From 54927db2fc91b639605d1bc3330747b00f41ea34 Mon Sep 17 00:00:00 2001
From: James Roseborough <james.roseborough@luaj.org>
Date: Sun, 17 Jun 2007 02:58:40 +0000
Subject: [PATCH] Implement most of metatables

---
 src/main/java/lua/Builtin.java         |  3 +-
 src/main/java/lua/GlobalState.java     |  2 ++
 src/main/java/lua/value/LFunction.java | 19 ++++++++++++
 src/main/java/lua/value/LTable.java    | 42 +++++++++++++++++++++-----
 src/main/java/lua/value/LValue.java    | 16 +++++++---
 src/test/res/test6.lua                 |  3 +-
 6 files changed, 68 insertions(+), 17 deletions(-)

diff --git a/src/main/java/lua/Builtin.java b/src/main/java/lua/Builtin.java
index 3b4b0be8..985b065e 100644
--- a/src/main/java/lua/Builtin.java
+++ b/src/main/java/lua/Builtin.java
@@ -4,7 +4,6 @@
 package lua;
 
 import lua.value.LFunction;
-import lua.value.LNil;
 import lua.value.LString;
 import lua.value.LTable;
 import lua.value.LValue;
@@ -13,7 +12,7 @@ final class Builtin extends LFunction {
 
 	static void addBuiltins(LTable table) {
 		for ( int i=0; i<NAMES.length; i++ )
-			table.luaSetTable( new LString( NAMES[i] ), new Builtin(i) );
+			table.m_hash.put( new LString( NAMES[i] ), new Builtin(i) );
 	}
 
 	private static final int PRINT = 0;
diff --git a/src/main/java/lua/GlobalState.java b/src/main/java/lua/GlobalState.java
index 17d5dcc1..850f4108 100644
--- a/src/main/java/lua/GlobalState.java
+++ b/src/main/java/lua/GlobalState.java
@@ -2,6 +2,7 @@ package lua;
 
 import java.util.Hashtable;
 
+import lua.value.LString;
 import lua.value.LTable;
 import lua.value.LValue;
 
@@ -44,6 +45,7 @@ public class GlobalState {
 	public static LValue getGlobalsTable() {
 		LTable table = new LTable();
 		Builtin.addBuiltins( table );
+		table.m_hash.put(new LString("_G"), table);
 		return table;
 	}
 }
diff --git a/src/main/java/lua/value/LFunction.java b/src/main/java/lua/value/LFunction.java
index 36e6911a..9b3b2cc0 100644
--- a/src/main/java/lua/value/LFunction.java
+++ b/src/main/java/lua/value/LFunction.java
@@ -1,9 +1,28 @@
 package lua.value;
 
+import lua.StackState;
+
 public class LFunction extends LValue {
 
 	public String toString() {
 		return "function: "+hashCode();
 	}
+
+	public void luaSetTable(StackState state, int base, LValue table, LValue key, LValue val) {
+		state.top = base;
+		state.push( this );
+		state.push( table );
+		state.push( key );
+		state.push( val );
+		this.luaStackCall(state, base, state.top, 1);
+	}
+
+	public void luaGetTable(StackState state, int base, LValue table, LValue key) {
+		state.top = base;
+		state.push( this );
+		state.push( table );
+		state.push( key );
+		this.luaStackCall(state, base, state.top, 1);
+	}
 	
 }
diff --git a/src/main/java/lua/value/LTable.java b/src/main/java/lua/value/LTable.java
index 6a5dc337..879eeb4b 100644
--- a/src/main/java/lua/value/LTable.java
+++ b/src/main/java/lua/value/LTable.java
@@ -6,9 +6,15 @@ import java.util.Hashtable;
 import lua.StackState;
 
 public class LTable extends LValue {
+
+	/** Metatable tag for intercepting table gets */
+	private static final LString TM_INDEX    = new LString("__index");
 	
-	private Hashtable m_hash = new Hashtable();
-	private LValue m_metatable;
+	/** Metatable tag for intercepting table sets */
+	private static final LString TM_NEWINDEX = new LString("__newindex");
+
+	public Hashtable m_hash = new Hashtable();
+	private LTable m_metatable;
 	
 	public LTable() {
 	}
@@ -16,13 +22,32 @@ public class LTable extends LValue {
 	public LTable(int narray, int nhash) {
 	}
 
-	public void luaSetTable(LValue key, LValue val) {
+	public void luaSetTable(StackState state, int base, LValue table, LValue key, LValue val) {
+		if ( m_metatable != null ) {
+			if ( ! m_hash.containsKey(key) ) {
+				LValue event = (LValue) m_metatable.m_hash.get( TM_NEWINDEX );
+				if ( event != null && event != LNil.NIL ) {
+					event.luaSetTable( state, base, table, key, val );
+					return;
+				}
+			}
+		}
 		m_hash.put( key, val );
 	}
 
-	public LValue luaGetTable(LValue key) {
-		Object o = m_hash.get(key);
-		return (o!=null? (LValue)o: LNil.NIL);
+	public void luaGetTable(StackState state, int base, LValue table, LValue key) {
+		LValue val = (LValue) m_hash.get(key);
+		if ( val == null || val == LNil.NIL ) {
+			if ( m_metatable != null ) {
+				LValue event = (LValue) m_metatable.m_hash.get( TM_INDEX );
+				if ( event != null && event != LNil.NIL ) {
+					event.luaGetTable( state, base, table, key );
+					return;
+				}
+			}
+			val = LNil.NIL;
+		}
+		state.stack[base] = val;
 	}
 	
 	public String luaAsString() {
@@ -41,7 +66,7 @@ public class LTable extends LValue {
 
 	/** Valid for tables */
 	public void luaSetMetatable(LValue metatable) {
-		this.m_metatable = metatable;
+		this.m_metatable = (LTable) metatable;
 	}
 	
 	/** Valid for tables */
@@ -64,8 +89,9 @@ public class LTable extends LValue {
 		public void luaStackCall(StackState state, int base, int top, int nresults) {
 			if ( e.hasMoreElements() ) {
 				LValue key = (LValue) e.nextElement();
+				LValue val = (LValue) t.m_hash.get(key);
 				state.stack[base] = key;
-				state.stack[base+1] = t.luaGetTable(key);
+				state.stack[base+1] = val;
 				state.top = base+2;
 			} else {
 				state.stack[base] = LNil.NIL;
diff --git a/src/main/java/lua/value/LValue.java b/src/main/java/lua/value/LValue.java
index c787495d..b5a36297 100644
--- a/src/main/java/lua/value/LValue.java
+++ b/src/main/java/lua/value/LValue.java
@@ -68,14 +68,21 @@ public class LValue {
 	}
 	
 	/** set a value in a table
+	 * @param state the stack state
+	 * @param base the base of the stack, in case a function is put on the stack
+	 * @param table the table to operate on
+	 * @param the key to set
+	 * @param the value to set
 	 */
-	public void luaSetTable(LValue key, LValue value) {
+	public void luaSetTable(StackState state, int base, LValue table, LValue key, LValue val) {
 		luaUnsupportedOperation();
 	}
 
-	/** Get a value from a table */
-	public LValue luaGetTable(LValue value) {
-		return luaUnsupportedOperation();
+	/** Get a value from a table 
+	 * @param base TODO
+	 * @param table TODO*/
+	public void luaGetTable(StackState state, int base, LValue table, LValue key) {
+		luaUnsupportedOperation();
 	}
 	
 	/** Get the value as a String
@@ -121,5 +128,4 @@ public class LValue {
 		luaUnsupportedOperation();
 	}
 
-	
 }
diff --git a/src/test/res/test6.lua b/src/test/res/test6.lua
index afb86252..8a750b2b 100644
--- a/src/test/res/test6.lua
+++ b/src/test/res/test6.lua
@@ -1,5 +1,5 @@
 t = { 11, 22, 33, you='one', me='two' }
---[[
+
 for a,b in pairs(t) do
 	print( a, b )
 end
@@ -12,7 +12,6 @@ print( "me", me )
 print( "fred", fred )
 print( "t[me]", t[me] )
 print( "t[fred]", t[fred] )
---]]
 
 -- basic metatable setting 
 t = { 11, 22, 33, you='one', me='two' }