stage1 完成ast 定义sema

stage1/spl_dumptree.c

@@ -0,0 +1,26 @@
+/* spl_dumptree.c 可配置的树形打印模块（只用基本 ASCII）*/
+
+#include "spl_dumptree.h"
+#include <stdarg.h>
+
+const spl_dumptree_style_t spl_dumptree_ascii_style = {
+    "| ",
+    "|-",
+    "`-",
+    "  ",
+};
+
+void spl_dumptree_print(const spl_dumptree_style_t *st, const char *prefix, int is_last,
+                        const char *fmt, ...) {
+    va_list ap;
+    printf("%s%s ", prefix, is_last ? st->last_branch : st->branch);
+    va_start(ap, fmt);
+    vprintf(fmt, ap);
+    va_end(ap);
+    printf("\n");
+}
+
+void spl_dumptree_child_prefix(const spl_dumptree_style_t *st, const char *prefix, int is_last,
+                               char *out, size_t cap) {
+    snprintf(out, cap, "%s%s", prefix, is_last ? st->space : st->vertical);
+}