How can I write a regular expression that identifies all patterns only if they are not preceded by another pattern?

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To identify all patterns that are not preceded by another pattern, you can use a negative lookbehind assertion in your regular expression. The general syntax of a negative lookbehind assertion is:

(?<!pattern)target

Where pattern is the pattern that should not immediately precede target. Here's an example:

(?<!pre-)[a-z]+

This regular expression will match any lowercase letters that are not immediately preceded by the string "pre-". For example, it will match "apple" and "banana", but not "pre-orange" or "pre-grape".

You can adjust the regular expression and the negative lookbehind assertion as needed to fit your specific pattern matching requirements.