1 files changed, 730 insertions, 0 deletions

diff --git a/crates/ra_ide/src/hover.rs b/crates/ra_ide/src/hover.rs
new file mode 100644
index 000000000..260a7b869
--- /dev/null
+++ b/crates/ra_ide/src/hover.rs
@@ -0,0 +1,730 @@
+//! FIXME: write short doc here
+
+use hir::{db::AstDatabase, Adt, HasSource, HirDisplay};
+use ra_db::SourceDatabase;
+use ra_syntax::{
+    algo::find_covering_element,
+    ast::{self, DocCommentsOwner},
+    match_ast, AstNode,
+};
+
+use crate::{
+    db::RootDatabase,
+    display::{
+        description_from_symbol, docs_from_symbol, macro_label, rust_code_markup,
+        rust_code_markup_with_doc, ShortLabel,
+    },
+    expand::descend_into_macros,
+    references::{classify_name, classify_name_ref, NameKind, NameKind::*},
+    FilePosition, FileRange, RangeInfo,
+};
+
+/// Contains the results when hovering over an item
+#[derive(Debug, Clone)]
+pub struct HoverResult {
+    results: Vec<String>,
+    exact: bool,
+}
+
+impl Default for HoverResult {
+    fn default() -> Self {
+        HoverResult::new()
+    }
+}
+
+impl HoverResult {
+    pub fn new() -> HoverResult {
+        HoverResult {
+            results: Vec::new(),
+            // We assume exact by default
+            exact: true,
+        }
+    }
+
+    pub fn extend(&mut self, item: Option<String>) {
+        self.results.extend(item);
+    }
+
+    pub fn is_exact(&self) -> bool {
+        self.exact
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.results.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.results.len()
+    }
+
+    pub fn first(&self) -> Option<&str> {
+        self.results.first().map(String::as_str)
+    }
+
+    pub fn results(&self) -> &[String] {
+        &self.results
+    }
+
+    /// Returns the results converted into markup
+    /// for displaying in a UI
+    pub fn to_markup(&self) -> String {
+        let mut markup = if !self.exact {
+            let mut msg = String::from("Failed to exactly resolve the symbol. This is probably because rust_analyzer does not yet support traits.");
+            if !self.results.is_empty() {
+                msg.push_str("  \nThese items were found instead:");
+            }
+            msg.push_str("\n\n---\n");
+            msg
+        } else {
+            String::new()
+        };
+
+        markup.push_str(&self.results.join("\n\n---\n"));
+
+        markup
+    }
+}
+
+fn hover_text(docs: Option<String>, desc: Option<String>) -> Option<String> {
+    match (desc, docs) {
+        (Some(desc), docs) => Some(rust_code_markup_with_doc(desc, docs)),
+        (None, Some(docs)) => Some(docs),
+        _ => None,
+    }
+}
+
+fn hover_text_from_name_kind(
+    db: &RootDatabase,
+    name_kind: NameKind,
+    no_fallback: &mut bool,
+) -> Option<String> {
+    return match name_kind {
+        Macro(it) => {
+            let src = it.source(db);
+            hover_text(src.value.doc_comment_text(), Some(macro_label(&src.value)))
+        }
+        Field(it) => {
+            let src = it.source(db);
+            match src.value {
+                hir::FieldSource::Named(it) => hover_text(it.doc_comment_text(), it.short_label()),
+                _ => None,
+            }
+        }
+        AssocItem(it) => match it {
+            hir::AssocItem::Function(it) => from_def_source(db, it),
+            hir::AssocItem::Const(it) => from_def_source(db, it),
+            hir::AssocItem::TypeAlias(it) => from_def_source(db, it),
+        },
+        Def(it) => match it {
+            hir::ModuleDef::Module(it) => match it.definition_source(db).value {
+                hir::ModuleSource::Module(it) => {
+                    hover_text(it.doc_comment_text(), it.short_label())
+                }
+                _ => None,
+            },
+            hir::ModuleDef::Function(it) => from_def_source(db, it),
+            hir::ModuleDef::Adt(Adt::Struct(it)) => from_def_source(db, it),
+            hir::ModuleDef::Adt(Adt::Union(it)) => from_def_source(db, it),
+            hir::ModuleDef::Adt(Adt::Enum(it)) => from_def_source(db, it),
+            hir::ModuleDef::EnumVariant(it) => from_def_source(db, it),
+            hir::ModuleDef::Const(it) => from_def_source(db, it),
+            hir::ModuleDef::Static(it) => from_def_source(db, it),
+            hir::ModuleDef::Trait(it) => from_def_source(db, it),
+            hir::ModuleDef::TypeAlias(it) => from_def_source(db, it),
+            hir::ModuleDef::BuiltinType(it) => Some(it.to_string()),
+        },
+        Local(_) => {
+            // Hover for these shows type names
+            *no_fallback = true;
+            None
+        }
+        GenericParam(_) | SelfType(_) => {
+            // FIXME: Hover for generic param
+            None
+        }
+    };
+
+    fn from_def_source<A, D>(db: &RootDatabase, def: D) -> Option<String>
+    where
+        D: HasSource<Ast = A>,
+        A: ast::DocCommentsOwner + ast::NameOwner + ShortLabel,
+    {
+        let src = def.source(db);
+        hover_text(src.value.doc_comment_text(), src.value.short_label())
+    }
+}
+
+pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<HoverResult>> {
+    let file = db.parse_or_expand(position.file_id.into())?;
+    let token = file.token_at_offset(position.offset).filter(|it| !it.kind().is_trivia()).next()?;
+    let token = descend_into_macros(db, position.file_id, token);
+
+    let mut res = HoverResult::new();
+
+    let mut range = match_ast! {
+        match (token.value.parent()) {
+            ast::NameRef(name_ref) => {
+                let mut no_fallback = false;
+                if let Some(name_kind) =
+                    classify_name_ref(db, token.with_value(&name_ref)).map(|d| d.kind)
+                {
+                    res.extend(hover_text_from_name_kind(db, name_kind, &mut no_fallback))
+                }
+
+                if res.is_empty() && !no_fallback {
+                    // Fallback index based approach:
+                    let symbols = crate::symbol_index::index_resolve(db, &name_ref);
+                    for sym in symbols {
+                        let docs = docs_from_symbol(db, &sym);
+                        let desc = description_from_symbol(db, &sym);
+                        res.extend(hover_text(docs, desc));
+                    }
+                }
+
+                if !res.is_empty() {
+                    Some(name_ref.syntax().text_range())
+                } else {
+                    None
+                }
+            },
+            ast::Name(name) => {
+                if let Some(name_kind) = classify_name(db, token.with_value(&name)).map(|d| d.kind) {
+                    res.extend(hover_text_from_name_kind(db, name_kind, &mut true));
+                }
+
+                if !res.is_empty() {
+                    Some(name.syntax().text_range())
+                } else {
+                    None
+                }
+            },
+            _ => None,
+        }
+    };
+
+    if range.is_none() {
+        let node = token.value.ancestors().find(|n| {
+            ast::Expr::cast(n.clone()).is_some() || ast::Pat::cast(n.clone()).is_some()
+        })?;
+        let frange = FileRange { file_id: position.file_id, range: node.text_range() };
+        res.extend(type_of(db, frange).map(rust_code_markup));
+        range = Some(node.text_range());
+    };
+
+    let range = range?;
+    if res.is_empty() {
+        return None;
+    }
+    Some(RangeInfo::new(range, res))
+}
+
+pub(crate) fn type_of(db: &RootDatabase, frange: FileRange) -> Option<String> {
+    let parse = db.parse(frange.file_id);
+    let leaf_node = find_covering_element(parse.tree().syntax(), frange.range);
+    // if we picked identifier, expand to pattern/expression
+    let node = leaf_node
+        .ancestors()
+        .take_while(|it| it.text_range() == leaf_node.text_range())
+        .find(|it| ast::Expr::cast(it.clone()).is_some() || ast::Pat::cast(it.clone()).is_some())?;
+    let analyzer =
+        hir::SourceAnalyzer::new(db, hir::Source::new(frange.file_id.into(), &node), None);
+    let ty = if let Some(ty) = ast::Expr::cast(node.clone()).and_then(|e| analyzer.type_of(db, &e))
+    {
+        ty
+    } else if let Some(ty) = ast::Pat::cast(node).and_then(|p| analyzer.type_of_pat(db, &p)) {
+        ty
+    } else {
+        return None;
+    };
+    Some(ty.display(db).to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::mock_analysis::{
+        analysis_and_position, single_file_with_position, single_file_with_range,
+    };
+    use ra_syntax::TextRange;
+
+    fn trim_markup(s: &str) -> &str {
+        s.trim_start_matches("```rust\n").trim_end_matches("\n```")
+    }
+
+    fn trim_markup_opt(s: Option<&str>) -> Option<&str> {
+        s.map(trim_markup)
+    }
+
+    fn check_hover_result(fixture: &str, expected: &[&str]) {
+        let (analysis, position) = analysis_and_position(fixture);
+        let hover = analysis.hover(position).unwrap().unwrap();
+        let mut results = Vec::from(hover.info.results());
+        results.sort();
+
+        for (markup, expected) in
+            results.iter().zip(expected.iter().chain(std::iter::repeat(&"<missing>")))
+        {
+            assert_eq!(trim_markup(&markup), *expected);
+        }
+
+        assert_eq!(hover.info.len(), expected.len());
+    }
+
+    #[test]
+    fn hover_shows_type_of_an_expression() {
+        let (analysis, position) = single_file_with_position(
+            "
+            pub fn foo() -> u32 { 1 }
+
+            fn main() {
+                let foo_test = foo()<|>;
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(hover.range, TextRange::from_to(95.into(), 100.into()));
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("u32"));
+    }
+
+    #[test]
+    fn hover_shows_fn_signature() {
+        // Single file with result
+        check_hover_result(
+            r#"
+            //- /main.rs
+            pub fn foo() -> u32 { 1 }
+
+            fn main() {
+                let foo_test = fo<|>o();
+            }
+        "#,
+            &["pub fn foo() -> u32"],
+        );
+
+        // Multiple results
+        check_hover_result(
+            r#"
+            //- /a.rs
+            pub fn foo() -> u32 { 1 }
+
+            //- /b.rs
+            pub fn foo() -> &str { "" }
+
+            //- /c.rs
+            pub fn foo(a: u32, b: u32) {}
+
+            //- /main.rs
+            mod a;
+            mod b;
+            mod c;
+
+            fn main() {
+                let foo_test = fo<|>o();
+            }
+        "#,
+            &["pub fn foo() -> &str", "pub fn foo() -> u32", "pub fn foo(a: u32, b: u32)"],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_signature_with_type_params() {
+        check_hover_result(
+            r#"
+            //- /main.rs
+            pub fn foo<'a, T: AsRef<str>>(b: &'a T) -> &'a str { }
+
+            fn main() {
+                let foo_test = fo<|>o();
+            }
+        "#,
+            &["pub fn foo<'a, T: AsRef<str>>(b: &'a T) -> &'a str"],
+        );
+    }
+
+    #[test]
+    fn hover_shows_fn_signature_on_fn_name() {
+        check_hover_result(
+            r#"
+            //- /main.rs
+            pub fn foo<|>(a: u32, b: u32) -> u32 {}
+
+            fn main() {
+            }
+        "#,
+            &["pub fn foo(a: u32, b: u32) -> u32"],
+        );
+    }
+
+    #[test]
+    fn hover_shows_struct_field_info() {
+        // Hovering over the field when instantiating
+        check_hover_result(
+            r#"
+            //- /main.rs
+            struct Foo {
+                field_a: u32,
+            }
+
+            fn main() {
+                let foo = Foo {
+                    field_a<|>: 0,
+                };
+            }
+        "#,
+            &["field_a: u32"],
+        );
+
+        // Hovering over the field in the definition
+        check_hover_result(
+            r#"
+            //- /main.rs
+            struct Foo {
+                field_a<|>: u32,
+            }
+
+            fn main() {
+                let foo = Foo {
+                    field_a: 0,
+                };
+            }
+        "#,
+            &["field_a: u32"],
+        );
+    }
+
+    #[test]
+    fn hover_const_static() {
+        check_hover_result(
+            r#"
+            //- /main.rs
+            const foo<|>: u32 = 0;
+        "#,
+            &["const foo: u32"],
+        );
+
+        check_hover_result(
+            r#"
+            //- /main.rs
+            static foo<|>: u32 = 0;
+        "#,
+            &["static foo: u32"],
+        );
+    }
+
+    #[test]
+    fn hover_some() {
+        let (analysis, position) = single_file_with_position(
+            "
+            enum Option<T> { Some(T) }
+            use Option::Some;
+
+            fn main() {
+                So<|>me(12);
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("Some"));
+
+        let (analysis, position) = single_file_with_position(
+            "
+            enum Option<T> { Some(T) }
+            use Option::Some;
+
+            fn main() {
+                let b<|>ar = Some(12);
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("Option<i32>"));
+    }
+
+    #[test]
+    fn hover_enum_variant() {
+        check_hover_result(
+            r#"
+            //- /main.rs
+            enum Option<T> {
+                /// The None variant
+                Non<|>e
+            }
+        "#,
+            &["
+None
+```
+
+The None variant
+            "
+            .trim()],
+        );
+
+        check_hover_result(
+            r#"
+            //- /main.rs
+            enum Option<T> {
+                /// The Some variant
+                Some(T)
+            }
+            fn main() {
+                let s = Option::Som<|>e(12);
+            }
+        "#,
+            &["
+Some
+```
+
+The Some variant
+            "
+            .trim()],
+        );
+    }
+
+    #[test]
+    fn hover_for_local_variable() {
+        let (analysis, position) = single_file_with_position("fn func(foo: i32) { fo<|>o; }");
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+    }
+
+    #[test]
+    fn hover_for_local_variable_pat() {
+        let (analysis, position) = single_file_with_position("fn func(fo<|>o: i32) {}");
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+    }
+
+    #[test]
+    fn hover_local_var_edge() {
+        let (analysis, position) = single_file_with_position(
+            "
+fn func(foo: i32) { if true { <|>foo; }; }
+",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+    }
+
+    #[test]
+    fn test_type_of_for_function() {
+        let (analysis, range) = single_file_with_range(
+            "
+            pub fn foo() -> u32 { 1 };
+
+            fn main() {
+                let foo_test = <|>foo()<|>;
+            }
+            ",
+        );
+
+        let type_name = analysis.type_of(range).unwrap().unwrap();
+        assert_eq!("u32", &type_name);
+    }
+
+    #[test]
+    fn test_type_of_for_expr() {
+        let (analysis, range) = single_file_with_range(
+            "
+            fn main() {
+                let foo: usize = 1;
+                let bar = <|>1 + foo<|>;
+            }
+            ",
+        );
+
+        let type_name = analysis.type_of(range).unwrap().unwrap();
+        assert_eq!("usize", &type_name);
+    }
+
+    #[test]
+    fn test_hover_infer_associated_method_result() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct Thing { x: u32 }
+
+            impl Thing {
+                fn new() -> Thing {
+                    Thing { x: 0 }
+                }
+            }
+
+            fn main() {
+                let foo_<|>test = Thing::new();
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("Thing"));
+    }
+
+    #[test]
+    fn test_hover_infer_associated_method_exact() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct Thing { x: u32 }
+
+            impl Thing {
+                fn new() -> Thing {
+                    Thing { x: 0 }
+                }
+            }
+
+            fn main() {
+                let foo_test = Thing::new<|>();
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("fn new() -> Thing"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
+
+    #[test]
+    fn test_hover_infer_associated_const_in_pattern() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct X;
+            impl X {
+                const C: u32 = 1;
+            }
+
+            fn main() {
+                match 1 {
+                    X::C<|> => {},
+                    2 => {},
+                    _ => {}
+                };
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("const C: u32"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
+
+    #[test]
+    fn test_hover_self() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct Thing { x: u32 }
+            impl Thing {
+                fn new() -> Self {
+                    Self<|> { x: 0 }
+                }
+            }
+        ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("Thing"));
+        assert_eq!(hover.info.is_exact(), true);
+
+        /* FIXME: revive these tests
+                let (analysis, position) = single_file_with_position(
+                    "
+                    struct Thing { x: u32 }
+                    impl Thing {
+                        fn new() -> Self<|> {
+                            Self { x: 0 }
+                        }
+                    }
+                    ",
+                );
+
+                let hover = analysis.hover(position).unwrap().unwrap();
+                assert_eq!(trim_markup_opt(hover.info.first()), Some("Thing"));
+                assert_eq!(hover.info.is_exact(), true);
+
+                let (analysis, position) = single_file_with_position(
+                    "
+                    enum Thing { A }
+                    impl Thing {
+                        pub fn new() -> Self<|> {
+                            Thing::A
+                        }
+                    }
+                    ",
+                );
+                let hover = analysis.hover(position).unwrap().unwrap();
+                assert_eq!(trim_markup_opt(hover.info.first()), Some("enum Thing"));
+                assert_eq!(hover.info.is_exact(), true);
+
+                let (analysis, position) = single_file_with_position(
+                    "
+                    enum Thing { A }
+                    impl Thing {
+                        pub fn thing(a: Self<|>) {
+                        }
+                    }
+                    ",
+                );
+                let hover = analysis.hover(position).unwrap().unwrap();
+                assert_eq!(trim_markup_opt(hover.info.first()), Some("enum Thing"));
+                assert_eq!(hover.info.is_exact(), true);
+        */
+    }
+
+    #[test]
+    fn test_hover_shadowing_pat() {
+        let (analysis, position) = single_file_with_position(
+            "
+            fn x() {}
+
+            fn y() {
+                let x = 0i32;
+                x<|>;
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
+
+    #[test]
+    fn test_hover_macro_invocation() {
+        let (analysis, position) = single_file_with_position(
+            "
+            macro_rules! foo {
+                () => {}
+            }
+
+            fn f() {
+                fo<|>o!();
+            }
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("macro_rules! foo"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
+
+    #[test]
+    fn test_hover_tuple_field() {
+        let (analysis, position) = single_file_with_position(
+            "
+            struct TS(String, i32<|>);
+            ",
+        );
+        let hover = analysis.hover(position).unwrap().unwrap();
+        assert_eq!(trim_markup_opt(hover.info.first()), Some("i32"));
+        assert_eq!(hover.info.is_exact(), true);
+    }
+
+    #[test]
+    fn test_hover_through_macro() {
+        check_hover_result(
+            "
+            //- /lib.rs
+            macro_rules! id {
+                ($($tt:tt)*) => { $($tt)* }
+            }
+            fn foo() {}
+            id! {
+                fn bar() {
+                    fo<|>o();
+                }
+            }
+            ",
+            &["fn foo()"],
+        );
+    }
+}