From 5366ab48889743eee672dfc148b83bfabd0ed696 Mon Sep 17 00:00:00 2001
From: Stuart Sierra <mail@stuartsierra.com>
Date: Fri, 2 Dec 2011 18:28:51 -0500
Subject: [PATCH] CLJ-890: Tagged reader literals like #foo/bar

---
 src/clj/clojure/main.clj             |    1 +
 src/jvm/clojure/lang/Compiler.java   |    3 +-
 src/jvm/clojure/lang/LispReader.java |   44 +++++++++++++++++++++++++++++++++-
 src/jvm/clojure/lang/RT.java         |    3 ++
 4 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/src/clj/clojure/main.clj b/src/clj/clojure/main.clj
index 8efff8d..487d0fd 100644
--- a/src/clj/clojure/main.clj
+++ b/src/clj/clojure/main.clj
@@ -94,6 +94,7 @@
              *print-meta* *print-meta*
              *print-length* *print-length*
              *print-level* *print-level*
+             *data-readers* *data-readers*
              *compile-path* (System/getProperty "clojure.compile.path" "classes")
              *command-line-args* *command-line-args*
              *unchecked-math* *unchecked-math*
diff --git a/src/jvm/clojure/lang/Compiler.java b/src/jvm/clojure/lang/Compiler.java
index cbcf58d..853e331 100644
--- a/src/jvm/clojure/lang/Compiler.java
+++ b/src/jvm/clojure/lang/Compiler.java
@@ -6894,7 +6894,8 @@ public static Object load(Reader rdr, String sourcePath, String sourceName) {
 			       LINE_AFTER, pushbackReader.getLineNumber()
 			       ,RT.UNCHECKED_MATH, RT.UNCHECKED_MATH.deref()
 					,RT.WARN_ON_REFLECTION, RT.WARN_ON_REFLECTION.deref()
-			));
+			       ,RT.DATA_READERS, RT.DATA_READERS.deref()
+                        ));
 
 	try
 		{
diff --git a/src/jvm/clojure/lang/LispReader.java b/src/jvm/clojure/lang/LispReader.java
index dbb59a6..857d839 100644
--- a/src/jvm/clojure/lang/LispReader.java
+++ b/src/jvm/clojure/lang/LispReader.java
@@ -1145,8 +1145,50 @@ public static List readDelimitedList(char delim, PushbackReader r, boolean isRec
 public static class CtorReader extends AFn{
 	public Object invoke(Object reader, Object firstChar){
 		PushbackReader r = (PushbackReader) reader;
+		Object name = read(r, true, null, false);
+                if (!(name instanceof Symbol)) 
+                        throw new RuntimeException("Reader tag must be a symbol");
+                Symbol sym = (Symbol)name;
+                if (sym.getNamespace() != null || RT.BUILTIN_DATA_TAGS.contains(sym))
+                        return readTagged(r, sym);
+                else
+                        return readRecord(r, sym);
+        }
+
+	private Object readTagged(PushbackReader reader, Symbol tag){
+		Object o = read(reader, true, null, true);
+
+		ILookup data_readers = (ILookup)RT.DATA_READERS.deref();
+		IFn data = (IFn)RT.get(data_readers, tag);
+		if(data != null)
+			return data.invoke(o);
+
+		// No data reader, just add :data metadata
+		Object meta = RT.map(RT.DATA_KEY, tag);
+		int line = -1;
+		if(reader instanceof LineNumberingPushbackReader)
+			line = ((LineNumberingPushbackReader) reader).getLineNumber();
+		if(o instanceof IMeta)
+			{
+			if(line != -1 && o instanceof ISeq)
+				meta = ((IPersistentMap) meta).assoc(RT.LINE_KEY, line);
+			if(o instanceof IReference)
+				{
+				((IReference)o).resetMeta((IPersistentMap) meta);
+				return o;
+				}
+			Object ometa = RT.meta(o);
+			for(ISeq s = RT.seq(meta); s != null; s = s.next()) {
+				IMapEntry kv = (IMapEntry) s.first();
+				ometa = RT.assoc(ometa, kv.getKey(), kv.getValue());
+				}
+			return ((IObj) o).withMeta((IPersistentMap) ometa);
+			}
+		else
+			return o;
+	}
 
-		Object recordName = read(r, true, null, false);
+        private Object readRecord(PushbackReader r, Symbol recordName){
 		Class recordClass = RT.classForName(recordName.toString());
 		char endch;
 		boolean shortForm = true;
diff --git a/src/jvm/clojure/lang/RT.java b/src/jvm/clojure/lang/RT.java
index 1d0fba8..9d5f386 100644
--- a/src/jvm/clojure/lang/RT.java
+++ b/src/jvm/clojure/lang/RT.java
@@ -180,8 +180,11 @@ final static public Var ERR =
 		           new PrintWriter(new OutputStreamWriter(System.err), true)).setDynamic();
 final static Keyword TAG_KEY = Keyword.intern(null, "tag");
 final static Keyword CONST_KEY = Keyword.intern(null, "const");
+final static Keyword DATA_KEY = Keyword.intern(null, "data");
 final static public Var AGENT = Var.intern(CLOJURE_NS, Symbol.intern("*agent*"), null).setDynamic();
 final static public Var READEVAL = Var.intern(CLOJURE_NS, Symbol.intern("*read-eval*"), T).setDynamic();
+final static public Var DATA_READERS = Var.intern(CLOJURE_NS, Symbol.intern("*data-readers*"), RT.map()).setDynamic();
+final static public IPersistentSet BUILTIN_DATA_TAGS = RT.set();
 final static public Var ASSERT = Var.intern(CLOJURE_NS, Symbol.intern("*assert*"), T).setDynamic();
 final static public Var MATH_CONTEXT = Var.intern(CLOJURE_NS, Symbol.intern("*math-context*"), null).setDynamic();
 static Keyword LINE_KEY = Keyword.intern(null, "line");
-- 
1.7.4.1