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split

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Splits $haystack into chunks by its substrings that match with $pattern

namespace HH\Lib\Regex;

function split(
  string $haystack,
  Pattern<Match> $delimiter,
  ?int $limit = NULL,
): vec<string>;

If $limit is given, the returned vec will have at most that many elements. The last element of the vec will be whatever is left of the haystack string after the appropriate number of splits. If no substrings of $haystack match $delimiter, a vec containing only $haystack will be returned. The regex pattern follows the PCRE library: https://www.pcre.org/original/doc/html/pcresyntax.html.

Throws InvariantException if $limit < 2.

Guide​

Parameters​

  • string $haystack
  • Pattern<Match> $delimiter
  • ?int $limit = NULL

Returns​

  • vec<string>