在ERB中缩进多行字符串

问题描述

我有一个来自外部库的字符串，如下所示：

I have a string from an external library that looks like this:

s = "  things.each do |thing|\n    thing += 5\n    thing.save\n  end\n\n"

此输入字符串将不会更改。我需要使用ERB将其插入文件中。例如：

This input string isn't going to change. I need to insert it into a file using ERB. e.g.:

erb = ERB.new("<%= s %>")
File.write("test.txt", erb.result(instance_eval('binding'))

我的问题是在不对字符串进行任何更改的情况下，文件将像这样编写：

My problem is the indentation. Without making any changes to the string, the file will be written like this:

  things.each do |thing|
    thing += 5
    thing.run
  end

注意但是，我想做的是在文本中均匀地再缩进两个空格，就像这样：

Note the indentation. What I want to do, however, is to insert the text uniformly indented another two spaces in, like so:

    things.each do |thing|
      thing += 5
      thing.run
    end

如果我这样做：

erb = ERB.new("  <%= s %>")

然后仅缩进第一行。

    things.each do |thing|
    thing += 5
    thing.run
  end

我可以通过mod实现

erb = ERB.new("<%= s.gsub(/  (\w)/, "    \\1") %>")

..但这感觉有点乱。我真的不想在视图中这样做。有没有办法在ERB中缩进整个字符串，还是我不走运？

.. but that feels a bit messy. I don't really want to do that in the view. Is there a way to indent the entire string in ERB, or am I out of luck? I think I might be.

推荐答案

我认为您的问题没有内置的解决方案。但这并不意味着您不应该只构建自己的：）

I don't think that there is any builtin solution for your problem. But this does not mean you shouldn't just build your own :)

类似的东西应该可以工作：

Something like this should work:

class CodeIndenter < Struct.new(:code, :indentation)
  def self.indent(*args)
    self.new(*args).indent
  end

  def separator
    "\n"
  end

  def indent
    code.split(separator).map do |line|
      indentation + line
    end.join(separator)
  end
end

s = "  things.each do |thing|\n    thing += 5\n    thing.save\n  end\n\n"
puts CodeIndenter.indent(s, "  ")

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