From 4551182f94fe81c314f79ddf8916a5520cfd03b0 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Tue, 17 Sep 2019 02:54:22 +0300
Subject: use usual token tree for macro expansion

---
 crates/ra_mbe/src/tt_iter.rs | 67 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 crates/ra_mbe/src/tt_iter.rs

(limited to 'crates/ra_mbe/src/tt_iter.rs')

diff --git a/crates/ra_mbe/src/tt_iter.rs b/crates/ra_mbe/src/tt_iter.rs
new file mode 100644
index 000000000..c53f99d1e
--- /dev/null
+++ b/crates/ra_mbe/src/tt_iter.rs
@@ -0,0 +1,67 @@
+#[derive(Debug, Clone)]
+pub(crate) struct TtIter<'a> {
+    pub(crate) inner: std::slice::Iter<'a, tt::TokenTree>,
+}
+
+impl<'a> TtIter<'a> {
+    pub(crate) fn new(subtree: &'a tt::Subtree) -> TtIter<'a> {
+        TtIter { inner: subtree.token_trees.iter() }
+    }
+
+    pub(crate) fn expect_char(&mut self, char: char) -> Result<(), ()> {
+        match self.next() {
+            Some(tt::TokenTree::Leaf(tt::Leaf::Punct(tt::Punct { char: c, .. }))) if *c == char => {
+                Ok(())
+            }
+            _ => Err(()),
+        }
+    }
+
+    pub(crate) fn expect_subtree(&mut self) -> Result<&'a tt::Subtree, ()> {
+        match self.next() {
+            Some(tt::TokenTree::Subtree(it)) => Ok(it),
+            _ => Err(()),
+        }
+    }
+
+    pub(crate) fn expect_leaf(&mut self) -> Result<&'a tt::Leaf, ()> {
+        match self.next() {
+            Some(tt::TokenTree::Leaf(it)) => Ok(it),
+            _ => Err(()),
+        }
+    }
+
+    pub(crate) fn expect_ident(&mut self) -> Result<&'a tt::Ident, ()> {
+        match self.expect_leaf()? {
+            tt::Leaf::Ident(it) => Ok(it),
+            _ => Err(()),
+        }
+    }
+
+    pub(crate) fn expect_literal(&mut self) -> Result<&'a tt::Literal, ()> {
+        match self.expect_leaf()? {
+            tt::Leaf::Literal(it) => Ok(it),
+            _ => Err(()),
+        }
+    }
+
+    pub(crate) fn expect_punct(&mut self) -> Result<&'a tt::Punct, ()> {
+        match self.expect_leaf()? {
+            tt::Leaf::Punct(it) => Ok(it),
+            _ => Err(()),
+        }
+    }
+}
+
+impl<'a> Iterator for TtIter<'a> {
+    type Item = &'a tt::TokenTree;
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<'a> std::iter::ExactSizeIterator for TtIter<'a> {}
-- 
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