5 files changed, 515 insertions, 130 deletions

diff --git a/crates/ra_assists/src/assists/add_new.rs b/crates/ra_assists/src/assists/add_new.rs
new file mode 100644
index 000000000..a8839cfba
--- /dev/null
+++ b/crates/ra_assists/src/assists/add_new.rs
@@ -0,0 +1,379 @@
+use format_buf::format;
+use hir::{db::HirDatabase, FromSource};
+use join_to_string::join;
+use ra_syntax::{
+    ast::{
+        self, AstNode, NameOwner, StructKind, TypeAscriptionOwner, TypeParamsOwner, VisibilityOwner,
+    },
+    TextUnit, T,
+};
+use std::fmt::Write;
+
+use crate::{Assist, AssistCtx, AssistId};
+
+// Assist: add_new
+//
+// Adds a new inherent impl for a type.
+//
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,<|>
+// }
+// ```
+// ->
+// ```
+// struct Ctx<T: Clone> {
+//      data: T,
+// }
+//
+// impl<T: Clone> Ctx<T> {
+//     fn new(data: T) -> Self { Self { data } }
+// }
+//
+// ```
+pub(crate) fn add_new(ctx: AssistCtx<impl HirDatabase>) -> Option<Assist> {
+    let strukt = ctx.find_node_at_offset::<ast::StructDef>()?;
+
+    // We want to only apply this to non-union structs with named fields
+    let field_list = match (strukt.kind(), strukt.is_union()) {
+        (StructKind::Named(named), false) => named,
+        _ => return None,
+    };
+
+    // Return early if we've found an existing new fn
+    let impl_block = find_struct_impl(&ctx, &strukt)?;
+
+    ctx.add_assist(AssistId("add_new"), "add new fn", |edit| {
+        edit.target(strukt.syntax().text_range());
+
+        let mut buf = String::with_capacity(512);
+
+        if impl_block.is_some() {
+            buf.push('\n');
+        }
+
+        let vis = strukt.visibility().map(|v| format!("{} ", v.syntax()));
+        let vis = vis.as_ref().map(String::as_str).unwrap_or("");
+        write!(&mut buf, "    {}fn new(", vis).unwrap();
+
+        join(field_list.fields().map(|f| {
+            format!(
+                "{}: {}",
+                f.name().unwrap().syntax().text(),
+                f.ascribed_type().unwrap().syntax().text()
+            )
+        }))
+        .separator(", ")
+        .to_buf(&mut buf);
+
+        buf.push_str(") -> Self { Self {");
+
+        join(field_list.fields().map(|f| f.name().unwrap().syntax().text()))
+            .separator(", ")
+            .surround_with(" ", " ")
+            .to_buf(&mut buf);
+
+        buf.push_str("} }");
+
+        let (start_offset, end_offset) = if let Some(impl_block) = impl_block {
+            buf.push('\n');
+            let start = impl_block
+                .syntax()
+                .descendants_with_tokens()
+                .find(|t| t.kind() == T!['{'])
+                .unwrap()
+                .text_range()
+                .end();
+
+            (start, TextUnit::from_usize(1))
+        } else {
+            buf = generate_impl_text(&strukt, &buf);
+            let start = strukt.syntax().text_range().end();
+
+            (start, TextUnit::from_usize(3))
+        };
+
+        edit.set_cursor(start_offset + TextUnit::of_str(&buf) - end_offset);
+        edit.insert(start_offset, buf);
+    })
+}
+
+// Generates the surrounding `impl Type { <code> }` including type and lifetime
+// parameters
+fn generate_impl_text(strukt: &ast::StructDef, code: &str) -> String {
+    let type_params = strukt.type_param_list();
+    let mut buf = String::with_capacity(code.len());
+    buf.push_str("\n\nimpl");
+    if let Some(type_params) = &type_params {
+        format!(buf, "{}", type_params.syntax());
+    }
+    buf.push_str(" ");
+    buf.push_str(strukt.name().unwrap().text().as_str());
+    if let Some(type_params) = type_params {
+        let lifetime_params = type_params
+            .lifetime_params()
+            .filter_map(|it| it.lifetime_token())
+            .map(|it| it.text().clone());
+        let type_params =
+            type_params.type_params().filter_map(|it| it.name()).map(|it| it.text().clone());
+        join(lifetime_params.chain(type_params)).surround_with("<", ">").to_buf(&mut buf);
+    }
+
+    format!(&mut buf, " {{\n{}\n}}\n", code);
+
+    buf
+}
+
+// Uses a syntax-driven approach to find any impl blocks for the struct that
+// exist within the module/file
+//
+// Returns `None` if we've found an existing `new` fn
+//
+// FIXME: change the new fn checking to a more semantic approach when that's more
+// viable (e.g. we process proc macros, etc)
+fn find_struct_impl(
+    ctx: &AssistCtx<impl HirDatabase>,
+    strukt: &ast::StructDef,
+) -> Option<Option<ast::ImplBlock>> {
+    let db = ctx.db;
+    let module = strukt.syntax().ancestors().find(|node| {
+        ast::Module::can_cast(node.kind()) || ast::SourceFile::can_cast(node.kind())
+    })?;
+
+    let struct_ty = {
+        let src = hir::Source { file_id: ctx.frange.file_id.into(), ast: strukt.clone() };
+        hir::Struct::from_source(db, src).unwrap().ty(db)
+    };
+
+    let mut found_new_fn = false;
+
+    let block = module.descendants().filter_map(ast::ImplBlock::cast).find(|impl_blk| {
+        if found_new_fn {
+            return false;
+        }
+
+        let src = hir::Source { file_id: ctx.frange.file_id.into(), ast: impl_blk.clone() };
+        let blk = hir::ImplBlock::from_source(db, src).unwrap();
+
+        let same_ty = blk.target_ty(db) == struct_ty;
+        let not_trait_impl = blk.target_trait(db).is_none();
+
+        found_new_fn = has_new_fn(impl_blk);
+
+        same_ty && not_trait_impl
+    });
+
+    if found_new_fn {
+        None
+    } else {
+        Some(block)
+    }
+}
+
+fn has_new_fn(imp: &ast::ImplBlock) -> bool {
+    if let Some(il) = imp.item_list() {
+        for item in il.impl_items() {
+            if let ast::ImplItem::FnDef(f) = item {
+                if f.name().unwrap().text().eq_ignore_ascii_case("new") {
+                    return true;
+                }
+            }
+        }
+    }
+
+    false
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::helpers::{check_assist, check_assist_not_applicable, check_assist_target};
+
+    #[test]
+    #[rustfmt::skip]
+    fn test_add_new() {
+        // Check output of generation
+        check_assist(
+            add_new,
+"struct Foo {<|>}",
+"struct Foo {}
+
+impl Foo {
+    fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"struct Foo<T: Clone> {<|>}",
+"struct Foo<T: Clone> {}
+
+impl<T: Clone> Foo<T> {
+    fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"struct Foo<'a, T: Foo<'a>> {<|>}",
+"struct Foo<'a, T: Foo<'a>> {}
+
+impl<'a, T: Foo<'a>> Foo<'a, T> {
+    fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"struct Foo { baz: String <|>}",
+"struct Foo { baz: String }
+
+impl Foo {
+    fn new(baz: String) -> Self { Self { baz } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"struct Foo { baz: String, qux: Vec<i32> <|>}",
+"struct Foo { baz: String, qux: Vec<i32> }
+
+impl Foo {
+    fn new(baz: String, qux: Vec<i32>) -> Self { Self { baz, qux } }<|>
+}
+",
+        );
+
+        // Check that visibility modifiers don't get brought in for fields
+        check_assist(
+            add_new,
+"struct Foo { pub baz: String, pub qux: Vec<i32> <|>}",
+"struct Foo { pub baz: String, pub qux: Vec<i32> }
+
+impl Foo {
+    fn new(baz: String, qux: Vec<i32>) -> Self { Self { baz, qux } }<|>
+}
+",
+        );
+
+        // Check that it reuses existing impls
+        check_assist(
+            add_new,
+"struct Foo {<|>}
+
+impl Foo {}
+",
+"struct Foo {}
+
+impl Foo {
+    fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"struct Foo {<|>}
+
+impl Foo {
+    fn qux(&self) {}
+}
+",
+"struct Foo {}
+
+impl Foo {
+    fn new() -> Self { Self {  } }<|>
+
+    fn qux(&self) {}
+}
+",
+        );
+
+        check_assist(
+            add_new,
+"struct Foo {<|>}
+
+impl Foo {
+    fn qux(&self) {}
+    fn baz() -> i32 {
+        5
+    }
+}
+",
+"struct Foo {}
+
+impl Foo {
+    fn new() -> Self { Self {  } }<|>
+
+    fn qux(&self) {}
+    fn baz() -> i32 {
+        5
+    }
+}
+",
+        );
+
+        // Check visibility of new fn based on struct
+        check_assist(
+            add_new,
+"pub struct Foo {<|>}",
+"pub struct Foo {}
+
+impl Foo {
+    pub fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+        check_assist(
+            add_new,
+"pub(crate) struct Foo {<|>}",
+"pub(crate) struct Foo {}
+
+impl Foo {
+    pub(crate) fn new() -> Self { Self {  } }<|>
+}
+",
+        );
+    }
+
+    #[test]
+    fn add_new_not_applicable_if_fn_exists() {
+        check_assist_not_applicable(
+            add_new,
+            "
+struct Foo {<|>}
+
+impl Foo {
+    fn new() -> Self {
+        Self
+    }    
+}",
+        );
+
+        check_assist_not_applicable(
+            add_new,
+            "
+struct Foo {<|>}
+
+impl Foo {
+    fn New() -> Self {
+        Self
+    }    
+}",
+        );
+    }
+
+    #[test]
+    fn add_new_target() {
+        check_assist_target(
+            add_new,
+            "
+struct SomeThingIrrelevant;
+/// Has a lifetime parameter
+struct Foo<'a, T: Foo<'a>> {<|>}
+struct EvenMoreIrrelevant;
+",
+            "/// Has a lifetime parameter
+struct Foo<'a, T: Foo<'a>> {}",
+        );
+    }
+}
diff --git a/crates/ra_assists/src/doc_tests/generated.rs b/crates/ra_assists/src/doc_tests/generated.rs
index 1bee76f59..176761efb 100644
--- a/crates/ra_assists/src/doc_tests/generated.rs
+++ b/crates/ra_assists/src/doc_tests/generated.rs
@@ -157,6 +157,28 @@ fn process(map: HashMap<String, String>) {}
 }
 
 #[test]
+fn doctest_add_new() {
+    check(
+        "add_new",
+        r#####"
+struct Ctx<T: Clone> {
+     data: T,<|>
+}
+"#####,
+        r#####"
+struct Ctx<T: Clone> {
+     data: T,
+}
+
+impl<T: Clone> Ctx<T> {
+    fn new(data: T) -> Self { Self { data } }
+}
+
+"#####,
+    )
+}
+
+#[test]
 fn doctest_apply_demorgan() {
     check(
         "apply_demorgan",
diff --git a/crates/ra_assists/src/lib.rs b/crates/ra_assists/src/lib.rs
index 39c1c283f..f2f0dacbf 100644
--- a/crates/ra_assists/src/lib.rs
+++ b/crates/ra_assists/src/lib.rs
@@ -95,6 +95,7 @@ mod assists {
     mod add_derive;
     mod add_explicit_type;
     mod add_impl;
+    mod add_new;
     mod apply_demorgan;
     mod flip_comma;
     mod flip_binexpr;
@@ -119,6 +120,7 @@ mod assists {
             add_derive::add_derive,
             add_explicit_type::add_explicit_type,
             add_impl::add_impl,
+            add_new::add_new,
             apply_demorgan::apply_demorgan,
             change_visibility::change_visibility,
             fill_match_arms::fill_match_arms,
diff --git a/crates/ra_ide_api/src/hover.rs b/crates/ra_ide_api/src/hover.rs
index 086e6dec3..07d511fb3 100644
--- a/crates/ra_ide_api/src/hover.rs
+++ b/crates/ra_ide_api/src/hover.rs
@@ -5,7 +5,7 @@ use ra_db::SourceDatabase;
 use ra_syntax::{
     algo::{ancestors_at_offset, find_covering_element, find_node_at_offset},
     ast::{self, DocCommentsOwner},
-    match_ast, AstNode,
+    AstNode,
 };
 
 use crate::{
@@ -14,7 +14,7 @@ use crate::{
         description_from_symbol, docs_from_symbol, macro_label, rust_code_markup,
         rust_code_markup_with_doc, ShortLabel,
     },
-    references::{classify_name_ref, NameKind::*},
+    references::{classify_name, classify_name_ref, NameKind, NameKind::*},
     FilePosition, FileRange, RangeInfo,
 };
 
@@ -92,65 +92,88 @@ fn hover_text(docs: Option<String>, desc: Option<String>) -> Option<String> {
     }
 }
 
+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.ast.doc_comment_text(), Some(macro_label(&src.ast)))
+        }
+        Field(it) => {
+            let src = it.source(db);
+            match src.ast {
+                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).ast {
+                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()),
+        },
+        SelfType(ty) => match ty.as_adt() {
+            Some((adt_def, _)) => match adt_def {
+                hir::Adt::Struct(it) => from_def_source(db, it),
+                hir::Adt::Union(it) => from_def_source(db, it),
+                hir::Adt::Enum(it) => from_def_source(db, it),
+            },
+            _ => None,
+        },
+        Local(_) => {
+            // Hover for these shows type names
+            *no_fallback = true;
+            None
+        }
+        GenericParam(_) => {
+            // 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.ast.doc_comment_text(), src.ast.short_label())
+    }
+}
+
 pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeInfo<HoverResult>> {
     let parse = db.parse(position.file_id);
     let file = parse.tree();
+
     let mut res = HoverResult::new();
 
-    let mut range = None;
-    if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset) {
+    let mut range = if let Some(name_ref) =
+        find_node_at_offset::<ast::NameRef>(file.syntax(), position.offset)
+    {
         let mut no_fallback = false;
-        let name_kind = classify_name_ref(db, position.file_id, &name_ref).map(|d| d.kind);
-        match name_kind {
-            Some(Macro(it)) => {
-                let src = it.source(db);
-                res.extend(hover_text(src.ast.doc_comment_text(), Some(macro_label(&src.ast))));
-            }
-            Some(Field(it)) => {
-                let src = it.source(db);
-                if let hir::FieldSource::Named(it) = src.ast {
-                    res.extend(hover_text(it.doc_comment_text(), it.short_label()));
-                }
-            }
-            Some(AssocItem(it)) => res.extend(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),
-            }),
-            Some(Def(it)) => match it {
-                hir::ModuleDef::Module(it) => {
-                    if let hir::ModuleSource::Module(it) = it.definition_source(db).ast {
-                        res.extend(hover_text(it.doc_comment_text(), it.short_label()))
-                    }
-                }
-                hir::ModuleDef::Function(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Adt(Adt::Struct(it)) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Adt(Adt::Union(it)) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Adt(Adt::Enum(it)) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::EnumVariant(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Const(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Static(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::Trait(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::TypeAlias(it) => res.extend(from_def_source(db, it)),
-                hir::ModuleDef::BuiltinType(it) => res.extend(Some(it.to_string())),
-            },
-            Some(SelfType(ty)) => {
-                if let Some((adt_def, _)) = ty.as_adt() {
-                    res.extend(match adt_def {
-                        hir::Adt::Struct(it) => from_def_source(db, it),
-                        hir::Adt::Union(it) => from_def_source(db, it),
-                        hir::Adt::Enum(it) => from_def_source(db, it),
-                    })
-                }
-            }
-            Some(Local(_)) => {
-                // Hover for these shows type names
-                no_fallback = true;
-            }
-            Some(GenericParam(_)) => {
-                // FIXME: Hover for generic param
-            }
-            None => {}
+        if let Some(name_kind) = classify_name_ref(db, position.file_id, &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 {
@@ -164,55 +187,24 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         }
 
         if !res.is_empty() {
-            range = Some(name_ref.syntax().text_range())
+            Some(name_ref.syntax().text_range())
+        } else {
+            None
         }
     } else if let Some(name) = find_node_at_offset::<ast::Name>(file.syntax(), position.offset) {
-        if let Some(parent) = name.syntax().parent() {
-            let text = match_ast! {
-                match parent {
-                    ast::StructDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::EnumDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::EnumVariant(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::FnDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::TypeAliasDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::ConstDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::StaticDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::TraitDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::RecordFieldDef(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::Module(it) => {
-                        hover_text(it.doc_comment_text(), it.short_label())
-                    },
-                    ast::MacroCall(it) => {
-                        hover_text(it.doc_comment_text(), None)
-                    },
-                    _ => None,
-                }
-            };
-            res.extend(text);
+        if let Some(name_kind) = classify_name(db, position.file_id, &name).map(|d| d.kind) {
+            let mut _b: bool = true;
+            res.extend(hover_text_from_name_kind(db, name_kind, &mut _b));
         }
 
-        if !res.is_empty() && range.is_none() {
-            range = Some(name.syntax().text_range());
+        if !res.is_empty() {
+            Some(name.syntax().text_range())
+        } else {
+            None
         }
-    }
+    } else {
+        None
+    };
 
     if range.is_none() {
         let node = ancestors_at_offset(file.syntax(), position.offset).find(|n| {
@@ -221,23 +213,13 @@ pub(crate) fn hover(db: &RootDatabase, position: FilePosition) -> Option<RangeIn
         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;
     }
-    let res = RangeInfo::new(range, res);
-    return Some(res);
-
-    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.ast.doc_comment_text(), src.ast.short_label())
-    }
+    Some(RangeInfo::new(range, res))
 }
 
 pub(crate) fn type_of(db: &RootDatabase, frange: FileRange) -> Option<String> {
diff --git a/crates/ra_prof/Cargo.toml b/crates/ra_prof/Cargo.toml
index bb241258c..751bcdeb8 100644
--- a/crates/ra_prof/Cargo.toml
+++ b/crates/ra_prof/Cargo.toml
@@ -1,19 +1,19 @@
-[package]

-edition = "2018"

-name = "ra_prof"

-version = "0.1.0"

-authors = ["rust-analyzer developers"]

-publish = false

-

-[dependencies]

-once_cell = "1.0.1"

-itertools = "0.8.0"

-backtrace = "0.3.28"

-

-[target.'cfg(not(target_env = "msvc"))'.dependencies]

-jemallocator = { version = "0.3.2", optional = true }

-jemalloc-ctl = { version = "0.3.2", optional = true }

-

-[features]

-jemalloc = [ "jemallocator", "jemalloc-ctl" ]

-cpu_profiler = []

+[package]
+edition = "2018"
+name = "ra_prof"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+publish = false
+
+[dependencies]
+once_cell = "1.0.1"
+itertools = "0.8.0"
+backtrace = "0.3.28"
+
+[target.'cfg(not(target_env = "msvc"))'.dependencies]
+jemallocator = { version = "0.3.2", optional = true }
+jemalloc-ctl = { version = "0.3.2", optional = true }
+
+[features]
+jemalloc = [ "jemallocator", "jemalloc-ctl" ]
+cpu_profiler = []