R/extract.R

In re2r: RE2 Regular Expression

## This file is part of the 're2r' package for R.
## Copyright (C) 2016, Qin Wenfeng
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#' Extract matching patterns from a string.
#'
#' Extract matching patterns from a string. Vectorised over string and pattern.
#'
#' @inheritParams re2_count
#' @examples
#' re2_extract("yabba dabba doo", "(.)")
#' re2_extract_all("yabba dabba doo", "(.)")
#'
#' str <- c("Aster", "Azalea x2", "Baby's Breath", "Bellflower")
#' re2_extract(str, "\\d")
#' re2_extract(str, "[a-z]+")
#' re2_extract(str, "\\b\\w{1,3}\\b")
#'
#' # Extract all matches
#' re2_extract_all(str, "[A-Za-z]+")
#' re2_extract_all(str, "\\b\\w{1,3}\\b")
#' re2_extract_all(str, "\\d")
#'
#' @return A character vector for \code{\link{re2_extract}}, and a list for \code{\link{re2_extract_all}}.
#' @seealso \code{\link{re2_match}} to extract matched groups.
#' @export
re2_extract = function(string,
                       pattern,
                       anchor = UNANCHORED,
                       parallel = FALSE,
                       grain_size = 100000,
                       ...) {
    if (is.character(pattern) || mode(pattern) == "logical") {
        pattern = re2(pattern, ...)
    }
    cpp_extract(stri_enc_toutf8(string), pattern, all = FALSE, anchor = anchor,  FALSE, 1)
}

#' @rdname re2_extract
#' @export
re2_extract_all = function(string,
                           pattern,
                           anchor = UNANCHORED,
                           parallel = FALSE,
                           grain_size = 100000,
                           ...) {
    if (is.character(pattern) || mode(pattern) == "logical") {
        pattern = re2(pattern, ...)
    }
    cpp_extract(stri_enc_toutf8(string), pattern, all= TRUE, anchor = anchor, FALSE, 1)
}