// Protocol Buffers - Google's data interchange format
// Copyright 2008 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;
import static com.google.protobuf.FieldInfo.forField;
import static com.google.protobuf.FieldInfo.forFieldWithEnumVerifier;
import static com.google.protobuf.FieldInfo.forMapField;
import static com.google.protobuf.FieldInfo.forOneofMemberField;
import static com.google.protobuf.FieldInfo.forPackedField;
import static com.google.protobuf.FieldInfo.forPackedFieldWithEnumVerifier;
import static com.google.protobuf.FieldInfo.forProto2OptionalField;
import static com.google.protobuf.FieldInfo.forProto2RequiredField;
import static com.google.protobuf.FieldInfo.forRepeatedMessageField;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.FieldDescriptor;
import com.google.protobuf.Descriptors.FieldDescriptor.Type;
import com.google.protobuf.Descriptors.OneofDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import java.util.concurrent.ConcurrentHashMap;
/** A factory for message info based on protobuf descriptors for a {@link GeneratedMessageV3}. */
@ExperimentalApi
final class DescriptorMessageInfoFactory implements MessageInfoFactory {
private static final String GET_DEFAULT_INSTANCE_METHOD_NAME = "getDefaultInstance";
private static final DescriptorMessageInfoFactory instance = new DescriptorMessageInfoFactory();
/**
* Names that should be avoided (in UpperCamelCase format). Using them causes the compiler to
* generate accessors whose names collide with methods defined in base classes.
*
* <p>Keep this list in sync with kForbiddenWordList in
* src/google/protobuf/compiler/java/java_helpers.cc
*/
private static final Set<String> specialFieldNames =
new HashSet<>(
Arrays.asList(
// java.lang.Object:
"Class",
// com.google.protobuf.MessageLiteOrBuilder:
"DefaultInstanceForType",
// com.google.protobuf.MessageLite:
"ParserForType",
"SerializedSize",
// com.google.protobuf.MessageOrBuilder:
"AllFields",
"DescriptorForType",
"InitializationErrorString",
"UnknownFields",
// obsolete. kept for backwards compatibility of generated code
"CachedSize"));
// Disallow construction - it's a singleton.
private DescriptorMessageInfoFactory() {}
public static DescriptorMessageInfoFactory getInstance() {
return instance;
}
@Override
public boolean isSupported(Class<?> messageType) {
return GeneratedMessageV3.class.isAssignableFrom(messageType);
}
@Override
public MessageInfo messageInfoFor(Class<?> messageType) {
if (!GeneratedMessageV3.class.isAssignableFrom(messageType)) {
throw new IllegalArgumentException("Unsupported message type: " + messageType.getName());
}
return convert(messageType, descriptorForType(messageType));
}
private static Message getDefaultInstance(Class<?> messageType) {
try {
Method method = messageType.getDeclaredMethod(GET_DEFAULT_INSTANCE_METHOD_NAME);
return (Message) method.invoke(null);
} catch (Exception e) {
throw new IllegalArgumentException(
"Unable to get default instance for message class " + messageType.getName(), e);
}
}
private static Descriptor descriptorForType(Class<?> messageType) {
return getDefaultInstance(messageType).getDescriptorForType();
}
private static MessageInfo convert(Class<?> messageType, Descriptor messageDescriptor) {
switch (messageDescriptor.getFile().getSyntax()) {
case PROTO2:
return convertProto2(messageType, messageDescriptor);
case PROTO3:
return convertProto3(messageType, messageDescriptor);
default:
throw new IllegalArgumentException(
"Unsupported syntax: " + messageDescriptor.getFile().getSyntax());
}
}
/**
* A helper class to determine whether a message type needs to implement {@code isInitialized()}.
*
* <p>If a message type doesn't have any required fields or extensions (directly and
* transitively), it doesn't need to implement isInitialized() and can always return true there.
* It's a bit tricky to determine whether a type has transitive required fields because protobuf
* allows cycle references within the same .proto file (e.g., message Foo has a Bar field, and
* message Bar has a Foo field). For that we use Tarjan's strongly connected components algorithm
* to classify messages into strongly connected groups. Messages in the same group are
* transitively including each other, so they should either all have transitive required fields
* (or extensions), or none have.
*
* <p>This class is thread-safe.
*/
// <p>The code is adapted from the C++ implementation:
// https://github.com/protocolbuffers/protobuf/blob/main/src/google/protobuf/compiler/java/java_helpers.h
static class IsInitializedCheckAnalyzer {
private final Map<Descriptor, Boolean> resultCache =
new ConcurrentHashMap<Descriptor, Boolean>();
// The following data members are part of Tarjan's SCC algorithm. See:
// https://en.wikipedia.org/wiki/Tarjan%27s_strongly_connected_components_algorithm
private int index = 0;
private final Stack<Node> stack = new Stack<Node>();
private final Map<Descriptor, Node> nodeCache = new HashMap<Descriptor, Node>();
public boolean needsIsInitializedCheck(Descriptor descriptor) {
Boolean cachedValue = resultCache.get(descriptor);
if (cachedValue != null) {
return cachedValue;
}
synchronized (this) {
// Double-check the cache because some other thread may have updated it while we
// were acquiring the lock.
cachedValue = resultCache.get(descriptor);
if (cachedValue != null) {
return cachedValue;
}
return dfs(descriptor).component.needsIsInitializedCheck;
}
}
private static class Node {
final Descriptor descriptor;
final int index;
int lowLink;
StronglyConnectedComponent component; // null if the node is still on stack.
Node(Descriptor descriptor, int index) {
this.descriptor = descriptor;
this.index = index;
this.lowLink = index;
this.component = null;
}
}
private static class StronglyConnectedComponent {
final List<Descriptor> messages = new ArrayList<Descriptor>();
boolean needsIsInitializedCheck = false;
}
private Node dfs(Descriptor descriptor) {
Node result = new Node(descriptor, index++);
stack.push(result);
nodeCache.put(descriptor, result);
// Recurse the fields / nodes in graph
for (FieldDescriptor field : descriptor.getFields()) {
if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
Node child = nodeCache.get(field.getMessageType());
if (child == null) {
// Unexplored node
child = dfs(field.getMessageType());
result.lowLink = Math.min(result.lowLink, child.lowLink);
} else {
if (child.component == null) {
// Still in the stack so we found a back edge.
result.lowLink = Math.min(result.lowLink, child.lowLink);
}
}
}
}
if (result.index == result.lowLink) {
// This is the root of a strongly connected component.
StronglyConnectedComponent component = new StronglyConnectedComponent();
while (true) {
Node node = stack.pop();
node.component = component;
component.messages.add(node.descriptor);
if (node == result) {
break;
}
}
analyze(component);
}
return result;
}
// Determine whether messages in this SCC needs isInitialized check.
private void analyze(StronglyConnectedComponent component) {
boolean needsIsInitializedCheck = false;
loop:
for (Descriptor descriptor : component.messages) {
if (descriptor.isExtendable()) {
needsIsInitializedCheck = true;
break;
}
for (FieldDescriptor field : descriptor.getFields()) {
if (field.isRequired()) {
needsIsInitializedCheck = true;
break loop;
}
if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
// Since we are analyzing the graph bottom-up, all referenced fields should either be
// in this same component or in a different already-analyzed component.
Node node = nodeCache.get(field.getMessageType());
if (node.component != component) {
if (node.component.needsIsInitializedCheck) {
needsIsInitializedCheck = true;
break loop;
}
}
}
}
}
component.needsIsInitializedCheck = needsIsInitializedCheck;
for (Descriptor descriptor : component.messages) {
resultCache.put(descriptor, component.needsIsInitializedCheck);
}
}
}
private static IsInitializedCheckAnalyzer isInitializedCheckAnalyzer =
new IsInitializedCheckAnalyzer();
private static boolean needsIsInitializedCheck(Descriptor descriptor) {
return isInitializedCheckAnalyzer.needsIsInitializedCheck(descriptor);
}
private static StructuralMessageInfo convertProto2(
Class<?> messageType, Descriptor messageDescriptor) {
List<FieldDescriptor> fieldDescriptors = messageDescriptor.getFields();
StructuralMessageInfo.Builder builder =
StructuralMessageInfo.newBuilder(fieldDescriptors.size());
builder.withDefaultInstance(getDefaultInstance(messageType));
builder.withSyntax(ProtoSyntax.PROTO2);
builder.withMessageSetWireFormat(messageDescriptor.getOptions().getMessageSetWireFormat());
OneofState oneofState = new OneofState();
int bitFieldIndex = 0;
int presenceMask = 1;
Field bitField = null;
// Fields in the descriptor are ordered by the index position in which they appear in the
// proto file. This is the same order used to determine the presence mask used in the
// bitFields. So to determine the appropriate presence mask to be used for a field, we simply
// need to shift the presence mask whenever a presence-checked field is encountered.
for (int i = 0; i < fieldDescriptors.size(); ++i) {
final FieldDescriptor fd = fieldDescriptors.get(i);
boolean enforceUtf8 = fd.getFile().getOptions().getJavaStringCheckUtf8();
Internal.EnumVerifier enumVerifier = null;
if (fd.getJavaType() == Descriptors.FieldDescriptor.JavaType.ENUM) {
enumVerifier =
new Internal.EnumVerifier() {
@Override
public boolean isInRange(int number) {
return fd.getEnumType().findValueByNumber(number) != null;
}
};
}
if (fd.getContainingOneof() != null) {
// Build a oneof member field.
builder.withField(buildOneofMember(messageType, fd, oneofState, enforceUtf8, enumVerifier));
} else {
Field field = field(messageType, fd);
int number = fd.getNumber();
FieldType type = getFieldType(fd);
if (fd.isMapField()) {
// Map field points to an auto-generated message entry type with the definition:
// message MapEntry {
// K key = 1;
// V value = 2;
// }
final FieldDescriptor valueField = fd.getMessageType().findFieldByNumber(2);
if (valueField.getJavaType() == Descriptors.FieldDescriptor.JavaType.ENUM) {
enumVerifier =
new Internal.EnumVerifier() {
@Override
public boolean isInRange(int number) {
return valueField.getEnumType().findValueByNumber(number) != null;
}
};
}
builder.withField(
forMapField(
field,
number,
SchemaUtil.getMapDefaultEntry(messageType, fd.getName()),
enumVerifier));
continue;
}
if (fd.isRepeated()) {
// Repeated fields are not presence-checked.
if (enumVerifier != null) {
if (fd.isPacked()) {
builder.withField(
forPackedFieldWithEnumVerifier(
field, number, type, enumVerifier, cachedSizeField(messageType, fd)));
} else {
builder.withField(forFieldWithEnumVerifier(field, number, type, enumVerifier));
}
} else if (fd.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
builder.withField(
forRepeatedMessageField(
field, number, type, getTypeForRepeatedMessageField(messageType, fd)));
} else {
if (fd.isPacked()) {
builder.withField(
forPackedField(field, number, type, cachedSizeField(messageType, fd)));
} else {
builder.withField(forField(field, number, type, enforceUtf8));
}
}
continue;
}
if (bitField == null) {
// Lazy-create the next bitfield since we know it must exist.
bitField = bitField(messageType, bitFieldIndex);
}
// It's a presence-checked field.
if (fd.isRequired()) {
builder.withField(
forProto2RequiredField(
field, number, type, bitField, presenceMask, enforceUtf8, enumVerifier));
} else {
builder.withField(
forProto2OptionalField(
field, number, type, bitField, presenceMask, enforceUtf8, enumVerifier));
}
}
// Update the presence mask for the next iteration. If the shift clears out the mask, we will
// go to the next bitField.
presenceMask <<= 1;
if (presenceMask == 0) {
bitField = null;
presenceMask = 1;
bitFieldIndex++;
}
}
List<Integer> fieldsToCheckIsInitialized = new ArrayList<Integer>();
for (int i = 0; i < fieldDescriptors.size(); ++i) {
FieldDescriptor fd = fieldDescriptors.get(i);
if (fd.isRequired()
|| (fd.getJavaType() == FieldDescriptor.JavaType.MESSAGE
&& needsIsInitializedCheck(fd.getMessageType()))) {
fieldsToCheckIsInitialized.add(fd.getNumber());
}
}
int[] numbers = new int[fieldsToCheckIsInitialized.size()];
for (int i = 0; i < fieldsToCheckIsInitialized.size(); i++) {
numbers[i] = fieldsToCheckIsInitialized.get(i);
}
builder.withCheckInitialized(numbers);
return builder.build();
}
private static StructuralMessageInfo convertProto3(
Class<?> messageType, Descriptor messageDescriptor) {
List<FieldDescriptor> fieldDescriptors = messageDescriptor.getFields();
StructuralMessageInfo.Builder builder =
StructuralMessageInfo.newBuilder(fieldDescriptors.size());
builder.withDefaultInstance(getDefaultInstance(messageType));
builder.withSyntax(ProtoSyntax.PROTO3);
OneofState oneofState = new OneofState();
boolean enforceUtf8 = true;
for (int i = 0; i < fieldDescriptors.size(); ++i) {
FieldDescriptor fd = fieldDescriptors.get(i);
if (fd.getContainingOneof() != null && !fd.getContainingOneof().isSynthetic()) {
// Build a oneof member field. But only if it is a real oneof, not a proto3 optional
builder.withField(buildOneofMember(messageType, fd, oneofState, enforceUtf8, null));
continue;
}
if (fd.isMapField()) {
builder.withField(
forMapField(
field(messageType, fd),
fd.getNumber(),
SchemaUtil.getMapDefaultEntry(messageType, fd.getName()),
null));
continue;
}
if (fd.isRepeated() && fd.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
builder.withField(
forRepeatedMessageField(
field(messageType, fd),
fd.getNumber(),
getFieldType(fd),
getTypeForRepeatedMessageField(messageType, fd)));
continue;
}
if (fd.isPacked()) {
builder.withField(
forPackedField(
field(messageType, fd),
fd.getNumber(),
getFieldType(fd),
cachedSizeField(messageType, fd)));
} else {
builder.withField(
forField(field(messageType, fd), fd.getNumber(), getFieldType(fd), enforceUtf8));
}
}
return builder.build();
}
/** Builds info for a oneof member field. */
private static FieldInfo buildOneofMember(
Class<?> messageType,
FieldDescriptor fd,
OneofState oneofState,
boolean enforceUtf8,
Internal.EnumVerifier enumVerifier) {
OneofInfo oneof = oneofState.getOneof(messageType, fd.getContainingOneof());
FieldType type = getFieldType(fd);
Class<?> oneofStoredType = getOneofStoredType(messageType, fd, type);
return forOneofMemberField(
fd.getNumber(), type, oneof, oneofStoredType, enforceUtf8, enumVerifier);
}
private static Class<?> getOneofStoredType(
Class<?> messageType, FieldDescriptor fd, FieldType type) {
switch (type.getJavaType()) {
case BOOLEAN:
return Boolean.class;
case BYTE_STRING:
return ByteString.class;
case DOUBLE:
return Double.class;
case FLOAT:
return Float.class;
case ENUM:
case INT:
return Integer.class;
case LONG:
return Long.class;
case STRING:
return String.class;
case MESSAGE:
return getOneofStoredTypeForMessage(messageType, fd);
default:
throw new IllegalArgumentException("Invalid type for oneof: " + type);
}
}
private static FieldType getFieldType(FieldDescriptor fd) {
switch (fd.getType()) {
case BOOL:
if (!fd.isRepeated()) {
return FieldType.BOOL;
}
return fd.isPacked() ? FieldType.BOOL_LIST_PACKED : FieldType.BOOL_LIST;
case BYTES:
return fd.isRepeated() ? FieldType.BYTES_LIST : FieldType.BYTES;
case DOUBLE:
if (!fd.isRepeated()) {
return FieldType.DOUBLE;
}
return fd.isPacked() ? FieldType.DOUBLE_LIST_PACKED : FieldType.DOUBLE_LIST;
case ENUM:
if (!fd.isRepeated()) {
return FieldType.ENUM;
}
return fd.isPacked() ? FieldType.ENUM_LIST_PACKED : FieldType.ENUM_LIST;
case FIXED32:
if (!fd.isRepeated()) {
return FieldType.FIXED32;
}
return fd.isPacked() ? FieldType.FIXED32_LIST_PACKED : FieldType.FIXED32_LIST;
case FIXED64:
if (!fd.isRepeated()) {
return FieldType.FIXED64;
}
return fd.isPacked() ? FieldType.FIXED64_LIST_PACKED : FieldType.FIXED64_LIST;
case FLOAT:
if (!fd.isRepeated()) {
return FieldType.FLOAT;
}
return fd.isPacked() ? FieldType.FLOAT_LIST_PACKED : FieldType.FLOAT_LIST;
case GROUP:
return fd.isRepeated() ? FieldType.GROUP_LIST : FieldType.GROUP;
case INT32:
if (!fd.isRepeated()) {
return FieldType.INT32;
}
return fd.isPacked() ? FieldType.INT32_LIST_PACKED : FieldType.INT32_LIST;
case INT64:
if (!fd.isRepeated()) {
return FieldType.INT64;
}
return fd.isPacked() ? FieldType.INT64_LIST_PACKED : FieldType.INT64_LIST;
case MESSAGE:
if (fd.isMapField()) {
return FieldType.MAP;
}
return fd.isRepeated() ? FieldType.MESSAGE_LIST : FieldType.MESSAGE;
case SFIXED32:
if (!fd.isRepeated()) {
return FieldType.SFIXED32;
}
return fd.isPacked() ? FieldType.SFIXED32_LIST_PACKED : FieldType.SFIXED32_LIST;
case SFIXED64:
if (!fd.isRepeated()) {
return FieldType.SFIXED64;
}
return fd.isPacked() ? FieldType.SFIXED64_LIST_PACKED : FieldType.SFIXED64_LIST;
case SINT32:
if (!fd.isRepeated()) {
return FieldType.SINT32;
}
return fd.isPacked() ? FieldType.SINT32_LIST_PACKED : FieldType.SINT32_LIST;
case SINT64:
if (!fd.isRepeated()) {
return FieldType.SINT64;
}
return fd.isPacked() ? FieldType.SINT64_LIST_PACKED : FieldType.SINT64_LIST;
case STRING:
return fd.isRepeated() ? FieldType.STRING_LIST : FieldType.STRING;
case UINT32:
if (!fd.isRepeated()) {
return FieldType.UINT32;
}
return fd.isPacked() ? FieldType.UINT32_LIST_PACKED : FieldType.UINT32_LIST;
case UINT64:
if (!fd.isRepeated()) {
return FieldType.UINT64;
}
return fd.isPacked() ? FieldType.UINT64_LIST_PACKED : FieldType.UINT64_LIST;
default:
throw new IllegalArgumentException("Unsupported field type: " + fd.getType());
}
}
private static Field bitField(Class<?> messageType, int index) {
return field(messageType, "bitField" + index + "_");
}
private static Field field(Class<?> messageType, FieldDescriptor fd) {
return field(messageType, getFieldName(fd));
}
private static Field cachedSizeField(Class<?> messageType, FieldDescriptor fd) {
return field(messageType, getCachedSizeFieldName(fd));
}
private static Field field(Class<?> messageType, String fieldName) {
try {
return messageType.getDeclaredField(fieldName);
} catch (Exception e) {
throw new IllegalArgumentException(
"Unable to find field " + fieldName + " in message class " + messageType.getName());
}
}
static String getFieldName(FieldDescriptor fd) {
String name = (fd.getType() == FieldDescriptor.Type.GROUP)
? fd.getMessageType().getName()
: fd.getName();
// convert to UpperCamelCase for comparison to the specialFieldNames
// (which are in UpperCamelCase)
String upperCamelCaseName = snakeCaseToUpperCamelCase(name);
// Append underscores to match the behavior of the protoc java compiler
final String suffix;
if (specialFieldNames.contains(upperCamelCaseName)) {
// For proto field names that match the specialFieldNames,
// the protoc java compiler appends "__" to the java field name
// to prevent the field's accessor method names from clashing with other methods.
// For example:
// proto field name = "class"
// java field name = "class__"
// accessor method name = "getClass_()" (so that it does not clash with
// Object.getClass())
suffix = "__";
} else {
// For other proto field names,
// the protoc java compiler appends "_" to the java field name
// to prevent field names from clashing with java keywords.
// For example:
// proto field name = "int"
// java field name = "int_" (so that it does not clash with int keyword)
// accessor method name = "getInt()"
suffix = "_";
}
return snakeCaseToLowerCamelCase(name) + suffix;
}
private static String getCachedSizeFieldName(FieldDescriptor fd) {
return snakeCaseToLowerCamelCase(fd.getName()) + "MemoizedSerializedSize";
}
/**
* Converts a snake case string into lower camel case.
*
* <p>Some examples:
*
* <pre>
* snakeCaseToLowerCamelCase("foo_bar") => "fooBar"
* snakeCaseToLowerCamelCase("foo") => "foo"
* </pre>
*
* @param snakeCase the string in snake case to convert
* @return the string converted to camel case, with a lowercase first character
*/
private static String snakeCaseToLowerCamelCase(String snakeCase) {
return snakeCaseToCamelCase(snakeCase, false);
}
/**
* Converts a snake case string into upper camel case.
*
* <p>Some examples:
*
* <pre>
* snakeCaseToUpperCamelCase("foo_bar") => "FooBar"
* snakeCaseToUpperCamelCase("foo") => "Foo"
* </pre>
*
* @param snakeCase the string in snake case to convert
* @return the string converted to camel case, with an uppercase first character
*/
private static String snakeCaseToUpperCamelCase(String snakeCase) {
return snakeCaseToCamelCase(snakeCase, true);
}
/**
* Converts a snake case string into camel case.
*
* <p>For better readability, prefer calling either {@link #snakeCaseToLowerCamelCase(String)} or
* {@link #snakeCaseToUpperCamelCase(String)}.
*
* <p>Some examples:
*
* <pre>
* snakeCaseToCamelCase("foo_bar", false) => "fooBar"
* snakeCaseToCamelCase("foo_bar", true) => "FooBar"
* snakeCaseToCamelCase("foo", false) => "foo"
* snakeCaseToCamelCase("foo", true) => "Foo"
* snakeCaseToCamelCase("Foo", false) => "foo"
* snakeCaseToCamelCase("fooBar", false) => "fooBar"
* </pre>
*
* <p>This implementation of this method must exactly match the corresponding function in the
* protocol compiler. Specifically, the {@code UnderscoresToCamelCase} function in {@code
* src/google/protobuf/compiler/java/java_helpers.cc}.
*
* @param snakeCase the string in snake case to convert
* @param capFirst true if the first letter of the returned string should be uppercase. false if
* the first letter of the returned string should be lowercase.
* @return the string converted to camel case, with an uppercase or lowercase first character
* depending on if {@code capFirst} is true or false, respectively
*/
private static String snakeCaseToCamelCase(String snakeCase, boolean capFirst) {
StringBuilder sb = new StringBuilder(snakeCase.length() + 1);
boolean capNext = capFirst;
for (int ctr = 0; ctr < snakeCase.length(); ctr++) {
char next = snakeCase.charAt(ctr);
if (next == '_') {
capNext = true;
} else if (Character.isDigit(next)) {
sb.append(next);
capNext = true;
} else if (capNext) {
sb.append(Character.toUpperCase(next));
capNext = false;
} else if (ctr == 0) {
sb.append(Character.toLowerCase(next));
} else {
sb.append(next);
}
}
return sb.toString();
}
/**
* Inspects the message to identify the stored type for a message field that is part of a oneof.
*/
private static Class<?> getOneofStoredTypeForMessage(Class<?> messageType, FieldDescriptor fd) {
try {
String name = fd.getType() == Type.GROUP ? fd.getMessageType().getName() : fd.getName();
Method getter = messageType.getDeclaredMethod(getterForField(name));
return getter.getReturnType();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/** Inspects the message to identify the message type of a repeated message field. */
private static Class<?> getTypeForRepeatedMessageField(Class<?> messageType, FieldDescriptor fd) {
try {
String name = fd.getType() == Type.GROUP ? fd.getMessageType().getName() : fd.getName();
Method getter = messageType.getDeclaredMethod(getterForField(name), int.class);
return getter.getReturnType();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/** Constructs the name of the get method for the given field in the proto. */
private static String getterForField(String snakeCase) {
String camelCase = snakeCaseToLowerCamelCase(snakeCase);
StringBuilder builder = new StringBuilder("get");
// Capitalize the first character in the field name.
builder.append(Character.toUpperCase(camelCase.charAt(0)));
builder.append(camelCase.substring(1, camelCase.length()));
return builder.toString();
}
private static final class OneofState {
private OneofInfo[] oneofs = new OneofInfo[2];
OneofInfo getOneof(Class<?> messageType, OneofDescriptor desc) {
int index = desc.getIndex();
if (index >= oneofs.length) {
// Grow the array.
oneofs = Arrays.copyOf(oneofs, index * 2);
}
OneofInfo info = oneofs[index];
if (info == null) {
info = newInfo(messageType, desc);
oneofs[index] = info;
}
return info;
}
private static OneofInfo newInfo(Class<?> messageType, OneofDescriptor desc) {
String camelCase = snakeCaseToLowerCamelCase(desc.getName());
String valueFieldName = camelCase + "_";
String caseFieldName = camelCase + "Case_";
return new OneofInfo(
desc.getIndex(), field(messageType, caseFieldName), field(messageType, valueFieldName));
}
}
}
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