2

我对 Rust 很陌生，所以这可能是一个非常菜鸟的问题。

我正在尝试使用 rust -> wasm 创建一个 Web 应用程序。尝试按照教程https://rustwasm.github.io/docs/book/introduction.html并尝试使用 crate 包“petgraph”我想出了以下内容

use petgraph::graph::Graph;
#[wasm_bindgen]
pub struct TreeStructure {
    directed_graph: Graph
}
#[wasm_bindgen]
impl TreeStructure {
    pub fn new() -> TreeStructure {
        TreeStructure {
            directed_graph: Graph::<&str, &str>::new()
        }
    }
     pub fn addNode(&mut self, newNode: &str) {
        let findIndex = self.findNode(newNode);
        if findIndex < 0 {
            self.directed_graph.add_node(newNode);
        } else {
            alert("cant add, this {} already exist in the nodes", newNode);
        }
    }

    pub fn removeNode(&mut self, toRemoveNode: &str) {
        let findIndex = self.findNode(toRemoveNode);
        if findIndex > -1 {
            self.directed_graph.remove_node(toRemoveNode);
        } else {
            alert("cant remove, cannot find {} in the nodes", toRemoveNode);
        }
    }

    pub fn addEdge(&mut self, fromNode: &str, toNode: &str) {
        let fromIndex = self.findNode(fromNode);
        let toIndex = self.findNode(toNode);
        if fromIndex > -1 && toIndex > -1 {
            let alreadyEdged = self.directed_graph.contains_edge(fromIndex, toIndex);
            if !alreadyEdged {
                self.directed_graph.add_edge(fromIndex, toIndex, "");
            } else {
                alert("edge already exist from {} to {}", fromNode, toNode);
            }
        }
    }

    pub fn getNeighbors(&self, checkNode: &str) -> Array {
        let checkIndex = self.findNode(checkNode);
        if checkIndex < 0 {
            return vec![].into_inter().collect();
        }
        self.directed_graph.neighbors_directed(checkIndex).collect();
    }
}
impl TreeStructure {
    pub fn findNode(&self, nodeToFind: &str) -> i32 {
        let findIndex = self.directed_graph.node_indices().collect::<Vec<_>>().iter().position(|&r| r == nodeToFind);
        match findIndex {
            Some(x) => x,
            None => -1
        }
    }
}

但这给了我编译错误

error[E0107]: wrong number of type arguments: expected at least 2, found 0
--> src/lib.rs:25:25
   |
25 |         directed_graph: Graph
   |                         ^^^^^ expected at least 2 type arguments

阅读https://docs.rs/petgraph/0.5.0/petgraph/graph/struct.Graph.html 然后我尝试了

use petgraph::graph::Node;
use petgraph::graph::Edge;
pub struct TreeStructure<N: Node, E: Edge> {
    directed_graph: Graph<N, E>
}

但是后来它说 wasm-bindgen 不支持该语法？我应该在这里做什么？

4

1 回答 1

3

鉴于您的new函数将 a Graph::<&str, &str>in directed_graph，这也是您应该在声明中使用的：

pub struct TreeStructure {
    directed_graph: Graph<&str, &str>,
}

但是，这需要您指定生命周期。我对 wasm 不太熟悉，无法说出哪个是最好的（另外，这取决于您在图表中的确切内容），但您可能需要使用'static一生：

pub struct TreeStructure {
    directed_graph: Graph<&'static str, & 'static str>,
}

这还需要您为'static方法参数提供生命周期。或者您将需要移动到拥有的字符串：

pub struct TreeStructure {
    directed_graph: Graph<String, String>,
}

再次对您的方法进行适当的更改。

于 2020-04-29T06:16:48.500 回答