表达模式匹配

发布于 2024-11-15 00:48:59 字数 713 浏览 2 评论 0原文

我有一个类似于这个问题的问题，只不过使用的是 Javascript 而不是 C#。

基本上，我希望能够对表达式进行模式匹配，而不是使用一长串 if 语句，如下所示：

var person.annoyingAction = match([person.gender, person.ageGroup],
      [male, child], breakingStuff,
      [male, teenager], drivingRecklessly,
      [male, adult], beingLazyAfterComingHomeFromWork
      [female, child], screechingInAnUnbelievablyHighPitchedVoice,
      [female, teenager], knowingEverything,
      [female, adult], askingPeopleIfTheyThinkIAmTooFat
      [_, baby], cryingEveryTwoHoursAtNight,
      [_,_], beingHuman);

有人知道如何实现在 Javascript 中执行类似操作的东西吗？

原文

I have a question similar to this one, except with Javascript instead of C#.

Basically, I want to be able to do pattern matching on an expression instead of using a long list of if statements, like this:

var person.annoyingAction = match([person.gender, person.ageGroup],
      [male, child], breakingStuff,
      [male, teenager], drivingRecklessly,
      [male, adult], beingLazyAfterComingHomeFromWork
      [female, child], screechingInAnUnbelievablyHighPitchedVoice,
      [female, teenager], knowingEverything,
      [female, adult], askingPeopleIfTheyThinkIAmTooFat
      [_, baby], cryingEveryTwoHoursAtNight,
      [_,_], beingHuman);

Does anybody know how to implement something that would do something like this in Javascript?

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多孤肩上扛 2024-11-22 00:48:59

我不知道现有的、干净的解决方案，但这里有一个与您的示例相匹配的简单实现：

var match = function(target) {
  for (i = 1; i < arguments.length; i += 2) {
    if (target[0] == arguments[i][0] && target[1] == arguments[i][1]) {
      return arguments[i + 1];
    }
  }
}

示例使用：

var result = match(["Yellow", "Food"],
  ["Red", "Food"], "Apple",
  ["Green", "Plant"], "Grass",
  ["Yellow", "Thing"], "Schoolbus",
  ["Yellow", "Food"], "Banana",
  ["Yellow", "Foot"], "Bad"
)

alert(result) # displays "Banana"

在 JavaScript 中，您无法直接比较数组 ([1, 2] != [1 , 2])，因此您需要单独比较元素。

I don't know of an existing, clean, solution, but here is a simple implementation that matches what your example:

var match = function(target) {
  for (i = 1; i < arguments.length; i += 2) {
    if (target[0] == arguments[i][0] && target[1] == arguments[i][1]) {
      return arguments[i + 1];
    }
  }
}

Example use:

var result = match(["Yellow", "Food"],
  ["Red", "Food"], "Apple",
  ["Green", "Plant"], "Grass",
  ["Yellow", "Thing"], "Schoolbus",
  ["Yellow", "Food"], "Banana",
  ["Yellow", "Foot"], "Bad"
)

alert(result) # displays "Banana"

In JavaScript you can't compare arrays directly ([1, 2] != [1, 2]) so you need to compare the elements individually.

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