Character classes
https://docs.rs/regex/latest/regex/#character-classes
Any named character class may appear inside a bracketed
[...]character class.
start_pattern: '^[^\s]'
condition_pattern: '^[\s]+'Note that in YAML, escape sequences are only interpreted in double-quoted scalars. Therefore, the example given in multiline.condition_pattern is also correct, albeit unnecessarily complex.
"^[\\s]+"