com.google.gwt.emul.java.lang.System Maven / Gradle / Ivy
/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package java.lang;
import com.google.gwt.core.client.impl.Impl;
import java.io.PrintStream;
/**
* General-purpose low-level utility methods. GWT only supports a limited subset
* of these methods due to browser limitations. Only the documented methods are
* available.
*/
public final class System {
/**
* Does nothing in web mode. To get output in web mode, subclass PrintStream
* and call {@link #setErr(PrintStream)}.
*/
public static final PrintStream err = new PrintStream(null);
/**
* Does nothing in web mode. To get output in web mode, subclass
* {@link PrintStream} and call {@link #setOut(PrintStream)}.
*/
public static final PrintStream out = new PrintStream(null);
public static void arraycopy(Object src, int srcOfs, Object dest,
int destOfs, int len) {
if (src == null || dest == null) {
throw new NullPointerException();
}
Class srcType = src.getClass();
Class destType = dest.getClass();
if (!srcType.isArray() || !destType.isArray()) {
throw new ArrayStoreException("Must be array types");
}
Class srcComp = srcType.getComponentType();
Class destComp = destType.getComponentType();
if (!arrayTypeMatch(srcComp, destComp)) {
throw new ArrayStoreException("Array types must match");
}
int srclen = getArrayLength(src);
int destlen = getArrayLength(dest);
if (srcOfs < 0 || destOfs < 0 || len < 0 || srcOfs + len > srclen
|| destOfs + len > destlen) {
throw new IndexOutOfBoundsException();
}
/*
* If the arrays are not references or if they are exactly the same type, we
* can copy them in native code for speed. Otherwise, we have to copy them
* in Java so we get appropriate errors.
*/
if ((!srcComp.isPrimitive() || srcComp.isArray())
&& !srcType.equals(destType)) {
// copy in Java to make sure we get ArrayStoreExceptions if the values
// aren't compatible
Object[] srcArray = (Object[]) src;
Object[] destArray = (Object[]) dest;
if (src == dest && srcOfs < destOfs) {
// TODO(jat): how does backward copies handle failures in the middle?
// copy backwards to avoid destructive copies
srcOfs += len;
for (int destEnd = destOfs + len; destEnd-- > destOfs;) {
destArray[destEnd] = srcArray[--srcOfs];
}
} else {
for (int destEnd = destOfs + len; destOfs < destEnd;) {
destArray[destOfs++] = srcArray[srcOfs++];
}
}
} else {
nativeArraycopy(src, srcOfs, dest, destOfs, len);
}
}
public static long currentTimeMillis() {
return (long) currentTimeMillis0();
}
/**
* Has no effect; just here for source compatibility.
*
* @skip
*/
public static void gc() {
}
public static int identityHashCode(Object o) {
return (o == null) ? 0 : (!(o instanceof String)) ? Impl.getHashCode(o)
: String.HashCache.getHashCode((String) o);
}
public static native void setErr(PrintStream err) /*-{
@java.lang.System::err = err;
}-*/;
public static native void setOut(PrintStream out) /*-{
@java.lang.System::out = out;
}-*/;
private static boolean arrayTypeMatch(Class srcComp, Class destComp) {
if (srcComp.isPrimitive()) {
return srcComp.equals(destComp);
} else {
return !destComp.isPrimitive();
}
}
private static native double currentTimeMillis0() /*-{
return (new Date()).getTime();
}-*/;
/**
* Returns the length of an array via Javascript.
*/
private static native int getArrayLength(Object array) /*-{
return array.length;
}-*/;
/**
* Copy an array using native Javascript. The destination array must be a real
* Java array (ie, already has the GWT type info on it). No error checking is
* performed -- the caller is expected to have verified everything first.
*
* @param src source array for copy
* @param srcOfs offset into source array
* @param dest destination array for copy
* @param destOfs offset into destination array
* @param len number of elements to copy
*/
private static native void nativeArraycopy(Object src, int srcOfs, Object dest, int destOfs,
int len) /*-{
Array.prototype.splice.apply(dest, [destOfs, len].concat(src.slice(srcOfs, srcOfs + len)));
}-*/;
}