Rust插件库garando_pos的使用，高效POS系统开发与支付处理解决方案

关于garando_pos

garando_pos是Rust编译器不稳定库的稳定版本移植，包含以下组件：

• libsyntax_pos => garando_pos
• libsyntax => garando_syntax
• librustc_errors => garando_errors

该库可以在最新的Rust稳定版上编译使用。

构建状态

最新版本：![Latest Version]

安装

在项目目录中运行以下Cargo命令：

cargo add garando_pos

或在Cargo.toml中添加以下行：

garando_pos = "0.1.0"

示例代码

以下是使用garando_pos开发POS系统的完整示例：

use garando_pos::Span;
use garando_syntax::ast;

// POS系统交易处理示例
struct Transaction {
    items: Vec<Item>,
    total: f64,
    tax: f64,
    span: Span, // 用于错误报告的位置信息
}

struct Item {
    name: String,
    price: f64,
    quantity: i32,
}

impl Transaction {
    fn new() -> Self {
        Transaction {
            items: Vec::new(),
            total: 0.0,
            tax: 0.0,
            span: Span::default(),
        }
    }

    fn add_item(&mut self, name: String, price: f64, quantity: i32) {
        let item = Item { name, price, quantity };
        self.items.push(item);
        self.total += price * quantity as f64;
    }

    fn calculate_tax(&mut self, tax_rate: f64) {
        self.tax = self.total * tax_rate;
    }

    fn finalize(&self) -> f64 {
        self.total + self.tax
    }
}

// 支付处理接口
trait PaymentProcessor {
    fn process_payment(&self, amount: f64) -> Result<(), String>;
}

// 信用卡支付实现
struct CreditCardProcessor;
impl PaymentProcessor for CreditCardProcessor {
    fn process_payment(&self, amount: f64) -> Result<(), String> {
        println!("Processing credit card payment of ${:.2}", amount);
        // 实际集成支付网关的代码
        Ok(())
    }
}

// POS系统主结构
struct POSSystem<P: PaymentProcessor> {
    processor: P,
    current_transaction: Option<Transaction>,
}

impl<P: PaymentProcessor> POSSystem<P> {
    fn new(processor: P) -> Self {
        POSSystem {
            processor,
            current_transaction: None,
        }
    }

    fn start_transaction(&mut self) {
        self.current_transaction = Some(Transaction::new());
    }

    fn add_item(&mut self, name: String, price: f64, quantity: i32) {
        if let Some(ref mut trans) = self.current_transaction {
            trans.add_item(name, price, quantity);
        }
    }

    fn complete_transaction(&mut self, tax_rate: f64) -> Result<f64, String> {
        if let Some(mut trans) = self.current_transaction.take() {
            trans.calculate_tax(tax_rate);
            let total = trans.finalize();
            self.processor.process_payment(total)?;
            Ok(total)
        else {
            Err("No active transaction".to_string())
        }
    }
}

fn main() {
    let processor = CreditCardProcessor;
    let mut pos = POSSystem::new(processor);

    pos.start_transaction();
    pos.add_item("Rust Book".to_string(), 39.99, 1);
    pos.add_item("Coffee".to_string(), 2.50, 2);

    match pos.complete_transaction(0.08) { // 8%税率
        Ok(total) => println!("Transaction completed. Total: ${:.2}", total),
        Err(e) => println!("Error: {}", e),
    }
}

许可证

garando_pos采用双许可证：

• Apache License, Version 2.0
• MIT license

您可以选择其中任意一种。

完整示例代码

以下是基于garando_pos的扩展POS系统实现，包含更多功能：

use garando_pos::Span;
use garando_syntax::ast;
use std::collections::HashMap;

// 商品库存管理
struct Inventory {
    items: HashMap<String, Item>,
}

impl Inventory {
    fn new() -> Self {
        Inventory {
            items: HashMap::new(),
        }
    }

    // 添加商品到库存
    fn add_item(&mut self, name: String, price: f64, quantity: i32) {
        let item = Item { name: name.clone(), price, quantity };
        self.items.insert(name, item);
    }

    // 检查商品库存
    fn check_stock(&self, name: &str, quantity: i32) -> bool {
        self.items.get(name).map_or(false, |item| item.quantity >= quantity)
    }

    // 更新库存
    fn update_stock(&mut self, name: &str, quantity: i32) -> Result<(), String> {
        if let Some(item) = self.items.get_mut(name) {
            if item.quantity >= quantity {
                item.quantity -= quantity;
                Ok(())
            } else {
                Err(format!("Insufficient stock for {}", name))
            }
        } else {
            Err(format!("Item {} not found", name))
        }
    }
}

// 增强的POS系统
struct EnhancedPOS<P: PaymentProcessor> {
    pos: POSSystem<P>,
    inventory: Inventory,
}

impl<P: PaymentProcessor> EnhancedPOS<P> {
    fn new(processor: P) -> Self {
        EnhancedPOS {
            pos: POSSystem::new(processor),
            inventory: Inventory::new(),
        }
    }

    // 添加商品到库存
    fn add_to_inventory(&mut self, name: String, price: f64, quantity: i32) {
        self.inventory.add_item(name, price, quantity);
    }

    // 销售商品
    fn sell_item(&mut self, name: String, quantity: i32) -> Result<(), String> {
        if !self.inventory.check_stock(&name, quantity) {
            return Err(format!("Not enough stock for {} (requested: {})", name, quantity));
        }

        if let Some(item) = self.inventory.items.get(&name) {
            self.pos.add_item(name, item.price, quantity);
            self.inventory.update_stock(&name, quantity)?;
            Ok(())
        } else {
            Err(format!("Item {} not found", name))
        }
    }

    // 完成交易(继承POSSystem的方法)
    fn complete_transaction(&mut self, tax_rate: f64) -> Result<f64, String> {
        self.pos.complete_transaction(tax_rate)
    }
}

fn main() {
    let processor = CreditCardProcessor;
    let mut enhanced_pos = EnhancedPOS::new(processor);

    // 初始化库存
    enhanced_pos.add_to_inventory("Rust Book".to_string(), 39.99, 10);
    enhanced_pos.add_to_inventory("Coffee".to_string(), 2.50, 100);

    // 开始交易
    enhanced_pos.pos.start_transaction();

    // 销售商品
    match enhanced_pos.sell_item("Rust Book".to_string(), 1) {
        Ok(_) => println!("Added Rust Book to transaction"),
        Err(e) => println!("Error: {}", e),
    }

    match enhanced_pos.sell_item("Coffee".to_string(), 2) {
        Ok(_) => println!("Added Coffee to transaction"),
        Err(e) => println!("Error: {}", e),
    }

    // 完成交易
    match enhanced_pos.complete_transaction(0.08) {
        Ok(total) => println!("Transaction completed. Total: ${:.2}", total),
        Err(e) => println!("Error: {}", e),
    }
}

这个扩展示例增加了库存管理功能，使POS系统更加完整实用。