R/search_subset_4.R

In stringi: Fast and Portable Character String Processing Facilities

# kate: default-dictionary en_US

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#' @title
#' Select Elements that Match a Given Pattern
#'
#' @description
#' These functions return or modify a sub-vector where there is a match to
#' a given pattern. In other words, they
#' are roughly equivalent (but faster and easier to use) to a call to
#' \code{str[\link{stri_detect}(str, ...)]} or
#' \code{str[\link{stri_detect}(str, ...)] <- value}.
#'
#' @details
#' Vectorized over \code{str} as well as partially over \code{pattern}
#' and \code{value},
#' with recycling of the elements in the shorter vector if necessary.
#' As the aim here is to subset \code{str}, \code{pattern}
#' cannot be longer than the former. Moreover, if the number of
#' items to replace is not a multiple of length of \code{value},
#' a warning is emitted and the unused elements are ignored.
#' Hence, the length of the output will be the same as length of \code{str}.
#'
#' \code{stri_subset} and \code{stri_subset<-} are convenience functions.
#' They call either \code{stri_subset_regex},
#' \code{stri_subset_fixed}, \code{stri_subset_coll},
#' or \code{stri_subset_charclass},
#' depending on the argument used.
#'
#' @param str character vector; strings to search within
#'
#' @param pattern,regex,fixed,coll,charclass character vector;
#'     search patterns (no more than the length of \code{str});
#'     for more details refer to \link{stringi-search}
#'
#' @param negate single logical value; whether a no-match is rather of interest
#'
#' @param omit_na single logical value; should missing values be excluded
#' from the result?
#'
#' @param opts_collator,opts_fixed,opts_regex a named list used 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 ... supplementary arguments passed to the underlying functions,
#'     including additional settings for \code{opts_collator}, \code{opts_regex},
#'     \code{opts_fixed}, and so on
#'
#' @param value non-empty character vector of replacement strings;
#'     replacement function only
#'
#'
#' @return The \code{stri_subset_*} functions return a character vector.
#' As usual, the output encoding is UTF-8.
#'
#' The \code{stri_subset_*<-} functions modifies \code{str} 'in-place'.
#'
#'
#' @examples
#' stri_subset_regex(c('stringi R', '123', 'ID456', ''), '^[0-9]+$')
#'
#' x <- c('stringi R', '123', 'ID456', '')
#' `stri_subset_regex<-`(x, '[0-9]+$', negate=TRUE, value=NA)  # returns a copy
#' stri_subset_regex(x, '[0-9]+$') <- NA  # modifies `x` in-place
#' print(x)
#'
#' @family search_subset
#' @export
#' @rdname stri_subset
stri_subset <- 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_subset_regex(str, regex, ...)
    else if (providedarg["fixed"])
        stri_subset_fixed(str, fixed, ...)
    else if (providedarg["coll"])
        stri_subset_coll(str, coll, ...)
    else if (providedarg["charclass"])
        stri_subset_charclass(str, charclass, ...)
}


#' @export
#' @rdname stri_subset
#' @usage stri_subset(str, ..., regex, fixed, coll, charclass) <- value
`stri_subset<-` <- function(str, ..., regex, fixed, coll, charclass, value)
{
    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_subset_regex<-`(str, regex, ..., value = value)
    else if (providedarg["fixed"])
        `stri_subset_fixed<-`(str, fixed, ..., value = value)
    else if (providedarg["coll"])
        `stri_subset_coll<-`(str, coll, ..., value = value)
    else if (providedarg["charclass"])
        `stri_subset_charclass<-`(str, charclass, ..., value = value)
}


#' @export
#' @rdname stri_subset
stri_subset_fixed <- function(str, pattern, omit_na = FALSE, negate = FALSE, ...,
    opts_fixed = NULL)
{
    if (!missing(...))
        opts_fixed <- do.call(stri_opts_fixed, as.list(c(opts_fixed, ...)))
    .Call(C_stri_subset_fixed, str, pattern, omit_na, negate, opts_fixed)
}


#' @export
#' @rdname stri_subset
#' @usage stri_subset_fixed(str, pattern, negate=FALSE, ..., opts_fixed=NULL) <- value
`stri_subset_fixed<-` <- function(str, pattern, negate = FALSE, ...,
    opts_fixed = NULL,  value)
{
    if (!missing(...))
        opts_fixed <- do.call(stri_opts_fixed, as.list(c(opts_fixed, ...)))
    .Call(C_stri_subset_fixed_replacement, str, pattern, negate, opts_fixed, value)
}


#' @export
#' @rdname stri_subset
stri_subset_charclass <- function(str, pattern, omit_na = FALSE, negate = FALSE)
{
    .Call(C_stri_subset_charclass, str, pattern, omit_na, negate)
}


#' @export
#' @rdname stri_subset
#' @usage stri_subset_charclass(str, pattern, negate=FALSE) <- value
`stri_subset_charclass<-` <- function(str, pattern, negate = FALSE, value)
{
    .Call(C_stri_subset_charclass_replacement, str, pattern, negate, value)
}


#' @export
#' @rdname stri_subset
stri_subset_coll <- function(str, pattern, omit_na = FALSE, negate = FALSE, ...,
    opts_collator = NULL)
{
    if (!missing(...))
        opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
    .Call(C_stri_subset_coll, str, pattern, omit_na, negate, opts_collator)
}


#' @export
#' @rdname stri_subset
#' @usage stri_subset_coll(str, pattern, negate=FALSE, ..., opts_collator=NULL) <- value
`stri_subset_coll<-` <- function(str, pattern, negate = FALSE, ..., opts_collator = NULL,
    value)
{
    if (!missing(...))
        opts_collator <- do.call(stri_opts_collator, as.list(c(opts_collator, ...)))
    .Call(C_stri_subset_coll_replacement, str, pattern, negate, opts_collator, value)
}


#' @export
#' @rdname stri_subset
stri_subset_regex <- function(str, pattern, omit_na = FALSE, negate = FALSE, ...,
    opts_regex = NULL)
{
    if (!missing(...))
        opts_regex <- do.call(stri_opts_regex, as.list(c(opts_regex, ...)))
    .Call(C_stri_subset_regex, str, pattern, omit_na, negate, opts_regex)
}


#' @export
#' @rdname stri_subset
#' @usage stri_subset_regex(str, pattern, negate=FALSE, ..., opts_regex=NULL) <- value
`stri_subset_regex<-` <- function(str, pattern, negate = FALSE, ..., opts_regex = NULL,
    value)
{
    if (!missing(...))
        opts_regex <- do.call(stri_opts_regex, as.list(c(opts_regex, ...)))
    .Call(C_stri_subset_regex_replacement, str, pattern, negate, opts_regex, value)
}