R/match.R

In re2r: RE2 Regular Expression

## This file is part of the 're2r' package for R.
## Copyright (C) 2016, Qin Wenfeng
## All rights reserved.
##
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## modification, are permitted provided that the following conditions are met:
##
## 1. Redistributions of source code must retain the above copyright notice,
## this list of conditions and the following disclaimer.
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## 2. Redistributions in binary form must reproduce the above copyright notice,
## this list of conditions and the following disclaimer in the documentation
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#' Get a match group
#' @export
#' @param self re2_matrix
#' @param group group name
#' @examples
#' text = c("this is test",
#'     "this is test, and this is not test",
#'     "they are tests")
#' res = re2_match(
#'     string = text,
#'     pattern = "(?P<testname>this)( is)"
#' )
#' class(res)
#' is.matrix(res)
#' is.character(res)
#' print(res)
#' res$testname
#' res$.match
#' res$`.2`
#' res[, ".2"]
#' res[, ".match"]
#' res[, "testname"]
`$.re2_matrix` = function (self, group) {
    return(self[, group])
}

#' Find matched groups from strings.
#'
#' @inheritParams re2_count
#' @examples
#'
#' strings <- c("Gym: 627-112-1433", "Apple x2",
#'              "888 888 8888", "This is a test.",
#'              "627-112-1433 223-343-2232")
#' phone <- "([2-9][0-9]{2})[- .](?P<second>[0-9]{3})[- .]([0-9]{4})"
#' re2_extract(strings, phone)
#' re2_match(strings, phone)
#'
#' re2_extract_all(strings, phone)
#' re2_match_all(strings, phone)
#'
#' regexp = re2("test",case_sensitive = FALSE)
#' re2_match("TEST", regexp)
#'
#' # differences from stringi
#'
#' # This kind of repeating capturing group works differently.
#' re2_match("aasd", "(a*)+")
#' stringi::stri_match("aasd", regex = "(a*)+")
#'
#' # In stringi, "" empty search patterns return NA.
#' # In re2r, empty search patterns will match
#' # empty string.
#'
#' re2_match("abc", "")
#' stringi::stri_match("abc", regex = "")
#'
#' dates <- c("2008-08-08", "2020", "a string",
#'            "12-12-72", "1989-06-30", "2115-11-21 09:21")
#' pattern <- "([0-9]{4})-([0-1][0-9])-([0-3][0-9])"
#' re2_match(dates, pattern)
#'
#' pattern <- "(?P<y>[0-9]{4})-(?P<m>[0-1][0-9])-(?P<d>[0-3][0-9])"
#' (res = re2_match(dates, pattern))
#' res$y
#' res$m
#' res$d
#'
#' pattern <- paste0(
#' "(?P<first>[A-Z][a-z]+) ",
#' "(?P<last>[A-Z][a-z]+)"
#' )
#' texts <- c(
#'     "  Taylor Swift and Lady Gaga",
#'     "One Direction hit the road agains"
#' )
#' re2_match_all(texts, pattern)
#'
#' texts = c("pi is 3.14529..",
#'           "-15.34 F",
#'           "128 days",
#'           "1.9e10",
#'           "123,340.00$",
#'           "only texts")
#' (number_pattern = re2(".*?(?P<number>-?\\d+(,\\d+)*(\\d+(e\\d+)?)?).*?"))
#'
#' (res = re2_match(texts, number_pattern))
#' res$number
#'
#' # show_regex(number_pattern)
#' @return For \code{\link{re2_match}}, a character matrix. First column
#'  is the complete match, followed by one column
#' for each capture group with names.
#'
#' For \code{\link{re2_match_all}}, a list of
#' character matrices.
#' @export
re2_match = function(string,
                     pattern,
                     anchor = UNANCHORED,
                     parallel = FALSE,
                     grain_size = 100000,
                     ...) {
    if (is.character(pattern) || mode(pattern) == "logical") {
        pattern = re2(pattern, ...)
    }
    cpp_match(stri_enc_toutf8(string),
              regexp = pattern,
              value = TRUE,
              anchor = anchor,
              all = FALSE,
              parallel = parallel,
              grain_size = grain_size)
}

#' @export
#' @rdname re2_match
re2_match_all = function(string,
                         pattern,
                         anchor = UNANCHORED,
                         parallel = FALSE,
                         grain_size = 100000,
                         ...) {
    if (is.character(pattern) || mode(pattern) == "logical") {
        pattern = re2(pattern, ...)
    }
    cpp_match(stri_enc_toutf8(string),
              regexp = pattern,
              value = TRUE,
              anchor = anchor,
              all = TRUE,
              parallel = parallel,
              grain_size = grain_size)
}