Add some temporary code to preprocess with gcc -E

src/main.c

@@ -1,8 +1,36 @@
 #include <stdio.h>
+#include "parser.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+void preprocess(const char * input_fname)
+{
+    char fname[] = "/tmp/cxlppXXXXXX";
+    int fd = mkstemp(fname);
+    pid_t pid = fork();
+    if (pid < 0)
+    {
+        perror("fork");
+    }
+    else if (pid == 0)
+    {
+        dup2(fd, STDOUT_FILENO);
+        close(fd);
+        execlp("gcc", "gcc", "-x", "c", "-E", input_fname, NULL);
+    }
+    else
+    {
+        close(fd);
+        waitpid(pid, NULL, 0);
+        unlink(fname);
+    }
+}
 
 int main(int argc, char * argv[])
 {
-    printf("coming soon...\n");
+    preprocess(argv[1]);
 
     return 0;
 }