expansion: Add `get_token_slice` to `MacroInvocLexer` class

gcc/rust/ChangeLog:

	* expand/rust-macro-invoc-lexer.cc (MacroInvocLexer::get_token_slice):
	Add API to retrieve token slices when lexing macro expansions.
	* expand/rust-macro-invoc-lexer.h: Declare `get_token_slice`.

2 files changed, 17 insertions, 0 deletions

diff --git a/gcc/rust/expand/rust-macro-invoc-lexer.cc b/gcc/rust/expand/rust-macro-invoc-lexer.cc
index 8a43d29..321f0f9 100644
--- a/gcc/rust/expand/rust-macro-invoc-lexer.cc
+++ b/gcc/rust/expand/rust-macro-invoc-lexer.cc
@@ -26,4 +26,18 @@ MacroInvocLexer::split_current_token (TokenId new_left __attribute__ ((unused)),
   // FIXME
   gcc_unreachable ();
 }
+
+std::vector<std::unique_ptr<AST::Token>>
+MacroInvocLexer::get_token_slice (size_t start_idx, size_t end_idx) const
+{
+  std::vector<std::unique_ptr<AST::Token>> slice;
+
+  rust_assert (end_idx < token_stream.size ());
+
+  for (size_t i = start_idx; i < end_idx; i++)
+    slice.emplace_back (token_stream[i]->clone_token ());
+
+  return slice;
+}
+
 } // namespace Rust
diff --git a/gcc/rust/expand/rust-macro-invoc-lexer.h b/gcc/rust/expand/rust-macro-invoc-lexer.h
index 0fd4554..8190d7b 100644
--- a/gcc/rust/expand/rust-macro-invoc-lexer.h
+++ b/gcc/rust/expand/rust-macro-invoc-lexer.h
@@ -55,6 +55,9 @@ public:
 
   size_t get_offs () const { return offs; }
 
+  std::vector<std::unique_ptr<AST::Token>>
+  get_token_slice (size_t start_idx, size_t end_idx) const;
+
 private:
   size_t offs;
   std::vector<std::unique_ptr<AST::Token>> token_stream;