# Functions
NewParser constructs a new parser that reads the input from r.
NewScanner constructs a new scanner that reads from r.
Parse parses the specified query string.
ParseDate parses s as a date string in the format used by DATE values.
ParseTime parses s as a timestamp in the format used by TIME values.
# Constants
DateFormat is the format string used for datestamp values.
operator: AND.
operator: CONTAINS.
datestamp: DATE yyyy-mm-dd.
operator: =.
operator: EXISTS.
operator: >=.
operator: >.
TimeFormat is the format string used for timestamp values.
invalid or unknown token.
operator: <=.
operator: <.
number: 0, 15.5, 100.
string value: 'foo bar'.
field tag: x.y.
timestamp: TIME yyyy-mm-ddThh:mm:ss([-+]hh:mm|Z).
# Structs
An Arg is the argument of a comparison operator.
A Condition is a single conditional expression, consisting of a tag, a comparison operator, and an optional argument.
Parser is a query expression parser.
Scanner reads lexical tokens of the query language from an input stream.