Search operator

A search operator specifies how the comparison of a search value and a zettel should be executed. Every comparison is done case-insensitive, treating all uppercase letters the same as lowercase letters.

The following are allowed search operator characters:

• The exclamation mark character (!, U+0021) negates the meaning
• The tilde character (~, U+007E) compares on matching (match operator)
• The greater-than sign character (>, U+003E) matches if there is some prefix (prefix operator)
• The less-than sign character (<, U+003C) compares a suffix relationship (suffix operator)
• The colon character (:, U+003A) compares on equal words (has operator)
• The question mark (?, U+003F) checks for an existing metadata key (exist operator)

Since the exclamation mark character can be combined with the other, there are 10 possible combinations:

1. !: is an abbreviation of the !~ operator.
2. ~: is successful if the search value matched the value to be compared.
3. !~: is successful if the search value does not match the value to be compared.
4. :: is successful if the search value is equal to one word of the value to be compared.
5. !:: is successful if the search value is not equal to any word of the value to be compared.
6. >: is successful if the search value is a prefix of the value to be compared.
7. !>: is successful if the search value is not a prefix of the value to be compared.
8. <: is successful if the search value is a suffix of the value to be compared.
9. !<: is successful if the search value is not a suffix of the value to be compared.
10. ?: is successful if the metadata contains the given key.
11. !?: is successful if the metadata does not contain the given key.
12. : a missing search operator can only occur for a full-text search. It is equal to the ~ operator.