README.rst

@@ -56,11 +56,6 @@ example as invalid: it misleads what the result of the operation is.
 This change is consistent with what is written in the SCU manual
 (ST-97-R5-072694), but is inconsistent with SEGA's SCU DSP examples.
 
-.. note::
-
-   It is currently unclear which of the two is correct. A future
-   version of scu-dsp-asm may change this behavior.
-
 Differences that affect code generation
 =======================================
 
@@ -90,8 +85,8 @@ In short:
 Spurious invalid X-bus opcode generation
 ----------------------------------------
 
-Under seemingly-random circumstances, ``dspasm.exe`` emits the
+Under seemly-random circumstances, ``dspasm.exe`` emits the undefined
-undefined X-bus opcode ``001``. Given:
+X-bus opcode ``001``. Given:
 
 .. code::
    

lexer_iterator.cpp

@@ -0,0 +1,35 @@
+#include "lexer.hpp"
+#include "token.hpp"
+
+namespace dsp {
+
+struct lexer_iterator_t
+{
+  token_t previous_token;
+  token_t current_token;
+  lexer_t& lexer;
+
+  lexer_iterator_t(lexer_t& lexer)
+    : lexer(lexer), previous_token(lexer.scan_token()), current_token(previous_token)
+  {
+  }
+
+  token_t& advance()
+  {
+    previous_token = current_token;
+    current_token = lexer.scan_token();
+    return previous_token;
+  }
+
+  token_t& peek()
+  {
+    return current_token;
+  }
+
+  token_t& previous()
+  {
+    return previous_token;
+  }
+};
+
+}