Some work

token.c

@@ -136,11 +136,32 @@ static bool read_next_ident(TokenStream *restrict stream, Token *restrict out);
 static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out,
                              ParseError *restrict error);
 
+bool token_stream_peek(TokenStream *restrict stream, Token *restrict out,
+                       ParseError *restrict error) {
+    if (error) {
+        error->set = false;
+    }
+    if (!stream->has_buffer) {
+        bool res = token_stream_next(stream, &stream->buffer, error);
+        if (!res) {
+            return false;
+        }
+        stream->has_buffer = true;
+    }
+    *out = stream->buffer;
+    return true;
+}
+
 bool token_stream_next(TokenStream *restrict stream, Token *restrict out,
                        ParseError *restrict error) {
     if (error) {
         error->set = false;
     }
+    if (stream->has_buffer) {
+        stream->has_buffer = false;
+        *out = stream->buffer;
+        return true;
+    }
 restart:
     skip_whitespace(stream);
     int c = peekc(stream);
@@ -232,3 +253,16 @@ static bool read_next_reduce(TokenStream *restrict stream, Token *restrict out,
         return false;
     }
 }
+
+bool token_stream_discard(TokenStream *restrict stream,
+                          ParseError *restrict error) {
+    if (stream->has_buffer) {
+        stream->has_buffer = false;
+        if (error) {
+            error->set = false;
+        }
+        return true;
+    }
+    Token tok;
+    return token_stream_next(stream, &tok, error);
+}