regex101: Word Wrap examples

Explanation

Pro

1st Alternative^[#].*\n*(*SKIP)(*F)

^start of line

Character Class[#]

#the literal # (35₁₀ / 43₈ / 23₁₆)

.*any character (except for line terminators), repeated any number of times

\n*a line-feed (newline) character (ASCII 10), repeated any number of times

(*SKIP)acts like (*PRUNE), but the next unanchored match attempt starts where (*SKIP) was reached instead of at the next subject character

(*F)forces the current match attempt to fail at this position

2nd Alternative # Version 1 (substitution: '$1$2\n'): # Match 1-80 characters, backtracking as necessary until whitespace or # EOL is reached. If words > 80 characters (w/o whitespace) are found, # no wrapping is performed on that word. # [1353 steps] #(.{1,80})(?:\s|$)|(\S{81,})(?:\s|$) # Version 2 (substitution: '$1$2\n'): # Same as Version 1 but with a negative look-ahead at the front to skip # to the alternate branch sooner. # [773 steps] #(?!\S{81})(.{1,80})(?:\s|$)|(\S{81,})(?:\s|$) # Version 3 (substitution: '$1$2\n'): # Same as Version 1 but alternations swapped. # [749 steps] #(\S{81,})(?:\s|$)|(.{1,80})(?:\s|$) # Version 4 (substitution: '$1\n'): # Combine alternations into one group. # [712 steps] (\S{79,}|.{1,80})(?:\s|$)

Comment: Version 1 (substitution: '$1$2\n'):

Comment: Match 1-80 characters, backtracking as necessary until whitespace or

Comment: EOL is reached. If words > 80 characters (w/o whitespace) are found,

Comment: no wrapping is performed on that word.

Comment: [1353 steps]

Comment: (.{1,80})(?:\s|$)|(\S{81,})(?:\s|$)

Comment: Version 2 (substitution: '$1$2\n'):

Comment: Same as Version 1 but with a negative look-ahead at the front to skip

Comment: to the alternate branch sooner.

Comment: [773 steps]

Comment: (?!\S{81})(.{1,80})(?:\s|$)|(\S{81,})(?:\s|$)

Comment: Version 3 (substitution: '$1$2\n'):

Comment: Same as Version 1 but alternations swapped.

Comment: [749 steps]

Comment: (\S{81,})(?:\s|$)|(.{1,80})(?:\s|$)

Comment: Version 4 (substitution: '$1\n'):

Comment: Combine alternations into one group.

Comment: [712 steps]

Group 1(\S{79,}|.{1,80})

1st Alternative\S{79,}

\S{79,}any non-whitespace character, repeated at least 79 times

2nd Alternative.{1,80}

.{1,80}any character (except for line terminators), repeated between 1 and 80 times

Non-Capturing Group(?:\s|$)

1st Alternative\s

\sany whitespace character

2nd Alternative$

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

Quick Reference

25 tokens

Regular Expression

^[#].*\n*(*SKIP)(*F)|

# Version 1 (substitution: '$1$2\n'):
# Match 1-80 characters, backtracking as necessary until whitespace or
#  EOL is reached. If words > 80 characters (w/o whitespace) are found,
#  no wrapping is performed on that word.
# [1353 steps]

#(.{1,80})(?:\s|$)|(\S{81,})(?:\s|$)

# Version 2 (substitution: '$1$2\n'):
# Same as Version 1 but with a negative look-ahead at the front to skip
#  to the alternate branch sooner.
# [773 steps]

#(?!\S{81})(.{1,80})(?:\s|$)|(\S{81,})(?:\s|$)

# Version 3 (substitution: '$1$2\n'):
# Same as Version 1 but alternations swapped.
# [749 steps]

#(\S{81,})(?:\s|$)|(.{1,80})(?:\s|$)

# Version 4 (substitution: '$1\n'):
# Combine alternations into one group.
# [712 steps]

(\S{79,}|.{1,80})(?:\s|$)

New

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


#### The following should remain on the same line (not wrap):

# Multiple words whose total character+whitespace count <= 80
123 5678 0 23 5678 012 45678 0 2345 789 12345 78901 3456 8901 3 56 89 12345 7890

# 78-character word followed by 1-character word
123456789012345678901234567890123456789012345678901234567890123456789012345678 1

# 1-character word followed by 78-character word
1 345678901234567890123456789012345678901234567890123456789012345678901234567890


#### The following should wrap to the next

Substitution

$1\n

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


#### The following should remain on the same line (not wrap):

# Multiple words whose total character+whitespace count <= 80
123 5678 0 23 5678 012 45678 0 2345 789 12345 78901 3456 8901 3 56 89 12345 7890

# 78-character word followed by 1-character word
123456789012345678901234567890123456789012345678901234567890123456789012345678 1

# 1-character word followed by 78-character word
1 345678901234567890123456789012345678901234567890123456789012345678901234567890


#### The following should wrap to the next