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Allow metatable operations on values of all types, and use the metatable

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on strings as the string package, so that string functions can be called
with self (:) syntax. Autoload test case now inexplicably fails more,
but it was already broken.
This commit is contained in:
Ian Farmer
2007-09-08 20:54:40 +00:00
parent e30646bcf8
commit aa44eedf4b
8 changed files with 86 additions and 30 deletions
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45
src/main/java/lua/value/LValue.java
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@@ -6,6 +6,12 @@ import lua.VM;
abstract
public class LValue {
/** Metatable tag for intercepting table gets */
public static final LString TM_INDEX = new LString("__index");
/** Metatable tag for intercepting table sets */
public static final LString TM_NEWINDEX = new LString("__newindex");
protected static LValue luaUnsupportedOperation() {
throw new java.lang.RuntimeException( "not supported" );
}
@@ -79,22 +85,39 @@ public class LValue {
}
/** set a value in a table
* For non-tables, goes straight to the meta-table.
* @param vm the calling vm
* @param table the table to operate on
* @param the key to set
* @param the value to set
*/
public void luaSetTable(VM vm, LValue table, LValue key, LValue val) {
luaUnsupportedOperation();
LTable mt = luaGetMetatable();
if ( mt != null ) {
LValue event = mt.get( TM_NEWINDEX );
if ( event != null && event != LNil.NIL ) {
event.luaSetTable( vm, table, key, val );
return;
}
}
vm.push( LNil.NIL );
}
/** Get a value from a table
* @param vm the calling vm
* @param table the table from which to get the value
* @param key the key to look up
*/
public void luaGetTable(VM vm, LValue table, LValue key) {
luaUnsupportedOperation();
LTable mt = luaGetMetatable();
if ( mt != null ) {
LValue event = mt.get( TM_INDEX );
if ( event != null && event != LNil.NIL ) {
event.luaGetTable( vm, table, key );
return;
}
}
vm.push(LNil.NIL);
}
/** Get the value as a String
@@ -135,9 +158,18 @@ public class LValue {
return luaUnsupportedOperation();
}
/** Valid for tables */
public LValue luaGetMetatable() {
return luaUnsupportedOperation();
/**
* Valid for all types: get a metatable. Only tables and userdata can have a
* different metatable per instance, though, other types are restricted to
* one metatable per type.
*
* Since metatables on non-tables can only be set through Java and not Lua,
* this function should be overridden for each value type as necessary.
*
* @return null if there is no meta-table
*/
public LTable luaGetMetatable() {
return null;
}
/** Valid for tables */
@@ -147,4 +179,5 @@ public class LValue {
/** Valid for all types: return the type of this value as an LString */
public abstract LString luaGetType();
}