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#
# Copyright (c) 2010, Stephen B. Weston
#
# This is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as published
# by the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
# USA
irep <- function(iterable, times, length.out, each) {
# Apply "each" first
it <- if (!missing(each)) {
irep.each(iter(iterable), each)
} else {
iter(iterable)
}
if (!missing(length.out)) {
# Ignore "times" if "length.out" is specified
ilimit(recycle(it), length.out)
} else if (!missing(times)) {
if (length(times) == 1) {
# If "times" has a single value, recycle that many times
recycle(it, times)
} else {
# If "times" has multiple values, it's kind of like "each"
irep.times(it, times)
}
} else {
# Neither "length.out" or "times" was specified
it
}
}
# Internal function used to handle the irep "each" argument
irep.each <- function(it, each) {
each <- as.integer(each[1])
if (is.na(each)) {
each <- 1L
} else if (each < 0) {
stop("invalid 'each' argument")
}
n <- 0L
value <- NULL
nextEl <- if (each == 0) {
function() stop('StopIteration', call.=FALSE)
} else if (each == 1) {
function() nextElem(it)
} else {
function() {
if (n <= 0) {
value <<- nextElem(it)
n <<- each
}
n <<- n - 1L
value
}
}
object <- list(nextElem=nextEl)
class(object) <- c('abstractiter', 'iter')
object
}
# Internal function used to handle the irep "times" argument
irep.times <- function(it, times) {
times <- as.integer(times)
if (length(times) == 0 || any(is.na(times) | times < 0)) {
stop("invalid 'times' argument")
}
i <- 0L
n <- 0L
value <- NULL
nextEl <- function() {
while (n <= 0 && i < length(times)) {
i <<- i + 1L
n <<- times[i]
value <<- nextElem(it)
}
if (n <= 0) {
stop('StopIteration', call.=FALSE)
}
n <<- n - 1L
value
}
object <- list(nextElem=nextEl)
class(object) <- c('abstractiter', 'iter')
object
}
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