114 lines
3.0 KiB
C++
114 lines
3.0 KiB
C++
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/json_pointer.h>
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#include <folly/String.h>
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namespace folly {
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// static, public
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Expected<json_pointer, json_pointer::parse_error> json_pointer::try_parse(
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StringPiece const str) {
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// pointer describes complete document
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if (str.empty()) {
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return json_pointer{};
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}
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if (str.at(0) != '/') {
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return makeUnexpected(parse_error::invalid_first_character);
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}
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std::vector<std::string> tokens;
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splitTo<std::string>("/", str, std::inserter(tokens, tokens.begin()));
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tokens.erase(tokens.begin());
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for (auto& token : tokens) {
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if (!unescape(token)) {
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return makeUnexpected(parse_error::invalid_escape_sequence);
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}
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}
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return json_pointer(std::move(tokens));
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}
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// static, public
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json_pointer json_pointer::parse(StringPiece const str) {
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auto res = try_parse(str);
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if (res.hasValue()) {
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return std::move(res.value());
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}
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switch (res.error()) {
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case parse_error::invalid_first_character:
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throw json_pointer::parse_exception(
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"non-empty JSON pointer string does not start with '/'");
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case parse_error::invalid_escape_sequence:
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throw json_pointer::parse_exception(
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"Invalid escape sequence in JSON pointer string");
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default:
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assume_unreachable();
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}
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}
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bool json_pointer::is_prefix_of(json_pointer const& other) const noexcept {
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auto const& other_tokens = other.tokens();
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if (tokens_.size() > other_tokens.size()) {
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return false;
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}
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auto const other_begin = other_tokens.cbegin();
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auto const other_end = other_tokens.cbegin() + tokens_.size();
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return std::equal(tokens_.cbegin(), tokens_.cend(), other_begin, other_end);
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}
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std::vector<std::string> const& json_pointer::tokens() const {
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return tokens_;
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}
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// private
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json_pointer::json_pointer(std::vector<std::string> tokens) noexcept
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: tokens_{std::move(tokens)} {}
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// private, static
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bool json_pointer::unescape(std::string& str) {
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char const* end = &str[str.size()];
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char* out = &str.front();
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char const* decode = out;
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while (decode < end) {
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if (*decode != '~') {
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*out++ = *decode++;
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continue;
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}
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if (decode + 1 == end) {
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return false;
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}
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switch (decode[1]) {
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case '1':
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*out++ = '/';
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break;
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case '0':
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*out++ = '~';
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break;
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default:
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return false;
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}
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decode += 2;
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}
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str.resize(out - &str.front());
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return true;
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}
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} // namespace folly
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