SOLR-1900: add missing ByteUtils.java

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@948215 13f79535-47bb-0310-9956-ffa450edef68

solr/src/java/org/apache/solr/util/ByteUtils.java

@@ -0,0 +1,76 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.solr.util;
+
+import org.apache.lucene.util.ArrayUtil;
+import org.apache.lucene.util.BytesRef;
+import org.apache.noggit.CharArr;
+
+
+public class ByteUtils {
+
+  /** Converts utf8 to utf16 and returns the number of 16 bit Java chars written.
+   * Full characters are read, even if this reads past the length passed (and can result in
+   * an exception if invalid UTF8 is passed).
+   * The char[] out should probably have enough room to hold the worst case of each byte becoming a Java char. */ 
+  public static int UTF8toUTF16(byte[] utf8, int offset, int len, char[] out, int out_offset) {
+    int out_start = out_offset;
+
+    while (offset < len) {
+      int b = utf8[offset++]&0xff;
+
+      if (b < 0xc0) {
+        assert b < 0x80;
+        out[out_offset++] = (char)b;
+      } else if (b < 0xe0) {
+        out[out_offset++] = (char)(((b&0x1f)<<6) + (utf8[offset++]&0x3f));
+      } else if (b < 0xf0) {
+        out[out_offset++] = (char)(((b&0xf)<<12) + ((utf8[offset]&0x3f)<<6) + (utf8[offset+1]&0x3f));
+        offset += 2;
+      } else {
+        assert b < 0xf8;
+        int ch = ((b&0x7)<<18) + ((utf8[offset]&0x3f)<<12) + ((utf8[offset+1]&0x3f)<<6) + (utf8[offset+2]&0x3f);
+        offset += 3;
+        if (ch < 0xffff) {
+          out[out_offset++] = (char)ch;
+        } else {
+          int chHalf = ch - 0x0010000;
+          out[out_offset++] = (char) ((chHalf >> 10) + 0xD800);
+          out[out_offset++] = (char) ((chHalf & 0x3FFL) + 0xDC00);          
+        }
+      }
+    }
+
+    return out_offset - out_start;
+  }
+
+  /** Convert UTF8 bytes into UTF16 characters. */
+  public static void UTF8toUTF16(BytesRef utf8, CharArr out) {
+    // TODO: do in chunks if the input is large
+    out.reserve(utf8.length);
+    int n = UTF8toUTF16(utf8.bytes, utf8.offset, utf8.length, out.getArray(), out.getEnd());
+    out.setEnd(out.getEnd() + n);
+  }
+
+  /** Convert UTF8 bytes into a String */
+  public static String UTF8toUTF16(BytesRef utf8) {
+    char[] out = new char[utf8.length];
+    int n = UTF8toUTF16(utf8.bytes, utf8.offset, utf8.length, out, 0);
+    return new String(out,0,n);
+  }
+}