Refactor primary IDE API

This introduces the new type -- Semantics.
Semantics maps SyntaxNodes to various semantic info, such as type,
name resolution or macro expansions.

To do so, Semantics maintains a HashMap which maps every node it saw
to the file from which the node originated. This is enough to get all
the necessary hir bits just from syntax.

1 files changed, 335 insertions, 0 deletions

diff --git a/crates/ra_hir/src/semantics.rs b/crates/ra_hir/src/semantics.rs
new file mode 100644
index 000000000..22a7e7588
--- /dev/null
+++ b/crates/ra_hir/src/semantics.rs
@@ -0,0 +1,335 @@
+//! See `Semantics`.
+
+use std::{cell::RefCell, fmt, iter::successors};
+
+use hir_def::{
+    resolver::{self, HasResolver, Resolver},
+    TraitId,
+};
+use ra_db::{FileId, FileRange};
+use ra_syntax::{ast, AstNode, SyntaxNode, SyntaxToken, TextRange, TextUnit};
+use rustc_hash::{FxHashMap, FxHashSet};
+
+use crate::{
+    db::HirDatabase,
+    source_analyzer::{resolve_hir_path, ReferenceDescriptor, SourceAnalyzer},
+    source_binder::{ChildContainer, SourceBinder, ToDef},
+    Function, HirFileId, InFile, Local, MacroDef, Module, Name, Origin, Path, PathResolution,
+    ScopeDef, StructField, Trait, Type, TypeParam, VariantDef,
+};
+use ra_prof::profile;
+
+/// Primary API to get semantic information, like types, from syntax trees.
+pub struct Semantics<'db, DB> {
+    pub db: &'db DB,
+    pub(crate) sb: RefCell<SourceBinder>,
+    cache: RefCell<FxHashMap<SyntaxNode, HirFileId>>,
+}
+
+impl<DB> fmt::Debug for Semantics<'_, DB> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "Semantics {{ ... }}")
+    }
+}
+
+impl<'db, DB: HirDatabase> Semantics<'db, DB> {
+    pub fn new(db: &DB) -> Semantics<DB> {
+        let sb = RefCell::new(SourceBinder::new());
+        Semantics { db, sb, cache: RefCell::default() }
+    }
+
+    pub fn parse(&self, file_id: FileId) -> ast::SourceFile {
+        let tree = self.db.parse(file_id).tree();
+        self.cache(tree.syntax().clone(), file_id.into());
+        tree
+    }
+
+    pub fn expand(&self, macro_call: &ast::MacroCall) -> Option<SyntaxNode> {
+        let macro_call = self.find_file(macro_call.syntax().clone()).with_value(macro_call);
+        let sa = self.analyze2(macro_call.map(|it| it.syntax()), None);
+        let file_id = sa.expand(self.db, macro_call)?;
+        let node = self.db.parse_or_expand(file_id)?;
+        self.cache(node.clone(), file_id);
+        Some(node)
+    }
+
+    pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
+        let parent = token.parent();
+        let parent = self.find_file(parent);
+        let sa = self.analyze2(parent.as_ref(), None);
+
+        let token = successors(Some(parent.with_value(token)), |token| {
+            let macro_call = token.value.ancestors().find_map(ast::MacroCall::cast)?;
+            let tt = macro_call.token_tree()?;
+            if !token.value.text_range().is_subrange(&tt.syntax().text_range()) {
+                return None;
+            }
+            let file_id = sa.expand(self.db, token.with_value(&macro_call))?;
+            let token = file_id.expansion_info(self.db)?.map_token_down(token.as_ref())?;
+
+            self.cache(find_root(&token.value.parent()), token.file_id);
+
+            Some(token)
+        })
+        .last()
+        .unwrap();
+
+        token.value
+    }
+
+    pub fn original_range(&self, node: &SyntaxNode) -> FileRange {
+        let node = self.find_file(node.clone());
+        original_range(self.db, node.as_ref())
+    }
+
+    pub fn ancestors_with_macros(&self, node: SyntaxNode) -> impl Iterator<Item = SyntaxNode> + '_ {
+        let node = self.find_file(node);
+        node.ancestors_with_macros(self.db).map(|it| it.value)
+    }
+
+    pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
+        self.analyze(expr.syntax()).type_of(self.db, &expr)
+    }
+
+    pub fn type_of_pat(&self, pat: &ast::Pat) -> Option<Type> {
+        self.analyze(pat.syntax()).type_of_pat(self.db, &pat)
+    }
+
+    pub fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<Function> {
+        self.analyze(call.syntax()).resolve_method_call(call)
+    }
+
+    pub fn resolve_field(&self, field: &ast::FieldExpr) -> Option<StructField> {
+        self.analyze(field.syntax()).resolve_field(field)
+    }
+
+    pub fn resolve_record_field(&self, field: &ast::RecordField) -> Option<StructField> {
+        self.analyze(field.syntax()).resolve_record_field(field)
+    }
+
+    pub fn resolve_record_literal(&self, record_lit: &ast::RecordLit) -> Option<VariantDef> {
+        self.analyze(record_lit.syntax()).resolve_record_literal(record_lit)
+    }
+
+    pub fn resolve_record_pattern(&self, record_pat: &ast::RecordPat) -> Option<VariantDef> {
+        self.analyze(record_pat.syntax()).resolve_record_pattern(record_pat)
+    }
+
+    pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<MacroDef> {
+        let sa = self.analyze(macro_call.syntax());
+        let macro_call = self.find_file(macro_call.syntax().clone()).with_value(macro_call);
+        sa.resolve_macro_call(self.db, macro_call)
+    }
+
+    pub fn resolve_path(&self, path: &ast::Path) -> Option<PathResolution> {
+        self.analyze(path.syntax()).resolve_path(self.db, path)
+    }
+
+    // FIXME: use this instead?
+    // pub fn resolve_name_ref(&self, name_ref: &ast::NameRef) -> Option<???>;
+
+    pub fn to_def<T: ToDef + Clone>(&self, src: &T) -> Option<T::Def> {
+        let src = self.find_file(src.syntax().clone()).with_value(src.clone());
+        let mut sb = self.sb.borrow_mut();
+        T::to_def(self.db, &mut sb, src)
+    }
+
+    pub fn to_module_def(&self, file: FileId) -> Option<Module> {
+        let mut sb = self.sb.borrow_mut();
+        sb.to_module_def(self.db, file)
+    }
+
+    pub fn scope(&self, node: &SyntaxNode) -> SemanticsScope<'db, DB> {
+        let node = self.find_file(node.clone());
+        let resolver = self.analyze2(node.as_ref(), None).resolver;
+        SemanticsScope { db: self.db, resolver }
+    }
+
+    pub fn scope_at_offset(&self, node: &SyntaxNode, offset: TextUnit) -> SemanticsScope<'db, DB> {
+        let node = self.find_file(node.clone());
+        let resolver = self.analyze2(node.as_ref(), Some(offset)).resolver;
+        SemanticsScope { db: self.db, resolver }
+    }
+
+    pub fn scope_for_def(&self, def: Trait) -> SemanticsScope<'db, DB> {
+        let resolver = def.id.resolver(self.db);
+        SemanticsScope { db: self.db, resolver }
+    }
+
+    // FIXME: we only use this in `inline_local_variable` assist, ideally, we
+    // should switch to general reference search infra there.
+    pub fn find_all_refs(&self, pat: &ast::BindPat) -> Vec<ReferenceDescriptor> {
+        self.analyze(pat.syntax()).find_all_refs(pat)
+    }
+
+    fn analyze(&self, node: &SyntaxNode) -> SourceAnalyzer {
+        let src = self.find_file(node.clone());
+        self.analyze2(src.as_ref(), None)
+    }
+
+    fn analyze2(&self, src: InFile<&SyntaxNode>, offset: Option<TextUnit>) -> SourceAnalyzer {
+        let _p = profile("Semantics::analyze2");
+
+        let container = match self.sb.borrow_mut().find_container(self.db, src) {
+            Some(it) => it,
+            None => return SourceAnalyzer::new_for_resolver(Resolver::default(), src),
+        };
+
+        let resolver = match container {
+            ChildContainer::DefWithBodyId(def) => {
+                return SourceAnalyzer::new_for_body(self.db, def, src, offset)
+            }
+            ChildContainer::TraitId(it) => it.resolver(self.db),
+            ChildContainer::ImplId(it) => it.resolver(self.db),
+            ChildContainer::ModuleId(it) => it.resolver(self.db),
+            ChildContainer::EnumId(it) => it.resolver(self.db),
+            ChildContainer::VariantId(it) => it.resolver(self.db),
+            ChildContainer::GenericDefId(it) => it.resolver(self.db),
+        };
+        SourceAnalyzer::new_for_resolver(resolver, src)
+    }
+
+    fn cache(&self, root_node: SyntaxNode, file_id: HirFileId) {
+        assert!(root_node.parent().is_none());
+        let mut cache = self.cache.borrow_mut();
+        let prev = cache.insert(root_node, file_id);
+        assert!(prev == None || prev == Some(file_id))
+    }
+
+    pub fn assert_contains_node(&self, node: &SyntaxNode) {
+        self.find_file(node.clone());
+    }
+
+    fn lookup(&self, root_node: &SyntaxNode) -> Option<HirFileId> {
+        let cache = self.cache.borrow();
+        cache.get(root_node).copied()
+    }
+
+    fn find_file(&self, node: SyntaxNode) -> InFile<SyntaxNode> {
+        let root_node = find_root(&node);
+        let file_id = self.lookup(&root_node).unwrap_or_else(|| {
+            panic!(
+                "\n\nFailed to lookup {:?} in this Semantics.\n\
+                 Make sure to use only query nodes, derived from this instance of Semantics.\n\
+                 root node:   {:?}\n\
+                 known nodes: {}\n\n",
+                node,
+                root_node,
+                self.cache
+                    .borrow()
+                    .keys()
+                    .map(|it| format!("{:?}", it))
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            )
+        });
+        InFile::new(file_id, node)
+    }
+}
+
+fn find_root(node: &SyntaxNode) -> SyntaxNode {
+    node.ancestors().last().unwrap()
+}
+
+pub struct SemanticsScope<'a, DB> {
+    pub db: &'a DB,
+    resolver: Resolver,
+}
+
+impl<'a, DB: HirDatabase> SemanticsScope<'a, DB> {
+    pub fn module(&self) -> Option<Module> {
+        Some(Module { id: self.resolver.module()? })
+    }
+
+    /// Note: `FxHashSet<TraitId>` should be treated as an opaque type, passed into `Type
+    // FIXME: rename to visible_traits to not repeat scope?
+    pub fn traits_in_scope(&self) -> FxHashSet<TraitId> {
+        let resolver = &self.resolver;
+        resolver.traits_in_scope(self.db)
+    }
+
+    pub fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
+        let resolver = &self.resolver;
+
+        resolver.process_all_names(self.db, &mut |name, def| {
+            let def = match def {
+                resolver::ScopeDef::PerNs(it) => it.into(),
+                resolver::ScopeDef::ImplSelfType(it) => ScopeDef::ImplSelfType(it.into()),
+                resolver::ScopeDef::AdtSelfType(it) => ScopeDef::AdtSelfType(it.into()),
+                resolver::ScopeDef::GenericParam(id) => ScopeDef::GenericParam(TypeParam { id }),
+                resolver::ScopeDef::Local(pat_id) => {
+                    let parent = resolver.body_owner().unwrap().into();
+                    ScopeDef::Local(Local { parent, pat_id })
+                }
+            };
+            f(name, def)
+        })
+    }
+
+    pub fn resolve_hir_path(&self, path: &Path) -> Option<PathResolution> {
+        resolve_hir_path(self.db, &self.resolver, path)
+    }
+}
+
+// FIXME: Change `HasSource` trait to work with `Semantics` and remove this?
+pub fn original_range(db: &impl HirDatabase, node: InFile<&SyntaxNode>) -> FileRange {
+    if let Some((range, Origin::Call)) = original_range_and_origin(db, node) {
+        return range;
+    }
+
+    if let Some(expansion) = node.file_id.expansion_info(db) {
+        if let Some(call_node) = expansion.call_node() {
+            return FileRange {
+                file_id: call_node.file_id.original_file(db),
+                range: call_node.value.text_range(),
+            };
+        }
+    }
+
+    FileRange { file_id: node.file_id.original_file(db), range: node.value.text_range() }
+}
+
+fn original_range_and_origin(
+    db: &impl HirDatabase,
+    node: InFile<&SyntaxNode>,
+) -> Option<(FileRange, Origin)> {
+    let expansion = node.file_id.expansion_info(db)?;
+
+    // the input node has only one token ?
+    let single = node.value.first_token()? == node.value.last_token()?;
+
+    // FIXME: We should handle recurside macro expansions
+    let (range, origin) = node.value.descendants().find_map(|it| {
+        let first = it.first_token()?;
+        let last = it.last_token()?;
+
+        if !single && first == last {
+            return None;
+        }
+
+        // Try to map first and last tokens of node, and, if success, return the union range of mapped tokens
+        let (first, first_origin) = expansion.map_token_up(node.with_value(&first))?;
+        let (last, last_origin) = expansion.map_token_up(node.with_value(&last))?;
+
+        if first.file_id != last.file_id || first_origin != last_origin {
+            return None;
+        }
+
+        // FIXME: Add union method in TextRange
+        Some((
+            first.with_value(union_range(first.value.text_range(), last.value.text_range())),
+            first_origin,
+        ))
+    })?;
+
+    return Some((
+        FileRange { file_id: range.file_id.original_file(db), range: range.value },
+        origin,
+    ));
+
+    fn union_range(a: TextRange, b: TextRange) -> TextRange {
+        let start = a.start().min(b.start());
+        let end = a.end().max(b.end());
+        TextRange::from_to(start, end)
+    }
+}