Project

General

Profile

Actions

Bug #13892

closed

Matching the end of a string followed by an empty greedy regex and a word boundary (.*\b) fails in all versions >= 1.9

Added by jhriggs (Jim Riggs) over 6 years ago. Updated over 6 years ago.

Status:
Closed
Target version:
-
ruby -v:
1.8.7, 1.9.3p551, 2.0.0p648, 2.1.9p490, 2.2.7p470, 2.3.4p301, 2.4.1p111
[ruby-core:82760]

Description

This is a very specific regex failure that occurs when the final character of the string is matched by the end of a pattern that terminates with .*\b. For example:

"abc" =~ /c.*\b/
"abc" =~ /abc.*\b/
"abc" =~ /\b.*abc.*\b/

In Ruby 1.8.7 and every other language I have tested (perl, pcre, javascript, python, go, ...) this matches. Starting in 1.9, it appears that the greedy .* causes the \b to fail, though it should match. This only occurs when the pattern matches at the end of the string being matched. Based on my non-exhaustive testing, this only occurs with .*\b; other patterns like.?\b and specific characters such as d*\b work as expected:

ruby1.8 : /c.*\b/       : true
ruby1.8 : /abc.*\b/     : true
ruby1.8 : /\b.*abc.*\b/ : true
ruby1.8 : /c.?\b/       : true
ruby1.8 : /abc.?\b/     : true
ruby1.8 : /\b.?abc.?\b/ : true
ruby1.8 : /d*\b/        : true
ruby1.8 : /abcd*\b/     : true
ruby1.8 : /\b.*abcd*\b/ : true

ruby1.9 : /c.*\b/       : false
ruby1.9 : /abc.*\b/     : false
ruby1.9 : /\b.*abc.*\b/ : false
ruby1.9 : /c.?\b/       : true
ruby1.9 : /abc.?\b/     : true
ruby1.9 : /\b.?abc.?\b/ : true
ruby1.9 : /d*\b/        : true
ruby1.9 : /abcd*\b/     : true
ruby1.9 : /\b.*abcd*\b/ : true

ruby2.0 : /c.*\b/       : false
ruby2.0 : /abc.*\b/     : false
ruby2.0 : /\b.*abc.*\b/ : false
ruby2.0 : /c.?\b/       : true
ruby2.0 : /abc.?\b/     : true
ruby2.0 : /\b.?abc.?\b/ : true
ruby2.0 : /d*\b/        : true
ruby2.0 : /abcd*\b/     : true
ruby2.0 : /\b.*abcd*\b/ : true

ruby2.1 : /c.*\b/       : false
ruby2.1 : /abc.*\b/     : false
ruby2.1 : /\b.*abc.*\b/ : false
ruby2.1 : /c.?\b/       : true
ruby2.1 : /abc.?\b/     : true
ruby2.1 : /\b.?abc.?\b/ : true
ruby2.1 : /d*\b/        : true
ruby2.1 : /abcd*\b/     : true
ruby2.1 : /\b.*abcd*\b/ : true

ruby2.2 : /c.*\b/       : false
ruby2.2 : /abc.*\b/     : false
ruby2.2 : /\b.*abc.*\b/ : false
ruby2.2 : /c.?\b/       : true
ruby2.2 : /abc.?\b/     : true
ruby2.2 : /\b.?abc.?\b/ : true
ruby2.2 : /d*\b/        : true
ruby2.2 : /abcd*\b/     : true
ruby2.2 : /\b.*abcd*\b/ : true

ruby2.3 : /c.*\b/       : false
ruby2.3 : /abc.*\b/     : false
ruby2.3 : /\b.*abc.*\b/ : false
ruby2.3 : /c.?\b/       : true
ruby2.3 : /abc.?\b/     : true
ruby2.3 : /\b.?abc.?\b/ : true
ruby2.3 : /d*\b/        : true
ruby2.3 : /abcd*\b/     : true
ruby2.3 : /\b.*abcd*\b/ : true

ruby2.4 : /c.*\b/       : false
ruby2.4 : /abc.*\b/     : false
ruby2.4 : /\b.*abc.*\b/ : false
ruby2.4 : /c.?\b/       : true
ruby2.4 : /abc.?\b/     : true
ruby2.4 : /\b.?abc.?\b/ : true
ruby2.4 : /d*\b/        : true
ruby2.4 : /abcd*\b/     : true
ruby2.4 : /\b.*abcd*\b/ : true

See also:

Actions

Also available in: Atom PDF

Like0
Like0Like0Like0Like0Like0