如何获取 Ballerina 数组中对象的索引？

如何有效地获取 Ballerina 数组中对象的索引？ 有没有内置函数可以做到这一点？

芭蕾舞演员现在提供indexOf https://github.com/ballerina-platform/ballerina-lang/blob/56c946b28cb7617974f4c290970fcd67505ab0ac/langlib/lang.array/src/main/java/org/ballerinalang/langlib/array/IndexOf.java#L47 and lastIndexOf https://github.com/ballerina-platform/ballerina-lang/blob/56c946b28cb7617974f4c290970fcd67505ab0ac/langlib/lang.array/src/main/java/org/ballerinalang/langlib/array/LastIndexOf.java#L45方法，截至语言规范 2020R1。

它们分别返回满足相等性的项目的第一个和最后一个索引。我们得到()如果没有找到该值。

import ballerina/io;


public function main() {
    string[*] example = ["this", "is", "an", "example", "for", "example"];

    // indexOf returns the index of the first element found
    io:println(example.indexOf("example")); // 3

    // The second parameter can be used to change the starting point
    // Here, "is" appears at index 1, so the return value is ()
    io:println(example.indexOf("is", 3) == ()); // true

    // lastIndexOf will find the last element instead
    // (the implementation will do the lookup backwards)
    io:println(example.lastIndexOf("example")); // 5

    // Here the second parameter is where to stop looking
    // (or where to start searching backwards from)
    io:println(example.lastIndexOf("example", 4)); // 3
}

这些和其他功能的描述可以找到在规范中 https://github.com/ballerina-platform/ballerina-spec/blob/master/lang/lib/array.bal.