Fix more bugs

crates/ra_mbe/src/mbe_expander.rs

@@ -21,7 +21,10 @@ fn expand_rule(rule: &crate::Rule, input: &tt::Subtree) -> Result<tt::Subtree, E
     if !input.is_eof() {
         return Err(ExpandError::UnexpectedToken);
     }
-    expand_subtree(&rule.rhs, &bindings, &mut Vec::new())
+
+    let mut ctx = ExpandCtx { bindings: &bindings, nesting: Vec::new(), var_expanded: false };
+
+    expand_subtree(&rule.rhs, &mut ctx)
 }
 
 /// The actual algorithm for expansion is not too hard, but is pretty tricky.
@@ -225,7 +228,7 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
             crate::TokenTree::Repeat(crate::Repeat { subtree, kind, separator }) => {
                 // Dirty hack to make macro-expansion terminate.
                 // This should be replaced by a propper macro-by-example implementation
-                let mut limit = 128;
+                let mut limit = 65536;
                 let mut counter = 0;
 
                 let mut memento = input.save();
@@ -236,6 +239,7 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
                             counter += 1;
                             limit -= 1;
                             if limit == 0 {
+                                log::warn!("match_lhs excced in repeat pattern exceed limit => {:#?}\n{:#?}\n{:#?}\n{:#?}", subtree, input, kind, separator);
                                 break;
                             }
 
@@ -303,15 +307,21 @@ fn match_lhs(pattern: &crate::Subtree, input: &mut TtCursor) -> Result<Bindings,
     Ok(res)
 }
 
+#[derive(Debug)]
+struct ExpandCtx<'a> {
+    bindings: &'a Bindings,
+    nesting: Vec<usize>,
+    var_expanded: bool,
+}
+
 fn expand_subtree(
     template: &crate::Subtree,
-    bindings: &Bindings,
-    nesting: &mut Vec<usize>,
+    ctx: &mut ExpandCtx,
 ) -> Result<tt::Subtree, ExpandError> {
     let token_trees = template
         .token_trees
         .iter()
-        .map(|it| expand_tt(it, bindings, nesting))
+        .map(|it| expand_tt(it, ctx))
         .collect::<Result<Vec<_>, ExpandError>>()?;
 
     Ok(tt::Subtree { token_trees, delimiter: template.delimiter })
@@ -333,26 +343,43 @@ fn reduce_single_token(mut subtree: tt::Subtree) -> tt::TokenTree {
 
 fn expand_tt(
     template: &crate::TokenTree,
-    bindings: &Bindings,
-    nesting: &mut Vec<usize>,
+    ctx: &mut ExpandCtx,
 ) -> Result<tt::TokenTree, ExpandError> {
     let res: tt::TokenTree = match template {
-        crate::TokenTree::Subtree(subtree) => expand_subtree(subtree, bindings, nesting)?.into(),
+        crate::TokenTree::Subtree(subtree) => expand_subtree(subtree, ctx)?.into(),
         crate::TokenTree::Repeat(repeat) => {
             let mut token_trees: Vec<tt::TokenTree> = Vec::new();
-            nesting.push(0);
+            ctx.nesting.push(0);
             // Dirty hack to make macro-expansion terminate.
             // This should be replaced by a propper macro-by-example implementation
-            let mut limit = 128;
+            let mut limit = 65536;
             let mut has_seps = 0;
+            let mut counter = 0;
 
-            while let Ok(t) = expand_subtree(&repeat.subtree, bindings, nesting) {
-                limit -= 1;
-                if limit == 0 {
+            let mut some_var_expanded = false;
+            ctx.var_expanded = false;
+
+            while let Ok(t) = expand_subtree(&repeat.subtree, ctx) {
+                // if no var expaned in the child, we count it as a fail
+                if !ctx.var_expanded {
                     break;
                 }
-                let idx = nesting.pop().unwrap();
-                nesting.push(idx + 1);
+                some_var_expanded = true;
+                ctx.var_expanded = false;
+
+                counter += 1;
+                limit -= 1;
+                if limit == 0 {
+                    log::warn!(
+                        "expand_tt excced in repeat pattern exceed limit => {:#?}\n{:#?}",
+                        template,
+                        ctx
+                    );
+                    break;
+                }
+
+                let idx = ctx.nesting.pop().unwrap();
+                ctx.nesting.push(idx + 1);
                 token_trees.push(reduce_single_token(t).into());
 
                 if let Some(ref sep) = repeat.separator {
@@ -374,12 +401,23 @@ fn expand_tt(
                         }
                     }
                 }
+
+                if let crate::RepeatKind::ZeroOrOne = repeat.kind {
+                    break;
+                }
             }
-            nesting.pop().unwrap();
+
+            ctx.var_expanded = some_var_expanded;
+
+            ctx.nesting.pop().unwrap();
             for _ in 0..has_seps {
                 token_trees.pop();
             }
 
+            if crate::RepeatKind::OneOrMore == repeat.kind && counter == 0 {
+                return Err(ExpandError::UnexpectedToken);
+            }
+
             // Check if it is a singel token subtree without any delimiter
             // e.g {Delimiter:None> ['>'] /Delimiter:None>}
             reduce_single_token(tt::Subtree { token_trees, delimiter: tt::Delimiter::None })
@@ -396,7 +434,8 @@ fn expand_tt(
                     tt::Leaf::from(tt::Ident { text: "$crate".into(), id: TokenId::unspecified() })
                         .into()
                 } else {
-                    let tkn = bindings.get(&v.text, nesting)?.clone();
+                    let tkn = ctx.bindings.get(&v.text, &ctx.nesting)?.clone();
+                    ctx.var_expanded = true;
 
                     if let tt::TokenTree::Subtree(subtree) = tkn {
                         reduce_single_token(subtree)