jjallaire · November 3, 2012 19:22 · Nov 3, 2012
diff --git a/gistfile1.r b/gistfile1.r
@@ -0,0 +1,109 @@
+
+# Setup the build environment based on the specified dependencies. Returns an
+# opaque object that can be passed to .restoreEnvironment to reverse whatever
+# changes that were made
+.setupBuildEnvironment <- function(depends) {
+
+    # discover dependencies
+    buildEnv <- list()
+    linkingToPackages <- c("Rcpp")
+    for (package in depends) {
+
+        # add a LinkingTo for this package
+        linkingToPackages <- unique(c(linkingToPackages, package))
+
+        # see if the package exports a plugin
+        plugin <- .getInlinePlugin(package)
+        if (!is.null(plugin)) {
+
+            # get the plugin settings 
+            settings <- plugin()
+
+            # merge environment variables
+            pluginEnv <- settings$env
+            for (name in names(pluginEnv)) {
+                # if it doesn't exist already just set it
+                if (is.null(buildEnv[[name]])) {
+                    buildEnv[[name]] <- pluginEnv[[name]]
+                }
+                # if it's not identical then append
+                else if (!identical(buildEnv[[name]],
+                    pluginEnv[[name]])) {
+                    buildEnv[[name]] <- paste(buildEnv[[name]], 
+                        pluginEnv[[name]]);
+                }
+                else {
+                    # it already exists and it's the same value, this 
+                    # likely means it's a flag-type variable so we 
+                    # do nothing rather than appending it
+                }   
+            }
+
+            # capture any LinkingTo elements defined by the plugin
+            linkingToPackages <- unique(c(linkingToPackages, 
+                settings$LinkingTo))
+        }
+    }
+
+    # if there is no buildEnv from a plugin then use the Rcpp plugin
+    if (length(buildEnv) == 0) {
+        buildEnv <- Rcpp:::inlineCxxPlugin()$env
+    } else {
+        # we are using a plugin -- confirm that the plugin includes the Rcpp
+        # PKG_LIBS and if it doesn't then add them
+        pkgLibs <- buildEnv$PKG_LIBS
+        rcppLibs <- Rcpp:::RcppLdFlags()
+        if (is.null(pkgLibs) || !grepl(rcppLibs, pkgLibs, fixed = TRUE))
+            buildEnv$PKG_LIBS <- paste(pkgLibs, rcppLibs)
+    }
+
+    # set cxxFlags based on the LinkingTo dependencies (and also respect
+    # any PKG_CXXFLAGS set by the plugin)
+    pkgCxxFlags <- .buildPkgCxxFlags(linkingToPackages)
+    buildEnv$PKG_CXXFLAGS <- paste(buildEnv$PKG_CXXFLAGS, pkgCxxFlags)        
+
+    # add cygwin message muffler
+    buildEnv$CYGWIN = "nodosfilewarning"
+
+    # create restore list
+    restore <- list()
+    for (name in names(buildEnv))
+        restore[[name]] <- Sys.getenv(name, unset = NA)
+
+    # set environment variables
+    do.call(Sys.setenv, buildEnv)
+
+    # return restore list
+    return (restore)
+}
+
+.restoreEnvironment <- function(restore) {
+    # variables to reset
+    setVars <- restore[!is.na(restore)]
+    if (length(setVars))
+        do.call(Sys.setenv, setVars)
+
+    # variables to remove
+    removeVars <- names(restore[is.na(restore)])
+    if (length(removeVars))
+        Sys.unsetenv(removeVars)
+}
+
+
+# Get the inline plugin for the specified package (return NULL if none found)
+.getInlinePlugin <- function(package) {
+    tryCatch(get("inlineCxxPlugin", asNamespace(package)),
+        error = function(e) NULL) 
+}
+
+# Build PKG_CXXFLAGS by from include directories of LinkingTo packages
+.buildPkgCxxFlags <- function(linkingToPackages) {
+    pkgCxxFlags <- NULL
+    for (package in linkingToPackages) {
+        packagePath <- find.package(package, NULL, quiet=TRUE)
+        pkgCxxFlags <- paste(pkgCxxFlags, 
+            paste0('-I"', packagePath, '/include"'), 
+            collapse=" ")
+    }
+    return (pkgCxxFlags)
+}