取消缩进多行字符串值

Question

I don't like the Go convention for multiline strings:

function main() {
  for {
    if something {
      text := `   Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna 
aliqua. 
   Ut enim ad minim veniam, quis nostrud exercitation 
ullamco laboris nisi ut aliquip ex ea commodo consequat.
      `
    }
  }
}

I prefer:

function main() {
  for {
    if something {
      text := `
           Lorem ipsum dolor sit amet, consectetur adipiscing elit,
        sed do eiusmod tempor incididunt ut labore et dolore magna
        aliqua. 
           Ut enim ad minim veniam, quis nostrud exercitation 
        ullamco laboris nisi ut aliquip ex ea commodo consequat.
      `
      // text = unindent(text, 8) ?
    }
  }
}

Efficiency isn't a concern.

How do I remove a fixed number of spaces from the start of each line in my string value?

Answer 1

That's a simple strings.Replace() call:

text = strings.Replace(text, "
        ", "
", -1)

Output before and after the replace (try it on the Go Playground):

           Lorem ipsum dolor sit amet, consectetur adipiscing elit,
        sed do eiusmod tempor incididunt ut labore et dolore magna
        aliqua. 
           Ut enim ad minim veniam, quis nostrud exercitation 
        ullamco laboris nisi ut aliquip ex ea commodo consequat.


   Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna
aliqua. 
   Ut enim ad minim veniam, quis nostrud exercitation 
ullamco laboris nisi ut aliquip ex ea commodo consequat.

Note that this will still leave newline character at the beginning and at the end of your text. If you also want to get rid of them, you may use strings.Trim():

text = strings.Replace(text, "
        ", "
", -1)
text = strings.Trim(text, "
")

Note: strings.TrimSpace() would come first to mind, but it's not a good choice as that would also remove the indentation from the first line (" Lorem") which is unwanted. We really just want to get rid of extra prefix and postfix newlines.

To verify the difference:

text = strings.Replace(text, "
        ", "
", -1)
fmt.Printf("%q
", text)
text = strings.Trim(text, "
")
fmt.Printf("%q
", text)

Output:

" Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. " " Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."

To wrap it in a helper function:

func unindent(s string, spaces int) string {
    old := "
" + strings.Repeat(" ", spaces)
    s = strings.Replace(s, old, "
", -1)
    return strings.Trim(s, "
")
}

And using it:

text = unindent(text, 8)

An alternative way to create the old replaceable string:

func unindent(s string, spaces int) string {
    old := fmt.Sprintf("%*c", -spaces-1, '
')
    s = strings.Replace(s, old, "
", -1)
    return strings.Trim(s, "
")
}