1 files changed, 57 insertions, 0 deletions
diff --git a/vendor/rustc_lexer/src/cursor.rs b/vendor/rustc_lexer/src/cursor.rs
new file mode 100644
index 00000000..5831159c
--- /dev/null
+++ b/vendor/rustc_lexer/src/cursor.rs
@@ -0,0 +1,57 @@
+use std::str::Chars;
+
+pub(crate) struct Cursor<'a> {
+    initial_len: usize,
+    chars: Chars<'a>,
+    #[cfg(debug_assertions)]
+    prev: char,
+}
+
+pub(crate) const EOF_CHAR: char = '\0';
+
+impl<'a> Cursor<'a> {
+    pub(crate) fn new(input: &'a str) -> Cursor<'a> {
+        Cursor {
+            initial_len: input.len(),
+            chars: input.chars(),
+            #[cfg(debug_assertions)]
+            prev: EOF_CHAR,
+        }
+    }
+    /// For debug assertions only
+    pub(crate) fn prev(&self) -> char {
+        #[cfg(debug_assertions)]
+        {
+            self.prev
+        }
+
+        #[cfg(not(debug_assertions))]
+        {
+            '\0'
+        }
+    }
+    pub(crate) fn nth_char(&self, n: usize) -> char {
+        self.chars().nth(n).unwrap_or(EOF_CHAR)
+    }
+    pub(crate) fn is_eof(&self) -> bool {
+        self.chars.as_str().is_empty()
+    }
+    pub(crate) fn len_consumed(&self) -> usize {
+        self.initial_len - self.chars.as_str().len()
+    }
+    /// Returns an iterator over the remaining characters.
+    fn chars(&self) -> Chars<'a> {
+        self.chars.clone()
+    }
+    /// Moves to the next character.
+    pub(crate) fn bump(&mut self) -> Option<char> {
+        let c = self.chars.next()?;
+
+        #[cfg(debug_assertions)]
+        {
+            self.prev = c;
+        }
+
+        Some(c)
+    }
+}