R/search_extract_4.R

In stringi: Fast and Portable Character String Processing Facilities

# kate: default-dictionary en_US

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#' @title
#' Extract Pattern Occurrences
#'
#' @description
#' These functions extract all substrings matching a given pattern.
#'
#' \code{stri_extract_all_*} extracts all the matches.
#' \code{stri_extract_first_*} and \code{stri_extract_last_*}
#' yield the first or the last matches, respectively.
#'
#' @details
#' Vectorized over \code{str} and \code{pattern} (with recycling
#' of the elements in the shorter vector if necessary). This allows to,
#' for instance, search for one pattern in each given string,
#' search for each pattern in one given string,
#' and search for the i-th pattern within the i-th string.
#'
#' Check out \code{\link{stri_match}} for the extraction of matches
#' to individual regex capture groups.
#'
#' \code{stri_extract}, \code{stri_extract_all}, \code{stri_extract_first},
#' and \code{stri_extract_last} are convenience functions.
#' They merely call \code{stri_extract_*_*}, depending on the arguments used.
#'
#' @param str character vector; strings to search in
#' @param pattern,regex,fixed,coll,charclass character vector;
#'     search patterns; for more details refer to \link{stringi-search}
#' @param opts_collator,opts_fixed,opts_regex a named list to tune up
#'     the search engine's settings; see \code{\link{stri_opts_collator}},
#'     \code{\link{stri_opts_fixed}}, and \code{\link{stri_opts_regex}},
#'     respectively; \code{NULL} for the defaults
#' @param merge single logical value; indicates whether consecutive pattern
#'     matches will be merged into one string;
#'     \code{stri_extract_all_charclass} only
#' @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;
#'     \code{stri_extract_all_*} only
#' @param omit_no_match single logical value; if \code{FALSE},
#'     then a missing value will indicate that there was no match;
#'     \code{stri_extract_all_*} only
#' @param mode single string;
#'     one of: \code{'first'} (the default), \code{'all'}, \code{'last'}
#' @param ... supplementary arguments passed to the underlying functions,
#'     including additional settings for \code{opts_collator}, \code{opts_regex},
#'     and so on
#'
#' @return
#' For \code{stri_extract_all*}, if \code{simplify=FALSE} (the default), then
#' a list of character vectors is returned. Each list element
#' represents the results of a different search scenario.
#' If a pattern is not found and \code{omit_no_match=FALSE},
#' then a character vector of length 1
#' with single \code{NA} value will be generated.
#'
#' Otherwise, i.e., if \code{simplify} is not \code{FALSE},
#' then \code{\link{stri_list2matrix}} with \code{byrow=TRUE} argument
#' is called on the resulting object.
#' In such a case, the function yields a character matrix with an appropriate
#' number of rows (according to the length of \code{str}, \code{pattern}, etc.).
#' Note that \code{\link{stri_list2matrix}}'s \code{fill} argument is set
#' either to an empty string or \code{NA}, depending on
#' whether \code{simplify} is \code{TRUE} or \code{NA}, respectively.
#'
#' \code{stri_extract_first*} and \code{stri_extract_last*}
#' return a character vector. A \code{NA} element indicates a no-match.
#'
#' Note that \code{stri_extract_last_regex} searches from start to end,
#' but skips overlapping matches, see the example below.
#'
#' @examples
#' stri_extract_all('XaaaaX', regex=c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
#' stri_extract_all('Bartolini', coll='i')
#' stri_extract_all('stringi is so good!', charclass='\\p{Zs}') # all white-spaces
#'
#' stri_extract_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}')
#' stri_extract_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}', merge=FALSE)
#' stri_extract_first_charclass('AaBbCc', '\\p{Ll}')
#' stri_extract_last_charclass('AaBbCc', '\\p{Ll}')
#'
#' \dontrun{
#' # emoji support available since ICU 57
#' stri_extract_all_charclass(stri_enc_fromutf32(32:55200), '\\p{EMOJI}')
#' }
#'
#' stri_extract_all_coll(c('AaaaaaaA', 'AAAA'), 'a')
#' stri_extract_first_coll(c('Yy\u00FD', 'AAA'), 'y', strength=2, locale='sk_SK')
#' stri_extract_last_coll(c('Yy\u00FD', 'AAA'), 'y',  strength=1, locale='sk_SK')
#'
#' stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
#' stri_extract_first_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
#' stri_extract_last_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
#'
#' stri_list2matrix(stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+')))
#' stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+'), simplify=TRUE)
#' stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+'), simplify=NA)
#'
#' stri_extract_all_fixed('abaBAba', 'Aba', case_insensitive=TRUE)
#' stri_extract_all_fixed('abaBAba', 'Aba', case_insensitive=TRUE, overlap=TRUE)
#'
#' # Searching for the last occurrence:
#' # Note the difference - regex searches left to right, with no overlaps.
#' stri_extract_last_fixed("agAGA", "aga", case_insensitive=TRUE)
#' stri_extract_last_regex("agAGA", "aga", case_insensitive=TRUE)
#'
#' @family search_extract
#'
#' @export
#' @rdname stri_extract
stri_extract_all <- function(str, ..., regex, fixed, coll, charclass)
{
    providedarg <- c(
        regex = !missing(regex),
        fixed = !missing(fixed),
        coll = !missing(coll),
        charclass = !missing(charclass))

    if (sum(providedarg) != 1)
        stop("you have to specify either `regex`, `fixed`, `coll`, or `charclass`")

    if (providedarg["regex"])
        stri_extract_all_regex(str, regex, ...)
    else if (providedarg["fixed"])
        stri_extract_all_fixed(str, fixed, ...)
    else if (providedarg["coll"])
        stri_extract_all_coll(str, coll, ...)
    else if (providedarg["charclass"])
        stri_extract_all_charclass(str, charclass, ...)
}


#' @export
#' @rdname stri_extract
stri_extract_first <- function(str, ..., regex, fixed, coll, charclass)
{
    providedarg <- c(
        regex = !missing(regex),
        fixed = !missing(fixed),
        coll = !missing(coll),
        charclass = !missing(charclass))

    if (sum(providedarg) != 1)
        stop("you have to specify either `regex`, `fixed`, `coll`, or `charclass`")

    if (providedarg["regex"])
        stri_extract_first_regex(str, regex, ...)
    else if (providedarg["fixed"])
        stri_extract_first_fixed(str, fixed, ...)
    else if (providedarg["coll"])
        stri_extract_first_coll(str, coll, ...)
    else if (providedarg["charclass"])
        stri_extract_first_charclass(str, charclass, ...)
}


#' @export
#' @rdname stri_extract
stri_extract_last <- function(str, ..., regex, fixed, coll, charclass)
{
    providedarg <- c(
        regex = !missing(regex),
        fixed = !missing(fixed),
        coll = !missing(coll),
        charclass = !missing(charclass))

    if (sum(providedarg) != 1)
        stop("you have to specify either `regex`, `fixed`, `coll`, or `charclass`")

    if (providedarg["regex"])
        stri_extract_last_regex(str, regex, ...)
    else if (providedarg["fixed"])
        stri_extract_last_fixed(str, fixed, ...)
    else if (providedarg["coll"])
        stri_extract_last_coll(str, coll, ...)
    else if (providedarg["charclass"])
        stri_extract_last_charclass(str, charclass, ...)
}


#' @export
#' @rdname stri_extract
stri_extract <- function(str, ..., regex, fixed, coll, charclass,
    mode = c("first", "all", "last"))
{
    # `first` is default for compatibility with stringr
    mode <- match.arg(mode)  # this is slow

    switch(mode,
        first = stri_extract_first(str, ..., regex = regex, fixed = fixed,
            coll = coll, charclass = charclass),
        last = stri_extract_last(str, ..., regex = regex,
            fixed = fixed, coll = coll, charclass = charclass),
        all = stri_extract_all(str, ..., regex = regex, fixed = fixed,
            coll = coll, charclass = charclass))
}


#' @export
#' @rdname stri_extract
stri_extract_all_charclass <- function(str, pattern, merge = TRUE, simplify = FALSE,
    omit_no_match = FALSE)
{
    .Call(C_stri_extract_all_charclass, str, pattern, merge, simplify, omit_no_match)
}


#' @export
#' @rdname stri_extract
stri_extract_first_charclass <- function(str, pattern)
{
    .Call(C_stri_extract_first_charclass, str, pattern)
}


#' @export
#' @rdname stri_extract
stri_extract_last_charclass <- function(str, pattern)
{
    .Call(C_stri_extract_last_charclass, str, pattern)
}


#' @export
#' @rdname stri_extract
stri_extract_all_coll <- function(str, pattern, simplify = FALSE,
    omit_no_match = FALSE, ..., opts_collator = NULL)
{
    if (!missing(...))
        opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
    .Call(C_stri_extract_all_coll, str, pattern, simplify, omit_no_match, opts_collator)
}


#' @export
#' @rdname stri_extract
stri_extract_first_coll <- function(str, pattern, ..., opts_collator = NULL)
{
    if (!missing(...))
        opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
    .Call(C_stri_extract_first_coll, str, pattern, opts_collator)
}


#' @export
#' @rdname stri_extract
stri_extract_last_coll <- function(str, pattern, ..., opts_collator = NULL)
{
    if (!missing(...))
        opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
    .Call(C_stri_extract_last_coll, str, pattern, opts_collator)
}


#' @export
#' @rdname stri_extract
stri_extract_all_regex <- function(str, pattern, simplify = FALSE,
    omit_no_match = FALSE, ..., opts_regex = NULL)
{
    if (!missing(...))
        opts_regex <- do.call(stri_opts_regex, as.list(c(opts_regex, ...)))
    .Call(C_stri_extract_all_regex, str, pattern, simplify, omit_no_match, opts_regex)
}


#' @export
#' @rdname stri_extract
stri_extract_first_regex <- function(str, pattern, ..., opts_regex = NULL)
{
    if (!missing(...))
        opts_regex <- do.call(stri_opts_regex, as.list(c(opts_regex, ...)))
    .Call(C_stri_extract_first_regex, str, pattern, opts_regex)
}


#' @export
#' @rdname stri_extract
stri_extract_last_regex <- function(str, pattern, ..., opts_regex = NULL)
{
    if (!missing(...))
        opts_regex <- do.call(stri_opts_regex, as.list(c(opts_regex, ...)))
    .Call(C_stri_extract_last_regex, str, pattern, opts_regex)
}


#' @export
#' @rdname stri_extract
stri_extract_all_fixed <- function(str, pattern, simplify = FALSE,
    omit_no_match = FALSE, ..., opts_fixed = NULL)
{
    if (!missing(...))
        opts_fixed <- do.call(stri_opts_fixed, as.list(c(opts_fixed, ...)))
    .Call(C_stri_extract_all_fixed, str, pattern, simplify, omit_no_match, opts_fixed)
}


#' @export
#' @rdname stri_extract
stri_extract_first_fixed <- function(str, pattern, ..., opts_fixed = NULL)
{
    if (!missing(...))
        opts_fixed <- do.call(stri_opts_fixed, as.list(c(opts_fixed, ...)))
    .Call(C_stri_extract_first_fixed, str, pattern, opts_fixed)
}


#' @export
#' @rdname stri_extract
stri_extract_last_fixed <- function(str, pattern, ..., opts_fixed = NULL)
{
    if (!missing(...))
        opts_fixed <- do.call(stri_opts_fixed, as.list(c(opts_fixed, ...)))
    .Call(C_stri_extract_last_fixed, str, pattern, opts_fixed)
}