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Initial commit of the FlatBuffers code.

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Change-Id: I4c9f0f722490b374257adb3fec63e44ae93da920
Tested: using VS2010 / Xcode / gcc on Linux.
This commit is contained in:
Wouter van Oortmerssen
2014-01-27 16:52:49 -08:00
parent c1b43e22b0
commit 26a30738a4
102 changed files with 12647 additions and 0 deletions
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248
java/flatbuffers/FlatBufferBuilder.java Executable file
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/*
* 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 flatbuffers;
import java.lang.String;
import java.util.Arrays;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.charset.Charset;
// Class that helps you build a FlatBuffer.
// See the section "Use in Java" in the main FlatBuffers documentation.
public class FlatBufferBuilder {
ByteBuffer bb; // Where we construct the FlatBuffer.
int space; // Remaining space in the ByteBuffer.
final Charset utf8charset = Charset.forName("UTF-8");
int minalign = 1; // Minimum alignment encountered so far.
int[] vtable; // The vtable for the current table, null otherwise.
int object_start; // Starting offset of the current struct/table.
int[] vtables = new int[16]; // List of offsets of all vtables.
int num_vtables = 0; // Number of entries in `vtables` in use.
int vector_num_elems = 0; // For the current vector being built.
// Java doesn't seem to have these.
final int SIZEOF_SHORT = 2;
final int SIZEOF_INT = 4;
// Start with a buffer of size `initial_size`, then grow as required.
public FlatBufferBuilder(int initial_size) {
space = initial_size;
bb = newByteBuffer(new byte[initial_size]);
}
ByteBuffer newByteBuffer(byte[] buf) {
ByteBuffer newbb = ByteBuffer.wrap(buf);
newbb.order(ByteOrder.LITTLE_ENDIAN);
return newbb;
}
// Doubles the size of the ByteBuffer, and copies the old data towards the
// end of the new buffer (since we build the buffer backwards).
ByteBuffer growByteBuffer(ByteBuffer bb) {
byte[] old_buf = bb.array();
int old_buf_size = old_buf.length;
int new_buf_size = old_buf_size * 2;
byte[] new_buf = new byte[new_buf_size];
System.arraycopy(old_buf, 0, new_buf, new_buf_size - old_buf_size, old_buf_size);
ByteBuffer nbb = newByteBuffer(new_buf);
nbb.position(bb.position());
return nbb;
}
// Offset relative to the end of the buffer.
public int offset() {
return bb.array().length - space;
}
public void pad(int byte_size) {
for (int i = 0; i < byte_size; i++) bb.put(--space, (byte)0);
}
// Prepare to write an element of `size` after `additional_bytes`
// have been written, e.g. if you write a string, you need to align such
// the int length field is aligned to SIZEOF_INT, and the string data follows it
// directly.
// If all you need to do is align, `additional_bytes` will be 0.
public void prep(int size, int additional_bytes) {
// Track the biggest thing we've ever aligned to.
if (size > minalign) minalign = size;
// Find the amount of alignment needed such that `size` is properly
// aligned after `additional_bytes`
int align_size = ((~(bb.array().length - space + additional_bytes)) + 1) & (size - 1);
// Reallocate the buffer if needed.
while (space < align_size + size + additional_bytes) {
int old_buf_size = bb.array().length;
bb = growByteBuffer(bb);
space += bb.array().length - old_buf_size;
}
pad(align_size);
}
// Add a scalar to the buffer, backwards from the current location.
// Doesn't align nor check for space.
public void putByte (byte x) { bb.put (space -= 1, x); }
public void putShort (short x) { bb.putShort (space -= 2, x); }
public void putInt (int x) { bb.putInt (space -= 4, x); }
public void putLong (long x) { bb.putLong (space -= 8, x); }
public void putFloat (float x) { bb.putFloat (space -= 4, x); }
public void putDouble(double x) { bb.putDouble(space -= 8, x); }
// Adds a scalar to the buffer, properly aligned, and the buffer grown
// if needed.
public void addByte (byte x) { prep(1, 0); putByte (x); }
public void addShort (short x) { prep(2, 0); putShort (x); }
public void addInt (int x) { prep(4, 0); putInt (x); }
public void addLong (long x) { prep(8, 0); putLong (x); }
public void addFloat (float x) { prep(4, 0); putFloat (x); }
public void addDouble(double x) { prep(8, 0); putDouble(x); }
// Adds on offset, relative to where it will be written.
public void addOffset(int off) {
prep(SIZEOF_INT, 0); // Ensure alignment is already done.
assert off <= offset();
off = offset() - off + SIZEOF_INT;
putInt(off);
}
public void startVector(int elem_size, int num_elems) {
notNested();
vector_num_elems = num_elems;
prep(SIZEOF_INT, elem_size * num_elems);
}
public int endVector() {
putInt(vector_num_elems);
return offset();
}
public int createString(String s) {
byte[] utf8 = s.getBytes(utf8charset);
bb.put(--space, (byte)0);
startVector(1, utf8.length);
System.arraycopy(utf8, 0, bb.array(), space -= utf8.length, utf8.length);
return endVector();
}
public void notNested() {
// You should not be creating any other objects or strings/vectors
// while an object is being constructed
if (vtable != null)
throw new AssertionError("FlatBuffers: object serialization must not be nested.");
}
public void Nested(int obj) {
// Structs are always stored inline, so need to be created right
// where they are used. You'll get this assert if you created it
// elsewhere.
if (obj != offset())
throw new AssertionError("FlatBuffers: struct must be serialized inline.");
}
public void startObject(int numfields) {
notNested();
vtable = new int[numfields];
object_start = offset();
}
// Add a scalar to a table at `o` into its vtable, with value `x` and default `d`
public void addByte (int o, byte x, int d) { if(x != d) { addByte (x); slot(o); } }
public void addShort (int o, short x, int d) { if(x != d) { addShort (x); slot(o); } }
public void addInt (int o, int x, int d) { if(x != d) { addInt (x); slot(o); } }
public void addLong (int o, long x, long d) { if(x != d) { addLong (x); slot(o); } }
public void addFloat (int o, float x, double d) { if(x != d) { addFloat (x); slot(o); } }
public void addDouble(int o, double x, double d) { if(x != d) { addDouble(x); slot(o); } }
public void addOffset(int o, int x, int d) { if(x != d) { addOffset(x); slot(o); } }
// Structs are stored inline, so nothing additional is being added. `d` is always 0.
public void addStruct(int voffset, int x, int d) {
if(x != d) {
Nested(x);
slot(voffset);
}
}
// Set the current vtable at `voffset` to the current location in the buffer.
public void slot(int voffset) {
vtable[voffset] = offset();
}
public int endObject() {
assert vtable != null; // calling endObject without a startObject
addInt(0);
int vtableloc = offset();
// Write out the current vtable.
for (int i = vtable.length - 1; i >= 0 ; i--) {
// Offset relative to the start of the table.
short off = (short)(vtable[i] != 0 ? vtableloc - vtable[i] : 0);
putShort(off);
}
final int standard_fields = 2; // The fields below:
putShort((short)(vtableloc - object_start));
putShort((short)((vtable.length + standard_fields) * SIZEOF_SHORT));
// Search for an existing vtable that matches the current one.
int existing_vtable = 0;
outer_loop:
for (int i = 0; i < num_vtables; i++) {
int vt1 = bb.array().length - vtables[i];
int vt2 = space;
short len = bb.getShort(vt1);
if (len == bb.getShort(vt2)) {
for (int j = SIZEOF_SHORT; j < len; j += SIZEOF_SHORT) {
if (bb.getShort(vt1 + j) != bb.getShort(vt2 + j)) {
continue outer_loop;
}
}
existing_vtable = vtables[i];
break outer_loop;
}
}
if (existing_vtable != 0) {
// Found a match:
// Remove the current vtable.
space = bb.array().length - vtableloc;
// Point table to existing vtable.
bb.putInt(space, existing_vtable - vtableloc);
} else {
// No match:
// Add the location of the current vtable to the list of vtables.
if (num_vtables == vtables.length) vtables = Arrays.copyOf(vtables, num_vtables * 2);
vtables[num_vtables++] = offset();
// Point table to current vtable.
bb.putInt(bb.array().length - vtableloc, offset() - vtableloc);
}
vtable = null;
return vtableloc;
}
public void finish(int root_table) {
prep(minalign, SIZEOF_INT);
addOffset(root_table);
}
public ByteBuffer dataBuffer() { return bb; }
// The FlatBuffer data doesn't start at offset 0 in the ByteBuffer:
public int dataStart() {
return bb.array().length - offset();
}
}

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java/flatbuffers/Struct.java Executable file
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/*
* 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 flatbuffers;
import java.nio.ByteBuffer;
// All structs in the generated code derive from this class, and add their own accessors.
public class Struct {
protected int bb_pos;
protected ByteBuffer bb;
}

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java/flatbuffers/Table.java Executable file
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/*
* 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 flatbuffers;
import java.lang.String;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
// All tables in the generated code derive from this class, and add their own accessors.
public class Table {
protected int bb_pos;
protected ByteBuffer bb;
final int SIZEOF_INT = 4;
// Look up a field in the vtable, return 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;
}
// Retrieve the relative offset stored at "offset"
protected int __indirect(int offset) {
return offset + bb.getInt(offset);
}
// Create a java String from UTF-8 data stored inside the flatbuffer.
protected String __string(int offset) {
offset += bb_pos;
offset += bb.getInt(offset);
return new String(bb.array(), offset + SIZEOF_INT, bb.getInt(offset), Charset.forName("UTF-8"));
}
// Get the length of a vector whose offset is stored at "offset" in this object.
protected int __vector_len(int offset) {
offset += bb_pos;
offset += bb.getInt(offset);
return bb.getInt(offset);
}
// Get the start of data of a vector whose offset is stored at "offset" in this object.
protected int __vector(int offset) {
offset += bb_pos;
return offset + bb.getInt(offset) + SIZEOF_INT; // data starts after the length
}
// Initialize any Table-derived type to point to the union at the given offset.
protected Table __union(Table t, int offset) {
offset += bb_pos;
t.bb_pos = offset + bb.getInt(offset);
t.bb = bb;
return t;
}
}