自动从Haml输出中删除所有换行符 [英] Auto-removing all newlines from Haml output

问题描述

我在Rails 3应用程序中使用Haml，它的换行符使我发疯！例如，

I'm using Haml in a Rails 3 app, and its newlines drive me nuts! For example,

%span
  foo

提供为

<span>
foo
</span>

但我宁愿想要

<span>foo</foo>

原因(除了更清晰的XML外)是，对于我的Selenium测试，多余的换行符是一个问题，因为它们使执行诸如"//span[.='foo']"之类的XPath查询的能力混乱了.因此，我不得不写'\nfoo\n'而不是(ew！)，或使用//span[contains(text(), 'foo')]，它们匹配的范围太广.

The reason (apart from being cleaner XML) is that extra newlines are a problem for my Selenium tests because they mess up the ability to do XPath queries like "//span[.='foo']". So I'd have to write '\nfoo\n' instead (ew!), or use //span[contains(text(), 'foo')], which matches too broadly.

我知道我可以使用鳄鱼运算符(<"和>")来去除空格，但是由于我从来没有想过 出现换行符，输出，最后我只是将它们机械地添加到每一行的末尾.看起来好像很干燥.

I know I could use the alligator operators ("<" and ">") to strip whitespace, but since I don't ever have a case where I want the newlines to appear in the output, I'd just end up adding them mechanically at the end of each line. And that just seems very unDRY.

所以现在我看到两个解决方案:

So now I see two solutions:

1. 强制Haml永远不要发出换行符，除非它们来自Ruby表达式.我看到一些nuke_inner_whitespace/nuke_outer_whitespace变量可能会在Haml代码周围散布，但我不确定如何在不借助免费的猴子补丁的情况下更改它们.
2. 插入Rails，将gsub!("\n", "")应用于所有渲染的HTML. (对于textarea和pres，我仍然可以使用~ "foo\nbar"来使Haml发出foo
bar.)但是，挂接到Rails的正确位置在哪里?我对代码有些迷茫.

1. Force Haml to never emit newlines unless they come from a Ruby expression. I see some nuke_inner_whitespace / nuke_outer_whitespace variables spread around the Haml code that might do the job, but I'm not sure how to change them without resorting to gratuitous monkey-patching.
2. Hook into Rails to apply a gsub!("\n", "") to all rendered HTML. (For textarea's and pre's, I could still use ~ "foo\nbar" to make Haml emit foo
bar.) But where's the right place to hook into Rails? I'm a little lost in the code.

任何指针或其他建议表示赞赏！

Any pointers or other suggestions appreciated!

更新:我已经在下面使用Jason的猴子补丁了一段时间，我开始认为这是不值得的.例如.如果要获取<span>[del]</span> <span>foo</span>，很难不在nuked之间留空格.甚至以下内容也会在页面上显示为[del]foo

Update: I've used Jason's monkey patch below for a while now and I'm beginning to think that it's not worth it. E.g. if I want to get <span>[del]</span> <span>foo</span>, it's difficult to not have the blank space in between nuked. Even the following will render as [del]foo on the page:

%span
  = '[del] '
%span
  foo

因此，我想我要回过头来手动添加鳄鱼操作员(请参见下面的自我解答).生活和学习.

So I think I'm going back to adding alligator operators manually (see my self-answer down below). Live and learn.

再次感谢Jason！ :)

Thanks again to Jason! :)

推荐答案

如果在元素名称的末尾放置一个小于号，则内容周围的空白将被抑制:

If you place a less-than sign at the end of the element name the whitespace around the content will be suppressed:

%span<
  foo

有关详细信息，请参见Haml参考中的去除空白

See whitespace removal in the Haml reference for more details.

似乎没有一种清除所有标签上这些标志的干净方法，但是以下猴子补丁在Haml 3.0.24上可以正常使用:

There doesn't appear to be any clean way to force these flags on for all tags but the following monkey patch works fine with Haml 3.0.24:

module Haml::Precompiler
  def parse_tag_with_nuked_whitespace(line)
    result = parse_tag_without_nuked_whitespace line
    unless result.size == 9 && [false,true].include?(result[4]) && [false,true].include?(result[5])
      raise "Unexpected parse_tag output: #{result.inspect}"
    end
    result[4] = true # nuke_outer_whitespace
    result[5] = true # nuke_inner_whitespace
    result
  end
  alias_method_chain :parse_tag, :nuked_whitespace
end

叉起Haml并在Engine选项中添加一个选项以始终删除空格可能并不难. parse_tag方法可以选中此选项(如果已启用)并将内部和外部标志设置为true.我将其留给读者练习. :)

It probably wouldn't be hard to fork Haml and add an option to the Engine options to always nuke whitespace. The parse_tag method could check this option if enabled and set the inner and outer flags to true. I'll leave this as an exercise for the reader. :)

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