Completion in macros

crates/ra_hir/Cargo.toml

@@ -12,6 +12,8 @@ log = "0.4.8"
 rustc-hash = "1.1.0"
 either = "1.5.3"
 
+itertools = "0.8.2"
+
 ra_syntax = { path = "../ra_syntax" }
 ra_db = { path = "../ra_db" }
 ra_prof = { path = "../ra_prof" }

crates/ra_hir/src/semantics.rs

@@ -6,7 +6,7 @@ use std::{cell::RefCell, fmt, iter::successors};
 
 use hir_def::{
     resolver::{self, HasResolver, Resolver},
-    TraitId,
+    AsMacroCall, TraitId,
 };
 use hir_expand::ExpansionInfo;
 use ra_db::{FileId, FileRange};
@@ -70,6 +70,20 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         Some(node)
     }
 
+    pub fn expand_hypothetical(
+        &self,
+        actual_macro_call: &ast::MacroCall,
+        hypothetical_args: &ast::TokenTree,
+        token_to_map: SyntaxToken,
+    ) -> Option<(SyntaxNode, SyntaxToken)> {
+        let macro_call =
+            self.find_file(actual_macro_call.syntax().clone()).with_value(actual_macro_call);
+        let sa = self.analyze2(macro_call.map(|it| it.syntax()), None);
+        let macro_call_id = macro_call
+            .as_call_id(self.db, |path| sa.resolver.resolve_path_as_macro(self.db, &path))?;
+        hir_expand::db::expand_hypothetical(self.db, macro_call_id, hypothetical_args, token_to_map)
+    }
+
     pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
         let parent = token.parent();
         let parent = self.find_file(parent);
@@ -104,6 +118,25 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         node.ancestors_with_macros(self.db).map(|it| it.value)
     }
 
+    pub fn ancestors_at_offset_with_macros(
+        &self,
+        node: &SyntaxNode,
+        offset: TextUnit,
+    ) -> impl Iterator<Item = SyntaxNode> + '_ {
+        use itertools::Itertools;
+        node.token_at_offset(offset)
+            .map(|token| self.ancestors_with_macros(token.parent()))
+            .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
+    }
+
+    pub fn find_node_at_offset_with_macros<N: AstNode>(
+        &self,
+        node: &SyntaxNode,
+        offset: TextUnit,
+    ) -> Option<N> {
+        self.ancestors_at_offset_with_macros(node, offset).find_map(N::cast)
+    }
+
     pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
         self.analyze(expr.syntax()).type_of(self.db, &expr)
     }

crates/ra_hir_expand/src/db.rs

@@ -72,6 +72,30 @@ pub trait AstDatabase: SourceDatabase {
     fn intern_eager_expansion(&self, eager: EagerCallLoc) -> EagerMacroId;
 }
 
+/// This expands the given macro call, but with different arguments. This is
+/// used for completion, where we want to see what 'would happen' if we insert a
+/// token. The `token_to_map` mapped down into the expansion, with the mapped
+/// token returned.
+pub fn expand_hypothetical(
+    db: &impl AstDatabase,
+    actual_macro_call: MacroCallId,
+    hypothetical_args: &ra_syntax::ast::TokenTree,
+    token_to_map: ra_syntax::SyntaxToken,
+) -> Option<(SyntaxNode, ra_syntax::SyntaxToken)> {
+    let macro_file = MacroFile { macro_call_id: actual_macro_call };
+    let (tt, tmap_1) = mbe::syntax_node_to_token_tree(hypothetical_args.syntax()).unwrap();
+    let range =
+        token_to_map.text_range().checked_sub(hypothetical_args.syntax().text_range().start())?;
+    let token_id = tmap_1.token_by_range(range)?;
+    let macro_def = expander(db, actual_macro_call)?;
+    let (node, tmap_2) =
+        parse_macro_with_arg(db, macro_file, Some(std::sync::Arc::new((tt, tmap_1))))?;
+    let token_id = macro_def.0.map_id_down(token_id);
+    let range = tmap_2.range_by_token(token_id)?.by_kind(token_to_map.kind())?;
+    let token = ra_syntax::algo::find_covering_element(&node.syntax_node(), range).into_token()?;
+    Some((node.syntax_node(), token))
+}
+
 pub(crate) fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
     let map =
         db.parse_or_expand(file_id).map_or_else(AstIdMap::default, |it| AstIdMap::from_source(&it));
@@ -129,16 +153,43 @@ pub(crate) fn macro_arg(
 pub(crate) fn macro_expand(
     db: &dyn AstDatabase,
     id: MacroCallId,
+) -> Result<Arc<tt::Subtree>, String> {
+    macro_expand_with_arg(db, id, None)
+}
+
+fn expander(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
+    let lazy_id = match id {
+        MacroCallId::LazyMacro(id) => id,
+        MacroCallId::EagerMacro(_id) => {
+            return None;
+        }
+    };
+
+    let loc = db.lookup_intern_macro(lazy_id);
+    let macro_rules = db.macro_def(loc.def)?;
+    Some(macro_rules)
+}
+
+fn macro_expand_with_arg(
+    db: &dyn AstDatabase,
+    id: MacroCallId,
+    arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> Result<Arc<tt::Subtree>, String> {
     let lazy_id = match id {
         MacroCallId::LazyMacro(id) => id,
         MacroCallId::EagerMacro(id) => {
-            return Ok(db.lookup_intern_eager_expansion(id).subtree);
+            if arg.is_some() {
+                return Err(
+                    "hypothetical macro expansion not implemented for eager macro".to_owned()
+                );
+            } else {
+                return Ok(db.lookup_intern_eager_expansion(id).subtree);
+            }
         }
     };
 
     let loc = db.lookup_intern_macro(lazy_id);
-    let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;
+    let macro_arg = arg.or_else(|| db.macro_arg(id)).ok_or("Fail to args in to tt::TokenTree")?;
 
     let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
     let tt = macro_rules.0.expand(db, lazy_id, &macro_arg.0).map_err(|err| format!("{:?}", err))?;
@@ -162,12 +213,24 @@ pub(crate) fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Optio
 pub(crate) fn parse_macro(
     db: &dyn AstDatabase,
     macro_file: MacroFile,
+) -> Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)> {
+    parse_macro_with_arg(db, macro_file, None)
+}
+
+pub fn parse_macro_with_arg(
+    db: &dyn AstDatabase,
+    macro_file: MacroFile,
+    arg: Option<Arc<(tt::Subtree, mbe::TokenMap)>>,
 ) -> Option<(Parse<SyntaxNode>, Arc<mbe::TokenMap>)> {
     let _p = profile("parse_macro_query");
 
     let macro_call_id = macro_file.macro_call_id;
-    let tt = db
-        .macro_expand(macro_call_id)
+    let expansion = if let Some(arg) = arg {
+        macro_expand_with_arg(db, macro_call_id, Some(arg))
+    } else {
+        db.macro_expand(macro_call_id)
+    };
+    let tt = expansion
         .map_err(|err| {
             // Note:
             // The final goal we would like to make all parse_macro success,

crates/ra_ide/src/completion/complete_dot.rs

@@ -38,7 +38,7 @@ pub(super) fn complete_dot(acc: &mut Completions, ctx: &CompletionContext) {
 fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
     for receiver in receiver.autoderef(ctx.db) {
         for (field, ty) in receiver.fields(ctx.db) {
-            if ctx.module.map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
+            if ctx.scope().module().map_or(false, |m| !field.is_visible_from(ctx.db, m)) {
                 // Skip private field. FIXME: If the definition location of the
                 // field is editable, we should show the completion
                 continue;
@@ -53,7 +53,7 @@ fn complete_fields(acc: &mut Completions, ctx: &CompletionContext, receiver: &Ty
 }
 
 fn complete_methods(acc: &mut Completions, ctx: &CompletionContext, receiver: &Type) {
-    if let Some(krate) = ctx.module.map(|it| it.krate()) {
+    if let Some(krate) = ctx.krate {
         let mut seen_methods = FxHashSet::default();
         let traits_in_scope = ctx.scope().traits_in_scope();
         receiver.iterate_method_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, func| {
@@ -584,4 +584,102 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn works_in_simple_macro_1() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.x<|>)
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [156; 157),
+                delete: [156; 157),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_recursive() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.x<|>)
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [156; 157),
+                delete: [156; 157),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_2() {
+        // this doesn't work yet because the macro doesn't expand without the token -- maybe it can be fixed with better recovery
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(a.<|>)
+                }
+                ",
+            ),
+            @r###"[]"###
+        );
+    }
+
+    #[test]
+    fn works_in_simple_macro_recursive_1() {
+        assert_debug_snapshot!(
+            do_ref_completion(
+                r"
+                macro_rules! m { ($e:expr) => { $e } }
+                struct A { the_field: u32 }
+                fn foo(a: A) {
+                    m!(m!(m!(a.x<|>)))
+                }
+                ",
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "the_field",
+                source_range: [162; 163),
+                delete: [162; 163),
+                insert: "the_field",
+                kind: Field,
+                detail: "u32",
+            },
+        ]
+        "###
+        );
+    }
 }

crates/ra_ide/src/completion/complete_keyword.rs

@@ -79,6 +79,7 @@ pub(super) fn complete_expr_keyword(acc: &mut Completions, ctx: &CompletionConte
 }
 
 fn is_in_loop_body(leaf: &SyntaxToken) -> bool {
+    // FIXME move this to CompletionContext and make it handle macros
     for node in leaf.parent().ancestors() {
         if node.kind() == FN_DEF || node.kind() == LAMBDA_EXPR {
             break;

crates/ra_ide/src/completion/complete_path.rs

@@ -1,4 +1,4 @@
-//! Completion of paths, including when writing a single name.
+//! Completion of paths, i.e. `some::prefix::<|>`.
 
 use hir::{Adt, PathResolution, ScopeDef};
 use ra_syntax::AstNode;
@@ -47,7 +47,7 @@ pub(super) fn complete_path(acc: &mut Completions, ctx: &CompletionContext) {
             };
             // Iterate assoc types separately
             // FIXME: complete T::AssocType
-            let krate = ctx.module.map(|m| m.krate());
+            let krate = ctx.krate;
             if let Some(krate) = krate {
                 let traits_in_scope = ctx.scope().traits_in_scope();
                 ty.iterate_path_candidates(ctx.db, krate, &traits_in_scope, None, |_ty, item| {
@@ -835,4 +835,37 @@ mod tests {
         "###
         );
     }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        let completions = do_reference_completion(
+            r#"
+                macro_rules! m { ($e:expr) => { $e } }
+                fn main() { m!(self::f<|>); }
+                fn foo() {}
+            "#,
+        );
+        assert_debug_snapshot!(completions, @r###"
+        [
+            CompletionItem {
+                label: "foo()",
+                source_range: [93; 94),
+                delete: [93; 94),
+                insert: "foo()$0",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo()",
+            },
+            CompletionItem {
+                label: "main()",
+                source_range: [93; 94),
+                delete: [93; 94),
+                insert: "main()$0",
+                kind: Function,
+                lookup: "main",
+                detail: "fn main()",
+            },
+        ]
+        "###);
+    }
 }

crates/ra_ide/src/completion/complete_pattern.rs

@@ -86,4 +86,22 @@ mod tests {
         ]
         "###);
     }
+
+    #[test]
+    fn completes_in_simple_macro_call() {
+        // FIXME: doesn't work yet because of missing error recovery in macro expansion
+        let completions = complete(
+            r"
+            macro_rules! m { ($e:expr) => { $e } }
+            enum E { X }
+
+            fn foo() {
+               m!(match E::X {
+                   <|>
+               })
+            }
+            ",
+        );
+        assert_debug_snapshot!(completions, @r###"[]"###);
+    }
 }