[嵌入式Rust修炼营] 初级 任务2：读写Cargo.toml 文件

跟着hunter老师学习了几天Rust，今天小试一下，来完成任务2 ，用fs的API trait来读写一下 Cargo.toml文件

我先写的code是这样的：

在terminal 中 cargo run 一下，如下

看一下，仅仅println!()  就少了好几个“！”，小菜鸟起步的必经之路，呜呜。。。

Rust编译非常好用和友善，错误都有提示，根据错误提示一步一步改bug，

得到了下面的code

  这一步有遇到了一个问题，就是所有权问题，使用clone 就可以了，看看提示

  修改这个问题后，接下来应该ok了吧，no no no...

追查了一下发现，错误发生在尝试将 Rust 数据结构序列化回 TOML 格式时，原因是 TOML 格式要求所有的值（values）必须在表（tables）之前出现。继续修改，最终code如下：

use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::fs;
use std::path::Path;

/*
// define a struct to represent Cargo.tom file
#[derive(Debug, Serialize, Deserialize)]
struct CargoTom {
    package: Package,
    dependencies: Option<toml::value::Table>,
    #[serde(rename = "dev-dependencies")]
    dev_dependencies: Option<toml::value::Table>,
    #[serde(rename = "build-dependencies")]
    build_dependencies: Option<toml::value::Table>,
}
*/
// define a struct to represent Cargo.toml file
#[derive(Debug, Serialize, Deserialize)]
struct CargoTom {
    package: Package,
    dependencies: Option<toml::value::Table>,
    #[serde(flatten)]
    other: toml::value::Table,
}

#[derive(Debug, Serialize, Deserialize)]
struct Package {
    name: String,
    version: String,
    authors: Option<Vec<String>>,
    edition: Option<String>,
}


fn main() -> Result<()> { 

    let cargo_toml_path = Path::new("./Cargo.toml") ;

    // read the Cargo.toml file
    let content = fs::read_to_string(cargo_toml_path).context("Failed to read Cargo.toml")?;

    // parse the Cargo.toml file
    let mut cargo_toml: CargoTom = toml::from_str(&content).context("Failed to parse Cargo.toml")?;

    // print the parsed Cargo.toml file
    println!(" == original Cargo.toml file ==");
    println!("{:#?}", cargo_toml);

    // modify the parsed Cargo.toml file
    cargo_toml.package.version = "0.2.0".to_string();

    // add a new dependency to the parsed Cargo.toml file
     if let Some(deps) = cargo_toml.other.get_mut("dependencies") {
        if let Some(table) = deps.as_table_mut() {
            table.insert("new_dep".to_string(), toml::value::Value::String("1.0.36".to_string()));
        }
    } else {
        let mut deps = toml::value::Table::new();
        deps.insert("new_dep".to_string(), toml::value::Value::String("1.0.36".to_string()));
        cargo_toml.other.insert("dependencies".to_string(), toml::value::Value::Table(deps));   
    }
 

   // serialize the modified Cargo.toml file to string
   let  mut update_content = String::new();

   // firstly, serialize the package section
   let package_toml = toml::to_string(&cargo_toml.package).context("Failed to serialize package section")?;
   update_content.push_str(&package_toml);

   // then, serialize the dependencies section
   if let Some(deps) = cargo_toml.other.get("dependencies") {
       let deps_toml = toml::to_string(deps).context("Failed to serialize dependencies section")?;
       update_content.push_str("\n");
       update_content.push_str(&deps_toml);
   }

   // finally, serialize the rest sections
   /*for (key, value) in cargo_toml.other.iter() {
       if key != "dependencies" {
           let section_toml = toml::to_string(value).context(format!("Failed to serialize section {}", key))?;
           update_content.push_str("\n");
           update_content.push_str(&section_toml);
       }
   }*/
  // 然后序列化其他部分
  for (key, value) in cargo_toml.other {
    update_content.push_str(&format!("\n[{}]\n", key));
    let section_toml = toml::to_string(&value)
        .context(format!("Failed to serialize {}", key))?;
    update_content.push_str(&section_toml);
}

   // print the modified Cargo.toml file
   println!(" == modified Cargo.toml file ==");
   println!("{:#?}", update_content);

   // write the modified Cargo.toml file back to disk
   //fs::write(cargo_toml_path, update_content).context("Failed to write Cargo.toml")?;

   Ok(())
}



/*
Cargo.toml file content:
[package]
name = "task3"
version = "0.1.0"
edition = "2021"

[dependencies]
toml = "0.7"
serde = { version = "1.0", features = ["derive"] }
anyhow = "1.0" 

*/

来看看我的最终结果吧

看看，虽然不算完美，但也算是一个历程，后续继续加油！！

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