Allowing timestamp functions in expressions

Current situation

Expressions are used in many places, and it often makes sense to have time-based behavior. Some contexts offers a timestamp, but there is no easy way (besides regular expressions) to use them.

Desired outcome

A set of functions dealing with timestamps that can be used in expressions.

They all return an empty string if the timestamp cannot be parsed.

Namely:

• year(timestamp): a number
• month(timestamp): a number (1-12)
• week(timestamp): a number (1-52 or 53), the week number according to ISO
• day(timestamp): a number(1-28,29,30,31), the day in the month
• dayOfWeek(timestamp): a string ('Monday', ...)
• dayOfWeekISO(timestamp): a number (1-7, 1==Monday)
• hour(timestamp): a number (0-23)
• minute(timestamp): a number (0-59)
• second(timestamp): a number (0-59)