There has been some back and forth previously about java language
support for generating a proto file from a Descriptor.
The suggested implementation was to either wrap or port the
DebugString capability from decriptor.cc
I recently ported the DebugString capability to java - it's a bit
rough as it's a by-hand port from the c code, but I also fixed some
bugs in the way the file was generated. For instance, extended types
were not output with correct parenthesis around them and options that
were messages did not have appropriate {} around them - these could
easily be due to differences in the C and Java code though. I'd be
glad to elaborate further for anyone interested, but for now I'm
simply providing the ported code as static functions in a java file.
Notably, if integrated with the java library these functions should
probably not be in a static file, they should be included with their
appropriate descriptor types.
If it is decided that this functionality should be part of the Java
library, I would be willing to do the leg work and get these functions
in better shape and update the appropriate files. I can pass them
along in an issue report for a committer to check in.
Notably, if you're looking for someone to work on the Java library /
outstanding issues at all, I'm looking for something to do in my
mythical free time. I could help with c too, but I'm much stronger in
Java.
PS: This is all based on release 2.4.1
======================= DebugString.java ===================
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.Stack;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.EnumDescriptor;
import com.google.protobuf.Descriptors.EnumValueDescriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import com.google.protobuf.Descriptors.FileDescriptor;
import com.google.protobuf.Descriptors.MethodDescriptor;
import com.google.protobuf.Descriptors.ServiceDescriptor;
import com.google.protobuf.Message;
import com.google.protobuf.TextFormat;
/**
* This class provides .proto file generation from Java Proto
Descriptors.
* <br>Derived from descriptor.cc in Protobuf 2.4.1
* <br>
* <br><b>Original Copyright Notice from descriptor.cc:</b>
* <br>
* <br> Protocol Buffers - Google's data interchange format
* <br> Copyright 2008 Google Inc. All rights reserved.
* <br> http://code.google.com/p/protobuf/
* <br>
* <br> Redistribution and use in source and binary forms, with or
without
* <br> modification, are permitted provided that the following
conditions are
* <br> met:
* <br>
* <br> * Redistributions of source code must retain the above
copyright
* <br> notice, this list of conditions and the following disclaimer.
* <br> * Redistributions in binary form must reproduce the above
* <br> copyright notice, this list of conditions and the following
disclaimer
* <br> in the documentation and/or other materials provided with the
* <br> distribution.
* <br> * Neither the name of Google Inc. nor the names of its
* <br> contributors may be used to endorse or promote products
derived from
* <br> this software without specific prior written permission.
* <br>
* <br> THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
CONTRIBUTORS
* <br> "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
NOT
* <br> LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR
* <br> A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT
* <br> OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL,
* <br> SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT
* <br> LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
OF USE,
* <br> DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY
* <br> THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
TORT
* <br> (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
THE USE
* <br> OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
DAMAGE.
* <br>
* <br> Author: ken...@google.com (Kenton Varda)
* <br> Based on original Protocol Buffers design by
* <br> Sanjay Ghemawat, Jeff Dean, and others.
*
* @author Benjamin Wright (compuware...@gmail.com)
*/
public class DebugString {
private static void SubstituteAndAppend(StringBuilder contents,
String replace, Object... objects ) {
for(int i = 0; i < objects.length; i++) {
final String old = "$"+i;
replace = replace.replace(old,
String.valueOf(objects[i]));
}
contents.append(replace);
}
private static String PrintFieldValueToString(Message message,
FieldDescriptor fieldDescriptor, int i) {
return valueAsString(fieldDescriptor,
message.getField(fieldDescriptor));
}
private static String DefaultValueAsString(FieldDescriptor
fieldDescriptor, boolean b) {
return valueAsString(fieldDescriptor,
fieldDescriptor.getDefaultValue());
}
private static String valueAsString(FieldDescriptor fieldDescriptor,
Object value) {
StringBuilder v = new StringBuilder();
try {
TextFormat.printFieldValue(fieldDescriptor, value, v);
} catch (IOException e) {
}
return v.toString();//.replace("\n", "").replace("\\", "\\\\");
}
private static String prefix(int d, char str) {
StringBuilder sb = new StringBuilder();
for(int i = 0; i < d; i++)
sb.append(str);
return sb.toString();
}
private static String join(Stack<String> all_options, String string)
{
boolean init = true;
StringBuilder sb = new StringBuilder();
for(String option : all_options) {
if(init) {
init = false;
} else {
sb.append(string);
}
sb.append(option);
}
return sb.toString();
}
// DebugString methods
===============================================
// Used by each of the option formatters.
static boolean RetrieveOptions(final Message options, Stack<String>
option_entries) {
option_entries.clear();
List<FieldDescriptor> fields = new
ArrayList<FieldDescriptor>(options.getAllFields().keySet());
for (int i = 0; i < fields.size(); i++) {
int count = 1;
boolean repeated = false;
if (fields.get(i).isRepeated()) {
count = options.getRepeatedFieldCount(fields.get(i));
repeated = true;
}
for (int j = 0; j < count; j++) {
String fieldval =
PrintFieldValueToString(options, fields.get(i),
repeated ? count : -1);
// .replace("google.protobuf.FileOptions.", "")
final boolean msg = (fields.get(i).getJavaType() ==
FieldDescriptor.JavaType.MESSAGE);
final String fullName = fields.get(i).getFullName();
option_entries.push(
(fields.get(i).isExtension() ? "(" : "") +
(fullName.startsWith("google.protobuf.") ?
fullName.substring(fullName.lastIndexOf('.')+1): fullName) +
(fields.get(i).isExtension() ? ")" : "") +
" = " +
(msg?"{\n":"") +
" "+ fieldval +
(msg?"}":"") );
}
}
return !option_entries.isEmpty();
}
// Formats options that all appear together in brackets. Does not
include
// brackets.
static boolean FormatBracketedOptions(final Message options,
StringBuilder output) {
Stack<String> all_options = new Stack<String>();
if (RetrieveOptions(options, all_options)) {
output.append(join(all_options, ",\n"));
}
return !all_options.isEmpty();
}
// Formats options one per line
static boolean FormatLineOptions(int depth, final Message options,
StringBuilder output) {
String prefix = prefix(depth * 2, ' ');
Stack<String> all_options = new Stack<String>();
if (RetrieveOptions(options, all_options)) {
for (int i = 0; i < all_options.size(); i++) {
SubstituteAndAppend(output, "$0option $1;\n",
prefix, all_options.get(i));
}
}
return !all_options.isEmpty();
}
// } // anonymous namespace
/**
* Top level return function
*/
static public StringBuilder FileDescriptor_DebugString(FileDescriptor
fd) {
return FileDescriptor_DebugString(fd, false);
}
/**
* Top level return function
*/
static public StringBuilder FileDescriptor_DebugString(FileDescriptor
fd, boolean includeProtocolSyntaxVersion) {
StringBuilder contents = new StringBuilder();
if(includeProtocolSyntaxVersion) {
contents.append("syntax = \"proto2\";\n\n");
}
if (!fd.getPackage().isEmpty()) {
SubstituteAndAppend(contents, "package $0;\n\n",
fd.getPackage());
}
for (FileDescriptor dependency : fd.getDependencies()) {
SubstituteAndAppend(contents, "import \"$0\";\n",
dependency.getName());
}
if(!fd.getDependencies().isEmpty()){
contents.append("\n");
}
if (FormatLineOptions(0, fd.getOptions(), contents)) {
contents.append("\n"); // add some space if we had options
}
for (EnumDescriptor enum_type : fd.getEnumTypes()) {
EnumDescriptor_DebugString(enum_type, 0, contents);
contents.append("\n");
}
// Find all the 'group' type extensions; we will not output their
nested
// definitions (those will be done with their group field
descriptor).
Set<Descriptor> groups = new HashSet<Descriptor>();
for (FieldDescriptor extension : fd.getExtensions()) {
if (extension.getType() == FieldDescriptor.Type.GROUP) {
groups.add(extension.getMessageType());
}
}
for (Descriptor message_type : fd.getMessageTypes()) {
if (!groups.contains(message_type)) {
SubstituteAndAppend(contents, "message $0",
message_type.getName());
Descriptor_DebugString(message_type, 0, contents);
contents.append("\n");
}
}
for (ServiceDescriptor service : fd.getServices()) {
ServiceDescriptor_DebugString(service, contents);
contents.append("\n");
}
Descriptor containing_type = null;
for (FieldDescriptor extension : fd.getExtensions()) {
if (extension.getContainingType() != containing_type) {
if (containing_type != null) contents.append("}\n\n");
containing_type = extension.getContainingType();
SubstituteAndAppend(contents, "extend $0 {\n",
containing_type.getFullName());
}
FieldDescriptor_DebugString(extension, 1, contents);
}
if (fd.getExtensions().size() > 0) contents.append("}\n\n");
return contents;
}
static public StringBuilder Descriptor_DebugString(Descriptor d) {
StringBuilder contents = new StringBuilder();
SubstituteAndAppend(contents, "message $0", d.getName());
Descriptor_DebugString(d, 0, contents);
return contents;
}
static void Descriptor_DebugString(Descriptor d, int depth,
StringBuilder contents) {
String prefix = prefix(depth * 2, ' ');
++depth;
contents.append(" {\n");
FormatLineOptions(depth, d.getOptions(), contents);
// Find all the 'group' types for fields and extensions; we will
not output
// their nested definitions (those will be done with their group
field
// descriptor).
Set<Descriptor> groups = new HashSet<Descriptor>();
for (int i = 0; i < d.getFields().size(); i++) {
if (d.getFields().get(i).getType() == FieldDescriptor.Type.GROUP)
{
groups.add(d.getFields().get(i).getMessageType());
}
}
for (int i = 0; i < d.getExtensions().size(); i++) {
if (d.getExtensions().get(i).getType() ==
FieldDescriptor.Type.GROUP) {
groups.add(d.getExtensions().get(i).getMessageType());
}
}
for (int i = 0; i < d.getNestedTypes().size(); i++) {
if (!groups.contains(d.getNestedTypes().get(i))) {
SubstituteAndAppend(contents, "$0 message $1",
prefix,
d.getNestedTypes().get(i).getName());
Descriptor_DebugString(d.getNestedTypes().get(i), depth,
contents);
}
}
for (int i = 0; i < d.getEnumTypes().size(); i++) {
EnumDescriptor_DebugString(d.getEnumTypes().get(i), depth,
contents);
}
for (int i = 0; i < d.getFields().size(); i++) {
FieldDescriptor_DebugString(d.getFields().get(i), depth,
contents);
}
final int max = 536870911;
for (int i = 0; i < d.toProto().getExtensionRangeCount(); i++) {
final int end = d.toProto().getExtensionRange(i).getEnd() - 1;
SubstituteAndAppend(contents, "$0 extensions $1 to $2;\n",
prefix,
d.toProto().getExtensionRange(i).getStart(),
(end == max ? "max" : end)
);
}
// Group extensions by what they extend, so they can be printed out
together.
Descriptor containing_type = null;
for (int i = 0; i < d.getExtensions().size(); i++) {
if (d.getExtensions().get(i).getContainingType() !=
containing_type) {
if (i > 0) SubstituteAndAppend(contents, "$0 }\n", prefix);
containing_type = d.getExtensions().get(i).getContainingType();
SubstituteAndAppend(contents, "$0 extend .$1 {\n",
prefix,
containing_type.getFullName());
}
FieldDescriptor_DebugString(d.getExtensions().get(i), depth + 1,
contents);
}
if (d.getExtensions().size() > 0)
SubstituteAndAppend(contents, "$0 }\n", prefix);
SubstituteAndAppend(contents, "$0}\n", prefix);
}
static public StringBuilder
FieldDescriptor_DebugString(FieldDescriptor d) {
StringBuilder contents = new StringBuilder();
int depth = 0;
if (d.isExtension()) {
SubstituteAndAppend(contents, "extend .$0 {\n",
d.getContainingType().getFullName());
depth = 1;
}
FieldDescriptor_DebugString(d, depth, contents);
if (d.isExtension()) {
contents.append("}\n");
}
return contents;
}
static void FieldDescriptor_DebugString(FieldDescriptor d, int depth,
StringBuilder contents) {
final String pckg = d.getFile().getPackage();
String prefix = prefix(depth * 2, ' ');
String field_type;
switch (d.getType()) {
case MESSAGE:
field_type =
d.getMessageType().getFile().getPackage().equals(pckg) ?
d.getMessageType().getName() : d.getMessageType().getFullName();
break;
case ENUM:
field_type =
d.getEnumType().getFile().getPackage().equals(pckg) ?
d.getEnumType().getName() : d.getEnumType().getFullName();
break;
default:
field_type = d.getType().name().toLowerCase();
}
final String label;
switch(d.toProto().getLabel()){
case LABEL_OPTIONAL:
default:
label = "optional";
break;
case LABEL_REPEATED:
label = "repeated";
break;
case LABEL_REQUIRED:
label = "required";
break;
}
SubstituteAndAppend(contents, "$0$1 $2 $3 = $4",
prefix,
label,
field_type,
d.getType() ==
FieldDescriptor.Type.GROUP ? d.getMessageType().getName() :
d.getName(),
d.getNumber());
boolean bracketed = false;
if (d.hasDefaultValue()) {
bracketed = true;
SubstituteAndAppend(contents, " [default = $0",
DefaultValueAsString(d, true));
}
StringBuilder formatted_options = new StringBuilder();
if (FormatBracketedOptions(d.getOptions(), formatted_options)) {
contents.append(bracketed ? ", " : " [");
bracketed = true;
contents.append(formatted_options);
}
if (bracketed) {
contents.append("]");
}
if (d.getType() == FieldDescriptor.Type.GROUP) {
Descriptor_DebugString(d.getMessageType(), depth, contents);
} else {
contents.append(";\n");
}
}
static public StringBuilder EnumDescriptor_DebugString(EnumDescriptor
d) {
StringBuilder contents = new StringBuilder();
EnumDescriptor_DebugString(d, 0, contents);
return contents;
}
static void EnumDescriptor_DebugString(EnumDescriptor d, int depth,
StringBuilder contents) {
String prefix = prefix(depth * 2, ' ');
++depth;
SubstituteAndAppend(contents, "$0enum $1 {\n",
prefix, d.getName());
FormatLineOptions(depth, d.getOptions(), contents);
for (EnumValueDescriptor value : d.getValues()) {
EnumValueDescriptor_DebugString(value, depth, contents);
}
SubstituteAndAppend(contents, "$0}\n", prefix);
}
static public StringBuilder
EnumValueDescriptor_DebugString(EnumValueDescriptor d) {
StringBuilder contents = new StringBuilder();
EnumValueDescriptor_DebugString(d, 0, contents);
return contents;
}
static void EnumValueDescriptor_DebugString(EnumValueDescriptor d,
int depth, StringBuilder contents) {
String prefix = prefix(depth * 2, ' ');
SubstituteAndAppend(contents, "$0$1 = $2",
prefix, d.getName(), d.getNumber());
StringBuilder formatted_options = new StringBuilder();
if (FormatBracketedOptions(d.getOptions(), formatted_options)) {
SubstituteAndAppend(contents, " [$0]", formatted_options);
}
contents.append(";\n");
}
static public StringBuilder
ServiceDescriptor_DebugString(ServiceDescriptor d) {
StringBuilder contents = new StringBuilder();
ServiceDescriptor_DebugString(d, contents);
return contents;
}
static void ServiceDescriptor_DebugString(ServiceDescriptor d,
StringBuilder contents) {
SubstituteAndAppend(contents, "service $0 {\n", d.getName());
FormatLineOptions(1, d.getOptions(), contents);
for (MethodDescriptor method : d.getMethods()) {
MethodDescriptor_DebugString(method, 1, contents);
}
contents.append("}\n");
}
static public StringBuilder
MethodDescriptor_DebugString(MethodDescriptor d) {
StringBuilder contents = new StringBuilder();
MethodDescriptor_DebugString(d, 0, contents);
return contents;
}
static void MethodDescriptor_DebugString(MethodDescriptor d, int
depth, StringBuilder contents) {
String prefix = prefix(depth * 2, ' ');
++depth;
SubstituteAndAppend(contents, "$0rpc $1(.$2) returns (.$3)",
prefix, d.getName(),
d.getInputType().getFullName(),
d.getOutputType().getFullName());
StringBuilder formatted_options = new StringBuilder();
if (FormatLineOptions(depth, d.getOptions(), formatted_options)) {
SubstituteAndAppend(contents, " {\n$0$1}\n",
formatted_options, prefix);
} else {
contents.append(";\n");
}
}
//
===================================================================
}
--
You received this message because you are subscribed to the Google Groups
"Protocol Buffers" group.
To post to this group, send email to protobuf@googlegroups.com.
To unsubscribe from this group, send email to
protobuf+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/protobuf?hl=en.
