First cut at a trampoline task.

bin/lein

@@ -119,10 +119,10 @@ if type -p curl >/dev/null 2>&1; then
     HTTP_CLIENT="curl $CURL_PROXY --insecure -f -L -o"
 fi
 
-JAVA_CMD=${JAVA_CMD:-"java"}
+export JAVA_CMD=${JAVA_CMD:-"java"}
 
 # Support $JAVA_OPTS for backwards-compatibility.
-JVM_OPTS=${JVM_OPTS:-$JAVA_OPTS}
+export JVM_OPTS=${JVM_OPTS:-$JAVA_OPTS}
 
 # If you're packaging this for a package manager (.deb, homebrew, etc)
 # you need to remove the self-install and upgrade functionality.
@@ -215,9 +215,23 @@ else
     # doesn't exist everything will still work, it will just have a
     # slower JVM boot.
     test $CYGWIN_JLINE && stty -icanon min 1 -echo
-    exec $RLWRAP $JAVA_CMD -Xbootclasspath/a:"$CLOJURE_JAR" -client $JVM_OPTS \
-        -Dleiningen.original.pwd="$ORIGINAL_PWD" \
-        -cp "$CLASSPATH" $JLINE clojure.main -e "(use 'leiningen.core)(-main)" \
-        $NULL_DEVICE "$@"
-    test $CYGWIN_JLINE && stty icanon echo
+    if [ "$1" = "trampoline" ]; then
+        TRAMPOLINE_COMMAND_FILE="/tmp/lein-trampoline-$$"
+        CMD=`$JAVA_CMD -Xbootclasspath/a:"$CLOJURE_JAR" -client $JVM_OPTS \
+            -Dleiningen.original.pwd="$ORIGINAL_PWD" \
+            -Dleiningen.trampoline-file=$TRAMPOLINE_COMMAND_FILE \
+            -cp "$CLASSPATH" $JLINE clojure.main -e "(use 'leiningen.core)(-main)" \
+            $NULL_DEVICE "$@"`
+        if [ -r $TRAMPOLINE_COMMAND_FILE ]; then
+            TRAMPOLINE_COMMAND=`cat $TRAMPOLINE_COMMAND_FILE`
+            rm $TRAMPOLINE_COMMAND_FILE
+            exec $TRAMPOLINE_COMMAND
+        fi
+    else
+        exec $RLWRAP $JAVA_CMD -Xbootclasspath/a:"$CLOJURE_JAR" -client $JVM_OPTS \
+            -Dleiningen.original.pwd="$ORIGINAL_PWD" \
+            -cp "$CLASSPATH" $JLINE clojure.main -e "(use 'leiningen.core)(-main)" \
+            $NULL_DEVICE "$@"
+        test $CYGWIN_JLINE && stty icanon echo
+    fi
 fi

src/leiningen/compile.clj

@@ -84,9 +84,10 @@
 (defn- get-raw-input-args []
   (.getInputArguments (ManagementFactory/getRuntimeMXBean)))
 
-(defn- get-input-args
+(defn ^{:internal true} get-input-args
   "Returns a vector of input arguments, accounting for a bug in RuntimeMXBean
-  that splits arguments which contain spaces."
+  that splits arguments which contain spaces. Removes -Xbootclasspath as it
+  requires special handling on the called code."
   []
   ;; RuntimeMXBean.getInputArguments() is buggy when an input argument
   ;; contains spaces. For an input argument of -Dprop="hello world" it
@@ -95,7 +96,8 @@
                                       (conj v arg)
                                       (conj (vec (butlast v))
                                             (format "%s %s" (last v) arg))))]
-         (reduce join-broken-args [] (get-raw-input-args))))
+    (remove #(re-find #"^-Xbootclasspath.+" %)
+            (reduce join-broken-args [] (get-raw-input-args)))))
 
 (defn- get-jvm-args [project]
   (concat (get-input-args) (:jvm-opts project) (:jvm-opts (user-settings))))
@@ -175,8 +177,7 @@
       (.setFork java true)
       (.setDir java (file (:root project)))
       (doseq [arg (get-jvm-args project)]
-        (when-not (re-matches #"^-Xbootclasspath.+" arg)
-          (.setValue (.createJvmarg java) arg)))
+        (.setValue (.createJvmarg java) arg))
       (.setClassname java "clojure.main")
       ;; to allow plugins and other tasks to customize
       (when handler

src/leiningen/trampoline.clj

@@ -0,0 +1,38 @@
+(ns leiningen.trampoline
+  (:refer-clojure :exclude [trampoline])
+  (:use [leiningen.core :only [apply-task task-not-found abort]]
+        [leiningen.compile :only [get-input-args eval-in-project
+                                  get-readable-form]]
+        [leiningen.classpath :only [get-classpath-string]])
+  (:require [clojure.string :as string]))
+
+(defn escape [form-string]
+  (format "\"%s\"" (.replaceAll form-string "\"" "\\\\\"")))
+
+(defn command-string [project java-cmd jvm-opts [_ form _ _ init]]
+  (string/join " " [java-cmd "-cp" (get-classpath-string project)
+                    "clojure.main" "-e"
+                    (escape (get-readable-form nil project form init))]))
+
+(defn write-trampoline [command]
+  (spit (System/getProperty "leiningen.trampoline-file") command))
+
+(defn trampoline
+  "Calculate what needs to run in the project's process for the
+provided task and run it after Leiningen's own process has exited
+rather than as a subprocess of Leiningen's project.
+
+Use this to save memory or to work around things like Ant's stdin
+issues. Not compatible with chaining."
+  [project task-name & args]
+  (let [java-cmd (format "%s/bin/java" (System/getProperty "java.home"))
+        jvm-opts (get-input-args)
+        jvm-opts (if (:debug project)
+                   (conj jvm-opts "-Dclojure.debug=true")
+                   jvm-opts)
+        eval-args (atom nil)]
+    (binding [eval-in-project #(do (reset! eval-args %&) 0)]
+      (apply-task task-name project args task-not-found))
+    (if @eval-args
+      (write-trampoline (command-string project java-cmd jvm-opts @eval-args))
+      (abort task-name "is not trampolineable."))))