Method: Janeway::Functions#parse_function_match

Defined in:
lib/janeway/functions/match.rb

#parse_function_match ⇒ Object

The match() function extension provides a way to check whether (the entirety of; see Section 2.4.7) a given string matches a given regular expression, which is in the form described in [RFC9485].

Its arguments are instances of ValueType (possibly taken from a singular query, as for the first argument in the example above). If the first argument is not a string or the second argument is not a string conforming to [RFC9485], the result is LogicalFalse. Otherwise, the string that is the first argument is matched against the I-Regexp contained in the string that is the second argument; the result is LogicalTrue if the string matches the I-Regexp and is LogicalFalse otherwise.

The regexp dialect is called “I-Regexp” and is defined in RFC9485.

Fortunately a shortcut is availalble, that RFC contains instructions for converting an I-Regexp to ruby’s regexp format. The instructions are:

* For any unescaped dots (.) outside character classes (first
  alternative of charClass production), replace the dot with [^\n\r].
* Enclose the regexp in \A(?: and )\z.

tl;dr: How is this different from the search function? “match” must match the entire string, “search” matches a substring.

Examples:

$[?match(@.date, “1974-05-..”)]

Raises:

See Also:



35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/janeway/functions/match.rb', line 35

def parse_function_match
  consume # function
  raise "expect group_start token, found #{current}" unless current.type == :group_start

  consume # (

  # Read first parameter
  parameters = []
  parameters << parse_function_parameter
  raise Error, 'Not enough parameters for match() function call' unless current.type == :union

  consume # ,

  # Read second parameter (the regexp)
  # This could be a string, in which case it is available now.
  # Otherwise it is an expression that takes the regexp from the input document,
  # and the iregexp will not be available until interpretation.
  parameters << parse_function_parameter
  raise Error, 'Too many parameters for match() function call' unless current.type == :group_end

  AST::Function.new('match', parameters) do |str, str_iregexp|
    if str.is_a?(String) && str_iregexp.is_a?(String)
      regexp = translate_iregex_to_ruby_regex(str_iregexp)
      regexp.match?(str)
    else
      false # result defined by RFC9535
    end
  end
end