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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/model/field_path.h"
#include <algorithm>
#include <utility>
#include "Firestore/core/src/firebase/firestore/util/hard_assert.h"
#include "absl/strings/str_join.h"
#include "absl/strings/str_replace.h"
#include "absl/strings/str_split.h"
namespace firebase {
namespace firestore {
namespace model {
namespace {
/**
* True if the string could be used as a segment in a field path without
* escaping. Valid identifies follow the regex [a-zA-Z_][a-zA-Z0-9_]*
*/
bool IsValidIdentifier(const std::string& segment) {
if (segment.empty()) {
return false;
}
// Note: strictly speaking, only digits are guaranteed by the Standard to
// be a contiguous range, while alphabetic characters may have gaps. Ignoring
// this peculiarity, because it doesn't affect the platforms that Firestore
// supports.
const unsigned char first = segment.front();
if (first != '_' && (first < 'a' || first > 'z') &&
(first < 'A' || first > 'Z')) {
return false;
}
for (size_t i = 1; i != segment.size(); ++i) {
const unsigned char c = segment[i];
if (c != '_' && (c < 'a' || c > 'z') && (c < 'A' || c > 'Z') &&
(c < '0' || c > '9')) {
return false;
}
}
return true;
}
} // namespace
FieldPath FieldPath::FromServerFormat(const absl::string_view path) {
// TODO(b/37244157): Once we move to v1beta1, we should make this more
// strict. Right now, it allows non-identifier path components, even if they
// aren't escaped. Technically, this will mangle paths with backticks in
// them used in v1alpha1, but that's fine.
SegmentsT segments;
std::string segment;
segment.reserve(path.size());
const auto finish_segment = [&segments, &segment, &path] {
HARD_ASSERT(!segment.empty(),
"Invalid field path (%s). Paths must not be empty, begin with "
"'.', end with '.', or contain '..'",
path);
// Move operation will clear segment, but capacity will remain the same
// (not, strictly speaking, required by the standard, but true in practice).
segments.push_back(std::move(segment));
};
// Inside backticks, dots are treated literally.
bool inside_backticks = false;
size_t i = 0;
while (i < path.size()) {
const char c = path[i];
// std::string (and string_view) may contain embedded nulls. For full
// compatibility with Objective C behavior, finish upon encountering the
// first terminating null.
if (c == '\0') {
break;
}
switch (c) {
case '.':
if (!inside_backticks) {
finish_segment();
} else {
segment += c;
}
break;
case '`':
inside_backticks = !inside_backticks;
break;
case '\\':
// TODO(b/37244157): Make this a user-facing exception once we
// finalize field escaping.
HARD_ASSERT(i + 1 != path.size(),
"Trailing escape characters not allowed in %s", path);
++i;
segment += path[i];
break;
default:
segment += c;
break;
}
++i;
}
finish_segment();
HARD_ASSERT(!inside_backticks, "Unterminated ` in path %s", path);
return FieldPath{std::move(segments)};
}
const FieldPath& FieldPath::EmptyPath() {
static const FieldPath empty_path;
return empty_path;
}
const FieldPath& FieldPath::KeyFieldPath() {
static const FieldPath key_field_path{FieldPath::kDocumentKeyPath};
return key_field_path;
}
bool FieldPath::IsKeyFieldPath() const {
return size() == 1 && first_segment() == FieldPath::kDocumentKeyPath;
}
std::string FieldPath::CanonicalString() const {
const auto escaped_segment = [](const std::string& segment) {
auto escaped = absl::StrReplaceAll(segment, {{"\\", "\\\\"}, {"`", "\\`"}});
const bool needs_escaping = !IsValidIdentifier(escaped);
if (needs_escaping) {
escaped.insert(escaped.begin(), '`');
escaped.push_back('`');
}
return escaped;
};
return absl::StrJoin(
begin(), end(), ".",
[escaped_segment](std::string* out, const std::string& segment) {
out->append(escaped_segment(segment));
});
}
} // namespace model
} // namespace firestore
} // namespace firebase
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