1 files changed, 211 insertions, 0 deletions

diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
new file mode 100644
index 000000000..c6ad85fc7
--- /dev/null
+++ b/crates/ra_hir/src/from_source.rs
@@ -0,0 +1,211 @@
+use ra_db::{FileId, FilePosition};
+use ra_syntax::{
+    algo::find_node_at_offset,
+    ast::{self, AstNode, NameOwner},
+    SyntaxNode,
+};
+
+use crate::{
+    db::{AstDatabase, DefDatabase, HirDatabase},
+    ids::{AstItemDef, LocationCtx},
+    name::AsName,
+    Const, Crate, Enum, EnumVariant, FieldSource, Function, HasSource, ImplBlock, Module,
+    ModuleSource, Source, Static, Struct, StructField, Trait, TypeAlias, Union, VariantDef,
+};
+
+pub trait FromSource: Sized {
+    type Ast;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self>;
+}
+
+impl FromSource for Struct {
+    type Ast = ast::StructDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Struct { id })
+    }
+}
+impl FromSource for Union {
+    type Ast = ast::StructDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Union { id })
+    }
+}
+impl FromSource for Enum {
+    type Ast = ast::EnumDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Enum { id })
+    }
+}
+impl FromSource for Trait {
+    type Ast = ast::TraitDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Trait { id })
+    }
+}
+impl FromSource for Function {
+    type Ast = ast::FnDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Function { id })
+    }
+}
+impl FromSource for Const {
+    type Ast = ast::ConstDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Const { id })
+    }
+}
+impl FromSource for Static {
+    type Ast = ast::StaticDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(Static { id })
+    }
+}
+impl FromSource for TypeAlias {
+    type Ast = ast::TypeAliasDef;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let id = from_source(db, src)?;
+        Some(TypeAlias { id })
+    }
+}
+// FIXME: add impl FromSource for MacroDef
+
+impl FromSource for ImplBlock {
+    type Ast = ast::ImplBlock;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let module_src = crate::ModuleSource::from_child_node(
+            db,
+            src.file_id.original_file(db),
+            &src.ast.syntax(),
+        );
+        let module = Module::from_definition(db, Source { file_id: src.file_id, ast: module_src })?;
+        let impls = module.impl_blocks(db);
+        impls.into_iter().find(|b| b.source(db) == src)
+    }
+}
+
+impl FromSource for EnumVariant {
+    type Ast = ast::EnumVariant;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let parent_enum = src.ast.parent_enum();
+        let src_enum = Source { file_id: src.file_id, ast: parent_enum };
+        let variants = Enum::from_source(db, src_enum)?.variants(db);
+        variants.into_iter().find(|v| v.source(db) == src)
+    }
+}
+
+impl FromSource for StructField {
+    type Ast = FieldSource;
+    fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
+        let variant_def: VariantDef = match src.ast {
+            FieldSource::Named(ref field) => {
+                let ast = field.syntax().ancestors().find_map(ast::StructDef::cast)?;
+                let src = Source { file_id: src.file_id, ast };
+                let def = Struct::from_source(db, src)?;
+                VariantDef::from(def)
+            }
+            FieldSource::Pos(ref field) => {
+                let ast = field.syntax().ancestors().find_map(ast::EnumVariant::cast)?;
+                let src = Source { file_id: src.file_id, ast };
+                let def = EnumVariant::from_source(db, src)?;
+                VariantDef::from(def)
+            }
+        };
+        variant_def
+            .variant_data(db)
+            .fields()
+            .into_iter()
+            .flat_map(|it| it.iter())
+            .map(|(id, _)| StructField { parent: variant_def.clone(), id })
+            .find(|f| f.source(db) == src)
+    }
+}
+
+// FIXME: simplify it
+impl ModuleSource {
+    pub fn from_position(
+        db: &(impl DefDatabase + AstDatabase),
+        position: FilePosition,
+    ) -> ModuleSource {
+        let parse = db.parse(position.file_id);
+        match &find_node_at_offset::<ast::Module>(parse.tree().syntax(), position.offset) {
+            Some(m) if !m.has_semi() => ModuleSource::Module(m.clone()),
+            _ => {
+                let source_file = parse.tree().to_owned();
+                ModuleSource::SourceFile(source_file)
+            }
+        }
+    }
+
+    pub fn from_child_node(
+        db: &(impl DefDatabase + AstDatabase),
+        file_id: FileId,
+        child: &SyntaxNode,
+    ) -> ModuleSource {
+        if let Some(m) = child.ancestors().filter_map(ast::Module::cast).find(|it| !it.has_semi()) {
+            ModuleSource::Module(m.clone())
+        } else {
+            let source_file = db.parse(file_id).tree().to_owned();
+            ModuleSource::SourceFile(source_file)
+        }
+    }
+
+    pub fn from_file_id(db: &(impl DefDatabase + AstDatabase), file_id: FileId) -> ModuleSource {
+        let source_file = db.parse(file_id).tree().to_owned();
+        ModuleSource::SourceFile(source_file)
+    }
+}
+
+impl Module {
+    pub fn from_declaration(db: &impl HirDatabase, src: Source<ast::Module>) -> Option<Self> {
+        let src_parent = Source {
+            file_id: src.file_id,
+            ast: ModuleSource::new(db, Some(src.file_id.original_file(db)), None),
+        };
+        let parent_module = Module::from_definition(db, src_parent)?;
+        let child_name = src.ast.name()?;
+        parent_module.child(db, &child_name.as_name())
+    }
+
+    pub fn from_definition(
+        db: &(impl DefDatabase + AstDatabase),
+        src: Source<ModuleSource>,
+    ) -> Option<Self> {
+        let decl_id = match src.ast {
+            ModuleSource::Module(ref module) => {
+                assert!(!module.has_semi());
+                let ast_id_map = db.ast_id_map(src.file_id);
+                let item_id = ast_id_map.ast_id(module).with_file_id(src.file_id);
+                Some(item_id)
+            }
+            ModuleSource::SourceFile(_) => None,
+        };
+
+        let source_root_id = db.file_source_root(src.file_id.original_file(db));
+        db.source_root_crates(source_root_id).iter().map(|&crate_id| Crate { crate_id }).find_map(
+            |krate| {
+                let def_map = db.crate_def_map(krate);
+                let module_id = def_map.find_module_by_source(src.file_id, decl_id)?;
+                Some(Module { krate, module_id })
+            },
+        )
+    }
+}
+
+fn from_source<N, DEF>(db: &(impl DefDatabase + AstDatabase), src: Source<N>) -> Option<DEF>
+where
+    N: AstNode,
+    DEF: AstItemDef<N>,
+{
+    let module_src =
+        crate::ModuleSource::from_child_node(db, src.file_id.original_file(db), &src.ast.syntax());
+    let module = Module::from_definition(db, Source { file_id: src.file_id, ast: module_src })?;
+    let ctx = LocationCtx::new(db, module, src.file_id);
+    Some(DEF::from_ast(ctx, &src.ast))
+}