Text pattern expressions perform operations on the sets of possible text values that one or more terms recognize.
A primary expression can be:
A text literal
A reference to a syntax or token rule
An expression indicating a repeated sequence of primary expressions of a specified length
An expression indicating any of a continuous range of characters
An inline sequence of pattern declarations
The following grammar reflects this structure.
A character class is a compact syntax for a range of continuous characters. This expression requires that the text literals be of length 1 and that ...