From 816147c4b508117fad4ca4d3cb6d77a3c4a683a9 Mon Sep 17 00:00:00 2001
From: Edwin Cheng <edwin0cheng@gmail.com>
Date: Sat, 25 May 2019 21:55:46 +0800
Subject: Simplify  token_tree_to_xxx

---
 crates/ra_mbe/src/syntax_bridge.rs | 67 ++++++++++++--------------------------
 1 file changed, 20 insertions(+), 47 deletions(-)

(limited to 'crates/ra_mbe/src')

diff --git a/crates/ra_mbe/src/syntax_bridge.rs b/crates/ra_mbe/src/syntax_bridge.rs
index 0aab5ea8b..6265fe462 100644
--- a/crates/ra_mbe/src/syntax_bridge.rs
+++ b/crates/ra_mbe/src/syntax_bridge.rs
@@ -45,18 +45,29 @@ pub fn syntax_node_to_token_tree(node: &SyntaxNode) -> Option<(tt::Subtree, Toke
 //
 //
 
-/// 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> {
+fn token_tree_to_syntax_node<F>(tt: &tt::Subtree, f: F) -> Result<TreeArc<SyntaxNode>, ExpandError>
+where
+    F: Fn(&mut ra_parser::TokenSource, &mut ra_parser::TreeSink),
+{
     let buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
     let mut token_source = SubtreeTokenSource::new(&buffer);
     let querier = token_source.querier();
     let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse_expr(&mut token_source, &mut tree_sink);
+    f(&mut token_source, &mut tree_sink);
+    if tree_sink.roots.len() != 1 {
+        return Err(ExpandError::ConversionError);
+    }
+
     if tree_sink.roots.len() != 1 {
         return Err(ExpandError::ConversionError);
     }
 
-    let syntax = tree_sink.inner.finish();
+    Ok(tree_sink.inner.finish())
+}
+
+/// 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 syntax = token_tree_to_syntax_node(tt, ra_parser::parse_expr)?;
     ast::Expr::cast(&syntax)
         .map(|m| m.to_owned())
         .ok_or_else(|| crate::ExpandError::ConversionError)
@@ -64,30 +75,13 @@ pub fn token_tree_to_expr(tt: &tt::Subtree) -> Result<TreeArc<ast::Expr>, Expand
 
 /// 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 buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
-    let mut token_source = SubtreeTokenSource::new(&buffer);
-    let querier = token_source.querier();
-    let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse_pat(&mut token_source, &mut tree_sink);
-    if tree_sink.roots.len() != 1 {
-        return Err(ExpandError::ConversionError);
-    }
-
-    let syntax = tree_sink.inner.finish();
+    let syntax = token_tree_to_syntax_node(tt, ra_parser::parse_pat)?;
     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 buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
-    let mut token_source = SubtreeTokenSource::new(&buffer);
-    let querier = token_source.querier();
-    let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse_ty(&mut token_source, &mut tree_sink);
-    if tree_sink.roots.len() != 1 {
-        return Err(ExpandError::ConversionError);
-    }
-    let syntax = tree_sink.inner.finish();
+    let syntax = token_tree_to_syntax_node(tt, ra_parser::parse_ty)?;
     ast::TypeRef::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
 }
 
@@ -95,15 +89,7 @@ pub fn token_tree_to_ty(tt: &tt::Subtree) -> Result<TreeArc<ast::TypeRef>, Expan
 pub fn token_tree_to_macro_stmts(
     tt: &tt::Subtree,
 ) -> Result<TreeArc<ast::MacroStmts>, ExpandError> {
-    let buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
-    let mut token_source = SubtreeTokenSource::new(&buffer);
-    let querier = token_source.querier();
-    let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse_macro_stmts(&mut token_source, &mut tree_sink);
-    if tree_sink.roots.len() != 1 {
-        return Err(ExpandError::ConversionError);
-    }
-    let syntax = tree_sink.inner.finish();
+    let syntax = token_tree_to_syntax_node(tt, ra_parser::parse_macro_stmts)?;
     ast::MacroStmts::cast(&syntax).map(|m| m.to_owned()).ok_or_else(|| ExpandError::ConversionError)
 }
 
@@ -111,26 +97,13 @@ pub fn token_tree_to_macro_stmts(
 pub fn token_tree_to_macro_items(
     tt: &tt::Subtree,
 ) -> Result<TreeArc<ast::MacroItems>, ExpandError> {
-    let buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
-    let mut token_source = SubtreeTokenSource::new(&buffer);
-    let querier = token_source.querier();
-    let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse_macro_items(&mut token_source, &mut tree_sink);
-    if tree_sink.roots.len() != 1 {
-        return Err(ExpandError::ConversionError);
-    }
-    let syntax = tree_sink.inner.finish();
+    let syntax = token_tree_to_syntax_node(tt, ra_parser::parse_macro_items)?;
     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 buffer = tt::buffer::TokenBuffer::new(&[tt.clone().into()]);
-    let mut token_source = SubtreeTokenSource::new(&buffer);
-    let querier = token_source.querier();
-    let mut tree_sink = TtTreeSink::new(querier.as_ref());
-    ra_parser::parse(&mut token_source, &mut tree_sink);
-    let syntax = tree_sink.inner.finish();
+    let syntax = token_tree_to_syntax_node(tt, ra_parser::parse).unwrap();
     ast::SourceFile::cast(&syntax).unwrap().to_owned()
 }
 
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