R/search_extract_bound.R

In stringi: Fast and Portable Character String Processing Facilities

# kate: default-dictionary en_US

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#' @title
#' Extract Data Between Text Boundaries
#'
#' @description
#' These functions extract data between text boundaries.
#'
#' @details
#' Vectorized over \code{str}.
#'
#' For more information on text boundary analysis
#' performed by \pkg{ICU}'s \code{BreakIterator}, see
#' \link{stringi-search-boundaries}.
#'
#' In case of \code{stri_extract_*_words},
#' just like in \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.
#'
#'
#' @param str character vector or an object coercible to
#' @param omit_no_match single logical value; if \code{FALSE},
#' then a missing value will indicate that there are no words
#' @param simplify single logical value;
#' if \code{TRUE} or \code{NA}, then a character matrix is returned;
#' otherwise (the default), a list of character vectors is given, see Value
#' @param opts_brkiter a named list with \pkg{ICU} BreakIterator's settings,
#' see \code{\link{stri_opts_brkiter}};
#' \code{NULL} for the 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}
#'
#' @return
#' For \code{stri_extract_all_*},
#' if \code{simplify=FALSE} (the default), then a
#'  list of character vectors is returned. Each string consists of
#' a separate word. In case of \code{omit_no_match=FALSE} and
#' if there are no words or if a string is missing,
#' a single \code{NA} is provided on output.
#'
#' Otherwise, \code{\link{stri_list2matrix}} with \code{byrow=TRUE} argument
#' is called on the resulting object.
#' In such a case, a character matrix with \code{length(str)} rows
#' is returned. Note that \code{\link{stri_list2matrix}}'s \code{fill} argument
#' is set to an empty string and \code{NA},
#' for \code{simplify} \code{TRUE} and \code{NA}, respectively.
#'
#' For \code{stri_extract_first_*} and \code{stri_extract_last_*},
#' a character vector is returned.
#' A \code{NA} element indicates a no-match.
#'
#' @examples
#' stri_extract_all_words('stringi: THE string processing package 123.48...')
#'
#' @export
#' @family search_extract
#' @family locale_sensitive
#' @family text_boundaries
#' @rdname stri_extract_boundaries
stri_extract_all_boundaries <- function(str, simplify = FALSE, omit_no_match = FALSE,
    ..., opts_brkiter = NULL)
{
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))
    .Call(C_stri_extract_all_boundaries, str, simplify, omit_no_match, opts_brkiter)
}


#' @export
#' @rdname stri_extract_boundaries
stri_extract_last_boundaries <- function(str, ..., opts_brkiter = NULL)
{
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))
    .Call(C_stri_extract_last_boundaries, str, opts_brkiter)
}


#' @export
#' @rdname stri_extract_boundaries
stri_extract_first_boundaries <- function(str, ..., opts_brkiter = NULL)
{
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))
    .Call(C_stri_extract_first_boundaries, str, opts_brkiter)
}


#' @export
#' @rdname stri_extract_boundaries
stri_extract_all_words <- function(str, simplify = FALSE, omit_no_match = FALSE,
    locale = NULL)
{
    stri_extract_all_boundaries(
        str, simplify, omit_no_match,
        opts_brkiter = stri_opts_brkiter(
            type = "word", skip_word_none = TRUE, locale = locale
        )
    )
}


#' @export
#' @rdname stri_extract_boundaries
stri_extract_first_words <- function(str, locale = NULL)
{
    stri_extract_first_boundaries(str,
        opts_brkiter = stri_opts_brkiter(type = "word",
        skip_word_none = TRUE, locale = locale))
}


#' @export
#' @rdname stri_extract_boundaries
stri_extract_last_words <- function(str, locale = NULL)
{
    stri_extract_last_boundaries(str,
        opts_brkiter = stri_opts_brkiter(type = "word",
        skip_word_none = TRUE, locale = locale))
}