Reads the text of a range, as range(from) does (DMN 1.6, Table 73, grammar rules 66 and 67; decision D-73).

The text is an interval: a bracket, an endpoint, .., an endpoint, and a bracket. [ is a closed start, ( and ] an open one; ] is a closed end, ) and [ an open one. An endpoint is a literal, which is not an expression that is run: a number (-5, 1.5, 1e3), a string ("a"), an @ literal (@"2020-01-01"), or date, time, date and time or duration called on one string (date("2020-01-01")). A name, an operation, a call of anything else and null are not endpoints, so no expression is evaluated and nothing of the run is read.

The interval is the value that the literal [18..21) is (Feel.Runtime.RangeLiteral.build/4). A range with an end that is not there is the one that the test >= 2 is (build_prefix/2), as the specification's examples have it (range("[2..)") is >=2), and not the interval [2..null), which is not equal to it (D-61).

The text is read with the lexer and the parser of the expressions, so the white space around the parts, the escapes of a string and the forms of a number are those of FEEL. A text that is not a range is a diagnostic with the code :argument_out_of_domain, and the reason.

An endpoint that is a time or a date and time is read as the extensions that are on spell it (D-81): [@"13:30"..@"14:00"] and [time("13:30")..time("14:00")] are ranges of times where :camunda is on, with the :info :temporal_spelling reported for each text, and the error of the specification where it is not.

iex> env = Feel.Runtime.Env.new()
iex> {:ok, range} = Feel.Runtime.RangeText.parse(~s|[18..21)|, env)
iex> {range.start, range.end, range.start_included, range.end_included}
{Decimal.new(18), Decimal.new(21), true, false}
iex> {:ok, range} = Feel.Runtime.RangeText.parse(~s|(..2)|, env)
iex> {range.start, range.end, range.operator}
{nil, Decimal.new(2), :lt}
iex> {:error, diagnostic} = Feel.Runtime.RangeText.parse(~s|[3..1]|, env)
iex> diagnostic.details.reason
"the start is after the end"