##-- Keep  'library' and 'library.dynam'  PLATFORM-Indepedent !
##-- Use  .Platform  in	 ./system.unix.R [./system.win.R , ...] to configure!
##	  ~~~~~~~~~

library <-
  function (name, help, lib.loc = .lib.loc, character.only = FALSE,
            logical.return = FALSE, warn.conflicts = name != "MASS")
{
    if (!missing(name)) {
        if (!character.only)
            name <- as.character(substitute(name))
        lib.source <- function(file, env) {
            exprs <- parse(n = -1, file = file)
            if (length(exprs) == 0)
                return(invisible())
            for (i in exprs) yy <- eval(i, env)
            invisible()
        }
        pkgname <- paste("package", name, sep = ":")
        if (is.na(match(pkgname, search()))) {
            packagedir <- system.file("", pkg = name, lib = lib.loc)
            if (packagedir == "") {
                txt <- paste("There is no package called `",
                             name, "'", sep = "")
                if (logical.return) {
                    warning(txt)
                    return(FALSE)
                }
                else stop(txt)
            }
            which.lib.loc <- lib.loc[match(packagedir[1], file.path(lib.loc, name))]
            if (length(packagedir) > 1) {
                warning(paste("Package `", name, "' found more than once,\n  ",
                              "using the one found in `", which.lib.loc,
                              "'", sep = ""))
            }
            file <- system.file("R", name, pkg = name, lib = lib.loc)
            ## allowed zipped R source files
            if (file == "") {
                tfile <- file.path(which.lib.loc, name, "R", name)
                zfile <- zip.file.extract(tfile)
                if (zfile != tfile) {
                    file <- zfile
                    on.exit(unlink(file))
                }
            }
            # create environment
            env <- attach(NULL, name = pkgname)
            # "source" file into env
            if (file == "")
                warning(paste("Package `", name, "' contains no R code",
                              sep = ""))
            else lib.source(file, env)
            lib.fixup(env, .GlobalEnv)
            if (exists(".First.lib", envir = env, inherits = FALSE)) {
                firstlib <- get(".First.lib", envir = env, inherits = FALSE)
                firstlib(which.lib.loc, name)
            }
            if (warn.conflicts) {
                ##-- Check for conflicts
                dont.mind <- c("last.dump", "last.warning", ".Last.value",
                               ".Random.seed")
                ## Currently, package is ALWAYS at "pos=2"
                lib.pos <- 2
                ob <- objects(lib.pos)
                ipos <- seq(along = sp <- search())[-c(lib.pos,
                            match("Autoloads", sp))]
                for (i in ipos) {
                    obj.same <- match(objects(i), ob, nomatch = 0)
                    fst <- TRUE
                    if (any(obj.same > 0) && length(same <- (ob <- ob[obj.same])[!ob %in% dont.mind])) {
                        if (fst) {
                            fst <- FALSE
                            cat("\nAttaching Package \"", pkgname,
                                "\":\n\n", sep = "")
                        }
                        cat("\n\tThe following object(s) are masked",
                            if (i < lib.pos)
                            "by"
                            else "from", sp[i], ":\n\n\t", same, "\n\n")
                    }
                }
            }
        }
        else {
            if (options()$verbose)
                warning(paste("Package", pkgname, "already present in search()"))
        }
    }
    else if (!missing(help)) {
        if (!character.only)
            help <- as.character(substitute(help))
        file <- system.file("INDEX", pkg=help, lib=lib.loc)
        if (file == "")
            stop(paste("No documentation for package `", help, "'", sep = ""))
        else file.show(file, title = paste("Contents of package", help))
    }
    else {
        ## library():
        libfil <- tempfile("R.")
        avail <- NULL
        for (lib in lib.loc) {
            cat("\nPackages in library `", lib, "':\n\n", sep = "",
                file = libfil, append = TRUE)
            if (file.exists(libind <- file.path(lib, "LibIndex")))
            {
                file.append(libfil, libind)
                ## This gives warnings and partly garbage,
                ## since contrib's LibIndex isn't really "clean":
                ## scan(libind, what=list("",""), sep="\t",
                a <- NULL
            }
            else {
                a <- .packages(all.available = TRUE, lib.loc = lib)
                for (i in sort(a)) {
                    title <- system.file("TITLE", pkg=i, lib=lib)
                    if (title != "")
                        file.append(libfil, title)
                    else cat(i, "\n", file = libfil, append = TRUE)
                }
            }
            avail <- c(avail, a)
        }
        file.show(libfil, delete.file = TRUE, title = "R packages available")
        return(invisible(avail))
    }
    if (logical.return)
        TRUE
    else invisible(.packages())
}

library.dynam <-
  function (chname, package = .packages(), lib.loc = .lib.loc,
            verbose = .Options$verbose, file.ext = .Platform$dynlib.ext)
{
  if (!exists(".Dyn.libs"))
    assign(".Dyn.libs", character(0), envir = .AutoloadEnv)
  if (missing(chname) || (LEN <- nchar(chname)) == 0)
    return(.Dyn.libs)
  nc.ext <- nchar(file.ext)
  if (substr(chname, LEN - nc.ext + 1, LEN) == file.ext)
    chname <- substr(chname, 1, LEN - nc.ext)
  if (is.na(match(chname, .Dyn.libs))) {
    file <- system.file(file.path("libs", paste(chname, file.ext,
                              sep = "")), pkg = package, lib = lib.loc)
    if (file == "") {
      stop(paste("dynamic library `", chname, "' not found",
                 sep = ""))
    }
    if (verbose)
      cat("now dyn.load(", file, ")..\n", sep = "")
    .Internal(dyn.load(file))
    assign(".Dyn.libs", c(.Dyn.libs, chname), envir = .AutoloadEnv)
  }
  invisible(.Dyn.libs)
}

require <- function(name, quietly = FALSE) {
    name <- as.character(substitute(name)) # allowing "require(eda)"
    if (!exists(".Provided", inherits = TRUE))
	assign(".Provided", character(0), envir = .GlobalEnv)
    if (is.na(match(paste("package", name, sep = ":"), search()))
	&& is.na(match(name, .Provided))) {
	if (!quietly)
	    cat("Loading required package:", name, "\n")
	library(name, char = TRUE, logical = TRUE)
    }
    else
	TRUE
}

provide <- function(name) {
    if (!exists(".Provided", inherits = TRUE))
	assign(".Provided", character(0), envir = .GlobalEnv)
    if (missing(name))
	.Provided
    else {
	name <- as.character(substitute(name))
	if (is.na(match(name, .packages())) &&
	    is.na(match(name, .Provided))) {
	    assign(".Provided", c(name, .Provided), envir = .GlobalEnv)
	    TRUE
	}
	else
	    FALSE
    }
}

.packages <- function(all.available = FALSE, lib.loc = .lib.loc) {
    if(all.available) {
        a <- list.files(lib.loc, all.files=FALSE, full.names=FALSE)
	ans <- character(0)
	for (name in a) {
	    pkg <- system.file(file.path("R",name), pkg=name, lib=lib.loc)
	    if (pkg != "") ans <- c(ans,name)
	}
	return(ans)
    } ## else
    s <- search()
    return(invisible(substring(s[substr(s, 1, 8) == "package:"], 9)))
}