FHIRPath Function: replaceMatches

Matches the input using the regular expression in regex and replaces each match with the substitution string. The substitution may refer to identified match groups in the regular expression, as illustrated by the example below that uses named capture groups for month, day, and year to perform a conversion from one date format to another.

If the input collection, regex, or substitution are empty, the result is empty ({ }).

If the input collection contains multiple items, the evaluation of the expression will end and signal an error to the calling environment.

The optional flags parameter can be set to: {:.stu}

• i to perform a case-insensitive search (otherwise is case-sensitive)
• m - Matches the start and end of each line using ^ and $ (multi-line)<br/>(not only begin/end of string) {:.stu}

This example of replaceMatches() will convert a string with a date formatted as MM/dd/yy to dd-MM-yy:

'11/30/1972'.replaceMatches('\\b(?<month>\\d{1,2})/(?<day>\\d{1,2})/(?<year>\\d{2,4})\\b',
       '${day}-${month}-${year}')

This example locates all the instances of aa and surrounds them with double quotes:

'aaabaa'.replaceMatches('aa', '"aa"') // returns "aa"ab"aa"

Note: Platforms will typically use native regular expression implementations. These are typically fairly similar, but there will always be small differences. As such, FHIRPath does not prescribe a particular dialect, but recommends the use of the [PCRE] flavor as the dialect most likely to be broadly supported and understood.

Summary

• Category: String Manipulation
• Section: 5.6.12
• Return Type: String
• Empty Input Result: empty
• Errors on Multiple Input: true

Description

Matches the input using the regular expression in regex and replaces each match with the substitution string. Within a substitution string, \n refers to the nth match group in the regex. \0 refers to the entire match.

Arguments

• regex: String - Regular expression to match against
• substitution: String - Substitution string, with \n referring to match groups
• flags (optional): String - Optional flags for the regex (i for case-insensitive, m for multi-line)

Type Mapping

• String-String

Example

'10/15/2014'.replaceMatches('[0-9]+', 'X') // 'X/X/X'
'Mary had a little lamb'.replaceMatches('(\\w+) (\\w+)', '\\2, \\1') // 'had, Mary a lamb, little'