refactor(argparse): 将null替换为nullptr以提高C++兼容性

- 在argparse库中将所有null指针常量替换为nullptr
- 更新头文件和源文件中的指针初始化和比较操作
- 修改测试文件中的相关断言检查
- 更新AST定义文件中的注释说明

libs/lexer/include/scc_lexer_token.h

@@ -193,11 +193,11 @@ scc_tok_subtype_t scc_get_tok_subtype(scc_tok_type_t type);
 const char *scc_get_tok_name(scc_tok_type_t type);
 
 static inline void scc_lexer_tok_drop(scc_lexer_tok_t *tok) {
-    Assert(tok != null);
+    Assert(tok != nullptr);
     tok->type = SCC_TOK_UNKNOWN;
     tok->loc.col = 0;
     tok->loc.line = 0;
-    tok->loc.name = null;
+    tok->loc.name = nullptr;
     tok->loc.offset = 0;
     scc_str_drop(&tok->lexeme);
 }
@@ -209,7 +209,7 @@ static inline cbool scc_lexer_tok_match(const scc_lexer_tok_t *tok,
 
 // 深拷贝 token
 static inline scc_lexer_tok_t scc_lexer_tok_copy(const scc_lexer_tok_t *src) {
-    Assert(src != null);
+    Assert(src != nullptr);
     scc_lexer_tok_t dst = *src;
     dst.lexeme = scc_str_copy(&src->lexeme);
     return dst;
@@ -218,9 +218,9 @@ static inline scc_lexer_tok_t scc_lexer_tok_copy(const scc_lexer_tok_t *src) {
 // 移动 token（源 token 不再拥有 lexeme）
 static inline void scc_lexer_tok_move(scc_lexer_tok_t *dst,
                                       scc_lexer_tok_t *src) {
-    Assert(src != null);
+    Assert(src != nullptr);
     *dst = *src;
-    src->lexeme.data = null;
+    src->lexeme.data = nullptr;
     src->lexeme.size = 0;
     src->lexeme.cap = 0;
 }

libs/lexer/include/scc_lexer_utils.h

@@ -4,13 +4,13 @@
 #include "scc_lexer.h"
 
 static inline void scc_lexer_gen_number_true(scc_lexer_tok_t *tok) {
-    Assert(tok != null && tok->type == SCC_TOK_UNKNOWN);
+    Assert(tok != nullptr && tok->type == SCC_TOK_UNKNOWN);
     tok->type = SCC_TOK_INT_LITERAL;
     tok->lexeme = scc_str_from_cstr("1");
 }
 
 static inline void scc_lexer_gen_number_false(scc_lexer_tok_t *tok) {
-    Assert(tok != null && tok->type == SCC_TOK_UNKNOWN);
+    Assert(tok != nullptr && tok->type == SCC_TOK_UNKNOWN);
     tok->type = SCC_TOK_INT_LITERAL;
     tok->lexeme = scc_str_from_cstr("0");
 }

libs/lexer/src/lexer.c

@@ -538,7 +538,7 @@ void scc_lexer_drop_ring(scc_lexer_tok_ring_t *ring_ref) {
 }
 
 void scc_lexer_drop(scc_lexer_t *lexer) {
-    Assert(lexer != null);
+    Assert(lexer != nullptr);
     if (lexer->ring_ref_count) {
         LOG_FATAL("drop sstream must be drop ring before ref [%d]",
                   lexer->ring_ref_count);

libs/lexer/src/main.c

@@ -24,12 +24,12 @@ int g_num_arr[3];
 int main(int argc, char *argv[]) {
     // int num = 0;
     if (argc == 3 && strcmp(argv[2], "--debug") == 0) {
-        log_set_level(NULL, LOG_LEVEL_ALL);
+        log_set_level(nullptr, LOG_LEVEL_ALL);
     } else {
         // FIXME it is a hack lexer_logger
         log_set_level(&__scc_lexer_log, LOG_LEVEL_NOTSET);
-        log_set_level(NULL, LOG_LEVEL_INFO | LOG_LEVEL_WARN | LOG_LEVEL_ERROR |
-                                LOG_LEVEL_FATAL);
+        log_set_level(nullptr, LOG_LEVEL_INFO | LOG_LEVEL_WARN |
+                                   LOG_LEVEL_ERROR | LOG_LEVEL_FATAL);
     }
 
     const char *file_name = __FILE__;

libs/lexer/tests/test_lexer.c

@@ -412,5 +412,5 @@ TEST_LIST = {
     {"edge_cases", test_edge_cases},
     {"sequences", test_sequences},
     {"error_recovery", test_error_recovery},
-    {NULL, NULL},
+    {nullptr, nullptr},
 };