refactor: improve item tree display (#547)

A refactor to format `ItemTree`s properly. I need this for testing
`impl`s.

crates/mun_hir/src/item_tree.rs

@@ -1,4 +1,5 @@
 mod lower;
+mod pretty;
 #[cfg(test)]
 mod tests;
 
@@ -306,7 +307,6 @@ pub struct Struct {
     pub types: TypeRefMap,
     pub fields: Fields,
     pub ast_id: FileAstId<ast::StructDef>,
-    pub kind: StructDefKind,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]

crates/mun_hir/src/item_tree/lower.rs

@@ -2,7 +2,7 @@
 
 use super::{
     diagnostics, Field, Fields, Function, IdRange, ItemTree, ItemTreeData, ItemTreeNode,
-    ItemVisibilities, LocalItemTreeId, ModItem, RawVisibilityId, Struct, StructDefKind, TypeAlias,
+    ItemVisibilities, LocalItemTreeId, ModItem, RawVisibilityId, Struct, TypeAlias,
 };
 use crate::item_tree::Import;
 use crate::type_ref::{TypeRefMap, TypeRefMapBuilder};
@@ -183,11 +183,6 @@ impl Context {
         let mut types = TypeRefMap::builder();
         let fields = self.lower_fields(&strukt.kind(), &mut types);
         let ast_id = self.source_ast_id_map.ast_id(strukt);
-        let kind = match strukt.kind() {
-            StructKind::Record(_) => StructDefKind::Record,
-            StructKind::Tuple(_) => StructDefKind::Tuple,
-            StructKind::Unit => StructDefKind::Unit,
-        };
 
         let (types, _types_source_map) = types.finish();
         let res = Struct {
@@ -196,7 +191,6 @@ impl Context {
             types,
             fields,
             ast_id,
-            kind,
         };
         Some(self.data.structs.alloc(res).into())
     }

crates/mun_hir/src/item_tree/pretty.rs

@@ -0,0 +1,224 @@
+use crate::item_tree::LocalItemTreeId;
+use crate::{
+    item_tree::{Fields, Function, Import, ItemTree, ModItem, RawVisibilityId, Struct, TypeAlias},
+    path::ImportAlias,
+    pretty::{print_path, print_type_ref},
+    type_ref::{LocalTypeRefId, TypeRefMap},
+    visibility::RawVisibility,
+    DefDatabase,
+};
+use std::{fmt, fmt::Write};
+
+/// A helper method to print an `ItemTree` to a string.
+pub(super) fn print_item_tree(db: &dyn DefDatabase, tree: &ItemTree) -> Result<String, fmt::Error> {
+    let mut p = Printer {
+        db,
+        tree,
+        buf: String::new(),
+        indent_level: 0,
+        needs_indent: true,
+    };
+
+    for item in tree.top_level_items() {
+        p.print_mod_item(*item)?;
+    }
+
+    let mut s = p.buf.trim_end_matches('\n').to_string();
+    s.push('\n');
+    Ok(s)
+}
+
+/// A helper struct for [`print_item_tree`] that keeps track of the current indentation level.
+struct Printer<'a> {
+    db: &'a dyn DefDatabase,
+    tree: &'a ItemTree,
+    buf: String,
+    indent_level: usize,
+    needs_indent: bool,
+}
+
+impl Printer<'_> {
+    /// Run the specified closure with an increased indentation level.
+    fn indented(&mut self, f: impl FnOnce(&mut Self) -> fmt::Result) -> fmt::Result {
+        self.indent_level += 1;
+        writeln!(self)?;
+        f(self)?;
+        self.indent_level -= 1;
+        self.buf = self.buf.trim_end_matches('\n').to_string();
+        Ok(())
+    }
+
+    // Add a whitespace to the end of the buffer if the last character is not a newline or space.
+    fn whitespace(&mut self) -> fmt::Result {
+        match self.buf.chars().next_back() {
+            None | Some('\n' | ' ') => {}
+            _ => self.buf.push(' '),
+        }
+        Ok(())
+    }
+
+    /// Print a module item to the buffer.
+    fn print_mod_item(&mut self, item: ModItem) -> fmt::Result {
+        match item {
+            ModItem::Function(it) => self.print_function(it),
+            ModItem::Struct(it) => self.print_struct(it),
+            ModItem::TypeAlias(it) => self.print_type_alias(it),
+            ModItem::Import(it) => self.print_use(it),
+        }
+    }
+
+    /// Prints a use statement to the buffer.
+    fn print_use(&mut self, it: LocalItemTreeId<Import>) -> fmt::Result {
+        let Import {
+            path,
+            alias,
+            visibility,
+            is_glob,
+            ast_id: _,
+            index: _,
+        } = &self.tree[it];
+        self.print_visibility(*visibility)?;
+        write!(self, "use ")?;
+        print_path(self.db, path, self)?;
+        if *is_glob {
+            write!(self, "::*")?;
+        }
+        match alias {
+            Some(ImportAlias::Alias(name)) => write!(self, " as {name}")?,
+            Some(ImportAlias::Underscore) => write!(self, " as _")?,
+            None => {}
+        }
+        writeln!(self, ";")
+    }
+
+    /// Prints a type alias to the buffer.
+    fn print_type_alias(&mut self, it: LocalItemTreeId<TypeAlias>) -> fmt::Result {
+        let TypeAlias {
+            name,
+            visibility,
+            types,
+            type_ref,
+            ast_id: _,
+        } = &self.tree[it];
+        self.print_visibility(*visibility)?;
+        write!(self, "type {name}")?;
+        if let Some(ty) = type_ref {
+            write!(self, " = ")?;
+            self.print_type_ref(*ty, types)?;
+        }
+        writeln!(self, ";")
+    }
+
+    /// Prints a struct to the buffer.
+    fn print_struct(&mut self, it: LocalItemTreeId<Struct>) -> fmt::Result {
+        let Struct {
+            visibility,
+            name,
+            types,
+            fields,
+            ast_id: _,
+        } = &self.tree[it];
+        self.print_visibility(*visibility)?;
+        write!(self, "struct {name}")?;
+        match fields {
+            Fields::Record(fields) => {
+                self.whitespace()?;
+                write!(self, "{{")?;
+                self.indented(|this| {
+                    for field in fields.clone() {
+                        let field = &this.tree[field];
+                        write!(this, "{}: ", field.name)?;
+                        this.print_type_ref(field.type_ref, types)?;
+                        writeln!(this, ",")?;
+                    }
+                    Ok(())
+                })?;
+                write!(self, "}}")?;
+            }
+            Fields::Tuple(fields) => {
+                write!(self, "(")?;
+                self.indented(|this| {
+                    for field in fields.clone() {
+                        let field = &this.tree[field];
+                        this.print_type_ref(field.type_ref, types)?;
+                        writeln!(this, ",")?;
+                    }
+                    Ok(())
+                })?;
+                write!(self, ")")?;
+            }
+            Fields::Unit => {}
+        };
+        if matches!(fields, Fields::Record(_)) {
+            writeln!(self)
+        } else {
+            writeln!(self, ";")
+        }
+    }
+
+    /// Prints a function to the buffer.
+    fn print_function(&mut self, it: LocalItemTreeId<Function>) -> fmt::Result {
+        let Function {
+            name,
+            visibility,
+            is_extern,
+            types,
+            params,
+            ret_type,
+            ast_id: _,
+        } = &self.tree[it];
+        self.print_visibility(*visibility)?;
+        if *is_extern {
+            write!(self, "extern ")?;
+        }
+        write!(self, "fn {name}")?;
+        write!(self, "(")?;
+        if !params.is_empty() {
+            self.indented(|this| {
+                for param in params.iter().copied() {
+                    this.print_type_ref(param, types)?;
+                    writeln!(this, ",")?;
+                }
+                Ok(())
+            })?;
+        }
+        write!(self, ") -> ")?;
+        self.print_type_ref(*ret_type, types)?;
+        writeln!(self, ";")
+    }
+
+    /// Prints a [`RawVisibilityId`] to the buffer.
+    fn print_visibility(&mut self, vis: RawVisibilityId) -> fmt::Result {
+        match &self.tree[vis] {
+            RawVisibility::This => Ok(()),
+            RawVisibility::Super => write!(self, "pub(super) "),
+            RawVisibility::Package => write!(self, "pub(package) "),
+            RawVisibility::Public => write!(self, "pub "),
+        }
+    }
+
+    /// Prints a type reference to the buffer.
+    fn print_type_ref(&mut self, type_ref: LocalTypeRefId, map: &TypeRefMap) -> fmt::Result {
+        print_type_ref(self.db, map, type_ref, self)
+    }
+}
+
+impl Write for Printer<'_> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for line in s.split_inclusive('\n') {
+            if self.needs_indent {
+                match self.buf.chars().last() {
+                    Some('\n') | None => {}
+                    _ => self.buf.push('\n'),
+                }
+                self.buf.push_str(&"  ".repeat(self.indent_level));
+                self.needs_indent = false;
+            }
+
+            self.buf.push_str(line);
+            self.needs_indent = line.ends_with('\n');
+        }
+
+        Ok(())
+    }
+}

crates/mun_hir/src/item_tree/snapshots/mun_hir__item_tree__tests__top_level_items.snap

@@ -1,27 +1,51 @@
 ---
 source: crates/mun_hir/src/item_tree/tests.rs
-assertion_line: 61
-expression: "print_item_tree(r#\"\n    fn foo(a:i32, b:u8, c:String) -> i32 {}\n    pub fn bar(a:i32, b:u8, c:String) ->  {}\n    pub(super) fn bar(a:i32, b:u8, c:String) ->  {}\n    pub(package) fn baz(a:i32, b:, c:String) ->  {}\n    extern fn eval(a:String) -> bool;\n\n    struct Foo {\n        a: i32,\n        b: u8,\n        c: String,\n    }\n    struct Foo2 {\n        a: i32,\n        b: ,\n        c: String,\n    }\n    struct Bar (i32, u32, String)\n    struct Baz;\n\n    type FooBar = Foo;\n    type FooBar = package::Foo;\n    \"#).unwrap()"
+expression: "print_item_tree(r#\"\n    fn foo(a:i32, b:u8, c:String) -> i32 {}\n    pub fn bar(a:i32, b:u8, c:String) ->  {}\n    pub(super) fn bar(a:i32, b:u8, c:String) ->  {}\n    pub(package) fn baz(a:i32, b:, c:String) ->  {}\n    extern fn eval(a:String) -> bool;\n\n    struct Foo {\n        a: i32,\n        b: u8,\n        c: String,\n    }\n    struct Foo2 {\n        a: i32,\n        b: ,\n        c: String,\n    }\n    struct Bar (i32, u32, String)\n    struct Baz;\n\n    type FooBar = Foo;\n    type FooBar = package::Foo;\n\n    pub use foo;\n    use super::bar;\n    use super::*;\n    use foo::{bar as _, baz::hello as world};\n    \"#).unwrap()"
 ---
-top-level items:
-Function { name: Name(Text("foo")), visibility: RawVisibilityId("pub(self)"), is_extern: false, types: TypeRefMap { type_refs: Arena { len: 4, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Path(Path { kind: Plain, segments: [Name(Text("u8"))] }), Path(Path { kind: Plain, segments: [Name(Text("String"))] }), Path(Path { kind: Plain, segments: [Name(Text("i32"))] })] } }, params: [Idx::<TypeRef>(0), Idx::<TypeRef>(1), Idx::<TypeRef>(2)], ret_type: Idx::<TypeRef>(3), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(0), _ty: PhantomData<fn() -> mun_syntax::ast::generated::FunctionDef> } }
-Function { name: Name(Text("bar")), visibility: RawVisibilityId("pub"), is_extern: false, types: TypeRefMap { type_refs: Arena { len: 4, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Path(Path { kind: Plain, segments: [Name(Text("u8"))] }), Path(Path { kind: Plain, segments: [Name(Text("String"))] }), Tuple([])] } }, params: [Idx::<TypeRef>(0), Idx::<TypeRef>(1), Idx::<TypeRef>(2)], ret_type: Idx::<TypeRef>(3), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(1), _ty: PhantomData<fn() -> mun_syntax::ast::generated::FunctionDef> } }
-Function { name: Name(Text("bar")), visibility: RawVisibilityId("pub(super)"), is_extern: false, types: TypeRefMap { type_refs: Arena { len: 4, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Path(Path { kind: Plain, segments: [Name(Text("u8"))] }), Path(Path { kind: Plain, segments: [Name(Text("String"))] }), Tuple([])] } }, params: [Idx::<TypeRef>(0), Idx::<TypeRef>(1), Idx::<TypeRef>(2)], ret_type: Idx::<TypeRef>(3), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(2), _ty: PhantomData<fn() -> mun_syntax::ast::generated::FunctionDef> } }
-Function { name: Name(Text("baz")), visibility: RawVisibilityId("pub(package)"), is_extern: false, types: TypeRefMap { type_refs: Arena { len: 4, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Error, Path(Path { kind: Plain, segments: [Name(Text("String"))] }), Tuple([])] } }, params: [Idx::<TypeRef>(0), Idx::<TypeRef>(1), Idx::<TypeRef>(2)], ret_type: Idx::<TypeRef>(3), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(3), _ty: PhantomData<fn() -> mun_syntax::ast::generated::FunctionDef> } }
-Function { name: Name(Text("eval")), visibility: RawVisibilityId("pub(self)"), is_extern: true, types: TypeRefMap { type_refs: Arena { len: 2, data: [Path(Path { kind: Plain, segments: [Name(Text("String"))] }), Path(Path { kind: Plain, segments: [Name(Text("bool"))] })] } }, params: [Idx::<TypeRef>(0)], ret_type: Idx::<TypeRef>(1), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(4), _ty: PhantomData<fn() -> mun_syntax::ast::generated::FunctionDef> } }
-Struct { name: Name(Text("Foo")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 3, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Path(Path { kind: Plain, segments: [Name(Text("u8"))] }), Path(Path { kind: Plain, segments: [Name(Text("String"))] })] } }, fields: Record(IdRange::<mun_hir::item_tree::Field>(0..3)), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(5), _ty: PhantomData<fn() -> mun_syntax::ast::generated::StructDef> }, kind: Record }
-> Field { name: Name(Text("a")), type_ref: Idx::<TypeRef>(0) }
-> Field { name: Name(Text("b")), type_ref: Idx::<TypeRef>(1) }
-> Field { name: Name(Text("c")), type_ref: Idx::<TypeRef>(2) }
-Struct { name: Name(Text("Foo2")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 3, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Error, Path(Path { kind: Plain, segments: [Name(Text("String"))] })] } }, fields: Record(IdRange::<mun_hir::item_tree::Field>(3..6)), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(6), _ty: PhantomData<fn() -> mun_syntax::ast::generated::StructDef> }, kind: Record }
-> Field { name: Name(Text("a")), type_ref: Idx::<TypeRef>(0) }
-> Field { name: Name(Text("b")), type_ref: Idx::<TypeRef>(1) }
-> Field { name: Name(Text("c")), type_ref: Idx::<TypeRef>(2) }
-Struct { name: Name(Text("Bar")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 3, data: [Path(Path { kind: Plain, segments: [Name(Text("i32"))] }), Path(Path { kind: Plain, segments: [Name(Text("u32"))] }), Path(Path { kind: Plain, segments: [Name(Text("String"))] })] } }, fields: Tuple(IdRange::<mun_hir::item_tree::Field>(6..9)), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(7), _ty: PhantomData<fn() -> mun_syntax::ast::generated::StructDef> }, kind: Tuple }
-> Field { name: Name(TupleField(0)), type_ref: Idx::<TypeRef>(0) }
-> Field { name: Name(TupleField(1)), type_ref: Idx::<TypeRef>(1) }
-> Field { name: Name(TupleField(2)), type_ref: Idx::<TypeRef>(2) }
-Struct { name: Name(Text("Baz")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 0, data: [] } }, fields: Unit, ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(8), _ty: PhantomData<fn() -> mun_syntax::ast::generated::StructDef> }, kind: Unit }
-TypeAlias { name: Name(Text("FooBar")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 1, data: [Path(Path { kind: Plain, segments: [Name(Text("Foo"))] })] } }, type_ref: Some(Idx::<TypeRef>(0)), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(9), _ty: PhantomData<fn() -> mun_syntax::ast::generated::TypeAliasDef> } }
-TypeAlias { name: Name(Text("FooBar")), visibility: RawVisibilityId("pub(self)"), types: TypeRefMap { type_refs: Arena { len: 1, data: [Path(Path { kind: Package, segments: [Name(Text("Foo"))] })] } }, type_ref: Some(Idx::<TypeRef>(0)), ast_id: FileAstId { raw: Idx::<SyntaxNodePtr>(10), _ty: PhantomData<fn() -> mun_syntax::ast::generated::TypeAliasDef> } }
+fn foo(
+  i32,
+  u8,
+  String,
+) -> i32;
+pub fn bar(
+  i32,
+  u8,
+  String,
+) -> ();
+pub(super) fn bar(
+  i32,
+  u8,
+  String,
+) -> ();
+pub(package) fn baz(
+  i32,
+  {unknown},
+  String,
+) -> ();
+extern fn eval(
+  String,
+) -> bool;
+struct Foo {
+  a: i32,
+  b: u8,
+  c: String,
+}
+struct Foo2 {
+  a: i32,
+  b: {unknown},
+  c: String,
+}
+struct Bar(
+  i32,
+  u32,
+  String,
+);
+struct Baz;
+type FooBar = Foo;
+type FooBar = package::Foo;
+pub use foo;
+use super::bar;
+use super::*;
+use foo::bar as _;
+use foo::baz::hello as world;