| /* |
| * Copyright 2014 Google Inc. All rights reserved. |
| * |
| * 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 com.google.flatbuffers; |
| |
| import static com.google.flatbuffers.Constants.*; |
| import java.nio.ByteBuffer; |
| import java.nio.ByteOrder; |
| import java.nio.CharBuffer; |
| import java.nio.charset.CharacterCodingException; |
| import java.nio.charset.Charset; |
| import java.nio.charset.CharsetDecoder; |
| import java.nio.charset.CoderResult; |
| |
| /// @cond FLATBUFFERS_INTERNAL |
| |
| /** |
| * All tables in the generated code derive from this class, and add their own accessors. |
| */ |
| public class Table { |
| private final static ThreadLocal<CharsetDecoder> UTF8_DECODER = new ThreadLocal<CharsetDecoder>() { |
| @Override |
| protected CharsetDecoder initialValue() { |
| return Charset.forName("UTF-8").newDecoder(); |
| } |
| }; |
| public final static ThreadLocal<Charset> UTF8_CHARSET = new ThreadLocal<Charset>() { |
| @Override |
| protected Charset initialValue() { |
| return Charset.forName("UTF-8"); |
| } |
| }; |
| private final static ThreadLocal<CharBuffer> CHAR_BUFFER = new ThreadLocal<CharBuffer>(); |
| /** Used to hold the position of the `bb` buffer. */ |
| protected int bb_pos; |
| /** The underlying ByteBuffer to hold the data of the Table. */ |
| protected ByteBuffer bb; |
| |
| /** |
| * Get the underlying ByteBuffer. |
| * |
| * @return Returns the Table's ByteBuffer. |
| */ |
| public ByteBuffer getByteBuffer() { return bb; } |
| |
| /** |
| * Look up a field in the vtable. |
| * |
| * @param vtable_offset An `int` offset to the vtable in the Table's ByteBuffer. |
| * @return Returns an offset into the object, or `0` if the field is not present. |
| */ |
| protected int __offset(int vtable_offset) { |
| int vtable = bb_pos - bb.getInt(bb_pos); |
| return vtable_offset < bb.getShort(vtable) ? bb.getShort(vtable + vtable_offset) : 0; |
| } |
| |
| protected static int __offset(int vtable_offset, int offset, ByteBuffer bb) { |
| int vtable = bb.array().length - offset; |
| return bb.getShort(vtable + vtable_offset - bb.getInt(vtable)) + vtable; |
| } |
| |
| /** |
| * Retrieve a relative offset. |
| * |
| * @param offset An `int` index into the Table's ByteBuffer containing the relative offset. |
| * @return Returns the relative offset stored at `offset`. |
| */ |
| protected int __indirect(int offset) { |
| return offset + bb.getInt(offset); |
| } |
| |
| protected static int __indirect(int offset, ByteBuffer bb) { |
| return offset + bb.getInt(offset); |
| } |
| |
| /** |
| * Create a Java `String` from UTF-8 data stored inside the FlatBuffer. |
| * |
| * This allocates a new string and converts to wide chars upon each access, |
| * which is not very efficient. Instead, each FlatBuffer string also comes with an |
| * accessor based on __vector_as_bytebuffer below, which is much more efficient, |
| * assuming your Java program can handle UTF-8 data directly. |
| * |
| * @param offset An `int` index into the Table's ByteBuffer. |
| * @return Returns a `String` from the data stored inside the FlatBuffer at `offset`. |
| */ |
| protected String __string(int offset) { |
| CharsetDecoder decoder = UTF8_DECODER.get(); |
| decoder.reset(); |
| |
| offset += bb.getInt(offset); |
| ByteBuffer src = bb.duplicate().order(ByteOrder.LITTLE_ENDIAN); |
| int length = src.getInt(offset); |
| src.position(offset + SIZEOF_INT); |
| src.limit(offset + SIZEOF_INT + length); |
| |
| int required = (int)((float)length * decoder.maxCharsPerByte()); |
| CharBuffer dst = CHAR_BUFFER.get(); |
| if (dst == null || dst.capacity() < required) { |
| dst = CharBuffer.allocate(required); |
| CHAR_BUFFER.set(dst); |
| } |
| |
| dst.clear(); |
| |
| try { |
| CoderResult cr = decoder.decode(src, dst, true); |
| if (!cr.isUnderflow()) { |
| cr.throwException(); |
| } |
| } catch (CharacterCodingException x) { |
| throw new Error(x); |
| } |
| |
| return dst.flip().toString(); |
| } |
| |
| /** |
| * Get the length of a vector. |
| * |
| * @param offset An `int` index into the Table's ByteBuffer. |
| * @return Returns the length of the vector whose offset is stored at `offset`. |
| */ |
| protected int __vector_len(int offset) { |
| offset += bb_pos; |
| offset += bb.getInt(offset); |
| return bb.getInt(offset); |
| } |
| |
| /** |
| * Get the start data of a vector. |
| * |
| * @param offset An `int` index into the Table's ByteBuffer. |
| * @return Returns the start of the vector data whose offset is stored at `offset`. |
| */ |
| protected int __vector(int offset) { |
| offset += bb_pos; |
| return offset + bb.getInt(offset) + SIZEOF_INT; // data starts after the length |
| } |
| |
| /** |
| * Get a whole vector as a ByteBuffer. |
| * |
| * This is efficient, since it only allocates a new {@link ByteBuffer} object, |
| * but does not actually copy the data, it still refers to the same bytes |
| * as the original ByteBuffer. Also useful with nested FlatBuffers, etc. |
| * |
| * @param vector_offset The position of the vector in the byte buffer |
| * @param elem_size The size of each element in the array |
| * @return The {@link ByteBuffer} for the array |
| */ |
| protected ByteBuffer __vector_as_bytebuffer(int vector_offset, int elem_size) { |
| int o = __offset(vector_offset); |
| if (o == 0) return null; |
| ByteBuffer bb = this.bb.duplicate().order(ByteOrder.LITTLE_ENDIAN); |
| int vectorstart = __vector(o); |
| bb.position(vectorstart); |
| bb.limit(vectorstart + __vector_len(o) * elem_size); |
| return bb; |
| } |
| |
| /** |
| * Initialize any Table-derived type to point to the union at the given `offset`. |
| * |
| * @param t A `Table`-derived type that should point to the union at `offset`. |
| * @param offset An `int` index into the Table's ByteBuffer. |
| * @return Returns the Table that points to the union at `offset`. |
| */ |
| protected Table __union(Table t, int offset) { |
| offset += bb_pos; |
| t.bb_pos = offset + bb.getInt(offset); |
| t.bb = bb; |
| return t; |
| } |
| |
| /** |
| * Check if a {@link ByteBuffer} contains a file identifier. |
| * |
| * @param bb A {@code ByteBuffer} to check if it contains the identifier |
| * `ident`. |
| * @param ident A `String` identifier of the FlatBuffer file. |
| * @return True if the buffer contains the file identifier |
| */ |
| protected static boolean __has_identifier(ByteBuffer bb, String ident) { |
| if (ident.length() != FILE_IDENTIFIER_LENGTH) |
| throw new AssertionError("FlatBuffers: file identifier must be length " + |
| FILE_IDENTIFIER_LENGTH); |
| for (int i = 0; i < FILE_IDENTIFIER_LENGTH; i++) { |
| if (ident.charAt(i) != (char)bb.get(bb.position() + SIZEOF_INT + i)) return false; |
| } |
| return true; |
| } |
| |
| /** |
| * Sort tables by the key. |
| * |
| * @param offsets An 'int' indexes of the tables into the bb. |
| * @param bb A {@code ByteBuffer} to get the tables. |
| */ |
| protected void sortTables(int[] offsets, final ByteBuffer bb) { |
| Integer[] off = new Integer[offsets.length]; |
| for (int i = 0; i < offsets.length; i++) off[i] = offsets[i]; |
| java.util.Arrays.sort(off, new java.util.Comparator<Integer>() { |
| public int compare(Integer o1, Integer o2) { |
| return keysCompare(o1, o2, bb); |
| } |
| }); |
| for (int i = 0; i < offsets.length; i++) offsets[i] = off[i]; |
| } |
| |
| /** |
| * Compare two tables by the key. |
| * |
| * @param o1 An 'Integer' index of the first key into the bb. |
| * @param o2 An 'Integer' index of the second key into the bb. |
| * @param bb A {@code ByteBuffer} to get the keys. |
| */ |
| protected int keysCompare(Integer o1, Integer o2, ByteBuffer bb) { return 0; } |
| |
| /** |
| * Compare two strings in the buffer. |
| * |
| * @param offset_1 An 'int' index of the first string into the bb. |
| * @param offset_2 An 'int' index of the second string into the bb. |
| * @param bb A {@code ByteBuffer} to get the strings. |
| */ |
| protected static int compareStrings(int offset_1, int offset_2, ByteBuffer bb) { |
| offset_1 += bb.getInt(offset_1); |
| offset_2 += bb.getInt(offset_2); |
| int len_1 = bb.getInt(offset_1); |
| int len_2 = bb.getInt(offset_2); |
| int startPos_1 = offset_1 + SIZEOF_INT; |
| int startPos_2 = offset_2 + SIZEOF_INT; |
| int len = Math.min(len_1, len_2); |
| byte[] bbArray = bb.array(); |
| for(int i = 0; i < len; i++) { |
| if (bbArray[i + startPos_1] != bbArray[i + startPos_2]) |
| return bbArray[i + startPos_1] - bbArray[i + startPos_2]; |
| } |
| return len_1 - len_2; |
| } |
| |
| /** |
| * Compare string from the buffer with the 'String' object. |
| * |
| * @param offset_1 An 'int' index of the first string into the bb. |
| * @param key Second string as a byte array. |
| * @param bb A {@code ByteBuffer} to get the first string. |
| */ |
| protected static int compareStrings(int offset_1, byte[] key, ByteBuffer bb) { |
| offset_1 += bb.getInt(offset_1); |
| int len_1 = bb.getInt(offset_1); |
| int len_2 = key.length; |
| int startPos_1 = offset_1 + Constants.SIZEOF_INT; |
| int len = Math.min(len_1, len_2); |
| byte[] bbArray = bb.array(); |
| for (int i = 0; i < len; i++) { |
| if (bbArray[i + startPos_1] != key[i]) |
| return bbArray[i + startPos_1] - key[i]; |
| } |
| return len_1 - len_2; |
| } |
| } |
| |
| /// @endcond |