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flatbuffers/src/idl_gen_java.cpp
Wouter van Oortmerssen 6df40a2471 pre-tag version bump for 1.12 
Change-Id: I84a9365e9d8a1afe333b1df85058401ffe0a6b7c
2020-03-12 15:33:39 -07:00

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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.
*/
// independent from idl_parser, since this code is not needed for most clients
#include "flatbuffers/code_generators.h"
#include "flatbuffers/flatbuffers.h"
#include "flatbuffers/idl.h"
#include "flatbuffers/util.h"
#if defined(FLATBUFFERS_CPP98_STL)
# include <cctype>
#endif // defined(FLATBUFFERS_CPP98_STL)
namespace flatbuffers {
namespace java {
static TypedFloatConstantGenerator JavaFloatGen("Double.", "Float.", "NaN",
"POSITIVE_INFINITY",
"NEGATIVE_INFINITY");
static CommentConfig comment_config = {
"/**",
" *",
" */",
};
class JavaGenerator : public BaseGenerator {
public:
JavaGenerator(const Parser &parser, const std::string &path,
const std::string &file_name)
: BaseGenerator(parser, path, file_name, "", ".", "java"),
cur_name_space_(nullptr) {}
JavaGenerator &operator=(const JavaGenerator &);
bool generate() {
std::string one_file_code;
cur_name_space_ = parser_.current_namespace_;
for (auto it = parser_.enums_.vec.begin(); it != parser_.enums_.vec.end();
++it) {
std::string enumcode;
auto &enum_def = **it;
if (!parser_.opts.one_file) cur_name_space_ = enum_def.defined_namespace;
GenEnum(enum_def, &enumcode);
if (parser_.opts.one_file) {
one_file_code += enumcode;
} else {
if (!SaveType(enum_def.name, *enum_def.defined_namespace, enumcode,
false))
return false;
}
}
for (auto it = parser_.structs_.vec.begin();
it != parser_.structs_.vec.end(); ++it) {
std::string declcode;
auto &struct_def = **it;
if (!parser_.opts.one_file)
cur_name_space_ = struct_def.defined_namespace;
GenStruct(struct_def, &declcode);
if (parser_.opts.one_file) {
one_file_code += declcode;
} else {
if (!SaveType(struct_def.name, *struct_def.defined_namespace, declcode,
true))
return false;
}
}
if (parser_.opts.one_file) {
return SaveType(file_name_, *parser_.current_namespace_, one_file_code,
true);
}
return true;
}
// Save out the generated code for a single class while adding
// declaration boilerplate.
bool SaveType(const std::string &defname, const Namespace &ns,
const std::string &classcode, bool needs_includes) const {
if (!classcode.length()) return true;
std::string code;
code = "// " + std::string(FlatBuffersGeneratedWarning()) + "\n\n";
std::string namespace_name = FullNamespace(".", ns);
if (!namespace_name.empty()) {
code += "package " + namespace_name + ";";
code += "\n\n";
}
if (needs_includes) {
code +=
"import java.nio.*;\nimport java.lang.*;\nimport "
"java.util.*;\nimport com.google.flatbuffers.*;\n";
if (parser_.opts.gen_nullable) {
code += "\nimport javax.annotation.Nullable;\n";
}
if (parser_.opts.java_checkerframework) {
code += "\nimport org.checkerframework.dataflow.qual.Pure;\n";
}
code += "\n@SuppressWarnings(\"unused\")\n";
}
if (parser_.opts.gen_generated) {
code += "\n@javax.annotation.Generated(value=\"flatc\")\n";
}
code += classcode;
if (!namespace_name.empty()) code += "";
auto filename = NamespaceDir(ns) + defname + ".java";
return SaveFile(filename.c_str(), code, false);
}
const Namespace *CurrentNameSpace() const { return cur_name_space_; }
std::string GenNullableAnnotation(const Type &t) const {
return parser_.opts.gen_nullable &&
!IsScalar(DestinationType(t, true).base_type) &&
t.base_type != BASE_TYPE_VECTOR
? " @Nullable "
: "";
}
std::string GenPureAnnotation(const Type &t) const {
return parser_.opts.java_checkerframework &&
!IsScalar(DestinationType(t, true).base_type)
? " @Pure "
: "";
}
std::string GenTypeBasic(const Type &type) const {
// clang-format off
static const char * const java_typename[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE, ...) \
#JTYPE,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
// clang-format on
return java_typename[type.base_type];
}
std::string GenTypePointer(const Type &type) const {
switch (type.base_type) {
case BASE_TYPE_STRING: return "String";
case BASE_TYPE_VECTOR: return GenTypeGet(type.VectorType());
case BASE_TYPE_STRUCT: return WrapInNameSpace(*type.struct_def);
case BASE_TYPE_UNION: FLATBUFFERS_FALLTHROUGH(); // else fall thru
default: return "Table";
}
}
std::string GenTypeGet(const Type &type) const {
return IsScalar(type.base_type)
? GenTypeBasic(type)
: (IsArray(type) ? GenTypeGet(type.VectorType())
: GenTypePointer(type));
}
// Find the destination type the user wants to receive the value in (e.g.
// one size higher signed types for unsigned serialized values in Java).
Type DestinationType(const Type &type, bool vectorelem) const {
switch (type.base_type) {
// We use int for both uchar/ushort, since that generally means less
// casting than using short for uchar.
case BASE_TYPE_UCHAR: return Type(BASE_TYPE_INT);
case BASE_TYPE_USHORT: return Type(BASE_TYPE_INT);
case BASE_TYPE_UINT: return Type(BASE_TYPE_LONG);
case BASE_TYPE_ARRAY:
case BASE_TYPE_VECTOR:
if (vectorelem) return DestinationType(type.VectorType(), vectorelem);
FLATBUFFERS_FALLTHROUGH(); // else fall thru
default: return type;
}
}
std::string GenOffsetType() const { return "int"; }
std::string GenOffsetConstruct(const std::string &variable_name) const {
return variable_name;
}
std::string GenVectorOffsetType() const { return "int"; }
// Generate destination type name
std::string GenTypeNameDest(const Type &type) const {
return GenTypeGet(DestinationType(type, true));
}
// Mask to turn serialized value into destination type value.
std::string DestinationMask(const Type &type, bool vectorelem) const {
switch (type.base_type) {
case BASE_TYPE_UCHAR: return " & 0xFF";
case BASE_TYPE_USHORT: return " & 0xFFFF";
case BASE_TYPE_UINT: return " & 0xFFFFFFFFL";
case BASE_TYPE_VECTOR:
if (vectorelem) return DestinationMask(type.VectorType(), vectorelem);
FLATBUFFERS_FALLTHROUGH(); // else fall thru
default: return "";
}
}
// Casts necessary to correctly read serialized data
std::string DestinationCast(const Type &type) const {
if (IsSeries(type)) {
return DestinationCast(type.VectorType());
} else {
// Cast necessary to correctly read serialized unsigned values.
if (type.base_type == BASE_TYPE_UINT) return "(long)";
}
return "";
}
// Cast statements for mutator method parameters.
// In Java, parameters representing unsigned numbers need to be cast down to
// their respective type. For example, a long holding an unsigned int value
// would be cast down to int before being put onto the buffer. In C#, one cast
// directly cast an Enum to its underlying type, which is essential before
// putting it onto the buffer.
std::string SourceCast(const Type &type, bool castFromDest) const {
if (IsSeries(type)) {
return SourceCast(type.VectorType(), castFromDest);
} else {
if (castFromDest) {
if (type.base_type == BASE_TYPE_UINT)
return "(int)";
else if (type.base_type == BASE_TYPE_USHORT)
return "(short)";
else if (type.base_type == BASE_TYPE_UCHAR)
return "(byte)";
}
}
return "";
}
std::string SourceCast(const Type &type) const {
return SourceCast(type, true);
}
std::string SourceCastBasic(const Type &type, bool castFromDest) const {
return IsScalar(type.base_type) ? SourceCast(type, castFromDest) : "";
}
std::string SourceCastBasic(const Type &type) const {
return SourceCastBasic(type, true);
}
std::string GenEnumDefaultValue(const FieldDef &field) const {
auto &value = field.value;
FLATBUFFERS_ASSERT(value.type.enum_def);
auto &enum_def = *value.type.enum_def;
auto enum_val = enum_def.FindByValue(value.constant);
return enum_val ? (WrapInNameSpace(enum_def) + "." + enum_val->name)
: value.constant;
}
std::string GenDefaultValue(const FieldDef &field) const {
auto &value = field.value;
auto longSuffix = "L";
switch (value.type.base_type) {
case BASE_TYPE_BOOL: return value.constant == "0" ? "false" : "true";
case BASE_TYPE_ULONG: {
// Converts the ulong into its bits signed equivalent
uint64_t defaultValue = StringToUInt(value.constant.c_str());
return NumToString(static_cast<int64_t>(defaultValue)) + longSuffix;
}
case BASE_TYPE_UINT:
case BASE_TYPE_LONG: return value.constant + longSuffix;
default:
if (IsFloat(value.type.base_type))
return JavaFloatGen.GenFloatConstant(field);
else
return value.constant;
}
}
std::string GenDefaultValueBasic(const FieldDef &field) const {
auto &value = field.value;
if (!IsScalar(value.type.base_type)) { return "0"; }
return GenDefaultValue(field);
}
void GenEnum(EnumDef &enum_def, std::string *code_ptr) const {
std::string &code = *code_ptr;
if (enum_def.generated) return;
// Generate enum definitions of the form:
// public static (final) int name = value;
// In Java, we use ints rather than the Enum feature, because we want them
// to map directly to how they're used in C/C++ and file formats.
// That, and Java Enums are expensive, and not universally liked.
GenComment(enum_def.doc_comment, code_ptr, &comment_config);
if (enum_def.attributes.Lookup("private")) {
// For Java, we leave the enum unmarked to indicate package-private
// For C# we mark the enum as internal
} else {
code += "public ";
}
code += "final class " + enum_def.name;
code += " {\n";
code += " private " + enum_def.name + "() { }\n";
for (auto it = enum_def.Vals().begin(); it != enum_def.Vals().end(); ++it) {
auto &ev = **it;
GenComment(ev.doc_comment, code_ptr, &comment_config, " ");
code += " public static final ";
code += GenTypeBasic(enum_def.underlying_type);
code += " ";
code += ev.name + " = ";
code += enum_def.ToString(ev);
code += ";\n";
}
// Generate a generate string table for enum values.
// We do not do that for C# where this functionality is native.
// Problem is, if values are very sparse that could generate really big
// tables. Ideally in that case we generate a map lookup instead, but for
// the moment we simply don't output a table at all.
auto range = enum_def.Distance();
// Average distance between values above which we consider a table
// "too sparse". Change at will.
static const uint64_t kMaxSparseness = 5;
if (range / static_cast<uint64_t>(enum_def.size()) < kMaxSparseness) {
code += "\n public static final String";
code += "[] names = { ";
auto val = enum_def.Vals().front();
for (auto it = enum_def.Vals().begin(); it != enum_def.Vals().end();
++it) {
auto ev = *it;
for (auto k = enum_def.Distance(val, ev); k > 1; --k) code += "\"\", ";
val = ev;
code += "\"" + (*it)->name + "\", ";
}
code += "};\n\n";
code += " public static ";
code += "String";
code += " " + MakeCamel("name", false);
code += "(int e) { return names[e";
if (enum_def.MinValue()->IsNonZero())
code += " - " + enum_def.MinValue()->name;
code += "]; }\n";
}
// Close the class
code += "}";
// Java does not need the closing semi-colon on class definitions.
code += "";
code += "\n\n";
}
// Returns the function name that is able to read a value of the given type.
std::string GenGetter(const Type &type) const {
switch (type.base_type) {
case BASE_TYPE_STRING: return "__string";
case BASE_TYPE_STRUCT: return "__struct";
case BASE_TYPE_UNION: return "__union";
case BASE_TYPE_VECTOR: return GenGetter(type.VectorType());
case BASE_TYPE_ARRAY: return GenGetter(type.VectorType());
default: {
std::string getter = "bb.get";
if (type.base_type == BASE_TYPE_BOOL) {
getter = "0!=" + getter;
} else if (GenTypeBasic(type) != "byte") {
getter += MakeCamel(GenTypeBasic(type));
}
return getter;
}
}
}
// Returns the function name that is able to read a value of the given type.
std::string GenGetterForLookupByKey(flatbuffers::FieldDef *key_field,
const std::string &data_buffer,
const char *num = nullptr) const {
auto type = key_field->value.type;
auto dest_mask = DestinationMask(type, true);
auto dest_cast = DestinationCast(type);
auto getter = data_buffer + ".get";
if (GenTypeBasic(type) != "byte") {
getter += MakeCamel(GenTypeBasic(type));
}
getter = dest_cast + getter + "(" + GenOffsetGetter(key_field, num) + ")" +
dest_mask;
return getter;
}
// Direct mutation is only allowed for scalar fields.
// Hence a setter method will only be generated for such fields.
std::string GenSetter(const Type &type) const {
if (IsScalar(type.base_type)) {
std::string setter = "bb.put";
if (GenTypeBasic(type) != "byte" && type.base_type != BASE_TYPE_BOOL) {
setter += MakeCamel(GenTypeBasic(type));
}
return setter;
} else {
return "";
}
}
// Returns the method name for use with add/put calls.
std::string GenMethod(const Type &type) const {
return IsScalar(type.base_type) ? MakeCamel(GenTypeBasic(type))
: (IsStruct(type) ? "Struct" : "Offset");
}
// Recursively generate arguments for a constructor, to deal with nested
// structs.
void GenStructArgs(const StructDef &struct_def, std::string *code_ptr,
const char *nameprefix, size_t array_count = 0) const {
std::string &code = *code_ptr;
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
const auto &field_type = field.value.type;
const auto array_field = IsArray(field_type);
const auto &type = array_field ? field_type.VectorType()
: DestinationType(field_type, false);
const auto array_cnt = array_field ? (array_count + 1) : array_count;
if (IsStruct(type)) {
// Generate arguments for a struct inside a struct. To ensure names
// don't clash, and to make it obvious these arguments are constructing
// a nested struct, prefix the name with the field name.
GenStructArgs(*field_type.struct_def, code_ptr,
(nameprefix + (field.name + "_")).c_str(), array_cnt);
} else {
code += ", ";
code += GenTypeBasic(type);
for (size_t i = 0; i < array_cnt; i++) code += "[]";
code += " ";
code += nameprefix;
code += MakeCamel(field.name, false);
}
}
}
// Recusively generate struct construction statements of the form:
// builder.putType(name);
// and insert manual padding.
void GenStructBody(const StructDef &struct_def, std::string *code_ptr,
const char *nameprefix, size_t index = 0,
bool in_array = false) const {
std::string &code = *code_ptr;
std::string indent((index + 1) * 2, ' ');
code += indent + " builder.prep(";
code += NumToString(struct_def.minalign) + ", ";
code += NumToString(struct_def.bytesize) + ");\n";
for (auto it = struct_def.fields.vec.rbegin();
it != struct_def.fields.vec.rend(); ++it) {
auto &field = **it;
const auto &field_type = field.value.type;
if (field.padding) {
code += indent + " builder.pad(";
code += NumToString(field.padding) + ");\n";
}
if (IsStruct(field_type)) {
GenStructBody(*field_type.struct_def, code_ptr,
(nameprefix + (field.name + "_")).c_str(), index,
in_array);
} else {
const auto &type =
IsArray(field_type) ? field_type.VectorType() : field_type;
const auto index_var = "_idx" + NumToString(index);
if (IsArray(field_type)) {
code += indent + " for (int " + index_var + " = ";
code += NumToString(field_type.fixed_length);
code += "; " + index_var + " > 0; " + index_var + "--) {\n";
in_array = true;
}
if (IsStruct(type)) {
GenStructBody(*field_type.struct_def, code_ptr,
(nameprefix + (field.name + "_")).c_str(), index + 1,
in_array);
} else {
code += IsArray(field_type) ? " " : "";
code += indent + " builder.put";
code += GenMethod(type) + "(";
code += SourceCast(type);
auto argname = nameprefix + MakeCamel(field.name, false);
code += argname;
size_t array_cnt = index + (IsArray(field_type) ? 1 : 0);
for (size_t i = 0; in_array && i < array_cnt; i++) {
code += "[_idx" + NumToString(i) + "-1]";
}
code += ");\n";
}
if (IsArray(field_type)) { code += indent + " }\n"; }
}
}
}
std::string GenByteBufferLength(const char *bb_name) const {
std::string bb_len = bb_name;
bb_len += ".capacity()";
return bb_len;
}
std::string GenOffsetGetter(flatbuffers::FieldDef *key_field,
const char *num = nullptr) const {
std::string key_offset = "";
key_offset += "__offset(" + NumToString(key_field->value.offset) + ", ";
if (num) {
key_offset += num;
key_offset += ", _bb)";
} else {
key_offset += GenByteBufferLength("bb");
key_offset += " - tableOffset, bb)";
}
return key_offset;
}
std::string GenLookupKeyGetter(flatbuffers::FieldDef *key_field) const {
std::string key_getter = " ";
key_getter += "int tableOffset = ";
key_getter += "__indirect(vectorLocation + 4 * (start + middle)";
key_getter += ", bb);\n ";
if (key_field->value.type.base_type == BASE_TYPE_STRING) {
key_getter += "int comp = ";
key_getter += "compareStrings(";
key_getter += GenOffsetGetter(key_field);
key_getter += ", byteKey, bb);\n";
} else {
auto get_val = GenGetterForLookupByKey(key_field, "bb");
key_getter += GenTypeNameDest(key_field->value.type) + " val = ";
key_getter += get_val + ";\n";
key_getter += " int comp = val > key ? 1 : val < key ? -1 : 0;\n";
}
return key_getter;
}
std::string GenKeyGetter(flatbuffers::FieldDef *key_field) const {
std::string key_getter = "";
auto data_buffer = "_bb";
if (key_field->value.type.base_type == BASE_TYPE_STRING) {
key_getter += " return ";
key_getter += "";
key_getter += "compareStrings(";
key_getter += GenOffsetGetter(key_field, "o1") + ", ";
key_getter += GenOffsetGetter(key_field, "o2") + ", " + data_buffer + ")";
key_getter += ";";
} else {
auto field_getter = GenGetterForLookupByKey(key_field, data_buffer, "o1");
key_getter +=
"\n " + GenTypeNameDest(key_field->value.type) + " val_1 = ";
key_getter +=
field_getter + ";\n " + GenTypeNameDest(key_field->value.type);
key_getter += " val_2 = ";
field_getter = GenGetterForLookupByKey(key_field, data_buffer, "o2");
key_getter += field_getter + ";\n";
key_getter += " return val_1 > val_2 ? 1 : val_1 < val_2 ? -1 : 0;\n ";
}
return key_getter;
}
void GenStruct(StructDef &struct_def, std::string *code_ptr) const {
if (struct_def.generated) return;
std::string &code = *code_ptr;
// Generate a struct accessor class, with methods of the form:
// public type name() { return bb.getType(i + offset); }
// or for tables of the form:
// public type name() {
// int o = __offset(offset); return o != 0 ? bb.getType(o + i) : default;
// }
GenComment(struct_def.doc_comment, code_ptr, &comment_config);
if (struct_def.attributes.Lookup("private")) {
// For Java, we leave the struct unmarked to indicate package-private
// For C# we mark the struct as internal
} else {
code += "public ";
}
code += "final ";
code += "class " + struct_def.name;
code += " extends ";
code += struct_def.fixed ? "Struct" : "Table";
code += " {\n";
if (!struct_def.fixed) {
// Generate verson check method.
// Force compile time error if not using the same version runtime.
code += " public static void ValidateVersion() {";
code += " Constants.";
code += "FLATBUFFERS_1_12_0(); ";
code += "}\n";
// Generate a special accessor for the table that when used as the root
// of a FlatBuffer
std::string method_name = "getRootAs" + struct_def.name;
std::string method_signature =
" public static " + struct_def.name + " " + method_name;
// create convenience method that doesn't require an existing object
code += method_signature + "(ByteBuffer _bb) ";
code += "{ return " + method_name + "(_bb, new " + struct_def.name +
"()); }\n";
// create method that allows object reuse
code +=
method_signature + "(ByteBuffer _bb, " + struct_def.name + " obj) { ";
code += "_bb.order(ByteOrder.LITTLE_ENDIAN); ";
code += "return (obj.__assign(_bb.getInt(_bb.";
code += "position()";
code += ") + _bb.";
code += "position()";
code += ", _bb)); }\n";
if (parser_.root_struct_def_ == &struct_def) {
if (parser_.file_identifier_.length()) {
// Check if a buffer has the identifier.
code += " public static ";
code += "boolean " + struct_def.name;
code += "BufferHasIdentifier(ByteBuffer _bb) { return ";
code += "__has_identifier(_bb, \"";
code += parser_.file_identifier_;
code += "\"); }\n";
}
}
}
// Generate the __init method that sets the field in a pre-existing
// accessor object. This is to allow object reuse.
code += " public void __init(int _i, ByteBuffer _bb) ";
code += "{ ";
code += "__reset(_i, _bb); ";
code += "}\n";
code +=
" public " + struct_def.name + " __assign(int _i, ByteBuffer _bb) ";
code += "{ __init(_i, _bb); return this; }\n\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
if (field.deprecated) continue;
GenComment(field.doc_comment, code_ptr, &comment_config, " ");
std::string type_name = GenTypeGet(field.value.type);
std::string type_name_dest = GenTypeNameDest(field.value.type);
std::string conditional_cast = "";
std::string optional = "";
std::string dest_mask = DestinationMask(field.value.type, true);
std::string dest_cast = DestinationCast(field.value.type);
std::string src_cast = SourceCast(field.value.type);
std::string method_start =
" public " +
(field.required ? "" : GenNullableAnnotation(field.value.type)) +
GenPureAnnotation(field.value.type) + type_name_dest + optional +
" " + MakeCamel(field.name, false);
std::string obj = "obj";
// Most field accessors need to retrieve and test the field offset first,
// this is the prefix code for that:
auto offset_prefix =
IsArray(field.value.type)
? " { return "
: (" { int o = __offset(" + NumToString(field.value.offset) +
"); return o != 0 ? ");
// Generate the accessors that don't do object reuse.
if (field.value.type.base_type == BASE_TYPE_STRUCT) {
// Calls the accessor that takes an accessor object with a new object.
code += method_start + "() { return ";
code += MakeCamel(field.name, false);
code += "(new ";
code += type_name + "()); }\n";
} else if (field.value.type.base_type == BASE_TYPE_VECTOR &&
field.value.type.element == BASE_TYPE_STRUCT) {
// Accessors for vectors of structs also take accessor objects, this
// generates a variant without that argument.
code += method_start + "(int j) { return ";
code += MakeCamel(field.name, false);
code += "(new " + type_name + "(), j); }\n";
}
std::string getter = dest_cast + GenGetter(field.value.type);
code += method_start;
std::string default_cast = "";
std::string member_suffix = "; ";
if (IsScalar(field.value.type.base_type)) {
code += "()";
member_suffix += "";
if (struct_def.fixed) {
code += " { return " + getter;
code += "(bb_pos + ";
code += NumToString(field.value.offset) + ")";
code += dest_mask;
} else {
code += offset_prefix + getter;
code += "(o + bb_pos)" + dest_mask;
code += " : " + default_cast;
code += GenDefaultValue(field);
}
} else {
switch (field.value.type.base_type) {
case BASE_TYPE_STRUCT:
code += "(" + type_name + " obj)";
if (struct_def.fixed) {
code += " { return " + obj + ".__assign(";
code += "bb_pos + " + NumToString(field.value.offset) + ", ";
code += "bb)";
} else {
code += offset_prefix + conditional_cast;
code += obj + ".__assign(";
code += field.value.type.struct_def->fixed
? "o + bb_pos"
: "__indirect(o + bb_pos)";
code += ", bb) : null";
}
break;
case BASE_TYPE_STRING:
code += "()";
member_suffix += "";
code += offset_prefix + getter + "(o + ";
code += "bb_pos) : null";
break;
case BASE_TYPE_ARRAY: FLATBUFFERS_FALLTHROUGH(); // fall thru
case BASE_TYPE_VECTOR: {
auto vectortype = field.value.type.VectorType();
code += "(";
if (vectortype.base_type == BASE_TYPE_STRUCT) {
code += type_name + " obj, ";
getter = obj + ".__assign";
} else if (vectortype.base_type == BASE_TYPE_UNION) {
code += type_name + " obj, ";
}
code += "int j)";
const auto body = offset_prefix + conditional_cast + getter + "(";
if (vectortype.base_type == BASE_TYPE_UNION) {
code += body + "obj, ";
} else {
code += body;
}
std::string index;
if (IsArray(field.value.type)) {
index += "bb_pos + " + NumToString(field.value.offset) + " + ";
} else {
index += "__vector(o) + ";
}
index += "j * " + NumToString(InlineSize(vectortype));
if (vectortype.base_type == BASE_TYPE_STRUCT) {
code += vectortype.struct_def->fixed
? index
: "__indirect(" + index + ")";
code += ", bb";
} else {
code += index;
}
code += ")" + dest_mask;
if (!IsArray(field.value.type)) {
code += " : ";
code +=
field.value.type.element == BASE_TYPE_BOOL
? "false"
: (IsScalar(field.value.type.element) ? default_cast + "0"
: "null");
}
break;
}
case BASE_TYPE_UNION:
code += "(" + type_name + " obj)" + offset_prefix + getter;
code += "(obj, o + bb_pos) : null";
break;
default: FLATBUFFERS_ASSERT(0);
}
}
code += member_suffix;
code += "}\n";
if (field.value.type.base_type == BASE_TYPE_VECTOR) {
code += " public int " + MakeCamel(field.name, false);
code += "Length";
code += "()";
code += offset_prefix;
code += "__vector_len(o) : 0; ";
code += "";
code += "}\n";
// See if we should generate a by-key accessor.
if (field.value.type.element == BASE_TYPE_STRUCT &&
!field.value.type.struct_def->fixed) {
auto &sd = *field.value.type.struct_def;
auto &fields = sd.fields.vec;
for (auto kit = fields.begin(); kit != fields.end(); ++kit) {
auto &key_field = **kit;
if (key_field.key) {
auto qualified_name = WrapInNameSpace(sd);
code += " public " + qualified_name + " ";
code += MakeCamel(field.name, false) + "ByKey(";
code += GenTypeNameDest(key_field.value.type) + " key)";
code += offset_prefix;
code += qualified_name + ".__lookup_by_key(";
code += "null, ";
code += "__vector(o), key, ";
code += "bb) : null; ";
code += "}\n";
code += " public " + qualified_name + " ";
code += MakeCamel(field.name, false) + "ByKey(";
code += qualified_name + " obj, ";
code += GenTypeNameDest(key_field.value.type) + " key)";
code += offset_prefix;
code += qualified_name + ".__lookup_by_key(obj, ";
code += "__vector(o), key, ";
code += "bb) : null; ";
code += "}\n";
break;
}
}
}
}
// Generate the accessors for vector of structs with vector access object
if (field.value.type.base_type == BASE_TYPE_VECTOR) {
std::string vector_type_name;
const auto &element_base_type = field.value.type.VectorType().base_type;
if (IsScalar(element_base_type)) {
vector_type_name = MakeCamel(type_name, true) + "Vector";
} else if (element_base_type == BASE_TYPE_STRING) {
vector_type_name = "StringVector";
} else if (element_base_type == BASE_TYPE_UNION) {
vector_type_name = "UnionVector";
} else {
vector_type_name = type_name + ".Vector";
}
auto vector_method_start = GenNullableAnnotation(field.value.type) +
" public " + vector_type_name + optional +
" " + MakeCamel(field.name, false) +
"Vector";
code += vector_method_start + "() { return ";
code += MakeCamel(field.name, false) + "Vector";
code += "(new " + vector_type_name + "()); }\n";
code += vector_method_start + "(" + vector_type_name + " obj)";
code += offset_prefix + conditional_cast + obj + ".__assign(";
code += "__vector(o), ";
if (!IsScalar(element_base_type)) {
auto vectortype = field.value.type.VectorType();
code += NumToString(InlineSize(vectortype)) + ", ";
}
code += "bb) : null" + member_suffix + "}\n";
}
// Generate a ByteBuffer accessor for strings & vectors of scalars.
if ((field.value.type.base_type == BASE_TYPE_VECTOR &&
IsScalar(field.value.type.VectorType().base_type)) ||
field.value.type.base_type == BASE_TYPE_STRING) {
code += " public ByteBuffer ";
code += MakeCamel(field.name, false);
code += "AsByteBuffer() { return ";
code += "__vector_as_bytebuffer(";
code += NumToString(field.value.offset) + ", ";
code += NumToString(field.value.type.base_type == BASE_TYPE_STRING
? 1
: InlineSize(field.value.type.VectorType()));
code += "); }\n";
code += " public ByteBuffer ";
code += MakeCamel(field.name, false);
code += "InByteBuffer(ByteBuffer _bb) { return ";
code += "__vector_in_bytebuffer(_bb, ";
code += NumToString(field.value.offset) + ", ";
code += NumToString(field.value.type.base_type == BASE_TYPE_STRING
? 1
: InlineSize(field.value.type.VectorType()));
code += "); }\n";
}
// generate object accessors if is nested_flatbuffer
if (field.nested_flatbuffer) {
auto nested_type_name = WrapInNameSpace(*field.nested_flatbuffer);
auto nested_method_name =
MakeCamel(field.name, false) + "As" + field.nested_flatbuffer->name;
auto get_nested_method_name = nested_method_name;
code += " public " + nested_type_name + " ";
code += nested_method_name + "() { return ";
code +=
get_nested_method_name + "(new " + nested_type_name + "()); }\n";
code += " public " + nested_type_name + " ";
code += get_nested_method_name + "(";
code += nested_type_name + " obj";
code += ") { int o = __offset(";
code += NumToString(field.value.offset) + "); ";
code += "return o != 0 ? " + conditional_cast + obj + ".__assign(";
code += "";
code += "__indirect(__vector(o)), ";
code += "bb) : null; }\n";
}
// Generate mutators for scalar fields or vectors of scalars.
if (parser_.opts.mutable_buffer) {
auto is_series = (IsSeries(field.value.type));
const auto &underlying_type =
is_series ? field.value.type.VectorType() : field.value.type;
// Boolean parameters have to be explicitly converted to byte
// representation.
auto setter_parameter = underlying_type.base_type == BASE_TYPE_BOOL
? "(byte)(" + field.name + " ? 1 : 0)"
: field.name;
auto mutator_prefix = MakeCamel("mutate", false);
// A vector mutator also needs the index of the vector element it should
// mutate.
auto mutator_params = (is_series ? "(int j, " : "(") +
GenTypeNameDest(underlying_type) + " " +
field.name + ") { ";
auto setter_index =
is_series
? (IsArray(field.value.type)
? "bb_pos + " + NumToString(field.value.offset)
: "__vector(o)") +
+" + j * " + NumToString(InlineSize(underlying_type))
: (struct_def.fixed
? "bb_pos + " + NumToString(field.value.offset)
: "o + bb_pos");
if (IsScalar(underlying_type.base_type) && !IsUnion(field.value.type)) {
code += " public ";
code += struct_def.fixed ? "void " : "boolean ";
code += mutator_prefix + MakeCamel(field.name, true);
code += mutator_params;
if (struct_def.fixed) {
code += GenSetter(underlying_type) + "(" + setter_index + ", ";
code += src_cast + setter_parameter + "); }\n";
} else {
code += "int o = __offset(";
code += NumToString(field.value.offset) + ");";
code += " if (o != 0) { " + GenSetter(underlying_type);
code += "(" + setter_index + ", " + src_cast + setter_parameter +
"); return true; } else { return false; } }\n";
}
}
}
if (parser_.opts.java_primitive_has_method &&
IsScalar(field.value.type.base_type) && !struct_def.fixed) {
auto vt_offset_constant = " public static final int VT_" +
MakeScreamingCamel(field.name) + " = " +
NumToString(field.value.offset) + ";";
code += vt_offset_constant;
code += "\n";
}
}
code += "\n";
flatbuffers::FieldDef *key_field = nullptr;
if (struct_def.fixed) {
// create a struct constructor function
code += " public static " + GenOffsetType() + " ";
code += "create";
code += struct_def.name + "(FlatBufferBuilder builder";
GenStructArgs(struct_def, code_ptr, "");
code += ") {\n";
GenStructBody(struct_def, code_ptr, "");
code += " return ";
code += GenOffsetConstruct("builder." + std::string("offset()"));
code += ";\n }\n";
} else {
// Generate a method that creates a table in one go. This is only possible
// when the table has no struct fields, since those have to be created
// inline, and there's no way to do so in Java.
bool has_no_struct_fields = true;
int num_fields = 0;
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
if (field.deprecated) continue;
if (IsStruct(field.value.type)) {
has_no_struct_fields = false;
} else {
num_fields++;
}
}
// JVM specifications restrict default constructor params to be < 255.
// Longs and doubles take up 2 units, so we set the limit to be < 127.
if (has_no_struct_fields && num_fields && num_fields < 127) {
// Generate a table constructor of the form:
// public static int createName(FlatBufferBuilder builder, args...)
code += " public static " + GenOffsetType() + " ";
code += "create" + struct_def.name;
code += "(FlatBufferBuilder builder";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
if (field.deprecated) continue;
code += ",\n ";
code += GenTypeBasic(DestinationType(field.value.type, false));
code += " ";
code += field.name;
if (!IsScalar(field.value.type.base_type)) code += "Offset";
}
code += ") {\n builder.";
code += "startTable(";
code += NumToString(struct_def.fields.vec.size()) + ");\n";
for (size_t size = struct_def.sortbysize ? sizeof(largest_scalar_t) : 1;
size; size /= 2) {
for (auto it = struct_def.fields.vec.rbegin();
it != struct_def.fields.vec.rend(); ++it) {
auto &field = **it;
if (!field.deprecated &&
(!struct_def.sortbysize ||
size == SizeOf(field.value.type.base_type))) {
code += " " + struct_def.name + ".";
code += "add";
code += MakeCamel(field.name) + "(builder, " + field.name;
if (!IsScalar(field.value.type.base_type)) code += "Offset";
code += ");\n";
}
}
}
code += " return " + struct_def.name + ".";
code += "end" + struct_def.name;
code += "(builder);\n }\n\n";
}
// Generate a set of static methods that allow table construction,
// of the form:
// public static void addName(FlatBufferBuilder builder, short name)
// { builder.addShort(id, name, default); }
// Unlike the Create function, these always work.
code += " public static void start";
code += struct_def.name;
code += "(FlatBufferBuilder builder) { builder.";
code += "startTable(";
code += NumToString(struct_def.fields.vec.size()) + "); }\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
if (field.deprecated) continue;
if (field.key) key_field = &field;
code += " public static void add";
code += MakeCamel(field.name);
code += "(FlatBufferBuilder builder, ";
code += GenTypeBasic(DestinationType(field.value.type, false));
auto argname = MakeCamel(field.name, false);
if (!IsScalar(field.value.type.base_type)) argname += "Offset";
code += " " + argname + ") { builder.add";
code += GenMethod(field.value.type) + "(";
code += NumToString(it - struct_def.fields.vec.begin()) + ", ";
code += SourceCastBasic(field.value.type);
code += argname;
code += ", ";
code += SourceCastBasic(field.value.type);
code += GenDefaultValue(field);
code += "); }\n";
if (field.value.type.base_type == BASE_TYPE_VECTOR) {
auto vector_type = field.value.type.VectorType();
auto alignment = InlineAlignment(vector_type);
auto elem_size = InlineSize(vector_type);
if (!IsStruct(vector_type)) {
// generate a method to create a vector from a java array.
if ((vector_type.base_type == BASE_TYPE_CHAR ||
vector_type.base_type == BASE_TYPE_UCHAR)) {
// Handle byte[] and ByteBuffers separately for Java
code += " public static " + GenVectorOffsetType() + " ";
code += "create";
code += MakeCamel(field.name);
code += "Vector(FlatBufferBuilder builder, byte[] data) ";
code += "{ return builder.createByteVector(data); }\n";
code += " public static " + GenVectorOffsetType() + " ";
code += "create";
code += MakeCamel(field.name);
code += "Vector(FlatBufferBuilder builder, ByteBuffer data) ";
code += "{ return builder.createByteVector(data); }\n";
} else {
code += " public static " + GenVectorOffsetType() + " ";
code += "create";
code += MakeCamel(field.name);
code += "Vector(FlatBufferBuilder builder, ";
code += GenTypeBasic(vector_type) + "[] data) ";
code += "{ builder.startVector(";
code += NumToString(elem_size);
code += ", data.length, ";
code += NumToString(alignment);
code += "); for (int i = data.";
code += "length - 1; i >= 0; i--) builder.";
code += "add";
code += GenMethod(vector_type);
code += "(";
code += SourceCastBasic(vector_type, false);
code += "data[i]";
code += "); return ";
code += "builder.endVector(); }\n";
}
}
// Generate a method to start a vector, data to be added manually
// after.
code += " public static void start";
code += MakeCamel(field.name);
code += "Vector(FlatBufferBuilder builder, int numElems) ";
code += "{ builder.startVector(";
code += NumToString(elem_size);
code += ", numElems, " + NumToString(alignment);
code += "); }\n";
}
}
code += " public static " + GenOffsetType() + " ";
code += "end" + struct_def.name;
code += "(FlatBufferBuilder builder) {\n int o = builder.";
code += "endTable();\n";
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end(); ++it) {
auto &field = **it;
if (!field.deprecated && field.required) {
code += " builder.required(o, ";
code += NumToString(field.value.offset);
code += "); // " + field.name + "\n";
}
}
code += " return " + GenOffsetConstruct("o") + ";\n }\n";
if (parser_.root_struct_def_ == &struct_def) {
std::string size_prefix[] = { "", "SizePrefixed" };
for (int i = 0; i < 2; ++i) {
code += " public static void ";
code += "finish" + size_prefix[i] + struct_def.name;
code += "Buffer(FlatBufferBuilder builder, " + GenOffsetType();
code += " offset) {";
code += " builder.finish" + size_prefix[i] + "(offset";
if (parser_.file_identifier_.length())
code += ", \"" + parser_.file_identifier_ + "\"";
code += "); }\n";
}
}
}
// Only generate key compare function for table,
// because `key_field` is not set for struct
if (struct_def.has_key && !struct_def.fixed) {
FLATBUFFERS_ASSERT(key_field);
code += "\n @Override\n protected int keysCompare(";
code += "Integer o1, Integer o2, ByteBuffer _bb) {";
code += GenKeyGetter(key_field);
code += " }\n";
code += "\n public static " + struct_def.name;
code += " __lookup_by_key(";
code += struct_def.name + " obj, ";
code += "int vectorLocation, ";
code += GenTypeNameDest(key_field->value.type);
code += " key, ByteBuffer bb) {\n";
if (key_field->value.type.base_type == BASE_TYPE_STRING) {
code += " byte[] byteKey = ";
code += "key.getBytes(java.nio.charset.StandardCharsets.UTF_8);\n";
}
code += " int span = ";
code += "bb.getInt(vectorLocation - 4);\n";
code += " int start = 0;\n";
code += " while (span != 0) {\n";
code += " int middle = span / 2;\n";
code += GenLookupKeyGetter(key_field);
code += " if (comp > 0) {\n";
code += " span = middle;\n";
code += " } else if (comp < 0) {\n";
code += " middle++;\n";
code += " start += middle;\n";
code += " span -= middle;\n";
code += " } else {\n";
code += " return ";
code += "(obj == null ? new " + struct_def.name + "() : obj)";
code += ".__assign(tableOffset, bb);\n";
code += " }\n }\n";
code += " return null;\n";
code += " }\n";
}
GenVectorAccessObject(struct_def, code_ptr);
code += "}";
code += "\n\n";
}
void GenVectorAccessObject(StructDef &struct_def,
std::string *code_ptr) const {
auto &code = *code_ptr;
// Generate a vector of structs accessor class.
code += "\n";
code += " ";
if (!struct_def.attributes.Lookup("private")) code += "public ";
code += "static ";
code += "final ";
code += "class Vector extends ";
code += "BaseVector {\n";
// Generate the __assign method that sets the field in a pre-existing
// accessor object. This is to allow object reuse.
std::string method_indent = " ";
code += method_indent + "public Vector ";
code += "__assign(int _vector, int _element_size, ByteBuffer _bb) { ";
code += "__reset(_vector, _element_size, _bb); return this; }\n\n";
auto type_name = struct_def.name;
auto method_start = method_indent + "public " + type_name + " get";
// Generate the accessors that don't do object reuse.
code += method_start + "(int j) { return get";
code += "(new " + type_name + "(), j); }\n";
code += method_start + "(" + type_name + " obj, int j) { ";
code += " return obj.__assign(";
std::string index = "__element(j)";
code += struct_def.fixed ? index : "__indirect(" + index + ", bb)";
code += ", bb); }\n";
// See if we should generate a by-key accessor.
if (!struct_def.fixed) {
auto &fields = struct_def.fields.vec;
for (auto kit = fields.begin(); kit != fields.end(); ++kit) {
auto &key_field = **kit;
if (key_field.key) {
auto nullable_annotation =
parser_.opts.gen_nullable ? "@Nullable " : "";
code += method_indent + nullable_annotation;
code += "public " + type_name + " ";
code += "getByKey(";
code += GenTypeNameDest(key_field.value.type) + " key) { ";
code += " return __lookup_by_key(null, ";
code += "__vector(), key, ";
code += "bb); ";
code += "}\n";
code += method_indent + nullable_annotation;
code += "public " + type_name + " ";
code += "getByKey(";
code += type_name + " obj, ";
code += GenTypeNameDest(key_field.value.type) + " key) { ";
code += " return __lookup_by_key(obj, ";
code += "__vector(), key, ";
code += "bb); ";
code += "}\n";
break;
}
}
}
code += " }\n";
}
// This tracks the current namespace used to determine if a type need to be
// prefixed by its namespace
const Namespace *cur_name_space_;
};
} // namespace java
bool GenerateJava(const Parser &parser, const std::string &path,
const std::string &file_name) {
java::JavaGenerator generator(parser, path, file_name);
return generator.generate();
}
} // namespace flatbuffers
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