THUAI6/CAPI/cpp/grpc/include/absl/strings/internal/escaping.h

// Copyright 2020 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef ABSL_STRINGS_INTERNAL_ESCAPING_H_
#define ABSL_STRINGS_INTERNAL_ESCAPING_H_

#include <cassert>

#include "absl/strings/internal/resize_uninitialized.h"

namespace absl
{
    ABSL_NAMESPACE_BEGIN
    namespace strings_internal
    {

        ABSL_CONST_INIT extern const char kBase64Chars[];

        // Calculates how long a string will be when it is base64 encoded given its
        // length and whether or not the result should be padded.
        size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding);

        // Base64-encodes `src` using the alphabet provided in `base64` and writes the
        // result to `dest`. If `do_padding` is true, `dest` is padded with '=' chars
        // until its length is a multiple of 3. Returns the length of `dest`.
        size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest, size_t szdest, const char* base64, bool do_padding);

        // Base64-encodes `src` using the alphabet provided in `base64` and writes the
        // result to `dest`. If `do_padding` is true, `dest` is padded with '=' chars
        // until its length is a multiple of 3.
        template<typename String>
        void Base64EscapeInternal(const unsigned char* src, size_t szsrc, String* dest, bool do_padding, const char* base64_chars)
        {
            const size_t calc_escaped_size =
                CalculateBase64EscapedLenInternal(szsrc, do_padding);
            STLStringResizeUninitialized(dest, calc_escaped_size);

            const size_t escaped_len = Base64EscapeInternal(
                src, szsrc, &(*dest)[0], dest->size(), base64_chars, do_padding
            );
            assert(calc_escaped_size == escaped_len);
            dest->erase(escaped_len);
        }

    }  // namespace strings_internal
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_STRINGS_INTERNAL_ESCAPING_H_