R/search_locate_bound.R

In stringi: Fast and Portable Character String Processing Facilities

# kate: default-dictionary en_US

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#' @title Locate Text Boundaries
#'
#' @description
#' These functions locate text boundaries
#' (like character, word, line, or sentence boundaries).
#' Use \code{stri_locate_all_*} to locate all the matches.
#' \code{stri_locate_first_*} and \code{stri_locate_last_*}
#' give the first or the last matches, respectively.
#'
#'
#' @details
#' Vectorized over \code{str}.
#'
#' For more information on text boundary analysis
#' performed by \pkg{ICU}'s \code{BreakIterator}, see
#' \link{stringi-search-boundaries}.
#'
#' For \code{stri_locate_*_words},
#' just like in \code{\link{stri_extract_all_words}} and \code{\link{stri_count_words}},
#' \pkg{ICU}'s word \code{BreakIterator} iterator is used
#' to locate the word boundaries, and all non-word characters
#' (\code{UBRK_WORD_NONE} rule status) are ignored.
#' This function is equivalent to a call to
#' \code{stri_locate_*_boundaries(str, type='word', skip_word_none=TRUE, locale=locale)}
#'
#'
#'
#' @param str character vector or an object coercible to
#'
#' @param omit_no_match single logical value; if \code{TRUE},
#'     a no-match will be indicated by a matrix with 0 rows
#'     \code{stri_locate_all_*} only
#'
#' @param opts_brkiter named list with \pkg{ICU} BreakIterator's settings,
#'     see \code{\link{stri_opts_brkiter}};
#'     \code{NULL} for default break iterator, i.e., \code{line_break}
#'
#' @param ... additional settings for \code{opts_brkiter}
#'
#' @param locale \code{NULL} or \code{''} for text boundary analysis following
#'     the conventions of the default locale, or a single string with
#'     locale identifier, see \link{stringi-locale}
#'
#' @param get_length single logical value; if \code{FALSE} (default),
#'     generate \emph{from-to} matrices; otherwise, output
#'     \emph{from-length} ones
#'
#'
#' @return
#' \code{stri_locate_all_*} yields a list of \code{length(str)}
#' integer matrices.
#' \code{stri_locate_first_*} and \code{stri_locate_last_*} generate
#' return an integer matrix.
#' See \code{\link{stri_locate}} for more details.
#'
#'
#' @examples
#' test <- 'The\u00a0above-mentioned    features are very useful. Spam, spam, eggs, bacon, and spam.'
#' stri_locate_all_words(test)
#' stri_locate_all_boundaries(
#'     'Mr. Jones and Mrs. Brown are very happy. So am I, Prof. Smith.',
#'     type='sentence',
#'     locale='en_US@ss=standard' # ICU >= 56 only
#' )
#'
#'
#'
#' @export
#' @family search_locate
#' @family indexing
#' @family locale_sensitive
#' @family text_boundaries
#' @rdname stri_locate_boundaries
stri_locate_all_boundaries <- function(
    str, omit_no_match=FALSE, get_length=FALSE, ..., opts_brkiter=NULL
) {
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))

    .Call(C_stri_locate_all_boundaries, str, omit_no_match, opts_brkiter, get_length)
}


#' @export
#' @rdname stri_locate_boundaries
stri_locate_last_boundaries <- function(
    str, get_length=FALSE, ..., opts_brkiter=NULL
) {
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))

    .Call(C_stri_locate_last_boundaries, str, opts_brkiter, get_length)
}


#' @export
#' @rdname stri_locate_boundaries
stri_locate_first_boundaries <- function(
    str, get_length=FALSE, ..., opts_brkiter=NULL
) {
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))

    .Call(C_stri_locate_first_boundaries, str, opts_brkiter, get_length)
}


#' @export
#' @rdname stri_locate_boundaries
stri_locate_all_words <- function(
    str, omit_no_match=FALSE, locale=NULL, get_length=FALSE
) {
    stri_locate_all_boundaries(
        str, omit_no_match=omit_no_match, get_length=get_length,
        opts_brkiter=stri_opts_brkiter(
            type="word", skip_word_none=TRUE, locale=locale
        )
    )
}


#' @export
#' @rdname stri_locate_boundaries
stri_locate_last_words <- function(
    str, locale=NULL, get_length=FALSE
) {
    stri_locate_last_boundaries(
        str, get_length=get_length,
        opts_brkiter=stri_opts_brkiter(
            type="word", skip_word_none=TRUE, locale=locale
        )
    )
}


#' @export
#' @rdname stri_locate_boundaries
stri_locate_first_words <- function(
    str, locale=NULL, get_length=FALSE
) {
    stri_locate_first_boundaries(
        str, get_length=get_length,
        opts_brkiter=stri_opts_brkiter(
            type="word", skip_word_none=TRUE, locale=locale
        )
    )
}