rust/crates/ide/src/expand_macro.rs

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use hir::Semantics;
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use ide_db::RootDatabase;
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use syntax::{
algo::{find_node_at_offset, SyntaxRewriter},
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ast, AstNode, NodeOrToken, SyntaxKind,
SyntaxKind::*,
SyntaxNode, WalkEvent, T,
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};
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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**
// |===
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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);
let name_ref = find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset)?;
let mac = name_ref.syntax().ancestors().find_map(ast::MacroCall::cast)?;
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let expanded = expand_macro_recur(&sema, &mac)?;
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// FIXME:
// macro expansion may lose all white space information
// But we hope someday we can use ra_fmt for that
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let expansion = insert_whitespaces(expanded);
Some(ExpandedMacro { name: name_ref.text().to_string(), expansion })
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}
fn expand_macro_recur(
sema: &Semantics<RootDatabase>,
macro_call: &ast::MacroCall,
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) -> Option<SyntaxNode> {
let mut expanded = sema.expand(macro_call)?;
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let children = expanded.descendants().filter_map(ast::MacroCall::cast);
let mut rewriter = SyntaxRewriter::default();
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for child in children.into_iter() {
if let Some(new_node) = expand_macro_recur(sema, &child) {
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// Replace the whole node if it is root
// `replace_descendants` will not replace the parent node
// but `SyntaxNode::descendants include itself
if expanded == *child.syntax() {
expanded = new_node;
} else {
rewriter.replace(child.syntax(), &new_node)
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}
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}
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}
let res = rewriter.rewrite(&expanded);
Some(res)
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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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let mut res = String::new();
let mut token_iter = syn
.preorder_with_tokens()
.filter_map(|event| {
if let WalkEvent::Enter(NodeOrToken::Token(token)) = event {
Some(token)
} else {
None
}
})
.peekable();
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let mut indent = 0;
let mut last: Option<SyntaxKind> = None;
while let Some(token) = token_iter.next() {
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let mut is_next = |f: fn(SyntaxKind) -> bool, default| -> bool {
token_iter.peek().map(|it| f(it.kind())).unwrap_or(default)
};
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let is_last =
|f: fn(SyntaxKind) -> bool, default| -> bool { last.map(f).unwrap_or(default) };
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res += &match token.kind() {
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k if is_text(k) && is_next(|it| !it.is_punct(), true) => token.text().to_string() + " ",
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L_CURLY if is_next(|it| it != R_CURLY, true) => {
indent += 1;
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let leading_space = if is_last(is_text, false) { " " } else { "" };
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format!("{}{{\n{}", leading_space, " ".repeat(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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format!("\n{}}}", " ".repeat(indent))
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}
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R_CURLY => format!("}}\n{}", " ".repeat(indent)),
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T![;] => format!(";\n{}", " ".repeat(indent)),
T![->] => " -> ".to_string(),
T![=] => " = ".to_string(),
T![=>] => " => ".to_string(),
_ => token.text().to_string(),
};
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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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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}
#[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#"
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 "#]],
);
}
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}