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class Pattern

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methods

Pattern.match

function Pattern.match(
  subject: string,
  init: integer?,
  ...: any
) ->  any ...

Match the given pattern against the subject string.

If the match succeeds, returns the index in the subject of the first character after the match, or the captured values (if the pattern captured any value).

An optional numeric argument init makes the match start at that position in the subject string. As usual in Lua libraries, a negative value counts from the end.

Unlike typical pattern-matching functions, match works only in anchored mode; that is, it tries to match the pattern with a prefix of the given subject string (at position init), not with an arbitrary substring of the subject. So, if we want to find a pattern anywhere in a string, we must either write a loop in Lua or write a pattern that matches anywhere. This second approach is easy and quite efficient;

Example:

local pattern = lpeg.R('az') ^ 1 * -1
assert(pattern:match('hello') == 6)
assert(lpeg.match(pattern, 'hello') == 6)
assert(pattern:match('1 hello') == nil)