acl/include/google/protobuf/descriptor_database.h

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// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// http://code.google.com/p/protobuf/
//
// 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.
// Author: kenton@google.com (Kenton Varda)
// Based on original Protocol Buffers design by
// Sanjay Ghemawat, Jeff Dean, and others.
//
// Interface for manipulating databases of descriptors.
#ifndef GOOGLE_PROTOBUF_DESCRIPTOR_DATABASE_H__
#define GOOGLE_PROTOBUF_DESCRIPTOR_DATABASE_H__
#include <map>
#include <string>
#include <utility>
#include <vector>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/descriptor.h>
namespace google {
namespace protobuf {
// Defined in this file.
class DescriptorDatabase;
class SimpleDescriptorDatabase;
class EncodedDescriptorDatabase;
class DescriptorPoolDatabase;
class MergedDescriptorDatabase;
// Abstract interface for a database of descriptors.
//
// This is useful if you want to create a DescriptorPool which loads
// descriptors on-demand from some sort of large database. If the database
// is large, it may be inefficient to enumerate every .proto file inside it
// calling DescriptorPool::BuildFile() for each one. Instead, a DescriptorPool
// can be created which wraps a DescriptorDatabase and only builds particular
// descriptors when they are needed.
class LIBPROTOBUF_EXPORT DescriptorDatabase {
public:
inline DescriptorDatabase() {}
virtual ~DescriptorDatabase();
// Find a file by file name. Fills in in *output and returns true if found.
// Otherwise, returns false, leaving the contents of *output undefined.
virtual bool FindFileByName(const string& filename,
FileDescriptorProto* output) = 0;
// Find the file that declares the given fully-qualified symbol name.
// If found, fills in *output and returns true, otherwise returns false
// and leaves *output undefined.
virtual bool FindFileContainingSymbol(const string& symbol_name,
FileDescriptorProto* output) = 0;
// Find the file which defines an extension extending the given message type
// with the given field number. If found, fills in *output and returns true,
// otherwise returns false and leaves *output undefined. containing_type
// must be a fully-qualified type name.
virtual bool FindFileContainingExtension(const string& containing_type,
int field_number,
FileDescriptorProto* output) = 0;
// Finds the tag numbers used by all known extensions of
// extendee_type, and appends them to output in an undefined
// order. This method is best-effort: it's not guaranteed that the
// database will find all extensions, and it's not guaranteed that
// FindFileContainingExtension will return true on all of the found
// numbers. Returns true if the search was successful, otherwise
// returns false and leaves output unchanged.
//
// This method has a default implementation that always returns
// false.
virtual bool FindAllExtensionNumbers(const string& /* extendee_type */,
vector<int>* /* output */) {
return false;
}
private:
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DescriptorDatabase);
};
// A DescriptorDatabase into which you can insert files manually.
//
// FindFileContainingSymbol() is fully-implemented. When you add a file, its
// symbols will be indexed for this purpose. Note that the implementation
// may return false positives, but only if it isn't possible for the symbol
// to be defined in any other file. In particular, if a file defines a symbol
// "Foo", then searching for "Foo.[anything]" will match that file. This way,
// the database does not need to aggressively index all children of a symbol.
//
// FindFileContainingExtension() is mostly-implemented. It works if and only
// if the original FieldDescriptorProto defining the extension has a
// fully-qualified type name in its "extendee" field (i.e. starts with a '.').
// If the extendee is a relative name, SimpleDescriptorDatabase will not
// attempt to resolve the type, so it will not know what type the extension is
// extending. Therefore, calling FindFileContainingExtension() with the
// extension's containing type will never actually find that extension. Note
// that this is an unlikely problem, as all FileDescriptorProtos created by the
// protocol compiler (as well as ones created by calling
// FileDescriptor::CopyTo()) will always use fully-qualified names for all
// types. You only need to worry if you are constructing FileDescriptorProtos
// yourself, or are calling compiler::Parser directly.
class LIBPROTOBUF_EXPORT SimpleDescriptorDatabase : public DescriptorDatabase {
public:
SimpleDescriptorDatabase();
~SimpleDescriptorDatabase();
// Adds the FileDescriptorProto to the database, making a copy. The object
// can be deleted after Add() returns. Returns false if the file conflicted
// with a file already in the database, in which case an error will have
// been written to GOOGLE_LOG(ERROR).
bool Add(const FileDescriptorProto& file);
// Adds the FileDescriptorProto to the database and takes ownership of it.
bool AddAndOwn(const FileDescriptorProto* file);
// implements DescriptorDatabase -----------------------------------
bool FindFileByName(const string& filename,
FileDescriptorProto* output);
bool FindFileContainingSymbol(const string& symbol_name,
FileDescriptorProto* output);
bool FindFileContainingExtension(const string& containing_type,
int field_number,
FileDescriptorProto* output);
bool FindAllExtensionNumbers(const string& extendee_type,
vector<int>* output);
private:
// So that it can use DescriptorIndex.
friend class EncodedDescriptorDatabase;
// An index mapping file names, symbol names, and extension numbers to
// some sort of values.
template <typename Value>
class DescriptorIndex {
public:
// Helpers to recursively add particular descriptors and all their contents
// to the index.
bool AddFile(const FileDescriptorProto& file,
Value value);
bool AddSymbol(const string& name, Value value);
bool AddNestedExtensions(const DescriptorProto& message_type,
Value value);
bool AddExtension(const FieldDescriptorProto& field,
Value value);
Value FindFile(const string& filename);
Value FindSymbol(const string& name);
Value FindExtension(const string& containing_type, int field_number);
bool FindAllExtensionNumbers(const string& containing_type,
vector<int>* output);
private:
map<string, Value> by_name_;
map<string, Value> by_symbol_;
map<pair<string, int>, Value> by_extension_;
// Invariant: The by_symbol_ map does not contain any symbols which are
// prefixes of other symbols in the map. For example, "foo.bar" is a
// prefix of "foo.bar.baz" (but is not a prefix of "foo.barbaz").
//
// This invariant is important because it means that given a symbol name,
// we can find a key in the map which is a prefix of the symbol in O(lg n)
// time, and we know that there is at most one such key.
//
// The prefix lookup algorithm works like so:
// 1) Find the last key in the map which is less than or equal to the
// search key.
// 2) If the found key is a prefix of the search key, then return it.
// Otherwise, there is no match.
//
// I am sure this algorithm has been described elsewhere, but since I
// wasn't able to find it quickly I will instead prove that it works
// myself. The key to the algorithm is that if a match exists, step (1)
// will find it. Proof:
// 1) Define the "search key" to be the key we are looking for, the "found
// key" to be the key found in step (1), and the "match key" to be the
// key which actually matches the serach key (i.e. the key we're trying
// to find).
// 2) The found key must be less than or equal to the search key by
// definition.
// 3) The match key must also be less than or equal to the search key
// (because it is a prefix).
// 4) The match key cannot be greater than the found key, because if it
// were, then step (1) of the algorithm would have returned the match
// key instead (since it finds the *greatest* key which is less than or
// equal to the search key).
// 5) Therefore, the found key must be between the match key and the search
// key, inclusive.
// 6) Since the search key must be a sub-symbol of the match key, if it is
// not equal to the match key, then search_key[match_key.size()] must
// be '.'.
// 7) Since '.' sorts before any other character that is valid in a symbol
// name, then if the found key is not equal to the match key, then
// found_key[match_key.size()] must also be '.', because any other value
// would make it sort after the search key.
// 8) Therefore, if the found key is not equal to the match key, then the
// found key must be a sub-symbol of the match key. However, this would
// contradict our map invariant which says that no symbol in the map is
// a sub-symbol of any other.
// 9) Therefore, the found key must match the match key.
//
// The above proof assumes the match key exists. In the case that the
// match key does not exist, then step (1) will return some other symbol.
// That symbol cannot be a super-symbol of the search key since if it were,
// then it would be a match, and we're assuming the match key doesn't exist.
// Therefore, step 2 will correctly return no match.
// Find the last entry in the by_symbol_ map whose key is less than or
// equal to the given name.
typename map<string, Value>::iterator FindLastLessOrEqual(
const string& name);
// True if either the arguments are equal or super_symbol identifies a
// parent symbol of sub_symbol (e.g. "foo.bar" is a parent of
// "foo.bar.baz", but not a parent of "foo.barbaz").
bool IsSubSymbol(const string& sub_symbol, const string& super_symbol);
// Returns true if and only if all characters in the name are alphanumerics,
// underscores, or periods.
bool ValidateSymbolName(const string& name);
};
DescriptorIndex<const FileDescriptorProto*> index_;
vector<const FileDescriptorProto*> files_to_delete_;
// If file is non-NULL, copy it into *output and return true, otherwise
// return false.
bool MaybeCopy(const FileDescriptorProto* file,
FileDescriptorProto* output);
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(SimpleDescriptorDatabase);
};
// Very similar to SimpleDescriptorDatabase, but stores all the descriptors
// as raw bytes and generally tries to use as little memory as possible.
//
// The same caveats regarding FindFileContainingExtension() apply as with
// SimpleDescriptorDatabase.
class LIBPROTOBUF_EXPORT EncodedDescriptorDatabase : public DescriptorDatabase {
public:
EncodedDescriptorDatabase();
~EncodedDescriptorDatabase();
// Adds the FileDescriptorProto to the database. The descriptor is provided
// in encoded form. The database does not make a copy of the bytes, nor
// does it take ownership; it's up to the caller to make sure the bytes
// remain valid for the life of the database. Returns false and logs an error
// if the bytes are not a valid FileDescriptorProto or if the file conflicted
// with a file already in the database.
bool Add(const void* encoded_file_descriptor, int size);
// Like Add(), but makes a copy of the data, so that the caller does not
// need to keep it around.
bool AddCopy(const void* encoded_file_descriptor, int size);
// Like FindFileContainingSymbol but returns only the name of the file.
bool FindNameOfFileContainingSymbol(const string& symbol_name,
string* output);
// implements DescriptorDatabase -----------------------------------
bool FindFileByName(const string& filename,
FileDescriptorProto* output);
bool FindFileContainingSymbol(const string& symbol_name,
FileDescriptorProto* output);
bool FindFileContainingExtension(const string& containing_type,
int field_number,
FileDescriptorProto* output);
bool FindAllExtensionNumbers(const string& extendee_type,
vector<int>* output);
private:
SimpleDescriptorDatabase::DescriptorIndex<pair<const void*, int> > index_;
vector<void*> files_to_delete_;
// If encoded_file.first is non-NULL, parse the data into *output and return
// true, otherwise return false.
bool MaybeParse(pair<const void*, int> encoded_file,
FileDescriptorProto* output);
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(EncodedDescriptorDatabase);
};
// A DescriptorDatabase that fetches files from a given pool.
class LIBPROTOBUF_EXPORT DescriptorPoolDatabase : public DescriptorDatabase {
public:
DescriptorPoolDatabase(const DescriptorPool& pool);
~DescriptorPoolDatabase();
// implements DescriptorDatabase -----------------------------------
bool FindFileByName(const string& filename,
FileDescriptorProto* output);
bool FindFileContainingSymbol(const string& symbol_name,
FileDescriptorProto* output);
bool FindFileContainingExtension(const string& containing_type,
int field_number,
FileDescriptorProto* output);
bool FindAllExtensionNumbers(const string& extendee_type,
vector<int>* output);
private:
const DescriptorPool& pool_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DescriptorPoolDatabase);
};
// A DescriptorDatabase that wraps two or more others. It first searches the
// first database and, if that fails, tries the second, and so on.
class LIBPROTOBUF_EXPORT MergedDescriptorDatabase : public DescriptorDatabase {
public:
// Merge just two databases. The sources remain property of the caller.
MergedDescriptorDatabase(DescriptorDatabase* source1,
DescriptorDatabase* source2);
// Merge more than two databases. The sources remain property of the caller.
// The vector may be deleted after the constructor returns but the
// DescriptorDatabases need to stick around.
MergedDescriptorDatabase(const vector<DescriptorDatabase*>& sources);
~MergedDescriptorDatabase();
// implements DescriptorDatabase -----------------------------------
bool FindFileByName(const string& filename,
FileDescriptorProto* output);
bool FindFileContainingSymbol(const string& symbol_name,
FileDescriptorProto* output);
bool FindFileContainingExtension(const string& containing_type,
int field_number,
FileDescriptorProto* output);
// Merges the results of calling all databases. Returns true iff any
// of the databases returned true.
bool FindAllExtensionNumbers(const string& extendee_type,
vector<int>* output);
private:
vector<DescriptorDatabase*> sources_;
GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MergedDescriptorDatabase);
};
} // namespace protobuf
} // namespace google
#endif // GOOGLE_PROTOBUF_DESCRIPTOR_DATABASE_H__