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·399 lines (371 loc) · 14.3 KB
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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/flatbuffers.h"
#include "flatbuffers/idl.h"
#include "flatbuffers/util.h"
#ifdef _WIN32
#include <direct.h>
#define PATH_SEPARATOR "\\"
#define mkdir(n, m) _mkdir(n)
#else
#include <sys/stat.h>
#define PATH_SEPARATOR "/"
#endif
namespace flatbuffers {
namespace java {
static std::string GenTypeBasic(const Type &type) {
static const char *ctypename[] = {
#define FLATBUFFERS_TD(ENUM, IDLTYPE, CTYPE, JTYPE) #JTYPE,
FLATBUFFERS_GEN_TYPES(FLATBUFFERS_TD)
#undef FLATBUFFERS_TD
};
return ctypename[type.base_type];
}
static std::string GenTypeGet(const Type &type);
static std::string GenTypePointer(const Type &type) {
switch (type.base_type) {
case BASE_TYPE_STRING:
return "String";
case BASE_TYPE_VECTOR:
return GenTypeGet(type.VectorType());
case BASE_TYPE_STRUCT:
return type.struct_def->name;
case BASE_TYPE_UNION:
// fall through
default:
return "Table";
}
}
static std::string GenTypeGet(const Type &type) {
return IsScalar(type.base_type)
? GenTypeBasic(type)
: GenTypePointer(type);
}
static void GenComment(const std::string &dc,
std::string *code_ptr,
const char *prefix = "") {
std::string &code = *code_ptr;
if (dc.length()) {
code += std::string(prefix) + "///" + dc + "\n";
}
}
// Convert an underscore_based_indentifier in to camelCase.
// Also uppercases the first character if first is true.
static std::string MakeCamel(const std::string &in, bool first = true) {
std::string s;
for (size_t i = 0; i < in.length(); i++) {
if (!i && first) s += toupper(in[0]);
else if (in[i] == '_' && i + 1 < in.length()) s += toupper(in[++i]);
else s += in[i];
}
return s;
}
static void GenEnum(EnumDef &enum_def, std::string *code_ptr) {
std::string &code = *code_ptr;
if (enum_def.generated) return;
// Generate enum definitions of the form:
// public static final int name = value;
// We use ints rather than the Java 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);
code += "public class " + enum_def.name + " {\n";
for (auto it = enum_def.vals.vec.begin();
it != enum_def.vals.vec.end();
++it) {
auto &ev = **it;
GenComment(ev.doc_comment, code_ptr, " ");
code += " public static final " + GenTypeBasic(enum_def.underlying_type);
code += " " + ev.name + " = ";
code += NumToString(ev.value) + ";\n";
}
code += "};\n\n";
}
// Returns the function name that is able to read a value of the given type.
static std::string GenGetter(const Type &type) {
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());
default:
return "bb.get" + (SizeOf(type.base_type) > 1
? MakeCamel(GenTypeGet(type))
: "");
}
}
// Returns the method name for use with add/put calls.
static std::string GenMethod(const FieldDef &field) {
return IsScalar(field.value.type.base_type)
? MakeCamel(GenTypeBasic(field.value.type))
: (IsStruct(field.value.type) ? "Struct" : "Offset");
}
// Recursively generate arguments for a constructor, to deal with nested
// structs.
static void GenStructArgs(const StructDef &struct_def, std::string *code_ptr,
const char *nameprefix) {
std::string &code = *code_ptr;
for (auto it = struct_def.fields.vec.begin();
it != struct_def.fields.vec.end();
++it) {
auto &field = **it;
if (IsStruct(field.value.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 struct name.
GenStructArgs(*field.value.type.struct_def, code_ptr,
(field.value.type.struct_def->name + "_").c_str());
} else {
code += ", " + GenTypeBasic(field.value.type) + " " + nameprefix;
code += MakeCamel(field.name, false);
}
}
}
// Recusively generate struct construction statements of the form:
// builder.putType(name);
// and insert manual padding.
static void GenStructBody(const StructDef &struct_def, std::string *code_ptr,
const char *nameprefix) {
std::string &code = *code_ptr;
code += " builder.prep(" + NumToString(struct_def.minalign) + ", 0);\n";
for (auto it = struct_def.fields.vec.rbegin();
it != struct_def.fields.vec.rend();
++it) {
auto &field = **it;
if (field.padding)
code += " builder.pad(" + NumToString(field.padding) + ");\n";
if (IsStruct(field.value.type)) {
GenStructBody(*field.value.type.struct_def, code_ptr,
(field.value.type.struct_def->name + "_").c_str());
} else {
code += " builder.put" + GenMethod(field) + "(";
code += nameprefix + MakeCamel(field.name, false) + ");\n";
}
}
}
static void GenStruct(StructDef &struct_def,
std::string *code_ptr,
StructDef *root_struct_def) {
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);
code += "public class " + struct_def.name + " extends ";
code += struct_def.fixed ? "Struct" : "Table";
code += " {\n";
if (&struct_def == root_struct_def) {
// Generate a special accessor for the table that has been declared as
// the root type.
code += " public static " + struct_def.name + " getRootAs";
code += struct_def.name;
code += "(ByteBuffer _bb, int offset) { ";
code += "_bb.order(ByteOrder.LITTLE_ENDIAN); ";
code += "return (new " + struct_def.name;
code += "()).__init(_bb.getInt(offset) + offset, _bb); }\n";
}
// Generate the __init method that sets the field in a pre-existing
// accessor object. This is to allow object reuse.
code += " public " + struct_def.name;
code += " __init(int _i, ByteBuffer _bb) ";
code += "{ bb_pos = _i; bb = _bb; return this; }\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, " ");
std::string type_name = GenTypeGet(field.value.type);
std::string method_start = " public " + type_name + " " +
MakeCamel(field.name, false);
// 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 " + 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 " + MakeCamel(field.name, false);
code += "(new ";
code += type_name + "(), j); }\n";
}
std::string getter = GenGetter(field.value.type);
code += method_start + "(";
// Most field accessors need to retrieve and test the field offset first,
// this is the prefix code for that:
auto offset_prefix = ") { int o = __offset(" +
NumToString(field.value.offset) +
"); return o != 0 ? ";
if (IsScalar(field.value.type.base_type)) {
if (struct_def.fixed) {
code += ") { return " + getter;
code += "(bb_pos + " + NumToString(field.value.offset) + ")";
} else {
code += offset_prefix + getter;
code += "(o + bb_pos) : " + field.value.constant;
}
} else {
switch (field.value.type.base_type) {
case BASE_TYPE_STRUCT:
code += type_name + " obj";
if (struct_def.fixed) {
code += ") { return obj.__init(bb_pos + ";
code += NumToString(field.value.offset) + ", bb)";
} else {
code += offset_prefix;
code += "obj.__init(";
code += field.value.type.struct_def->fixed
? "o + bb_pos"
: "__indirect(o + i)";
code += ", bb) : null";
}
break;
case BASE_TYPE_STRING:
code += offset_prefix + getter +"(o) : null";
break;
case BASE_TYPE_VECTOR: {
auto vectortype = field.value.type.VectorType();
if (vectortype.base_type == BASE_TYPE_STRUCT) {
code += type_name + " obj, ";
getter = "obj.__init";
}
code += "int j" + offset_prefix + getter +"(";
auto index = "__vector(o) + 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 += ") : ";
code += IsScalar(field.value.type.element) ? "0" : "null";
break;
}
case BASE_TYPE_UNION:
code += type_name + " obj" + offset_prefix + getter;
code += "(obj, o) : null";
break;
default:
assert(0);
}
}
code += "; }\n";
if (field.value.type.base_type == BASE_TYPE_VECTOR) {
code += " public int " + MakeCamel(field.name, false) + "Length(";
code += offset_prefix;
code += "__vector_len(o) : 0; }\n";
}
}
code += "\n";
if (struct_def.fixed) {
// create a struct constructor function
code += " public static int create" + struct_def.name;
code += "(FlatBufferBuilder builder";
GenStructArgs(struct_def, code_ptr, "");
code += ") {\n";
GenStructBody(struct_def, code_ptr, "");
code += " return builder.offset();\n }\n";
} else {
// Create 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); }
code += " public static void start" + struct_def.name;
code += "(FlatBufferBuilder builder) { builder.startObject(";
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;
code += " public static void add" + MakeCamel(field.name);
code += "(FlatBufferBuilder builder, " + GenTypeBasic(field.value.type);
code += " " + MakeCamel(field.name, false) + ") { builder.add";
code += GenMethod(field) + "(";
code += NumToString(it - struct_def.fields.vec.begin()) + ", ";
code += MakeCamel(field.name, false) + ", " + field.value.constant;
code += "); }\n";
if (field.value.type.base_type == BASE_TYPE_VECTOR) {
code += " public static void start" + MakeCamel(field.name);
code += "Vector(FlatBufferBuilder builder, int numElems) ";
code += "{ builder.startVector(";
code += NumToString(InlineSize(field.value.type));
code += ", numElems); }\n";
}
}
code += " public static int end" + struct_def.name;
code += "(FlatBufferBuilder builder) { return builder.endObject(); }\n";
}
code += "};\n\n";
}
// Save out the generated code for a single Java class while adding
// declaration boilerplate.
static bool SaveClass(const Parser &parser, const Definition &def,
const std::string &classcode, const std::string &path) {
if (!classcode.length()) return true;
std::string name_space_java;
std::string name_space_dir = path;
for (auto it = parser.name_space_.begin();
it != parser.name_space_.end(); ++it) {
if (name_space_java.length()) {
name_space_java += ".";
name_space_dir += PATH_SEPARATOR;
}
name_space_java += *it;
name_space_dir += *it;
mkdir(name_space_dir.c_str(), S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
}
std::string code = "// automatically generated, do not modify\n\n";
code += "package " + name_space_java + ";\n\n";
code += "import java.nio.*;\nimport java.lang.*;\nimport java.util.*;\n";
code += "import flatbuffers.*;\n\n";
code += classcode;
auto filename = name_space_dir + PATH_SEPARATOR + def.name + ".java";
return SaveFile(filename.c_str(), code, false);
}
} // namespace java
bool GenerateJava(const Parser &parser,
const std::string &path,
const std::string &file_name) {
using namespace java;
for (auto it = parser.enums_.vec.begin();
it != parser.enums_.vec.end(); ++it) {
std::string enumcode;
GenEnum(**it, &enumcode);
if (!SaveClass(parser, **it, enumcode, path))
return false;
}
for (auto it = parser.structs_.vec.begin();
it != parser.structs_.vec.end(); ++it) {
std::string declcode;
GenStruct(**it, &declcode, parser.root_struct_def);
if (!SaveClass(parser, **it, declcode, path))
return false;
}
return true;
}
} // namespace flatbuffers