自动把RUST代码翻译成java

Rust的第三方库syn提供了将源代码翻译成抽象语法树的功能，利用这个功能我们可以将任意语言程序源码翻译为另外一门完全不同的语言程序源码

下面我们举例将rust语言的源码翻译为java源码

首先我们准备一个要翻译的源码文件 mystruct.rs

struct Person{
    pub name:String,
    pub age:u64
}

使用rust写一个翻译器，使用File::open 函数来打开mystruct.rs文件，并且暂存到String变量之中

use std::any::Any;
use std::fs::File;
use std::io::{BufReader, Read};
use syn::{parse_file, DeriveInput, Item, ItemStruct};

fn main() {
    let file = File::open("mystruct.rs").expect("Failed to open file");
    let mut buf_reader = BufReader::new(file);
    let mut contents = String::new();
    buf_reader
        .read_to_string(&mut contents)
        .expect("Failed to read file");

    let ast = parse_file(&contents).expect("Failed to parse file as Rust code");

    let java_code = translate_to_java(&ast);
    println!("{}", java_code);
}

fn translate_to_java(ast: &syn::File) -> String {
    let mut java_code = String::new();

    for item in &ast.items {
        if let Item::Struct(struct_item) = item {
            let struct_name = struct_item.ident.to_string();
            java_code.push_str(&format!("public class {} {{\n", struct_name));

            for field in &struct_item.fields {
                let field_name = field.ident.as_ref().unwrap().to_string();
                let field_type = translate_type(&field.ty);
                java_code.push_str(&format!("    private {} {};\n", field_type, field_name));
            }

            java_code.push_str("}\n");
        }
    }

    java_code
}

fn translate_type(ty: &syn::Type) -> String {
    match ty {
        syn::Type::Path(type_path) => {
            let path = &type_path.path;
            let mut path_str = String::new();
            for segment in &path.segments {
                path_str.push_str(&segment.ident.to_string());
            }
            match path_str.as_str() {
                "i32" => "int".to_string(),
                "f32" => "float".to_string(),
                "f64" => "double".to_string(),
                "bool" => "boolean".to_string(),
                "String" => "String".to_string(),
                _ => path_str.to_string(),
            }
        }
        _ => panic!("Unsupported field type {:?}",ty.type_id()),
    }
}

最后我们来看看翻译器给出的结果

public class Person {
    private String name;
    private u64 age;
}