added empty

15 files changed, 55 insertions, 1 deletions

diff --git a/src/boot.clj b/src/boot.clj
index 98d78c88..3bd38a05 100644
--- a/src/boot.clj
+++ b/src/boot.clj
@@ -2427,3 +2427,8 @@ not-every? (comp not every?))
        (defn ~name ~args ~(apply inline args))
        (let [v# (var ~name)]
          (.setMeta v# (assoc ^v# :inline ~inline))))))
+
+(defn empty 
+  "Returns an empty collection of the same category as coll, or null"
+  [#^ clojure.lang.IPersistentCollection coll]
+  (.empty coll))
\ No newline at end of file
diff --git a/src/jvm/clojure/lang/AMapEntry.java b/src/jvm/clojure/lang/AMapEntry.java
index ce4c219c..5496f0eb 100644
--- a/src/jvm/clojure/lang/AMapEntry.java
+++ b/src/jvm/clojure/lang/AMapEntry.java
@@ -15,6 +15,9 @@ package clojure.lang;
 import java.io.StringWriter;
 
 public abstract class AMapEntry implements IMapEntry, IPersistentVector{
+public IPersistentCollection empty(){
+	return null;
+}
 
 public boolean equals(Object obj){
 	return APersistentVector.doEquals(this, obj);
diff --git a/src/jvm/clojure/lang/APersistentVector.java b/src/jvm/clojure/lang/APersistentVector.java
index 086d8369..46dfbb25 100644
--- a/src/jvm/clojure/lang/APersistentVector.java
+++ b/src/jvm/clojure/lang/APersistentVector.java
@@ -357,6 +357,10 @@ static class SubVector extends APersistentVector{
 		return new SubVector(_meta, v.assocN(end, o), start, end + 1);
 	}
 
+	public IPersistentCollection empty(){
+		return PersistentVector.EMPTY.withMeta(meta());		
+	}
+
 	public IPersistentStack pop(){
 		if(end - 1 == start)
 			{
diff --git a/src/jvm/clojure/lang/ASeq.java b/src/jvm/clojure/lang/ASeq.java
index 2dca27a5..e519621d 100644
--- a/src/jvm/clojure/lang/ASeq.java
+++ b/src/jvm/clojure/lang/ASeq.java
@@ -17,6 +17,10 @@ public abstract class ASeq extends Obj implements ISeq, Collection, Sequential{
 transient int _hash = -1;

 

 

+public IPersistentCollection empty(){

+	return null;

+}

+

 protected ASeq(IPersistentMap meta){

 	super(meta);

 }

diff --git a/src/jvm/clojure/lang/IPersistentCollection.java b/src/jvm/clojure/lang/IPersistentCollection.java
index 77e32738..f97b02cd 100644
--- a/src/jvm/clojure/lang/IPersistentCollection.java
+++ b/src/jvm/clojure/lang/IPersistentCollection.java
@@ -18,4 +18,6 @@ int count();
 ISeq seq();

 

 IPersistentCollection cons(Object o);

+

+IPersistentCollection empty();

 }

diff --git a/src/jvm/clojure/lang/LazilyPersistentVector.java b/src/jvm/clojure/lang/LazilyPersistentVector.java
index 9c4c9a0a..bbe580fa 100644
--- a/src/jvm/clojure/lang/LazilyPersistentVector.java
+++ b/src/jvm/clojure/lang/LazilyPersistentVector.java
@@ -54,6 +54,10 @@ public IPersistentVector cons(Object o){
 	return v().cons(o);
 }
 
+public IPersistentCollection empty(){
+	return PersistentVector.EMPTY.withMeta(meta());	
+}
+
 public IPersistentStack pop(){
 	return v().pop();
 }
diff --git a/src/jvm/clojure/lang/PersistentArrayMap.java b/src/jvm/clojure/lang/PersistentArrayMap.java
index 63516714..969ec701 100644
--- a/src/jvm/clojure/lang/PersistentArrayMap.java
+++ b/src/jvm/clojure/lang/PersistentArrayMap.java
@@ -142,7 +142,7 @@ public IPersistentMap without(Object key){
 	return this;

 }

 

-IPersistentMap empty(){

+public IPersistentMap empty(){

 	return (IPersistentMap) EMPTY.withMeta(meta());

 }

 

diff --git a/src/jvm/clojure/lang/PersistentHashMap.java b/src/jvm/clojure/lang/PersistentHashMap.java
index adf3beeb..49530586 100644
--- a/src/jvm/clojure/lang/PersistentHashMap.java
+++ b/src/jvm/clojure/lang/PersistentHashMap.java
@@ -146,6 +146,10 @@ public ISeq seq(){
 	return root.nodeSeq();
 }
 
+public IPersistentCollection empty(){
+	return EMPTY.withMeta(meta());	
+}
+
 static int mask(int hash, int shift){
 	//return ((hash << shift) >>> 27);// & 0x01f;
 	return (hash >>> shift) & 0x01f;
diff --git a/src/jvm/clojure/lang/PersistentHashSet.java b/src/jvm/clojure/lang/PersistentHashSet.java
index 60794b97..9f216010 100644
--- a/src/jvm/clojure/lang/PersistentHashSet.java
+++ b/src/jvm/clojure/lang/PersistentHashSet.java
@@ -63,6 +63,10 @@ public IPersistentSet cons(Object o){
 	return new PersistentHashSet(meta(),impl.assoc(o,o));
 }
 
+public IPersistentCollection empty(){
+	return EMPTY.withMeta(meta());	
+}
+
 public PersistentHashSet withMeta(IPersistentMap meta){
 	return new PersistentHashSet(meta, impl);
 }
diff --git a/src/jvm/clojure/lang/PersistentList.java b/src/jvm/clojure/lang/PersistentList.java
index 112eede6..cd86b033 100644
--- a/src/jvm/clojure/lang/PersistentList.java
+++ b/src/jvm/clojure/lang/PersistentList.java
@@ -88,6 +88,10 @@ public PersistentList cons(Object o){
 	return new PersistentList(meta(), o, this, _count + 1);

 }

 

+public IPersistentCollection empty(){

+	return EMPTY.withMeta(meta());	

+}

+

 public PersistentList withMeta(IPersistentMap meta){

 	if(meta != _meta)

 		return new PersistentList(meta, _first, _rest, _count);

diff --git a/src/jvm/clojure/lang/PersistentQueue.java b/src/jvm/clojure/lang/PersistentQueue.java
index 054b21af..53f35479 100644
--- a/src/jvm/clojure/lang/PersistentQueue.java
+++ b/src/jvm/clojure/lang/PersistentQueue.java
@@ -99,6 +99,10 @@ public PersistentQueue cons(Object o){
 		return new PersistentQueue(meta(), f, (r != null ? r : PersistentVector.EMPTY).cons(o));

 }

 

+public IPersistentCollection empty(){

+	return EMPTY.withMeta(meta());	

+}

+

 public PersistentQueue withMeta(IPersistentMap meta){

 	return new PersistentQueue(meta, f, r);

 }

diff --git a/src/jvm/clojure/lang/PersistentStructMap.java b/src/jvm/clojure/lang/PersistentStructMap.java
index 2b371ffc..2b651c1b 100644
--- a/src/jvm/clojure/lang/PersistentStructMap.java
+++ b/src/jvm/clojure/lang/PersistentStructMap.java
@@ -177,6 +177,10 @@ public ISeq seq(){
 	return new Seq(null, def.keys, vals, 0, ext);
 }
 
+public IPersistentCollection empty(){
+	return construct(def, null);
+}
+
 static class Seq extends ASeq{
 	final int i;
 	final ISeq keys;
diff --git a/src/jvm/clojure/lang/PersistentTreeMap.java b/src/jvm/clojure/lang/PersistentTreeMap.java
index fb9df3ad..a89cab38 100644
--- a/src/jvm/clojure/lang/PersistentTreeMap.java
+++ b/src/jvm/clojure/lang/PersistentTreeMap.java
@@ -126,6 +126,10 @@ public ISeq seq(){
 	return null;
 }
 
+public IPersistentCollection empty(){
+	return EMPTY.withMeta(meta());	
+}
+
 public ISeq rseq() throws Exception{
 	if(_count > 0)
 		return Seq.create(tree, false, _count);
diff --git a/src/jvm/clojure/lang/PersistentTreeSet.java b/src/jvm/clojure/lang/PersistentTreeSet.java
index 8ffdb0d9..9055a05f 100644
--- a/src/jvm/clojure/lang/PersistentTreeSet.java
+++ b/src/jvm/clojure/lang/PersistentTreeSet.java
@@ -63,6 +63,10 @@ public IPersistentSet cons(Object o){
 	return new PersistentTreeSet(meta(),impl.assoc(o,o));
 }
 
+public IPersistentCollection empty(){
+	return EMPTY.withMeta(meta());	
+}
+
 public ISeq rseq() throws Exception{
 	return APersistentMap.KeySeq.create(((Reversible) impl).rseq());
 }
diff --git a/src/jvm/clojure/lang/PersistentVector.java b/src/jvm/clojure/lang/PersistentVector.java
index ca00fc76..f6158791 100644
--- a/src/jvm/clojure/lang/PersistentVector.java
+++ b/src/jvm/clojure/lang/PersistentVector.java
@@ -139,6 +139,10 @@ public PersistentVector cons(Object val){
 	return new PersistentVector(meta(), cnt + 1, newshift, newroot, new Object[]{val});
 }
 
+public IPersistentCollection empty(){
+	return EMPTY.withMeta(meta());
+}
+
 private Object[] pushTail(int level, Object[] arr, Object[] tailNode, Box expansion){
 	Object newchild;
 	if(level == 0)