feat: L Language v0.1 编译器完整实现

5 阶段编译流水线: 词法分析 → 语法分析(Pratt) → 语义分析(类型推断) → LLVM IR → .exe

模块:
- lexer: 手写状态机, 40 种 Token, // 和 /* */ 注释
- parser: Pratt 表达式解析(9 级优先级) + 递归下降语句/函数
- ast: 14 种节点类型 + 工厂函数
- sema: 作用域链符号表 + 类型推断 + 类型检查
- codegen: AST → LLVM-C API, print_i64/f64/bool 内建
- driver: 命令行 + 流水线串联 + 错误报告
- util: Arena bump allocator (8MB)

测试: 65 单元测试(词法41+语法15+语义9) + 5 集成测试 全部通过

语言特性: i64/f64/bool/void, let不可变变量, if/else, while, 递归函数

test/test_lexer.c

@@ -0,0 +1,53 @@
+#include "test_utils.h"
+#include "lexer.h"
+#include "arena.h"
+
+void test_simple_tokens() {
+    Arena a = arena_create(1);
+    const char* src = "fn main() { return 42; }";
+    size_t count; ErrorInfo error = {0};
+    Token* tokens = lex(&a, src, "test", &count, &error);
+    ASSERT(tokens != NULL);
+    ASSERT(count >= 8);
+    ASSERT(tokens[0].kind == TOK_FN);
+    ASSERT(tokens[1].kind == TOK_IDENT);
+    ASSERT(tokens[2].kind == TOK_LPAREN);
+    ASSERT(tokens[3].kind == TOK_RPAREN);
+    ASSERT(tokens[4].kind == TOK_LBRACE);
+    ASSERT(tokens[5].kind == TOK_RETURN);
+    ASSERT(tokens[6].kind == TOK_INT_LIT);
+    ASSERT(tok_int_value(&tokens[6]) == 42);
+    arena_destroy(&a);
+}
+
+void test_keywords() {
+    Arena a = arena_create(1);
+    const char* src = "fn let if else while return i64 f64 bool void true false";
+    TokenKind expected[] = {TOK_FN, TOK_LET, TOK_IF, TOK_ELSE, TOK_WHILE,
+        TOK_RETURN, TOK_I64, TOK_F64, TOK_BOOL, TOK_VOID, TOK_TRUE, TOK_FALSE, TOK_EOF};
+    size_t count; ErrorInfo error = {0};
+    Token* tokens = lex(&a, src, "test", &count, &error);
+    ASSERT(tokens != NULL);
+    for (int i = 0; i < 13; i++) ASSERT(tokens[i].kind == expected[i]);
+    arena_destroy(&a);
+}
+
+void test_operators() {
+    Arena a = arena_create(1);
+    const char* src = "+ - * / % == != < > <= >= && || ! ->";
+    TokenKind expected[] = {TOK_PLUS, TOK_MINUS, TOK_STAR, TOK_SLASH, TOK_PERCENT,
+        TOK_EQ_EQ, TOK_BANG_EQ, TOK_LT, TOK_GT, TOK_LT_EQ, TOK_GT_EQ,
+        TOK_AND_AND, TOK_PIPE_PIPE, TOK_BANG, TOK_ARROW, TOK_EOF};
+    size_t count; ErrorInfo error = {0};
+    Token* tokens = lex(&a, src, "test", &count, &error);
+    ASSERT(tokens != NULL);
+    for (int i = 0; i < 16; i++) ASSERT(tokens[i].kind == expected[i]);
+    arena_destroy(&a);
+}
+
+int main(void) {
+    TEST_RUN(test_simple_tokens);
+    TEST_RUN(test_keywords);
+    TEST_RUN(test_operators);
+    return test_summary();
+}