From cca0792839393b596b19b4492131523fbc8400de Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Sat, 11 Nov 2023 17:13:20 +0100
Subject: [PATCH] Added #undef directive

---
 include/ulas.h |  1 +
 src/test.c     | 10 ++++++++++
 src/ulas.c     | 36 ++++++++++++++++++++++++++++--------
 3 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/include/ulas.h b/include/ulas.h
index ebc779c..7369010 100644
--- a/include/ulas.h
+++ b/include/ulas.h
@@ -26,6 +26,7 @@
 #define ULAS_PPSTR_ENDIF "#endif"
 #define ULAS_PPSTR_IFNDEF "#ifndef"
 #define ULAS_PPSTR_ENDMACRO "#endmacro"
+#define ULAS_PPSTR_UNDEF "#undefine"
 
 // configurable tokens
 #define ULAS_TOK_COMMENT ';'
diff --git a/src/test.c b/src/test.c
index 4827502..4968d4f 100644
--- a/src/test.c
+++ b/src/test.c
@@ -92,11 +92,21 @@ void test_strbuf(void) {
 void test_preproc(void) {
   TESTBEGIN("preproc");
 
+  // no directive
   assert_preproc("  test line", 0, "  test line");
+
+  // define
   assert_preproc(" 123", 0, "  #define test 123\ntest");
   assert_preproc("", -1, "  #define 1test 123\n");
+  assert_preproc("", -1, "  #define\n");
   assert_preproc("this is a 123 for defs", 0,
                  "  #define test 123\nthis is a test for defs");
+
+  // undefined
+  assert_preproc(" 123\ntest", 0,
+                 "#define test 123\ntest\n#undefine test\ntest");
+
+  // macro
   assert_preproc("  line p1 1\n  line p2 2\n  line p3 3 p1, p2, p3\n", 0,
                  "#macro test\n  line $1 1\n  line $2 2\n  line $3 3 "
                  "$0\n#endmacro\ntest p1, p2, p3");
diff --git a/src/ulas.c b/src/ulas.c
index 30411c1..f6b04bf 100644
--- a/src/ulas.c
+++ b/src/ulas.c
@@ -204,12 +204,21 @@ char *ulas_preprocexpand(struct ulas_preproc *pp, const char *raw_line,
   memset(pp->line.buf, 0, pp->line.maxlen);
 
   int read = 0;
+  int first_tok = 1;
 
   // go through all tokens, see if a define matches the token,
   // if so expand it
   // only expand macros if they match toks[0] though!
   // otherwise memcpy the read bytes 1:1 into the new string
   while ((read = ulas_tok(&pp->tok, &praw_line, *n))) {
+    // if it is the first token, and it begins with a # do not process at all!
+    if (first_tok && pp->tok.buf[0] == ULAS_TOK_PREPROC_BEGIN) {
+      ulas_strensr(&pp->line, (*n) + 1);
+      strncat(pp->line.buf, raw_line, *n);
+      break;
+    }
+    first_tok = 0;
+
     struct ulas_ppdef *def =
         ulas_preprocgetdef(pp, pp->tok.buf, pp->tok.maxlen);
     if (def) {
@@ -337,16 +346,14 @@ int ulas_preprocline(struct ulas_preproc *pp, FILE *dst, FILE *src,
   char *line = ulas_preprocexpand(pp, raw_line, &n);
   const char *pline = line;
 
-  const char *dirstrs[] = {ULAS_PPSTR_DEF,
-                           ULAS_PPSTR_MACRO,
-                           ULAS_PPSTR_IFDEF,
-                           ULAS_PPSTR_IFNDEF,
-                           ULAS_PPSTR_ENDIF,
-                           ULAS_PPSTR_ENDMACRO,
-                           NULL};
+  const char *dirstrs[] = {ULAS_PPSTR_DEF,   ULAS_PPSTR_MACRO,
+                           ULAS_PPSTR_IFDEF, ULAS_PPSTR_IFNDEF,
+                           ULAS_PPSTR_ENDIF, ULAS_PPSTR_ENDMACRO,
+                           ULAS_PPSTR_UNDEF, NULL};
   enum ulas_ppdirs dirs[] = {ULAS_PPDIR_DEF,   ULAS_PPDIR_MACRO,
                              ULAS_PPDIR_IFDEF, ULAS_PPDIR_IFNDEF,
-                             ULAS_PPDIR_ENDIF, ULAS_PPDIR_ENDMACRO};
+                             ULAS_PPDIR_ENDIF, ULAS_PPDIR_ENDMACRO,
+                             ULAS_PPDIR_UNDEF};
 
   enum ulas_ppdirs found_dir = ULAS_PPDIR_NONE;
 
@@ -456,7 +463,19 @@ found:
     case ULAS_PPDIR_ENDIF:
       // TODO: implement
       ULASPANIC("Preproc directive is not implemented!\n");
+    case ULAS_PPDIR_UNDEF: {
+      if (ulas_tok(&pp->tok, &pline, n) == 0) {
+        ULASERR("Expected name for #undef\n");
+        return -1;
+      }
+      struct ulas_ppdef *def = NULL;
+      printf("name: %s\n", pp->tok.buf);
+      while ((def = ulas_preprocgetdef(pp, pp->tok.buf, pp->tok.maxlen))) {
+        def->undef = 1;
+      }
+
       break;
+    }
     default:
       // this should not happen!
       break;
@@ -464,6 +483,7 @@ found:
 
     // the end of a directive should have no further tokens!
     if (ulas_preprochasstray(pp, pline, n)) {
+      ULASERR("Stray token at end of preprocessor directive!");
       return -1;
     }
   dirdone:
-- 
2.30.2