]
fn macro_expand_derive() {
check(
r#"
#[rustc_builtin_macro]
pub macro Clone {}
#[derive(C$0lone)]
struct Foo {}
"#,
expect![[r#"
Clone
impl< >crate::clone::Clone for Foo< >{}
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"#]],
);
}
#[test]
fn macro_expand_derive2() {
check(
r#"
#[rustc_builtin_macro]
pub macro Clone {}
#[rustc_builtin_macro]
pub macro Copy {}
#[derive(Cop$0y)]
#[derive(Clone)]
struct Foo {}
"#,
expect![[r#"
Copy
impl< >crate::marker::Copy for Foo< >{}
"#]],
);
}
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}