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/*
* Copyright 2018 Google
*
* 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
*
* http://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.
*/
#include "Firestore/core/src/firebase/firestore/util/string_format.h"
namespace firebase {
namespace firestore {
namespace util {
namespace internal {
static const char* kMissing = "<missing>";
static const char* kInvalid = "<invalid>";
std::string StringFormatPieces(
const char* format, std::initializer_list<absl::string_view> pieces) {
std::string result;
const char* format_iter = format;
const char* format_end = format + strlen(format);
auto pieces_iter = pieces.begin();
auto pieces_end = pieces.end();
auto append_next_piece = [&](std::string* dest) {
if (pieces_iter == pieces_end) {
dest->append(kMissing);
} else {
// Pass a piece through
dest->append(pieces_iter->data(), pieces_iter->size());
++pieces_iter;
}
};
auto append_specifier = [&](char spec) {
switch (spec) {
case '%':
// Pass through literal %.
result.push_back('%');
break;
case 's': {
append_next_piece(&result);
break;
}
default:
result.append(kInvalid);
break;
}
};
// Iterate through the format string, advancing `format_iter` as we go.
while (true) {
const char* percent_ptr = std::find(format_iter, format_end, '%');
// percent either points to the next format specifier or the end of the
// format string. Either is safe to append here:
result.append(format_iter, percent_ptr);
if (percent_ptr == format_end) {
// No further pieces to format
break;
}
// Examine the specifier:
const char* spec_ptr = percent_ptr + 1;
if (spec_ptr == format_end) {
// Incomplete specifier, treat as a literal "%" and be done.
append_specifier('%');
break;
}
append_specifier(*spec_ptr);
format_iter = spec_ptr + 1;
}
return result;
}
} // namespace internal
} // namespace util
} // namespace firestore
} // namespace firebase
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