2 files changed, 142 insertions, 10 deletions

diff --git a/crates/ra_mbe/src/lib.rs b/crates/ra_mbe/src/lib.rs
index 8d5008d20..9d4744838 100644
--- a/crates/ra_mbe/src/lib.rs
+++ b/crates/ra_mbe/src/lib.rs
@@ -37,9 +37,19 @@ pub enum ExpandError {
     NoMatchingRule,
     UnexpectedToken,
     BindingError(String),
+    ConversionError,
 }
 
-pub use crate::syntax_bridge::{ast_to_token_tree, token_tree_to_ast_item_list, syntax_node_to_token_tree};
+pub use crate::syntax_bridge::{
+    ast_to_token_tree,
+    token_tree_to_ast_item_list,
+    syntax_node_to_token_tree,
+    token_tree_to_expr,
+    token_tree_to_pat,
+    token_tree_to_ty,
+    token_tree_to_macro_items,
+    token_tree_to_macro_stmts,
+};
 
 /// This struct contains AST for a single `macro_rules` definition. What might
 /// be very confusing is that AST has almost exactly the same shape as
@@ -192,23 +202,26 @@ impl_froms!(TokenTree: Leaf, Subtree);
     pub(crate) fn expand_to_syntax(
         rules: &MacroRules,
         invocation: &str,
-    ) -> ra_syntax::TreeArc<ast::SourceFile> {
+    ) -> ra_syntax::TreeArc<ast::MacroItems> {
         let expanded = expand(rules, invocation);
-        token_tree_to_ast_item_list(&expanded)
+        token_tree_to_macro_items(&expanded).unwrap()
     }
 
     pub(crate) fn assert_expansion(rules: &MacroRules, invocation: &str, expansion: &str) {
         let expanded = expand(rules, invocation);
         assert_eq!(expanded.to_string(), expansion);
 
-        let tree = token_tree_to_ast_item_list(&expanded);
+        let tree = token_tree_to_macro_items(&expanded);
 
         // Eat all white space by parse it back and forth
         let expansion = ast::SourceFile::parse(expansion);
         let expansion = syntax_node_to_token_tree(expansion.syntax()).unwrap().0;
-        let file = token_tree_to_ast_item_list(&expansion);
+        let file = token_tree_to_macro_items(&expansion);
 
-        assert_eq!(tree.syntax().debug_dump().trim(), file.syntax().debug_dump().trim());
+        assert_eq!(
+            tree.unwrap().syntax().debug_dump().trim(),
+            file.unwrap().syntax().debug_dump().trim()
+        );
     }
 
     #[test]
@@ -346,11 +359,11 @@ impl_froms!(TokenTree: Leaf, Subtree);
             ",
         );
         let expansion = expand(&rules, "structs!(Foo, Bar)");
-        let tree = token_tree_to_ast_item_list(&expansion);
+        let tree = token_tree_to_macro_items(&expansion);
         assert_eq!(
-            tree.syntax().debug_dump().trim(),
+            tree.unwrap().syntax().debug_dump().trim(),
             r#"
-SOURCE_FILE@[0; 40)
+MACRO_ITEMS@[0; 40)
   STRUCT_DEF@[0; 20)
     STRUCT_KW@[0; 6) "struct"
     NAME@[6; 9)
@@ -444,6 +457,59 @@ SOURCE_FILE@[0; 40)
         assert_expansion(&rules, "foo! { foo, bar }", "fn foo () {let a = foo ; let b = bar ;}");
     }
 
+    #[test]
+    fn test_tt_to_stmts() {
+        let rules = create_rules(
+            r#"
+        macro_rules! foo {
+            () => {
+                 let a = 0;
+                 a = 10 + 1;
+                 a
+            }
+        }
+"#,
+        );
+
+        let expanded = expand(&rules, "foo!{}");
+        let stmts = token_tree_to_macro_stmts(&expanded);
+
+        assert_eq!(
+            stmts.unwrap().syntax().debug_dump().trim(),
+            r#"MACRO_STMTS@[0; 15)
+  LET_STMT@[0; 7)
+    LET_KW@[0; 3) "let"
+    BIND_PAT@[3; 4)
+      NAME@[3; 4)
+        IDENT@[3; 4) "a"
+    EQ@[4; 5) "="
+    LITERAL@[5; 6)
+      INT_NUMBER@[5; 6) "0"
+    SEMI@[6; 7) ";"
+  EXPR_STMT@[7; 14)
+    BIN_EXPR@[7; 13)
+      PATH_EXPR@[7; 8)
+        PATH@[7; 8)
+          PATH_SEGMENT@[7; 8)
+            NAME_REF@[7; 8)
+              IDENT@[7; 8) "a"
+      EQ@[8; 9) "="
+      BIN_EXPR@[9; 13)
+        LITERAL@[9; 11)
+          INT_NUMBER@[9; 11) "10"
+        PLUS@[11; 12) "+"
+        LITERAL@[12; 13)
+          INT_NUMBER@[12; 13) "1"
+    SEMI@[13; 14) ";"
+  EXPR_STMT@[14; 15)
+    PATH_EXPR@[14; 15)
+      PATH@[14; 15)
+        PATH_SEGMENT@[14; 15)
+          NAME_REF@[14; 15)
+            IDENT@[14; 15) "a""#,
+        );
+    }
+
     // The following tests are port from intellij-rust directly
     // https://github.com/intellij-rust/intellij-rust/blob/c4e9feee4ad46e7953b1948c112533360b6087bb/src/test/kotlin/org/rust/lang/core/macros/RsMacroExpansionTest.kt
 
@@ -527,7 +593,7 @@ SOURCE_FILE@[0; 40)
 
         assert_eq!(
             expand_to_syntax(&rules, "foo! { 1 + 1  }").syntax().debug_dump().trim(),
-            r#"SOURCE_FILE@[0; 15)
+            r#"MACRO_ITEMS@[0; 15)
   FN_DEF@[0; 15)
     FN_KW@[0; 2) "fn"
     NAME@[2; 5)
diff --git a/crates/ra_mbe/src/syntax_bridge.rs b/crates/ra_mbe/src/syntax_bridge.rs
index 28ded7870..5844d3f12 100644
--- a/crates/ra_mbe/src/syntax_bridge.rs
+++ b/crates/ra_mbe/src/syntax_bridge.rs
@@ -5,6 +5,7 @@ use ra_syntax::{
 };
 
 use crate::subtree_source::{SubtreeTokenSource, Querier};
+use crate::ExpandError;
 
 /// Maps `tt::TokenId` to the relative range of the original token.
 #[derive(Default)]
@@ -30,6 +31,71 @@ pub fn syntax_node_to_token_tree(node: &SyntaxNode) -> Option<(tt::Subtree, Toke
     Some((tt, token_map))
 }
 
+// The following items are what `rustc` macro can be parsed into :
+// link: https://github.com/rust-lang/rust/blob/9ebf47851a357faa4cd97f4b1dc7835f6376e639/src/libsyntax/ext/expand.rs#L141
+// * Expr(P<ast::Expr>)                     -> token_tree_to_expr
+// * Pat(P<ast::Pat>)                       -> token_tree_to_pat
+// * Ty(P<ast::Ty>)                         -> token_tree_to_ty
+// * Stmts(SmallVec<[ast::Stmt; 1]>)        -> token_tree_to_stmts
+// * Items(SmallVec<[P<ast::Item>; 1]>)     -> token_tree_to_items
+//
+// * TraitItems(SmallVec<[ast::TraitItem; 1]>)
+// * ImplItems(SmallVec<[ast::ImplItem; 1]>)
+// * ForeignItems(SmallVec<[ast::ForeignItem; 1]>
+//
+//
+
+/// Parses the token tree (result of macro expansion) to an expression
+pub fn token_tree_to_expr(tt: &tt::Subtree) -> Result<TreeArc<ast::Expr>, ExpandError> {
+    let token_source = SubtreeTokenSource::new(tt);
+    let mut tree_sink = TtTreeSink::new(token_source.querier());
+    ra_parser::parse_expr(&token_source, &mut tree_sink);
+    let syntax = tree_sink.inner.finish();
+    ast::Expr::cast(&syntax)
+        .map(|m| m.to_owned())
+        .ok_or_else(|| crate::ExpandError::ConversionError)
+}
+
+/// Parses the token tree (result of macro expansion) to a Pattern
+pub fn token_tree_to_pat(tt: &tt::Subtree) -> Result<TreeArc<ast::Pat>, ExpandError> {
+    let token_source = SubtreeTokenSource::new(tt);
+    let mut tree_sink = TtTreeSink::new(token_source.querier());
+    ra_parser::parse_pat(&token_source, &mut tree_sink);
+    let syntax = tree_sink.inner.finish();
+    ast::Pat::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
+}
+
+/// Parses the token tree (result of macro expansion) to a Type
+pub fn token_tree_to_ty(tt: &tt::Subtree) -> Result<TreeArc<ast::TypeRef>, ExpandError> {
+    let token_source = SubtreeTokenSource::new(tt);
+    let mut tree_sink = TtTreeSink::new(token_source.querier());
+    ra_parser::parse_ty(&token_source, &mut tree_sink);
+    let syntax = tree_sink.inner.finish();
+    ast::TypeRef::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
+}
+
+/// Parses the token tree (result of macro expansion) as a sequence of stmts
+pub fn token_tree_to_macro_stmts(
+    tt: &tt::Subtree,
+) -> Result<TreeArc<ast::MacroStmts>, ExpandError> {
+    let token_source = SubtreeTokenSource::new(tt);
+    let mut tree_sink = TtTreeSink::new(token_source.querier());
+    ra_parser::parse_macro_stmts(&token_source, &mut tree_sink);
+    let syntax = tree_sink.inner.finish();
+    ast::MacroStmts::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
+}
+
+/// Parses the token tree (result of macro expansion) as a sequence of items
+pub fn token_tree_to_macro_items(
+    tt: &tt::Subtree,
+) -> Result<TreeArc<ast::MacroItems>, ExpandError> {
+    let token_source = SubtreeTokenSource::new(tt);
+    let mut tree_sink = TtTreeSink::new(token_source.querier());
+    ra_parser::parse_macro_items(&token_source, &mut tree_sink);
+    let syntax = tree_sink.inner.finish();
+    ast::MacroItems::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
+}
+
 /// Parses the token tree (result of macro expansion) as a sequence of items
 pub fn token_tree_to_ast_item_list(tt: &tt::Subtree) -> TreeArc<ast::SourceFile> {
     let token_source = SubtreeTokenSource::new(tt);