stage1 完成ast 定义sema

stage1/spl_dumptree.h

@@ -0,0 +1,31 @@
+/* spl_dumptree.h 可配置的树形打印模块（只用基本 ASCII）*/
+
+#ifndef __SPL_DUMPTREE_H__
+#define __SPL_DUMPTREE_H__
+
+#include <stddef.h>
+#include <stdio.h>
+
+/* 可配置的缩进字符串 */
+typedef struct {
+    const char *vertical;    /* "| "  */
+    const char *branch;      /* "|-"  */
+    const char *last_branch; /* "`-"  */
+    const char *space;       /* "  "  */
+} spl_dumptree_style_t;
+
+/* 默认 ASCII 风格 */
+extern const spl_dumptree_style_t spl_dumptree_ascii_style;
+
+/* 打印一行节点标签：prefix + 分支符 + label
+ * prefix  已累积的缩进骨架（不含分支符）
+ * is_last 本节点是否为同级最后一个子节点
+ * fmt     printf 风格 label */
+void spl_dumptree_print(const spl_dumptree_style_t *st, const char *prefix, int is_last,
+                        const char *fmt, ...);
+
+/* 生成子节点的缩进骨架：parent_prefix + (parent_is_last ? space : vertical) */
+void spl_dumptree_child_prefix(const spl_dumptree_style_t *st, const char *prefix, int is_last,
+                               char *out, size_t cap);
+
+#endif /* __SPL_DUMPTREE_H__ */