From 1699d97db7659d471390d2e173dbca6b35747f68 Mon Sep 17 00:00:00 2001
From: nsfisis <nsfisis@gmail.com>
Date: Mon, 5 May 2025 14:43:17 +0900
Subject: support #define that replaces name with identifiers

---
 README.md    |  2 +-
 main.c       | 21 +++++++++++++++++----
 tests/042.sh | 20 ++++++++++++++++++++
 3 files changed, 38 insertions(+), 5 deletions(-)
 create mode 100644 tests/042.sh

diff --git a/README.md b/README.md
index dc1f776..cf02911 100644
--- a/README.md
+++ b/README.md
@@ -47,7 +47,7 @@ To meet the four-day goal, many design decisions were made to reduce complexity
     * ~~No `while`~~
         * Implemented after self-hosting
 * Limited preprocessor
-    * Supports only simple `#define` that replaces identifiers with integer literals
+    * Supports only simple `#define` that replaces identifiers with single integer or identifier
 * No global variables
     * Including `stdin`, `stdout`, and `stderr`
     * Only function/struct definitions/declarations are allowed at the top level
diff --git a/main.c b/main.c
index 988d524..83f7a22 100644
--- a/main.c
+++ b/main.c
@@ -334,16 +334,29 @@ struct Token* tokenize(char* src, int len) {
                 pos += 1;
             }
             int start2 = pos;
-            while (isdigit(src[pos])) {
-                pos += 1;
+            int is_digit = isdigit(src[pos]);
+            if (is_digit) {
+                while (isdigit(src[pos])) {
+                    pos += 1;
+                }
+            } else {
+                while (isalnum(src[pos]) || src[pos] == '_') {
+                    pos += 1;
+                }
             }
             def->to = calloc(1, sizeof(struct Token));
-            def->to->kind = TK_L_INT;
+            if (is_digit) {
+                def->to->kind = TK_L_INT;
+            } else {
+                def->to->kind = TK_IDENT;
+            }
             def->to->value = calloc(pos - start2 + 1, sizeof(char));
             memcpy(def->to->value, src + start2, pos - start2);
             def += 1;
         } else {
-            fatal_error("unknown token");
+            char* buf = calloc(1024, sizeof(char));
+            sprintf(buf, "!!! %d", c);
+            fatal_error(buf);
         }
     }
     return tokens;
diff --git a/tests/042.sh b/tests/042.sh
new file mode 100644
index 0000000..b9f1749
--- /dev/null
+++ b/tests/042.sh
@@ -0,0 +1,20 @@
+set -e
+
+cat <<'EOF' > expected
+42,123
+EOF
+bash ../../test_diff.sh <<'EOF'
+int printf();
+
+#define A foo_a
+#define B foo_b
+
+int main() {
+    int foo_a = 42;
+    int foo_b = 123;
+
+    printf("%d,%d\n", A, B);
+
+    return 0;
+}
+EOF
-- 
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