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initial changes to support size prefixed buffers in Java

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This commit is contained in:
Robert Schmidtke
2017-10-02 09:29:46 +02:00
parent 7a6b2bf521
commit 9b8bb2e8a3
2 changed files with 94 additions and 21 deletions
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65
java/com/google/flatbuffers/FlatBufferBuilder.java
View File

@@ -816,14 +816,55 @@ public class FlatBufferBuilder {
* Finalize a buffer, pointing to the given `root_table`.
*
* @param root_table An offset to be added to the buffer.
* @param size_prefix Whether to prefix the size to the buffer.
*/
public void finish(int root_table) {
prep(minalign, SIZEOF_INT);
protected void finish(int root_table, boolean size_prefix) {
prep(minalign, SIZEOF_INT + (size_prefix ? SIZEOF_INT : 0));
addOffset(root_table);
if (size_prefix) {
addInt(bb.capacity() - space);
}
bb.position(space);
finished = true;
}
/**
* Finalize a buffer, pointing to the given `root_table`.
*
* @param root_table An offset to be added to the buffer.
*/
public void finish(int root_table) {
finish(root_table, false);
}
/**
* Finalize a buffer, pointing to the given `root_table`.+, with the size prefixed.
*
* @param root_table An offset to be added to the buffer.
*/
public void finishSizePrefixed(int root_table) {
finish(root_table, true);
}
/**
* Finalize a buffer, pointing to the given `root_table`.
*
* @param root_table An offset to be added to the buffer.
* @param file_identifier A FlatBuffer file identifier to be added to the buffer before
* `root_table`.
* @param size_prefix Whether to prefix the size to the buffer.
*/
protected void finish(int root_table, String file_identifier, boolean size_prefix) {
prep(minalign, SIZEOF_INT + FILE_IDENTIFIER_LENGTH + (size_prefix ? SIZEOF_INT : 0));
if (file_identifier.length() != FILE_IDENTIFIER_LENGTH)
throw new AssertionError("FlatBuffers: file identifier must be length " +
FILE_IDENTIFIER_LENGTH);
for (int i = FILE_IDENTIFIER_LENGTH - 1; i >= 0; i--) {
addByte((byte)file_identifier.charAt(i));
}
finish(root_table, size_prefix);
}
/**
* Finalize a buffer, pointing to the given `root_table`.
*
@@ -832,14 +873,18 @@ public class FlatBufferBuilder {
* `root_table`.
*/
public void finish(int root_table, String file_identifier) {
prep(minalign, SIZEOF_INT + FILE_IDENTIFIER_LENGTH);
if (file_identifier.length() != FILE_IDENTIFIER_LENGTH)
throw new AssertionError("FlatBuffers: file identifier must be length " +
FILE_IDENTIFIER_LENGTH);
for (int i = FILE_IDENTIFIER_LENGTH - 1; i >= 0; i--) {
addByte((byte)file_identifier.charAt(i));
}
finish(root_table);
finish(root_table, file_identifier, false);
}
/**
* Finalize a buffer, pointing to the given `root_table`, with the size prefixed.
*
* @param root_table An offset to be added to the buffer.
* @param file_identifier A FlatBuffer file identifier to be added to the buffer before
* `root_table`.
*/
public void finishSizePrefixed(int root_table, String file_identifier) {
finish(root_table, file_identifier, true);
}
/**

50
src/idl_gen_general.cpp
View File

@@ -828,6 +828,30 @@ void GenStruct(StructDef &struct_def, std::string *code_ptr) {
code += ") + _bb.";
code += lang_.get_bb_position;
code += ", _bb)); }\n";
// recreate both methods for the prefixed size version
std::string ps_method_name = FunctionStart('G') + "etSizePrefixedRootAs" +
struct_def.name;
std::string ps_method_signature = " public static " + struct_def.name + " " +
ps_method_name;
// create convenience method that doesn't require an existing object
code += ps_method_signature + "(ByteBuffer _psbb) ";
code += "{ return " + ps_method_name + "(_psbb, new " + struct_def.name+ "()); }\n";
// TODO this part needs a C# equivalent
// use a slice that skips the size, then proceed as normal
code += ps_method_signature + "(ByteBuffer _psbb, " + struct_def.name + " obj) { ";
code += "ByteBuffer _bb = _psbb.slice(); ";
code += "_bb.position(4); ";
code += "return " + method_name + "(_bb, obj); }\n";
// method that returns the size for a size prefixed buffer
code += " public static int " + FunctionStart('G') + "etSizePrefix(ByteBuffer _bb) { ";
code += lang_.set_bb_byteorder;
code += "return _bb." + FunctionStart('G') + "etInt(_bb.";
code += lang_.get_bb_position + "); }\n";
if (parser_.root_struct_def_ == &struct_def) {
if (parser_.file_identifier_.length()) {
// Check if a buffer has the identifier.
@@ -1305,18 +1329,22 @@ void GenStruct(StructDef &struct_def, std::string *code_ptr) {
}
code += " return " + GenOffsetConstruct(struct_def, "o") + ";\n }\n";
if (parser_.root_struct_def_ == &struct_def) {
code += " public static void ";
code += FunctionStart('F') + "inish" + struct_def.name;
code += "Buffer(FlatBufferBuilder builder, " + GenOffsetType(struct_def);
code += " offset) {";
code += " builder." + FunctionStart('F') + "inish(offset";
if (lang_.language == IDLOptions::kCSharp) {
code += ".Value";
}
std::string size_prefix[] = { "", "SizePrefixed" };
for (int i = 0; i < 2; ++i) {
code += " public static void ";
code += FunctionStart('F') + "inish" + size_prefix[i] + struct_def.name;
code += "Buffer(FlatBufferBuilder builder, " + GenOffsetType(struct_def);
code += " offset) {";
code += " builder." + FunctionStart('F') + "inish" + size_prefix[i] +
"(offset";
if (lang_.language == IDLOptions::kCSharp) {
code += ".Value";
}
if (parser_.file_identifier_.length())
code += ", \"" + parser_.file_identifier_ + "\"";
code += "); }\n";
if (parser_.file_identifier_.length())
code += ", \"" + parser_.file_identifier_ + "\"";
code += "); }\n";
}
}
}
// Only generate key compare function for table,