objectivec/GPBCodedInputStream.h

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#import <Foundation/Foundation.h>

#import "GPBExtensionRegistry.h"

#import "GPBMessage.h"

NS_ASSUME_NONNULL_BEGIN

CF_EXTERN_C_BEGIN

/**
 * @c GPBCodedInputStream exception name. Exceptions raised from
 * @c GPBCodedInputStream contain an underlying error in the userInfo dictionary
 * under the GPBCodedInputStreamUnderlyingErrorKey key.
 **/
extern NSString *const GPBCodedInputStreamException;

/** The key under which the underlying NSError from the exception is stored. */
extern NSString *const GPBCodedInputStreamUnderlyingErrorKey;

/** NSError domain used for @c GPBCodedInputStream errors. */
extern NSString *const GPBCodedInputStreamErrorDomain;

/**
 * Error code for NSError with @c GPBCodedInputStreamErrorDomain.
 **/
typedef NS_ENUM(NSInteger, GPBCodedInputStreamErrorCode) {
  /** The size does not fit in the remaining bytes to be read. */
  GPBCodedInputStreamErrorInvalidSize = -100,
  /** Attempted to read beyond the subsection limit. */
  GPBCodedInputStreamErrorSubsectionLimitReached = -101,
  /** The requested subsection limit is invalid. */
  GPBCodedInputStreamErrorInvalidSubsectionLimit = -102,
  /** Invalid tag read. */
  GPBCodedInputStreamErrorInvalidTag = -103,
  /** Invalid UTF-8 character in a string. */
  GPBCodedInputStreamErrorInvalidUTF8 = -104,
  /** Invalid VarInt read. */
  GPBCodedInputStreamErrorInvalidVarInt = -105,
  /** The maximum recursion depth of messages was exceeded. */
  GPBCodedInputStreamErrorRecursionDepthExceeded = -106,
};

CF_EXTERN_C_END

/**
 * Reads and decodes protocol message fields.
 *
 * The common uses of protocol buffers shouldn't need to use this class.
 * @c GPBMessage's provide a @c +parseFromData:error: and
 * @c +parseFromData:extensionRegistry:error: method that will decode a
 * message for you.
 *
 * @note Subclassing of @c GPBCodedInputStream is NOT supported.
 **/
__attribute__((objc_subclassing_restricted))
@interface GPBCodedInputStream : NSObject

/**
 * Creates a new stream wrapping some data.
 *
 * @param data The data to wrap inside the stream.
 *
 * @return A newly instanced GPBCodedInputStream.
 **/
+ (instancetype)streamWithData:(NSData *)data;

/**
 * Initializes a stream wrapping some data.
 *
 * @param data The data to wrap inside the stream.
 *
 * @return A newly initialized GPBCodedInputStream.
 **/
- (instancetype)initWithData:(NSData *)data;

/**
 * Attempts to read a field tag, returning zero if we have reached EOF.
 * Protocol message parsers use this to read tags, since a protocol message
 * may legally end wherever a tag occurs, and zero is not a valid tag number.
 *
 * @return The field tag, or zero if EOF was reached.
 **/
- (int32_t)readTag;

/**
 * @return A double read from the stream.
 **/
- (double)readDouble;
/**
 * @return A float read from the stream.
 **/
- (float)readFloat;
/**
 * @return A uint64 read from the stream.
 **/
- (uint64_t)readUInt64;
/**
 * @return A uint32 read from the stream.
 **/
- (uint32_t)readUInt32;
/**
 * @return An int64 read from the stream.
 **/
- (int64_t)readInt64;
/**
 * @return An int32 read from the stream.
 **/
- (int32_t)readInt32;
/**
 * @return A fixed64 read from the stream.
 **/
- (uint64_t)readFixed64;
/**
 * @return A fixed32 read from the stream.
 **/
- (uint32_t)readFixed32;
/**
 * @return An enum read from the stream.
 **/
- (int32_t)readEnum;
/**
 * @return A sfixed32 read from the stream.
 **/
- (int32_t)readSFixed32;
/**
 * @return A fixed64 read from the stream.
 **/
- (int64_t)readSFixed64;
/**
 * @return A sint32 read from the stream.
 **/
- (int32_t)readSInt32;
/**
 * @return A sint64 read from the stream.
 **/
- (int64_t)readSInt64;
/**
 * @return A boolean read from the stream.
 **/
- (BOOL)readBool;
/**
 * @return A string read from the stream.
 **/
- (NSString *)readString;
/**
 * @return Data read from the stream.
 **/
- (NSData *)readBytes;

/**
 * Read an embedded message field value from the stream.
 *
 * @param message           The message to set fields on as they are read.
 * @param extensionRegistry An optional extension registry to use to lookup
 *                          extensions for message.
 **/
- (void)readMessage:(GPBMessage *)message
    extensionRegistry:(nullable id<GPBExtensionRegistry>)extensionRegistry;

/**
 * Reads and discards a single field, given its tag value.
 *
 * @param tag The tag number of the field to skip.
 *
 * @return NO if the tag is an endgroup tag (in which case nothing is skipped),
 *         YES in all other cases.
 **/
- (BOOL)skipField:(int32_t)tag;

/**
 * Reads and discards an entire message. This will read either until EOF or
 * until an endgroup tag, whichever comes first.
 **/
- (void)skipMessage;

/**
 * Check to see if the logical end of the stream has been reached.
 *
 * @note This can return NO when there is no more data, but the current parsing
 *       expected more data.
 *
 * @return YES if the logical end of the stream has been reached, NO otherwise.
 **/
- (BOOL)isAtEnd;

/**
 * @return The offset into the stream.
 **/
- (size_t)position;

/**
 * Moves the limit to the given byte offset starting at the current location.
 *
 * @exception GPBCodedInputStreamException If the requested bytes exceed the
 *            current limit.
 *
 * @param byteLimit The number of bytes to move the limit, offset to the current
 *                  location.
 *
 * @return The limit offset before moving the new limit.
 */
- (size_t)pushLimit:(size_t)byteLimit;

/**
 * Moves the limit back to the offset as it was before calling pushLimit:.
 *
 * @param oldLimit The number of bytes to move the current limit. Usually this
 *                 is the value returned by the pushLimit: method.
 */
- (void)popLimit:(size_t)oldLimit;

/**
 * @return The number of bytes from the current position to the current limit.
 */
- (size_t)bytesUntilLimit;

/**
 * Verifies that the last call to -readTag returned the given tag value. This
 * is used to verify that a nested group ended with the correct end tag.
 *
 * @exception NSParseErrorException If the value does not match the last tag.
 *
 * @param expected The tag that was expected.
 **/
- (void)checkLastTagWas:(int32_t)expected;

@end

NS_ASSUME_NONNULL_END