Why does Regexp::escape backslash spaces?!?

Ruby
1

$ ruby -v
ruby 1.8.7 (2008-08-11 patchlevel 72) [universal-darwin10.0]
$ irb
irb(main):001:0> Regexp::escape(‘a b’)
=> “a\ b”

Why? This doesn’t seem to make any sense. Is it a bug?

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

2

Marnen Laibow-Koser wrote:

irb(main):001:0> Regexp::escape(‘a b’)
=> “a\ b”

Why? This doesn’t seem to make any sense. Is it a bug?

Maybe spaces are escaped so the resulting string be compatible with an
“extended” pattern, where non-escaped spaces are ignored:

/ (\w+) \s (\w+) /x

is the same as:

/(\w+)\s(\w+)/

3

Albert S. wrote:

Marnen Laibow-Koser wrote:

irb(main):001:0> Regexp::escape(‘a b’)
=> “a\ b”

Why? This doesn’t seem to make any sense. Is it a bug?

Maybe spaces are escaped so the resulting string be compatible with an
“extended” pattern, where non-escaped spaces are ignored:

/ (\w+) \s (\w+) /x

is the same as:

/(\w+)\s(\w+)/

Good point. And anyway, it causes no problems: when I first posted, I
thought it did, but those problems actually came from elsewhere.

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

4

On Tue, Jan 26, 2010 at 1:12 PM, Marnen Laibow-Koser [email protected]
wrote:

$ ruby -v
ruby 1.8.7 (2008-08-11 patchlevel 72) [universal-darwin10.0]
$ irb
irb(main):001:0> Regexp::escape(‘a b’)
=> “a\ b”

Why? This doesn’t seem to make any sense. Is it a bug?

It is intentional. In re.c:rb_reg_quote()

    switch (c) {
      case '[': case ']': case '{': case '}':
      case '(': case ')': case '|': case '-':
      case '*': case '.': case '\\':
      case '?': case '+': case '^': case '$':
      case ' ': case '#':
      case '\t': case '\f': case '\n': case '\r':
        goto meta_found;
    }

And then down in meta_found:

      case ' ':
        *t++ = '\\';
        *t++ = ' ';
        continue;

Kirk H.