578 lines
9.4 KiB
Markdown
578 lines
9.4 KiB
Markdown
# L Language 语言参考手册
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> 版本 v0.5 | 158 测试全部通过 | LLVM 后端编译型语言
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---
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## 目录
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1. [快速开始](#1-快速开始)
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2. [基本类型](#2-基本类型)
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3. [变量](#3-变量)
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4. [运算符](#4-运算符)
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5. [控制流](#5-控制流)
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6. [函数](#6-函数)
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7. [结构体](#7-结构体)
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8. [枚举](#8-枚举)
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9. [数组](#9-数组)
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10. [类型别名](#10-类型别名)
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11. [内置函数](#11-内置函数)
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12. [注释](#12-注释)
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13. [完整示例](#13-完整示例)
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14. [编译与运行](#14-编译与运行)
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---
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## 1. 快速开始
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### Hello, World
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```rust
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fn main() -> i64 {
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print_i64(42);
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return 0;
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}
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```
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编译运行：
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```bash
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l_lang.exe hello.l -o hello.exe
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./hello.exe
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# 输出: 42
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```
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### 程序结构
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- 文件扩展名 `.l`
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- 一个 `.l` 文件包含若干函数和类型声明
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- 必须有 `main` 函数作为入口点
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- 所有声明在顶层，不支持嵌套函数
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---
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## 2. 基本类型
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| 类型 | 关键字 | 范围/说明 | 示例 |
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|------|--------|----------|------|
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| 整数 | `i64` | 64位有符号，`-2^63 ~ 2^63-1` | `42`, `-7`, `0` |
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| 浮点 | `f64` | 64位双精度 | `3.14`, `-0.5`, `1.0` |
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| 布尔 | `bool` | `true` 或 `false` | `true`, `false` |
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| 字符串 | `str` | UTF-8 文本 | `"Hello"`, `"你好"` |
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| 空类型 | `void` | 无返回值 | 用于函数返回类型 |
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### 类型转换
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- `i64` 和 `f64` 混合运算时，`i64` 自动提升为 `f64`
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- `bool` 和数值之间**不能**隐式转换
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- `str` 不能隐式转换为其他类型
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---
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## 3. 变量
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### 声明
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```rust
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let x = 42; // 不可变，类型推断为 i64
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let y: i64 = 100; // 不可变，显式类型标注
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let z = 3.14; // 类型推断为 f64
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let msg = "hello"; // 类型推断为 str
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let flag = true; // 类型推断为 bool
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```
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### 可变变量
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```rust
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let mut count: i64 = 0; // 可变变量
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count = count + 1; // 赋值
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count += 1; // 复合赋值 (等价于 count = count + 1)
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```
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> **规则**: 对 `let` 声明的不可变变量赋值会在编译时报错。
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### 类型标注语法
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```rust
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let name: Type = value; // 完整写法
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let name = value; // 类型推断
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let mut name: Type = value; // 可变变量
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```
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---
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## 4. 运算符
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### 算术
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| 运算符 | 说明 | 示例 |
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|--------|------|------|
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| `+` | 加法 | `1 + 2` → `3` |
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| `-` | 减法 | `5 - 3` → `2` |
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| `*` | 乘法 | `3 * 4` → `12` |
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| `/` | 除法 | `10 / 3` → `3` (整数) |
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| `%` | 取模 | `10 % 3` → `1` |
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### 比较（返回 bool）
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| 运算符 | 说明 |
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|--------|------|
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| `==` | 等于 |
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| `!=` | 不等于 |
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| `<` | 小于 |
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| `>` | 大于 |
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| `<=` | 小于等于 |
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| `>=` | 大于等于 |
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### 逻辑
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| 运算符 | 说明 |
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|--------|------|
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| `&&` | 逻辑与 |
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| `\|\|` | 逻辑或 |
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| `!` | 逻辑非 |
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### 复合赋值
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| 运算符 | 等价于 |
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|--------|--------|
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| `x += y` | `x = x + y` |
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| `x -= y` | `x = x - y` |
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| `x *= y` | `x = x * y` |
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| `x /= y` | `x = x / y` |
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### 字符串拼接
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```rust
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let greeting = "Hello, " + "World!";
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// greeting = "Hello, World!"
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```
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### 优先级（从高到低）
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```
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! -(一元负)
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* / %
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+ -
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== != < > <= >=
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&&
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```
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---
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## 5. 控制流
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### if / else
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```rust
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if x > 0 {
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print_i64(1);
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} else if x == 0 {
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print_i64(0);
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} else {
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print_i64(-1);
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}
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```
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### while 循环
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```rust
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let mut i: i64 = 0;
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while i < 5 {
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print_i64(i);
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i += 1;
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}
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// 输出: 0 1 2 3 4
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```
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### for 循环
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```rust
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for i in 0 to 5 {
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print_i64(i);
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}
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// 输出: 0 1 2 3 4
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```
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`for i in start to end` 等价于 `let mut i = start; while i < end { ...; i += 1; }`
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### match
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```rust
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enum Color { Red, Green, Blue }
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let c = Color::Green;
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match c {
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Color::Red => { print_i64(10); }
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Color::Green => { print_i64(20); }
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_ => { print_i64(0); } // 通配符
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}
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// 输出: 20
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```
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- 每个分支用 `=>` 分隔，花括号包围
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- `_` 表示通配符（匹配所有未列出的情况）
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- `match` 是语句，不是表达式
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---
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## 6. 函数
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### 定义
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```rust
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fn add(a: i64, b: i64) -> i64 {
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return a + b;
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}
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fn greet() -> void {
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print_str("Hello");
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}
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```
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- `fn` 关键字定义函数
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- 参数格式: `name: Type`
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- 返回类型: `-> Type`，可省略（默认 `void`）
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- 支持递归调用
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### 调用
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```rust
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let result = add(3, 5);
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greet();
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```
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---
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## 7. 结构体
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### 声明
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```rust
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struct Point {
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x: i64,
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y: i64,
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}
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```
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### 初始化
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```rust
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let p = Point { x: 10, y: 20 };
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```
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### 字段访问
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```rust
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print_i64(p.x); // 10
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print_i64(p.y); // 20
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```
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### 嵌套结构体
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```rust
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struct Rect {
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tl: Point, // 左上角
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br: Point, // 右下角
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}
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let r = Rect {
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tl: Point { x: 0, y: 10 },
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br: Point { x: 5, y: 0 },
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};
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print_i64(r.tl.x); // 0 (链式访问)
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```
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### 函数参数和返回值
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```rust
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fn make_point(x: i64, y: i64) -> Point {
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return Point { x: x, y: y };
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}
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fn print_point(p: Point) -> void {
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print_i64(p.x);
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print_i64(p.y);
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}
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```
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### impl — 方法
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```rust
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impl Point {
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fn new(x: i64, y: i64) -> Point {
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return Point { x: x, y: y };
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}
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fn get_x(self: Point) -> i64 {
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return self.x;
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}
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}
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let p = Point.new(10, 20); // 方法调用
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print_i64(p.get_x()); // 10
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```
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- `impl StructName { fn ... }` 定义方法
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- 第一个参数必须是 `self: StructName`
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- 调用: `instance.method(args)`
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---
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## 8. 枚举
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### 声明
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```rust
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enum Color {
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Red,
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Green,
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Blue,
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}
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```
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### 访问变体
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```rust
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let c = Color::Green;
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print_i64(c); // 1 (索引值: Red=0, Green=1, Blue=2)
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```
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```rust
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let is_red = (c == Color::Red); // false
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```
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---
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## 9. 数组
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### 声明类型
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```rust
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let arr: [i64; 5] = arr; // 声明未初始化的 5 个 i64 数组
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```
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数组类型语法: `[元素类型; 大小]`
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- `= arr` 是固定写法，表示声明未初始化的数组（`arr` 是变量名自身）
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- 大小必须是整数常量
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- 元素类型支持: `i64`, `f64`, `bool`
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- 数组元素默认值为零值（`0` / `0.0` / `false`）
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### 索引
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```rust
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arr[0] = 100; // 给第一个元素赋值
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arr[1] = 200;
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print_i64(arr[0]); // 100
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print_i64(arr[1]); // 200
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```
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### 循环遍历
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```rust
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let mut arr: [i64; 5] = arr;
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let mut i: i64 = 0;
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while i < 5 {
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arr[i] = i * 10;
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i += 1;
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}
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```
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---
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## 10. 类型别名
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```rust
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type Meters = i64;
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type Kilometers = i64;
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fn run(distance: Meters) -> void {
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print_i64(distance);
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}
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let d: Meters = 5000;
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run(d); // 输出: 5000
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```
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支持别名指向 struct:
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```rust
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type P = Point;
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let p: P = Point { x: 1, y: 2 };
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```
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---
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## 11. 内置函数
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| 函数 | 参数 | 输出 |
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|------|------|------|
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| `print_i64(x)` | `i64` | 整数 + 换行 |
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| `print_f64(x)` | `f64` | 浮点 + 换行 |
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| `print_bool(x)` | `bool` | `true`/`false` + 换行 |
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| `print_str(s)` | `str` | 字符串 + 换行 |
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---
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## 12. 注释
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```rust
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// 这是单行注释
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/*
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这是
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多行注释
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*/
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```
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---
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## 13. 完整示例
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### 斐波那契
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```rust
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fn fib(n: i64) -> i64 {
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if n < 2 {
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return n;
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}
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return fib(n - 1) + fib(n - 2);
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}
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fn main() -> i64 {
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print_i64(fib(10)); // 55
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return 0;
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}
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```
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### 学生成绩统计
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```rust
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struct Student {
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name_id: i64,
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score: i64,
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}
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impl Student {
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fn new(id: i64, score: i64) -> Student {
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return Student { name_id: id, score: score };
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}
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fn is_pass(self: Student) -> bool {
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return self.score >= 60;
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}
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}
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enum Grade { A, B, C, D, F }
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fn get_grade(score: i64) -> i64 {
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match score {
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90 => { return 0; }
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80 => { return 1; }
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70 => { return 2; }
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60 => { return 3; }
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_ => { return 4; }
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}
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}
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fn main() -> i64 {
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let s = Student.new(1001, 85);
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print_i64(s.name_id);
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print_i64(s.score);
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if s.is_pass() {
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print_str("PASS");
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} else {
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print_str("FAIL");
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}
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print_i64(get_grade(85)); // 1 (Grade::B)
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return 0;
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}
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```
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### 数组操作
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```rust
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fn main() -> i64 {
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let mut arr: [i64; 5] = arr;
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// 填充数组
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let mut i: i64 = 0;
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while i < 5 {
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arr[i] = i * i;
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i += 1;
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}
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// 打印数组
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i = 0;
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while i < 5 {
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print_i64(arr[i]);
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i += 1;
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}
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return 0;
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}
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// 输出: 0 1 4 9 16
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```
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---
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## 14. 编译与运行
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### 安装编译器
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```bash
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# 从源码构建
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git clone git@lhy-git.liuhangyv.top:Serendipity/l-language.git
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cd l-language
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mkdir build && cd build
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cmake .. -G "MinGW Makefiles" -DCMAKE_PREFIX_PATH="D:/settings/Language/LLVM"
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mingw32-make -j4
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```
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依赖: GCC 15.x (MinGW-w64), CMake 3.20+, LLVM 22.x
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### 使用
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```bash
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# 编译
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l_lang.exe source.l -o program.exe
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# 运行
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./program.exe
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# 查看生成的 LLVM IR
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l_lang.exe source.l --emit-ir
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```
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### 错误信息格式
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```
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错误: 文件名:行号:列号: 错误描述
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```
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- 词法/语法错误: 立即终止
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- 类型错误: 收集所有错误后统一输出
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---
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## 快速参考卡片
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```
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类型: i64 f64 bool str void struct enum [T;N]
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声明: let x = val let mut x = val
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let x: Type = val type Alias = Type
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控制流: if/else while for i in 0 to N match
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函数: fn name(p: T) -> Ret { return expr; }
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结构体: struct Name { f: Type } Name { f: val }
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枚举: enum Name { A, B, C } Name::B
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方法: impl T { fn m(self: T) } obj.m()
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内建: print_i64 print_f64 print_bool print_str
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运算符: + - * / % == != < > <= >= && || ! += -= *= /=
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注释: // 行注释 /* 块注释 */
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```
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