// Copyright 2008 Google Inc. All Rights Reserved.
package com.google.common.io.protocol;
import java.io.*;
/**
* Utility functions for dealing with ProtoBuf objects consolidated from
* previous spot implementations across the codebase.
*
*/
public final class ProtoBufUtil {
private ProtoBufUtil() {
}
/** Convenience method to return a string value from of a proto or "". */
public static String getProtoValueOrEmpty(ProtoBuf proto, int tag) {
try {
return (proto != null && proto.has(tag)) ? proto.getString(tag) : "";
} catch (ClassCastException e) {
return "";
}
}
/** Convenience method to return a string value from of a sub-proto or "". */
public static String getSubProtoValueOrEmpty(
ProtoBuf proto, int sub, int tag) {
try {
return getProtoValueOrEmpty(getSubProtoOrNull(proto, sub), tag);
} catch (ClassCastException e) {
return "";
}
}
/** Convenience method to get a subproto if the proto has it. */
public static ProtoBuf getSubProtoOrNull(ProtoBuf proto, int sub) {
return (proto != null && proto.has(sub)) ? proto.getProtoBuf(sub) : null;
}
/**
* Get an int with "tag" from the proto buffer. If the given field can't be
* retrieved, return the provided default value.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @param defaultValue The value to return if the field can't be retrieved.
* @return The result which should be an integer.
*/
public static int getProtoValueOrDefault(ProtoBuf proto, int tag,
int defaultValue) {
try {
return (proto != null && proto.has(tag))
? proto.getInt(tag) : defaultValue;
} catch (IllegalArgumentException e) {
return defaultValue;
} catch (ClassCastException e) {
return defaultValue;
}
}
/**
* Get an Int with "tag" from the proto buffer.
* If the given field can't be retrieved, return 0.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @return The result which should be an integer.
*/
public static int getProtoValueOrZero(ProtoBuf proto, int tag) {
return getProtoValueOrDefault(proto, tag, 0);
}
/**
* Get an Long with "tag" from the proto buffer.
* If the given field can't be retrieved, return 0.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @return The result which should be an integer.
*/
public static long getProtoLongValueOrZero(ProtoBuf proto, int tag) {
try {
return (proto != null && proto.has(tag)) ? proto.getLong(tag) : 0L;
} catch (IllegalArgumentException e) {
return 0L;
} catch (ClassCastException e) {
return 0L;
}
}
/**
* Get an Int with "tag" from the proto buffer.
* If the given field can't be retrieved, return -1.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @return The result which should be a long.
*/
public static long getProtoValueOrNegativeOne(ProtoBuf proto, int tag) {
try {
return (proto != null && proto.has(tag)) ? proto.getLong(tag) : -1;
} catch (IllegalArgumentException e) {
return -1;
} catch (ClassCastException e) {
return -1;
}
}
/**
* Reads a single protocol buffer from the given input stream. This method is
* provided where the client needs incremental access to the contents of a
* protocol buffer which contains a sequence of protocol buffers.
* <p />
* Please use {@link #getInputStreamForProtoBufResponse} to obtain an input
* stream suitable for this method.
*
* @param umbrellaType the type of the "outer" protocol buffer containing
* the message to read
* @param is the stream to read the protocol buffer from
* @param result the result protocol buffer (must be empty, will be filled
* with the data read and the type will be set)
* @return the tag id of the message, -1 at the end of the stream
*/
public static int readNextProtoBuf(ProtoBufType umbrellaType,
InputStream is, ProtoBuf result) throws IOException {
long tagAndType = ProtoBuf.readVarInt(is, true /* permits EOF */);
if (tagAndType == -1) {
return -1;
}
if ((tagAndType & 7) != ProtoBuf.WIRETYPE_LENGTH_DELIMITED) {
throw new IOException("Message expected");
}
int tag = (int) (tagAndType >>> 3);
result.setType((ProtoBufType) umbrellaType.getData(tag));
int length = (int) ProtoBuf.readVarInt(is, false);
result.parse(is, length);
return tag;
}
/**
* A wrapper for <code> getProtoValueOrNegativeOne </code> that drills into
* a sub message returning the long value if it exists, returning -1 if it
* does not.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @param sub The sub tag value that identifies which protocol buffer
* sub-field to retrieve.n
* @return The result which should be a long.
*/
public static long getSubProtoValueOrNegativeOne(
ProtoBuf proto, int sub, int tag) {
try {
return getProtoValueOrNegativeOne(getSubProtoOrNull(proto, sub), tag);
} catch (IllegalArgumentException e) {
return -1;
} catch (ClassCastException e) {
return -1;
}
}
/**
* A wrapper for {@link #getProtoValueOrDefault(ProtoBuf, int, int)} that
* drills into a sub message returning the int value if it exists, returning
* the given default if it does not.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* retrieve.
* @param sub The sub tag value that identifies which protocol buffer
* sub-field to retrieve.
* @param defaultValue The value to return if the field is not present.
* @return The result which should be a long.
*/
public static int getSubProtoValueOrDefault(ProtoBuf proto, int sub, int tag,
int defaultValue) {
try {
return getProtoValueOrDefault(getSubProtoOrNull(proto, sub), tag,
defaultValue);
} catch (IllegalArgumentException e) {
return defaultValue;
} catch (ClassCastException e) {
return defaultValue;
}
}
/**
* Creates a sub ProtoBuf of the given Protobuf and sets it.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* create.
* @return the sub ProtoBuf generated.
*/
public static ProtoBuf createProtoBuf(ProtoBuf proto, int tag) {
ProtoBuf child = proto.createGroup(tag);
proto.setProtoBuf(tag, child);
return child;
}
/**
* Creates a sub ProtoBuf of the given Protobuf and adds it.
*
* @param proto The proto buffer.
* @param tag The tag value that identifies which protocol buffer field to
* add.
* @return the sub ProtoBuf generated.
*/
public static ProtoBuf addProtoBuf(ProtoBuf proto, int tag) {
ProtoBuf child = proto.createGroup(tag);
proto.addProtoBuf(tag, child);
return child;
}
/**
* Writes the ProtoBuf to the given DataOutput. This is useful for unit
* tests.
*
* @param output The data output to write to.
* @param protoBuf The proto buffer.
*/
public static void writeProtoBufToOutput(DataOutput output, ProtoBuf protoBuf)
throws IOException {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
protoBuf.outputTo(baos);
byte[] bytes = baos.toByteArray();
output.writeInt(bytes.length);
output.write(bytes);
}
}
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