如何从结构向量中过滤出字符串向量

Question

与结构向量相比，我有一个过滤掉字符串输入vec的工作解决方案。但是，我的代码似乎很复杂，我尝试使用iter::filter（https://doc.rust-lang.org/stable/std/iter/struct.Filter.html）简化代码。这引起了问题，因为迭代器返回的值是引用，不能直接使用。似乎我对iter的理解以及在结构向量中可以做什么需要刷新。下面是工作的简化过滤代码：

#[derive(Debug)]
pub struct Widget {
    name: String,
    pin: u16,
}

impl Widget{
    pub fn new(widget_name: String, widget_pin: String) -> Widget {
        let widget_pin_u16 = widget_pin.parse::<u16>().expect("Unable to parse");
        let nw = Widget {
            name: widget_name,
            pin: widget_pin_u16
        };
        return nw
    }
}

pub struct WidgetHolder {
    widgets: Vec<Widget>,
    widget_holder_name: String
}

impl WidgetHolder {
    fn add_widgets(&mut self, valid_widgets_found: Vec<String>) {
        let mut widgets_to_add: Vec<String> = Vec::new();
        for widget in valid_widgets_found {
            // The string musy be compared to pin field, so we're converting
            let widget_offset = widget
                .clone()
                .parse::<u16>()
                .expect("Unable to parse widget base into int.");
            // If it doesnt exist in our widgetHolder widgets vector, then lets add it.
            let mut widget_exists = false;
            for existing_widget in &self.widgets {
                if widget_offset == existing_widget.pin {
                    widget_exists = true;
                    break;
                }
            }
            if !widget_exists {
                widgets_to_add.push(widget.clone());
            }
        }
        
        if widgets_to_add.is_empty() {
            return;
        }
        
        for widget in widgets_to_add {
            let loaded_widget = Widget::new(self.widget_holder_name.clone(), widget);
            self.widgets.push(loaded_widget);
        }
    }
}


pub fn main() {
    let init_vec = Vec::new();
    let mut wh = WidgetHolder {
        widgets: init_vec,
        widget_holder_name: "MyWidget".to_string()
    };
    let vec1 = vec!["1".to_string(), "2".to_string(), "3".to_string()];
    wh.add_widgets(vec1);
    println!("{:?}", wh.widgets);

    let vec2 = vec!["2".to_string(), "3".to_string(), "4".to_string()];
    wh.add_widgets(vec2);
    println!("{:?}", wh.widgets);
}

有没有一种方法可以在不使用太多数据结构和循环的情况下清理此代码？过滤器api看起来很干净，但它是否与我试图变异（附加到它）的结构内部的向量一起工作？

在尝试获取堆栈跟踪后，我实际上让过滤器工作了...

    fn add_widgets(&mut self, valid_widgets_found: Vec<String>) {
        let widgets_to_add: Vec<String> = valid_widgets_found.into_iter()
                .filter(|widget_pin| {
                    let widget_offset = widget_pin.clone().parse::<u16>().expect("Unable to parse widget base into int.");
                    let mut widget_exists = false;
                    for existing_widget in &self.widgets {
                        if widget_offset == existing_widget.pin {
                            widget_exists = true;
                            break;
                        }
                    }
                    !widget_exists
                })
                .collect();
        
        if widgets_to_add.is_empty() {
            return;
        }
        
        for widget in widgets_to_add {
            let loaded_widget = Widget::new(self.widget_holder_name.clone(), widget);
            self.widgets.push(loaded_widget);
        }
    }

Answer 1

我想出了答案。当我第一次尝试时，似乎是一个语法错误。对于将来寻找滤波器示例的人:

    fn add_widgets(&mut self, valid_widgets_found: Vec<String>) {
        let widgets_to_add: Vec<String> = valid_widgets_found.into_iter()
                .filter(|widget_pin| {
                    let widget_offset = widget_pin.clone().parse::<u16>().expect("Unable to parse widget base into int.");
                    let mut widget_exists = false;
                    for existing_widget in &self.widgets {
                        if widget_offset == existing_widget.pin {
                            widget_exists = true;
                            break;
                        }
                    }
                    !widget_exists
                })
                .collect();
        
        if widgets_to_add.is_empty() {
            return;
        }
        
        for widget in widgets_to_add {
            let loaded_widget = Widget::new(self.widget_holder_name.clone(), widget);
            self.widgets.push(loaded_widget);
        }
    }