1 files changed, 673 insertions, 0 deletions

diff --git a/crates/ra_ide/src/completion/presentation.rs b/crates/ra_ide/src/completion/presentation.rs
new file mode 100644
index 000000000..97475fc0b
--- /dev/null
+++ b/crates/ra_ide/src/completion/presentation.rs
@@ -0,0 +1,673 @@
+//! This modules takes care of rendering various definitions as completion items.
+
+use hir::{db::HirDatabase, Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, Type};
+use join_to_string::join;
+use ra_syntax::ast::NameOwner;
+use test_utils::tested_by;
+
+use crate::completion::{
+    CompletionContext, CompletionItem, CompletionItemKind, CompletionKind, Completions,
+};
+
+use crate::display::{const_label, function_label, macro_label, type_label};
+
+impl Completions {
+    pub(crate) fn add_field(
+        &mut self,
+        ctx: &CompletionContext,
+        field: hir::StructField,
+        ty: &Type,
+    ) {
+        let is_deprecated = is_deprecated(field, ctx.db);
+        CompletionItem::new(
+            CompletionKind::Reference,
+            ctx.source_range(),
+            field.name(ctx.db).to_string(),
+        )
+        .kind(CompletionItemKind::Field)
+        .detail(ty.display(ctx.db).to_string())
+        .set_documentation(field.docs(ctx.db))
+        .set_deprecated(is_deprecated)
+        .add_to(self);
+    }
+
+    pub(crate) fn add_tuple_field(&mut self, ctx: &CompletionContext, field: usize, ty: &Type) {
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), field.to_string())
+            .kind(CompletionItemKind::Field)
+            .detail(ty.display(ctx.db).to_string())
+            .add_to(self);
+    }
+
+    pub(crate) fn add_resolution(
+        &mut self,
+        ctx: &CompletionContext,
+        local_name: String,
+        resolution: &ScopeDef,
+    ) {
+        use hir::ModuleDef::*;
+
+        let completion_kind = match resolution {
+            ScopeDef::ModuleDef(BuiltinType(..)) => CompletionKind::BuiltinType,
+            _ => CompletionKind::Reference,
+        };
+
+        let kind = match resolution {
+            ScopeDef::ModuleDef(Module(..)) => CompletionItemKind::Module,
+            ScopeDef::ModuleDef(Function(func)) => {
+                return self.add_function_with_name(ctx, Some(local_name), *func);
+            }
+            ScopeDef::ModuleDef(Adt(hir::Adt::Struct(_))) => CompletionItemKind::Struct,
+            // FIXME: add CompletionItemKind::Union
+            ScopeDef::ModuleDef(Adt(hir::Adt::Union(_))) => CompletionItemKind::Struct,
+            ScopeDef::ModuleDef(Adt(hir::Adt::Enum(_))) => CompletionItemKind::Enum,
+
+            ScopeDef::ModuleDef(EnumVariant(..)) => CompletionItemKind::EnumVariant,
+            ScopeDef::ModuleDef(Const(..)) => CompletionItemKind::Const,
+            ScopeDef::ModuleDef(Static(..)) => CompletionItemKind::Static,
+            ScopeDef::ModuleDef(Trait(..)) => CompletionItemKind::Trait,
+            ScopeDef::ModuleDef(TypeAlias(..)) => CompletionItemKind::TypeAlias,
+            ScopeDef::ModuleDef(BuiltinType(..)) => CompletionItemKind::BuiltinType,
+            ScopeDef::GenericParam(..) => CompletionItemKind::TypeParam,
+            ScopeDef::Local(..) => CompletionItemKind::Binding,
+            // (does this need its own kind?)
+            ScopeDef::AdtSelfType(..) | ScopeDef::ImplSelfType(..) => CompletionItemKind::TypeParam,
+            ScopeDef::MacroDef(mac) => {
+                return self.add_macro(ctx, Some(local_name), *mac);
+            }
+            ScopeDef::Unknown => {
+                return self.add(CompletionItem::new(
+                    CompletionKind::Reference,
+                    ctx.source_range(),
+                    local_name,
+                ));
+            }
+        };
+
+        let docs = match resolution {
+            ScopeDef::ModuleDef(Module(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Adt(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(EnumVariant(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Const(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Static(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(Trait(it)) => it.docs(ctx.db),
+            ScopeDef::ModuleDef(TypeAlias(it)) => it.docs(ctx.db),
+            _ => None,
+        };
+
+        let mut completion_item =
+            CompletionItem::new(completion_kind, ctx.source_range(), local_name.clone());
+        if let ScopeDef::Local(local) = resolution {
+            let ty = local.ty(ctx.db);
+            if !ty.is_unknown() {
+                completion_item = completion_item.detail(ty.display(ctx.db).to_string());
+            }
+        };
+
+        // If not an import, add parenthesis automatically.
+        if ctx.is_path_type
+            && !ctx.has_type_args
+            && ctx.db.feature_flags.get("completion.insertion.add-call-parenthesis")
+        {
+            let has_non_default_type_params = match resolution {
+                ScopeDef::ModuleDef(Adt(it)) => it.has_non_default_type_params(ctx.db),
+                ScopeDef::ModuleDef(TypeAlias(it)) => it.has_non_default_type_params(ctx.db),
+                _ => false,
+            };
+            if has_non_default_type_params {
+                tested_by!(inserts_angle_brackets_for_generics);
+                completion_item = completion_item
+                    .lookup_by(local_name.clone())
+                    .label(format!("{}<…>", local_name))
+                    .insert_snippet(format!("{}<$0>", local_name));
+            }
+        }
+
+        completion_item.kind(kind).set_documentation(docs).add_to(self)
+    }
+
+    pub(crate) fn add_function(&mut self, ctx: &CompletionContext, func: hir::Function) {
+        self.add_function_with_name(ctx, None, func)
+    }
+
+    fn guess_macro_braces(&self, macro_name: &str, docs: &str) -> &'static str {
+        let mut votes = [0, 0, 0];
+        for (idx, s) in docs.match_indices(&macro_name) {
+            let (before, after) = (&docs[..idx], &docs[idx + s.len()..]);
+            // Ensure to match the full word
+            if after.starts_with('!')
+                && before
+                    .chars()
+                    .rev()
+                    .next()
+                    .map_or(true, |c| c != '_' && !c.is_ascii_alphanumeric())
+            {
+                // It may have spaces before the braces like `foo! {}`
+                match after[1..].chars().find(|&c| !c.is_whitespace()) {
+                    Some('{') => votes[0] += 1,
+                    Some('[') => votes[1] += 1,
+                    Some('(') => votes[2] += 1,
+                    _ => {}
+                }
+            }
+        }
+
+        // Insert a space before `{}`.
+        // We prefer the last one when some votes equal.
+        *votes.iter().zip(&[" {$0}", "[$0]", "($0)"]).max_by_key(|&(&vote, _)| vote).unwrap().1
+    }
+
+    pub(crate) fn add_macro(
+        &mut self,
+        ctx: &CompletionContext,
+        name: Option<String>,
+        macro_: hir::MacroDef,
+    ) {
+        let name = match name {
+            Some(it) => it,
+            None => return,
+        };
+
+        let ast_node = macro_.source(ctx.db).value;
+        let detail = macro_label(&ast_node);
+
+        let docs = macro_.docs(ctx.db);
+        let macro_declaration = format!("{}!", name);
+
+        let mut builder =
+            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), &macro_declaration)
+                .kind(CompletionItemKind::Macro)
+                .set_documentation(docs.clone())
+                .set_deprecated(is_deprecated(macro_, ctx.db))
+                .detail(detail);
+
+        builder = if ctx.use_item_syntax.is_some() {
+            builder.insert_text(name)
+        } else {
+            let macro_braces_to_insert =
+                self.guess_macro_braces(&name, docs.as_ref().map_or("", |s| s.as_str()));
+            builder.insert_snippet(macro_declaration + macro_braces_to_insert)
+        };
+
+        self.add(builder);
+    }
+
+    fn add_function_with_name(
+        &mut self,
+        ctx: &CompletionContext,
+        name: Option<String>,
+        func: hir::Function,
+    ) {
+        let func_name = func.name(ctx.db);
+        let has_self_param = func.has_self_param(ctx.db);
+        let params = func.params(ctx.db);
+
+        let name = name.unwrap_or_else(|| func_name.to_string());
+        let ast_node = func.source(ctx.db).value;
+        let detail = function_label(&ast_node);
+
+        let mut builder =
+            CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.clone())
+                .kind(if has_self_param {
+                    CompletionItemKind::Method
+                } else {
+                    CompletionItemKind::Function
+                })
+                .set_documentation(func.docs(ctx.db))
+                .set_deprecated(is_deprecated(func, ctx.db))
+                .detail(detail);
+
+        // Add `<>` for generic types
+        if ctx.use_item_syntax.is_none()
+            && !ctx.is_call
+            && ctx.db.feature_flags.get("completion.insertion.add-call-parenthesis")
+        {
+            tested_by!(inserts_parens_for_function_calls);
+            let (snippet, label) = if params.is_empty() || has_self_param && params.len() == 1 {
+                (format!("{}()$0", func_name), format!("{}()", name))
+            } else {
+                (format!("{}($0)", func_name), format!("{}(…)", name))
+            };
+            builder = builder.lookup_by(name).label(label).insert_snippet(snippet);
+        }
+
+        self.add(builder)
+    }
+
+    pub(crate) fn add_const(&mut self, ctx: &CompletionContext, constant: hir::Const) {
+        let ast_node = constant.source(ctx.db).value;
+        let name = match ast_node.name() {
+            Some(name) => name,
+            _ => return,
+        };
+        let detail = const_label(&ast_node);
+
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.text().to_string())
+            .kind(CompletionItemKind::Const)
+            .set_documentation(constant.docs(ctx.db))
+            .set_deprecated(is_deprecated(constant, ctx.db))
+            .detail(detail)
+            .add_to(self);
+    }
+
+    pub(crate) fn add_type_alias(&mut self, ctx: &CompletionContext, type_alias: hir::TypeAlias) {
+        let type_def = type_alias.source(ctx.db).value;
+        let name = match type_def.name() {
+            Some(name) => name,
+            _ => return,
+        };
+        let detail = type_label(&type_def);
+
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.text().to_string())
+            .kind(CompletionItemKind::TypeAlias)
+            .set_documentation(type_alias.docs(ctx.db))
+            .set_deprecated(is_deprecated(type_alias, ctx.db))
+            .detail(detail)
+            .add_to(self);
+    }
+
+    pub(crate) fn add_enum_variant(&mut self, ctx: &CompletionContext, variant: hir::EnumVariant) {
+        let is_deprecated = is_deprecated(variant, ctx.db);
+        let name = variant.name(ctx.db);
+        let detail_types = variant.fields(ctx.db).into_iter().map(|field| field.ty(ctx.db));
+        let detail = join(detail_types.map(|t| t.display(ctx.db).to_string()))
+            .separator(", ")
+            .surround_with("(", ")")
+            .to_string();
+        CompletionItem::new(CompletionKind::Reference, ctx.source_range(), name.to_string())
+            .kind(CompletionItemKind::EnumVariant)
+            .set_documentation(variant.docs(ctx.db))
+            .set_deprecated(is_deprecated)
+            .detail(detail)
+            .add_to(self);
+    }
+}
+
+fn is_deprecated(node: impl HasAttrs, db: &impl HirDatabase) -> bool {
+    node.attrs(db).by_key("deprecated").exists()
+}
+
+#[cfg(test)]
+mod tests {
+    use insta::assert_debug_snapshot;
+    use test_utils::covers;
+
+    use crate::completion::{do_completion, CompletionItem, CompletionKind};
+
+    fn do_reference_completion(code: &str) -> Vec<CompletionItem> {
+        do_completion(code, CompletionKind::Reference)
+    }
+
+    #[test]
+    fn sets_deprecated_flag_in_completion_items() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r#"
+                #[deprecated]
+                fn something_deprecated() {}
+
+                #[deprecated(since = "1.0.0")]
+                fn something_else_deprecated() {}
+
+                fn main() { som<|> }
+                "#,
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "main()",
+                source_range: [203; 206),
+                delete: [203; 206),
+                insert: "main()$0",
+                kind: Function,
+                lookup: "main",
+                detail: "fn main()",
+            },
+            CompletionItem {
+                label: "something_deprecated()",
+                source_range: [203; 206),
+                delete: [203; 206),
+                insert: "something_deprecated()$0",
+                kind: Function,
+                lookup: "something_deprecated",
+                detail: "fn something_deprecated()",
+                deprecated: true,
+            },
+            CompletionItem {
+                label: "something_else_deprecated()",
+                source_range: [203; 206),
+                delete: [203; 206),
+                insert: "something_else_deprecated()$0",
+                kind: Function,
+                lookup: "something_else_deprecated",
+                detail: "fn something_else_deprecated()",
+                deprecated: true,
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn inserts_parens_for_function_calls() {
+        covers!(inserts_parens_for_function_calls);
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                fn no_args() {}
+                fn main() { no_<|> }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "main()",
+                source_range: [61; 64),
+                delete: [61; 64),
+                insert: "main()$0",
+                kind: Function,
+                lookup: "main",
+                detail: "fn main()",
+            },
+            CompletionItem {
+                label: "no_args()",
+                source_range: [61; 64),
+                delete: [61; 64),
+                insert: "no_args()$0",
+                kind: Function,
+                lookup: "no_args",
+                detail: "fn no_args()",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                fn with_args(x: i32, y: String) {}
+                fn main() { with_<|> }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "main()",
+                source_range: [80; 85),
+                delete: [80; 85),
+                insert: "main()$0",
+                kind: Function,
+                lookup: "main",
+                detail: "fn main()",
+            },
+            CompletionItem {
+                label: "with_args(…)",
+                source_range: [80; 85),
+                delete: [80; 85),
+                insert: "with_args($0)",
+                kind: Function,
+                lookup: "with_args",
+                detail: "fn with_args(x: i32, y: String)",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                struct S {}
+                impl S {
+                    fn foo(&self) {}
+                }
+                fn bar(s: &S) {
+                    s.f<|>
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "foo()",
+                source_range: [163; 164),
+                delete: [163; 164),
+                insert: "foo()$0",
+                kind: Method,
+                lookup: "foo",
+                detail: "fn foo(&self)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn dont_render_function_parens_in_use_item() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                mod m { pub fn foo() {} }
+                use crate::m::f<|>;
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "foo",
+                source_range: [40; 41),
+                delete: [40; 41),
+                insert: "foo",
+                kind: Function,
+                detail: "pub fn foo()",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn dont_render_function_parens_if_already_call() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                fn frobnicate() {}
+                fn main() {
+                    frob<|>();
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "frobnicate",
+                source_range: [35; 39),
+                delete: [35; 39),
+                insert: "frobnicate",
+                kind: Function,
+                detail: "fn frobnicate()",
+            },
+            CompletionItem {
+                label: "main",
+                source_range: [35; 39),
+                delete: [35; 39),
+                insert: "main",
+                kind: Function,
+                detail: "fn main()",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                "
+                //- /lib.rs
+                struct Foo {}
+                impl Foo { fn new() -> Foo {} }
+                fn main() {
+                    Foo::ne<|>();
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "new",
+                source_range: [67; 69),
+                delete: [67; 69),
+                insert: "new",
+                kind: Function,
+                detail: "fn new() -> Foo",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn inserts_angle_brackets_for_generics() {
+        covers!(inserts_angle_brackets_for_generics);
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                struct Vec<T> {}
+                fn foo(xs: Ve<|>)
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "Vec<…>",
+                source_range: [61; 63),
+                delete: [61; 63),
+                insert: "Vec<$0>",
+                kind: Struct,
+                lookup: "Vec",
+            },
+            CompletionItem {
+                label: "foo(…)",
+                source_range: [61; 63),
+                delete: [61; 63),
+                insert: "foo($0)",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo(xs: Ve)",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                type Vec<T> = (T,);
+                fn foo(xs: Ve<|>)
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "Vec<…>",
+                source_range: [64; 66),
+                delete: [64; 66),
+                insert: "Vec<$0>",
+                kind: TypeAlias,
+                lookup: "Vec",
+            },
+            CompletionItem {
+                label: "foo(…)",
+                source_range: [64; 66),
+                delete: [64; 66),
+                insert: "foo($0)",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo(xs: Ve)",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                struct Vec<T = i128> {}
+                fn foo(xs: Ve<|>)
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "Vec",
+                source_range: [68; 70),
+                delete: [68; 70),
+                insert: "Vec",
+                kind: Struct,
+            },
+            CompletionItem {
+                label: "foo(…)",
+                source_range: [68; 70),
+                delete: [68; 70),
+                insert: "foo($0)",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo(xs: Ve)",
+            },
+        ]
+        "###
+        );
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                struct Vec<T> {}
+                fn foo(xs: Ve<|><i128>)
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "Vec",
+                source_range: [61; 63),
+                delete: [61; 63),
+                insert: "Vec",
+                kind: Struct,
+            },
+            CompletionItem {
+                label: "foo(…)",
+                source_range: [61; 63),
+                delete: [61; 63),
+                insert: "foo($0)",
+                kind: Function,
+                lookup: "foo",
+                detail: "fn foo(xs: Ve<i128>)",
+            },
+        ]
+        "###
+        );
+    }
+
+    #[test]
+    fn dont_insert_macro_call_braces_in_use() {
+        assert_debug_snapshot!(
+            do_reference_completion(
+                r"
+                //- /main.rs
+                use foo::<|>;
+
+                //- /foo/lib.rs
+                #[macro_export]
+                macro_rules frobnicate {
+                    () => ()
+                }
+                "
+            ),
+            @r###"
+        [
+            CompletionItem {
+                label: "frobnicate!",
+                source_range: [9; 9),
+                delete: [9; 9),
+                insert: "frobnicate",
+                kind: Macro,
+                detail: "#[macro_export]\nmacro_rules! frobnicate",
+            },
+        ]
+        "###
+        )
+    }
+}