Vim regexp help: change spaces to “ ”

问题:

I've had this problem many times: I have a source code, but if I copy / paste it into Wordpress and enclose it with <code> </code> the beginning spaces are "compressed" into one.

Thus I'd like to know how I could change all the spaces only at the beginning of the line by  .

I.e.

    extend: 'Ext.panel.Panel',

becomes

    extend: 'Ext.panel.Panel',

回答1:

I would propose the following three solutions addressing the issue that are listed below in order of my personal preference.

1. Substitution using the preceding atom matching syntax (see :help \@<=).

   :%s/\%(^ *\)\@<= /\&nbsp;/g
   

   If brevity of the command is crucial, one can shorten it using "very magic" mode (see :help \v) and changing capturing group (:help \%() to non-capturing.

   :%s/\v(^ *)@<= /\&nbsp;/g
   

2. Two-staged substitution that splits a line just after leading spaces, replaces those spaces, and rejoins that line.

   :g/^/s/^ \+/&\r/|-s/ /\ /g|j!
   

3. Another two-step substitution that replaces each of the leading spaces by certain symbol that does not occur in the text, and changes that symbol to  .

   :exe"g/^ \\+/norm!v//e\rr\r"|%s/\r/\ /g
   

回答2:

:%s/^ \+/\=repeat(" ",strlen(submatch(0)))

But it wouldn't surprise me if there's a shorter substitute command. Come on Vimgolfers!

回答3:

Using a look-behind assertion to replace spaces precedeed by only spaces at the beginning of a line:

%s/\(^ *\)\@<= /\&nbsp;/g