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package org.luaj.vm2.lib.jse;
import java.lang.reflect.Array;
import java.util.HashMap;
import java.util.Map;
import org.luaj.vm2.LuaDouble;
import org.luaj.vm2.LuaInteger;
import org.luaj.vm2.LuaString;
import org.luaj.vm2.LuaTable;
import org.luaj.vm2.LuaUserdata;
import org.luaj.vm2.LuaValue;
/**
* Helper class to coerce values from Java to lua within the luajava library.
*
* This class is primarily used by the {@link LuajavaLib},
* but can also be used directly when working with Java/lua bindings.
*
* To coerce scalar types, the various, generally the {@code valueOf(type)} methods
* on {@link LuaValue} may be used:
*
* - {@link LuaValue#valueOf(boolean)}
* - {@link LuaValue#valueOf(byte[])}
* - {@link LuaValue#valueOf(double)}
* - {@link LuaValue#valueOf(int)}
* - {@link LuaValue#valueOf(String)}
*
*
* To coerce arrays of objects and lists, the {@code listOf(..)} and {@code tableOf(...)} methods
* on {@link LuaValue} may be used:
*
* - {@link LuaValue#listOf(LuaValue[])}
* - {@link LuaValue#listOf(LuaValue[], org.luaj.vm2.Varargs)}
* - {@link LuaValue#tableOf(LuaValue[])}
* - {@link LuaValue#tableOf(LuaValue[], LuaValue[], org.luaj.vm2.Varargs)}
*
* The method {@link CoerceJavaToLua#coerce(Object)} looks as the type and dimesioning
* of the argument and tries to guess the best fit for corrsponding lua scalar,
* table, or table of tables.
*
* @see CoerceJavaToLua#coerce(Object)
* @see LuajavaLib
*/
public class CoerceJavaToLua {
static interface Coercion {
public LuaValue coerce( Object javaValue );
};
static final Map COERCIONS = new HashMap();
static {
Coercion boolCoercion = new Coercion() {
public LuaValue coerce( Object javaValue ) {
Boolean b = (Boolean) javaValue;
return b.booleanValue()? LuaValue.TRUE: LuaValue.FALSE;
}
} ;
Coercion intCoercion = new Coercion() {
public LuaValue coerce( Object javaValue ) {
Number n = (Number) javaValue;
return LuaInteger.valueOf( n.intValue() );
}
} ;
Coercion charCoercion = new Coercion() {
public LuaValue coerce( Object javaValue ) {
Character c = (Character) javaValue;
return LuaInteger.valueOf( c.charValue() );
}
} ;
Coercion doubleCoercion = new Coercion() {
public LuaValue coerce( Object javaValue ) {
Number n = (Number) javaValue;
return LuaDouble.valueOf( n.doubleValue() );
}
} ;
Coercion stringCoercion = new Coercion() {
public LuaValue coerce( Object javaValue ) {
return LuaString.valueOf( javaValue.toString() );
}
} ;
COERCIONS.put( Boolean.class, boolCoercion );
COERCIONS.put( Byte.class, intCoercion );
COERCIONS.put( Character.class, charCoercion );
COERCIONS.put( Short.class, intCoercion );
COERCIONS.put( Integer.class, intCoercion );
COERCIONS.put( Long.class, doubleCoercion );
COERCIONS.put( Float.class, doubleCoercion );
COERCIONS.put( Double.class, doubleCoercion );
COERCIONS.put( String.class, stringCoercion );
}
/**
* Coerse a Java object to a corresponding lua value.
*
* Integral types {@code boolean}, {@code byte}, {@code char}, and {@code int}
* will become {@link LuaInteger};
* {@code long}, {@code float}, and {@code double} will become {@link LuaDouble};
* {@code String} and {@code byte[]} will become {@link LuaString};
* other types will become {@link LuaUserdata}.
* @param o Java object needing conversion
* @return {@link LuaValue} corresponding to the supplied Java value.
* @see LuaValue
* @see LuaInteger
* @see LuaDouble
* @see LuaString
* @see LuaUserdata
*/
public static LuaValue coerce(Object o) {
if ( o == null )
return LuaValue.NIL;
Class clazz = o.getClass();
Coercion c = (Coercion) COERCIONS.get( clazz );
if ( c == null ) {
c = o instanceof Class? JavaClass.forClass((Class)o):
clazz.isArray()? arrayCoercion:
instanceCoercion;
COERCIONS.put( clazz, c );
}
return c.coerce(o);
}
static final Coercion instanceCoercion = new Coercion() {
public LuaValue coerce(Object javaValue) {
return new JavaInstance(javaValue);
}
};
// should be userdata?
static final Coercion arrayCoercion = new Coercion() {
public LuaValue coerce(Object javaValue) {
return new JavaArray(javaValue);
}
};
}