nqasm: Improve parsing at end of file

Bison's implicit $accept rule ends with the END token.  The fact that input
could also end with END (via the line non-terminal) resulted in a shift
reduce conflict.

We resolve the conflict by modifying the lexer so that if it encounters end
of file partway through a line, it produces a final EOL token before EOF.

2 files changed, 6 insertions, 4 deletions

diff --git a/lexer.l b/lexer.l
index 9a34d66..6b6b121 100644
--- a/lexer.l
+++ b/lexer.l
@@ -55,7 +55,10 @@ EOI        [ \t\n#]
 <inst>nop/{EOI}          { BEGIN(args);    return T_NOP;    }
 
 {SP}*{COMMENT}?\n        { BEGIN(INITIAL); return T_EOL;    }
-{SP}*{COMMENT}           { BEGIN(INITIAL); return T_SPACE;  }
+{SP}*{COMMENT}           { BEGIN(INITIAL); return T_EOL;    }
 {SP}+                    {                 return T_SPACE;  }
 
+<INITIAL><<EOF>>         {                 return 0;        }
+<<EOF>>                  { BEGIN(INITIAL); return T_EOL;    }
+
 %%
diff --git a/parser.y b/parser.y
index 78bf123..48bd13f 100644
--- a/parser.y
+++ b/parser.y
@@ -69,7 +69,7 @@ void yyerror(const char *msg)
 %type <inst> inst
 %%
 
-input:	%empty
+input:	line
 	|	input line
 	;
 
@@ -151,6 +151,5 @@ inst:	T_ADD
 	;
 
 eol:	T_EOL
-	|	T_SPACE END
-	|	END
+	|	T_SPACE T_EOL
 	;