1 files changed, 22 insertions, 14 deletions

diff --git a/byterun/lexing.c b/byterun/lexing.c
index 8a3219f6c..86387a911 100644
--- a/byterun/lexing.c
+++ b/byterun/lexing.c
@@ -13,6 +13,7 @@
 
 /* The table-driven automaton for lexers generated by camllex. */
 
+#include "fail.h"
 #include "mlvalues.h"
 #include "stacks.h"
 #include "str.h"
@@ -25,6 +26,8 @@ struct lexer_buffer {
   value lex_start_pos;
   value lex_curr_pos;
   value lex_last_pos;
+  value lex_saved_state;
+  value lex_last_action;
 };
 
 struct lexing_table {
@@ -48,11 +51,16 @@ value lex_engine(tbl, start_state, lexbuf)     /* ML */
      value start_state;
      struct lexer_buffer * lexbuf;
 {
-  int state, last_action, base, backtrk, c;
+  int state, base, backtrk, c;
   
-  state = Int_val(start_state);
-  lexbuf->lex_last_pos = lexbuf->lex_start_pos = lexbuf->lex_curr_pos;
-  last_action = -1;
+  if (Int_val(lexbuf->lex_saved_state) >= 0) {
+    state = Int_val(lexbuf->lex_saved_state);
+    lexbuf->lex_saved_state = Val_int(-1);
+  } else {
+    state = Int_val(start_state);
+    lexbuf->lex_last_pos = lexbuf->lex_start_pos = lexbuf->lex_curr_pos;
+    lexbuf->lex_last_action = Val_int(-1);
+  }
   while(1) {
     /* Lookup base address or action number for current state */
     base = Short(tbl->lex_base, state);
@@ -61,18 +69,14 @@ value lex_engine(tbl, start_state, lexbuf)     /* ML */
     backtrk = Short(tbl->lex_backtrk, state);
     if (backtrk >= 0) {
       lexbuf->lex_last_pos = lexbuf->lex_curr_pos;
-      last_action = backtrk;
+      lexbuf->lex_last_action = Val_int(backtrk);
     }
-    /* Read next input char */
+    /* See if we need a refill */
     if (lexbuf->lex_curr_pos >= lexbuf->lex_buffer_len) {
-      Push_roots (r, 2);
-      r[0] = (value) tbl;
-      r[1] = (value) lexbuf;
-      callback(lexbuf->refill_buff, (value) lexbuf);
-      tbl = (struct lexing_table *) r[0];
-      lexbuf = (struct lexer_buffer *) r[1];
-      Pop_roots ();
+      lexbuf->lex_saved_state = Val_int(state);
+      return (-1);
     }
+    /* Read next input char */
     c = Byte_u(lexbuf->lex_buffer, Long_val(lexbuf->lex_curr_pos));
     lexbuf->lex_curr_pos += 2;
     /* Determine next state */
@@ -83,7 +87,11 @@ value lex_engine(tbl, start_state, lexbuf)     /* ML */
     /* If no transition on this char, return to last backtrack point */
     if (state < 0) {
       lexbuf->lex_curr_pos = lexbuf->lex_last_pos;
-      return Val_int(last_action);
+      if (lexbuf->lex_last_action == Val_int(-1)) {
+        failwith("lexing: empty token");
+      } else {
+        return lexbuf->lex_last_action;
+      }
     }
   }
 }