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Protocol Buffers are a way of encoding structured data in an efficient yet
extensible format.
// Protocol Buffers - Google's data interchange format
// Copyright 2013 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package com.google.protobuf.nano;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Map;
/**
* Static helper methods for printing nano protos.
*
* @author [email protected] Andrew Flynn
*/
public final class MessageNanoPrinter {
// Do not allow instantiation
private MessageNanoPrinter() {}
private static final String INDENT = " ";
private static final int MAX_STRING_LEN = 200;
/**
* Returns an text representation of a MessageNano suitable for debugging. The returned string
* is mostly compatible with Protocol Buffer's TextFormat (as provided by non-nano protocol
* buffers) -- groups (which are deprecated) are output with an underscore name (e.g. foo_bar
* instead of FooBar) and will thus not parse.
*
* Employs Java reflection on the given object and recursively prints primitive fields,
* groups, and messages.
*/
public static String print(T message) {
if (message == null) {
return "";
}
StringBuffer buf = new StringBuffer();
try {
print(null, message, new StringBuffer(), buf);
} catch (IllegalAccessException e) {
return "Error printing proto: " + e.getMessage();
} catch (InvocationTargetException e) {
return "Error printing proto: " + e.getMessage();
}
return buf.toString();
}
/**
* Function that will print the given message/field into the StringBuffer.
* Meant to be called recursively.
*
* @param identifier the identifier to use, or {@code null} if this is the root message to
* print.
* @param object the value to print. May in fact be a primitive value or byte array and not a
* message.
* @param indentBuf the indentation each line should begin with.
* @param buf the output buffer.
*/
private static void print(String identifier, Object object,
StringBuffer indentBuf, StringBuffer buf) throws IllegalAccessException,
InvocationTargetException {
if (object == null) {
// This can happen if...
// - we're about to print a message, String, or byte[], but it not present;
// - we're about to print a primitive, but "reftype" optional style is enabled, and
// the field is unset.
// In both cases the appropriate behavior is to output nothing.
} else if (object instanceof MessageNano) { // Nano proto message
int origIndentBufLength = indentBuf.length();
if (identifier != null) {
buf.append(indentBuf).append(deCamelCaseify(identifier)).append(" <\n");
indentBuf.append(INDENT);
}
Class clazz = object.getClass();
// Proto fields follow one of two formats:
//
// 1) Public, non-static variables that do not begin or end with '_'
// Find and print these using declared public fields
for (Field field : clazz.getFields()) {
int modifiers = field.getModifiers();
String fieldName = field.getName();
if ("cachedSize".equals(fieldName)) {
// TODO(bduff): perhaps cachedSize should have a more obscure name.
continue;
}
if ((modifiers & Modifier.PUBLIC) == Modifier.PUBLIC
&& (modifiers & Modifier.STATIC) != Modifier.STATIC
&& !fieldName.startsWith("_")
&& !fieldName.endsWith("_")) {
Class fieldType = field.getType();
Object value = field.get(object);
if (fieldType.isArray()) {
Class arrayType = fieldType.getComponentType();
// bytes is special since it's not repeated, but is represented by an array
if (arrayType == byte.class) {
print(fieldName, value, indentBuf, buf);
} else {
int len = value == null ? 0 : Array.getLength(value);
for (int i = 0; i < len; i++) {
Object elem = Array.get(value, i);
print(fieldName, elem, indentBuf, buf);
}
}
} else {
print(fieldName, value, indentBuf, buf);
}
}
}
// 2) Fields that are accessed via getter methods (when accessors
// mode is turned on)
// Find and print these using getter methods.
for (Method method : clazz.getMethods()) {
String name = method.getName();
// Check for the setter accessor method since getters and hazzers both have
// non-proto-field name collisions (hashCode() and getSerializedSize())
if (name.startsWith("set")) {
String subfieldName = name.substring(3);
Method hazzer = null;
try {
hazzer = clazz.getMethod("has" + subfieldName);
} catch (NoSuchMethodException e) {
continue;
}
// If hazzer doesn't exist or returns false, no need to continue
if (!(Boolean) hazzer.invoke(object)) {
continue;
}
Method getter = null;
try {
getter = clazz.getMethod("get" + subfieldName);
} catch (NoSuchMethodException e) {
continue;
}
print(subfieldName, getter.invoke(object), indentBuf, buf);
}
}
if (identifier != null) {
indentBuf.setLength(origIndentBufLength);
buf.append(indentBuf).append(">\n");
}
} else if (object instanceof Map) {
Map map = (Map) object;
identifier = deCamelCaseify(identifier);
for (Map.Entry entry : map.entrySet()) {
buf.append(indentBuf).append(identifier).append(" <\n");
int origIndentBufLength = indentBuf.length();
indentBuf.append(INDENT);
print("key", entry.getKey(), indentBuf, buf);
print("value", entry.getValue(), indentBuf, buf);
indentBuf.setLength(origIndentBufLength);
buf.append(indentBuf).append(">\n");
}
} else {
// Non-null primitive value
identifier = deCamelCaseify(identifier);
buf.append(indentBuf).append(identifier).append(": ");
if (object instanceof String) {
String stringMessage = sanitizeString((String) object);
buf.append("\"").append(stringMessage).append("\"");
} else if (object instanceof byte[]) {
appendQuotedBytes((byte[]) object, buf);
} else {
buf.append(object);
}
buf.append("\n");
}
}
/**
* Converts an identifier of the format "FieldName" into "field_name".
*/
private static String deCamelCaseify(String identifier) {
StringBuffer out = new StringBuffer();
for (int i = 0; i < identifier.length(); i++) {
char currentChar = identifier.charAt(i);
if (i == 0) {
out.append(Character.toLowerCase(currentChar));
} else if (Character.isUpperCase(currentChar)) {
out.append('_').append(Character.toLowerCase(currentChar));
} else {
out.append(currentChar);
}
}
return out.toString();
}
/**
* Shortens and escapes the given string.
*/
private static String sanitizeString(String str) {
if (!str.startsWith("http") && str.length() > MAX_STRING_LEN) {
// Trim non-URL strings.
str = str.substring(0, MAX_STRING_LEN) + "[...]";
}
return escapeString(str);
}
/**
* Escape everything except for low ASCII code points.
*/
private static String escapeString(String str) {
int strLen = str.length();
StringBuilder b = new StringBuilder(strLen);
for (int i = 0; i < strLen; i++) {
char original = str.charAt(i);
if (original >= ' ' && original <= '~' && original != '"' && original != '\'') {
b.append(original);
} else {
b.append(String.format("\\u%04x", (int) original));
}
}
return b.toString();
}
/**
* Appends a quoted byte array to the provided {@code StringBuffer}.
*/
private static void appendQuotedBytes(byte[] bytes, StringBuffer builder) {
if (bytes == null) {
builder.append("\"\"");
return;
}
builder.append('"');
for (int i = 0; i < bytes.length; ++i) {
int ch = bytes[i] & 0xff;
if (ch == '\\' || ch == '"') {
builder.append('\\').append((char) ch);
} else if (ch >= 32 && ch < 127) {
builder.append((char) ch);
} else {
builder.append(String.format("\\%03o", ch));
}
}
builder.append('"');
}
}