vscode 用户定义代码段中的 if/else 条件

问题描述

查看用户定义片段的vscode文档，它会出现使用正则表达式转换，您可以执行 if/else 条件.

Looking at the vscode documentation for user defined snippets, it would appear that using the regex transform, you can do if/else conditions.

但是，我似乎找不到任何这样的例子，而且我正在努力理解仅基于 BNF 的正确语法.

However, I can't seem to find any examples of this and I'm struggling to understand the correct syntax based on the BNF alone.

有人可以解释一下这个语法吗?

Can someone explain the syntax for this?

例如

假设我有一个这样的片段:

Lets say I have a snippet like this:

"body": [
    "let color = '${1|white,black|}';",
    "let hex = '${???}';"
]

如果color==white，我希望十六进制输出#fff，否则如果黑色#000.

If color==white, I want hex to output #fff, otherwise if black #000.

推荐答案

这有效:

"color conditional": {
  "prefix": "_hex",
  "body": [

    "let color = '${1};",
    "let hex = '${1/(white)|(black)|(red)/${1:+#fff}${2:+#000}${3:+#f00}/}';" //works
  ],
  "description": "conditional color"
},

但是，一旦我尝试使用默认占位符和选项，例如

However, as soon as I try it with default placeholders and choices, like

"let color = '${1|white,black|}';",   // does not work

显然，您不能对默认占位符值进行片段转换.请参阅占位符值问题的转换

Apparently, you cannot do snippet transforms on default placeholder values. See transforms on placeholder values issues

我使用了更简单的 if 转换样式，所以在这里:

I used the simpler if transform style, so here:

${1/(white)|(black)|(red)/${1:+#fff}${2:+#000}${3:+#f00}

如果有第 1 组 $[1} 在这种情况下 white 然后用 #fff 替换第 1 组，如果第 2 组(black) 替换为 #000 等

if there is a group 1 $[1} in this case white then replace that group 1 with #fff and if group 2 (black) replace with #000, etc.

你可以把它变成一个 if/else (white) 或者不是很容易.

You could make it just an if/else (white) or not pretty easily.

"let hex = '${1/(white)/${1:?#fff:#000}/}';"  // any non-`white` entry will print `#000`.

${1:? => 如果组 1 (white) 打印 #fff ，否则打印 #000

${1:? => if group 1 (white) print #fff , else print #000

vscode 文档对这些条件替换不是很有帮助，如果您对它们的语法有更多疑问，请告诉我.

The vscode docs are not very helpful on these conditional replacements, if you have more questions on their syntax, let me know.

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