Add support for the #undef macro.

This isn't ideal for two reasons:

1. There's a bunch of stateful redundancy in the lexer that should be
   cleaned up.

2. The hash table does not provide a mechanism to delete an entry, so
   we waste memory to add a new NULL entry in front of the existing
   entry with the same key.

But this does at least work, (it passes the recently added undef test
case).

1 files changed, 18 insertions, 1 deletions

diff --git a/glcpp-lex.l b/glcpp-lex.l
index ec91538a73..9ec4deb718 100644
--- a/glcpp-lex.l
+++ b/glcpp-lex.l
@@ -33,7 +33,7 @@
 %option extra-type="glcpp_parser_t *"
 
 %x ST_DEFINE
-%x ST_DEFVAL
+%x ST_UNDEF
 
 SPACE		[[:space:]]
 NONSPACE	[^[:space:]]
@@ -67,6 +67,23 @@ TOKEN		{NONSPACE}+
 
 <ST_DEFINE>{SPACE}+
 
+{HASH}undef{HSPACE}*	{
+	BEGIN ST_UNDEF;
+	return UNDEF;
+}
+
+<ST_UNDEF>{IDENTIFIER}	{
+	yylval.str = xtalloc_strdup (yyextra, yytext);
+	return IDENTIFIER;
+}
+
+<ST_UNDEF>\n {
+	BEGIN INITIAL;
+	return NEWLINE;
+}
+
+<ST_UNDEF>{SPACE}+
+
 	/* Anything we don't specifically recognize is a stream of tokens */
 {NONSPACE}+ {
 	yylval.str = xtalloc_strdup (yyextra, yytext);