1 files changed, 104 insertions, 0 deletions

diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
new file mode 100644
index 000000000..a4ee9a529
--- /dev/null
+++ b/crates/ra_hir_expand/src/db.rs
@@ -0,0 +1,104 @@
+//! Defines database & queries for macro expansion.
+
+use std::sync::Arc;
+
+use mbe::MacroRules;
+use ra_db::{salsa, SourceDatabase};
+use ra_prof::profile;
+use ra_syntax::{AstNode, Parse, SyntaxNode};
+
+use crate::{
+    ast_id_map::AstIdMap, HirFileId, HirFileIdRepr, MacroCallId, MacroCallLoc, MacroDefId,
+    MacroFile, MacroFileKind,
+};
+
+// FIXME: rename to ExpandDatabase
+#[salsa::query_group(AstDatabaseStorage)]
+pub trait AstDatabase: SourceDatabase {
+    fn ast_id_map(&self, file_id: HirFileId) -> Arc<AstIdMap>;
+
+    #[salsa::transparent]
+    fn parse_or_expand(&self, file_id: HirFileId) -> Option<SyntaxNode>;
+
+    #[salsa::interned]
+    fn intern_macro(&self, macro_call: MacroCallLoc) -> MacroCallId;
+    fn macro_arg(&self, id: MacroCallId) -> Option<Arc<tt::Subtree>>;
+    fn macro_def(&self, id: MacroDefId) -> Option<Arc<mbe::MacroRules>>;
+    fn parse_macro(&self, macro_file: MacroFile) -> Option<Parse<SyntaxNode>>;
+    fn macro_expand(&self, macro_call: MacroCallId) -> Result<Arc<tt::Subtree>, String>;
+}
+
+pub(crate) fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
+    let map =
+        db.parse_or_expand(file_id).map_or_else(AstIdMap::default, |it| AstIdMap::from_source(&it));
+    Arc::new(map)
+}
+
+pub(crate) fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<MacroRules>> {
+    let macro_call = id.ast_id.to_node(db);
+    let arg = macro_call.token_tree()?;
+    let (tt, _) = mbe::ast_to_token_tree(&arg).or_else(|| {
+        log::warn!("fail on macro_def to token tree: {:#?}", arg);
+        None
+    })?;
+    let rules = MacroRules::parse(&tt).ok().or_else(|| {
+        log::warn!("fail on macro_def parse: {:#?}", tt);
+        None
+    })?;
+    Some(Arc::new(rules))
+}
+
+pub(crate) fn macro_arg(db: &dyn AstDatabase, id: MacroCallId) -> Option<Arc<tt::Subtree>> {
+    let loc = db.lookup_intern_macro(id);
+    let macro_call = loc.ast_id.to_node(db);
+    let arg = macro_call.token_tree()?;
+    let (tt, _) = mbe::ast_to_token_tree(&arg)?;
+    Some(Arc::new(tt))
+}
+
+pub(crate) fn macro_expand(
+    db: &dyn AstDatabase,
+    id: MacroCallId,
+) -> Result<Arc<tt::Subtree>, String> {
+    let loc = db.lookup_intern_macro(id);
+    let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;
+
+    let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
+    let tt = macro_rules.expand(&macro_arg).map_err(|err| format!("{:?}", err))?;
+    // Set a hard limit for the expanded tt
+    let count = tt.count();
+    if count > 65536 {
+        return Err(format!("Total tokens count exceed limit : count = {}", count));
+    }
+    Ok(Arc::new(tt))
+}
+
+pub(crate) fn parse_or_expand(db: &dyn AstDatabase, file_id: HirFileId) -> Option<SyntaxNode> {
+    match file_id.0 {
+        HirFileIdRepr::FileId(file_id) => Some(db.parse(file_id).tree().syntax().clone()),
+        HirFileIdRepr::MacroFile(macro_file) => {
+            db.parse_macro(macro_file).map(|it| it.syntax_node())
+        }
+    }
+}
+
+pub(crate) fn parse_macro(
+    db: &dyn AstDatabase,
+    macro_file: MacroFile,
+) -> Option<Parse<SyntaxNode>> {
+    let _p = profile("parse_macro_query");
+    let macro_call_id = macro_file.macro_call_id;
+    let tt = db
+        .macro_expand(macro_call_id)
+        .map_err(|err| {
+            // Note:
+            // The final goal we would like to make all parse_macro success,
+            // such that the following log will not call anyway.
+            log::warn!("fail on macro_parse: (reason: {})", err,);
+        })
+        .ok()?;
+    match macro_file.macro_file_kind {
+        MacroFileKind::Items => mbe::token_tree_to_items(&tt).ok().map(Parse::to_syntax),
+        MacroFileKind::Expr => mbe::token_tree_to_expr(&tt).ok().map(Parse::to_syntax),
+    }
+}