regex101: Python Match Workspace

(?mx)applies the following effective flags to the remainder of the pattern: gmx

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

Group 1( # the 1st capture group will contain this sequence 1 # this sequence should begin with 1 (?=(?:[01]{6,19}) # let's see that there are enough 0s and 1s in a line (.*$)) # the 2nd capture group will contain all characters to the end of a line (?:0*1){6})

Comment: the 1st capture group will contain this sequence

1 the literal text 1

Comment: this sequence should begin with 1

Positive Lookahead(?=(?:[01]{6,19}) # let's see that there are enough 0s and 1s in a line (.*$))

Non-Capturing Group(?:[01]{6,19})

Character Class[01]{6,19}

{6,19}matches between 6 and 19 characters from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Comment: let's see that there are enough 0s and 1s in a line

Group 2(.*$)

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

$end of line

Comment: the 2nd capture group will contain all characters to the end of a line

Non-Capturing Group(?:0*1){6}

{6}repeats the group contents below exactly 6 times:

0*the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated any number of times

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Comment: there must be six more 1s in the sequence

Positive Lookahead(?=.{0,13} # complement the 1st capture group to 20 characters \2)

.{0,13}any Unicode character (except for line terminators), repeated between 0 and 13 times

Comment: complement the 1st capture group to 20 characters

\2the text saved by group 2

Comment: the rest of a line should be 2nd capture group

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

Search reference

Regular Expression

(?mx)
(                 # the 1st capture group will contain this sequence
1                 # this sequence should begin with 1
(?=(?:[01]{6,19}) # let's see that there are enough 0s and 1s in a line
   (.*$))         # the 2nd capture group will contain all characters to the end of a line
(?:0*1){6})       # there must be six more 1s in the sequence
(?=.{0,13}        # complement the 1st capture group to 20 characters
\2)               # the rest of a line should be 2nd capture group

Unit Tests

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