regex: match multiple lines until a line contains

Question

I have the following string:

foo.a = [10
20
30
40];

foo.b = 'foobar';

I am using the foo\.[ab]\s*= regex.

I try to match all the lines that follow until a line contains a certain character.

The first match should cover everything except of the last line, because that line contains an equal sign. I tried a lot of things with (negative) lookahead, but I can't figure it out.

Answer 1

You need a positive lookahead.

foo\.[ab][\s\S]*?(?=\n.*?=|$)

• [\s\S]*? matches lazily any character
• (?=\n.*?=|$) until a newline containing an = is ahead or $ end.

See demo at regex101

Answer 2

Variation 1

foo\.[ab]\s*=[\s\S]*?(?=foo\.[ab]\s*=)

It matches what you want up until another foo.a = or foo.b = using a positive lookahead.

Demo: https://regex101.com/r/xV9wL4/2

Variation 2

(foo\.[ab]\s*=)[\s\S]*?(?=(?1))

This works the same as above but using a capturing group and a reference to that capturing group (by (?1)) to simplify it down

Demo: https://regex101.com/r/xV9wL4/3