C++ port: port FSTFieldPath and FSTResourcePath to C++ (#749)

Similar to Objective-C, FieldPath and ResourcePath share most of their interface (and implementation) by deriving from BasePath (using CRTP, so that factory methods in BasePath can return an instance of the derived class).

6 files changed, 595 insertions, 0 deletions

diff --git a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
index aee0d86..8bdbe18 100644
--- a/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
+++ b/Firestore/core/src/firebase/firestore/model/CMakeLists.txt
@@ -15,8 +15,11 @@
 cc_library(
   firebase_firestore_model
   SOURCES
+    base_path.h
     database_id.cc
     database_id.h
+    field_path.cc
+    field_path.h
     field_value.cc
     field_value.h
     timestamp.cc
diff --git a/Firestore/core/src/firebase/firestore/model/base_path.h b/Firestore/core/src/firebase/firestore/model/base_path.h
new file mode 100644
index 0000000..f5a8ab7
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/base_path.h
@@ -0,0 +1,181 @@
+/*
+ * 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_BASE_PATH_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_BASE_PATH_H_
+
+#include <algorithm>
+#include <cctype>
+#include <initializer_list>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+namespace impl {
+
+/**
+ * BasePath represents a path sequence in the Firestore database. It is composed
+ * of an ordered sequence of string segments.
+ *
+ * BasePath is reassignable and movable. Apart from those, all other mutating
+ * operations return new independent instances.
+ *
+ * ## Subclassing Notes
+ *
+ * BasePath is strictly meant as a base class for concrete implementations. It
+ * doesn't contain a single virtual method, can't be instantiated, and should
+ * never be used in any polymorphic way. BasePath is templated to allow static
+ * factory methods to return objects of the derived class (the expected
+ * inheritance would use CRTP: struct Derived : BasePath<Derived>).
+ */
+template <typename T>
+class BasePath {
+ protected:
+  using SegmentsT = std::vector<std::string>;
+
+ public:
+  using const_iterator = SegmentsT::const_iterator;
+
+  /** Returns i-th segment of the path. */
+  const std::string& operator[](const size_t i) const {
+    FIREBASE_ASSERT_MESSAGE(i < segments_.size(), "index %u out of range", i);
+    return segments_[i];
+  }
+
+  /** Returns the first segment of the path. */
+  const std::string& first_segment() const {
+    FIREBASE_ASSERT_MESSAGE(!empty(),
+                            "Cannot call first_segment on empty path");
+    return segments_[0];
+  }
+  /** Returns the last segment of the path. */
+  const std::string& last_segment() const {
+    FIREBASE_ASSERT_MESSAGE(!empty(), "Cannot call last_segment on empty path");
+    return segments_[size() - 1];
+  }
+
+  size_t size() const {
+    return segments_.size();
+  }
+  bool empty() const {
+    return segments_.empty();
+  }
+
+  const_iterator begin() const {
+    return segments_.begin();
+  }
+  const_iterator end() const {
+    return segments_.end();
+  }
+
+  /**
+   * Returns a new path which is the result of concatenating this path with an
+   * additional segment.
+   */
+  T Append(const std::string& segment) const {
+    auto appended = segments_;
+    appended.push_back(segment);
+    return T{std::move(appended)};
+  }
+  T Append(std::string&& segment) const {
+    auto appended = segments_;
+    appended.push_back(std::move(segment));
+    return T{std::move(appended)};
+  }
+
+  /**
+   * Returns a new path which is the result of concatenating this path with an
+   * another path.
+   */
+  T Append(const T& path) const {
+    auto appended = segments_;
+    appended.insert(appended.end(), path.begin(), path.end());
+    return T{std::move(appended)};
+  }
+
+  /**
+   * Returns a new path which is the result of omitting the first n segments of
+   * this path.
+   */
+  T PopFirst(const size_t n = 1) const {
+    FIREBASE_ASSERT_MESSAGE(n <= size(),
+                            "Cannot call PopFirst(%u) on path of length %u", n,
+                            size());
+    return T{begin() + n, end()};
+  }
+
+  /**
+   * Returns a new path which is the result of omitting the last segment of
+   * this path.
+   */
+  T PopLast() const {
+    FIREBASE_ASSERT_MESSAGE(!empty(), "Cannot call PopLast() on empty path");
+    return T{begin(), end() - 1};
+  }
+
+  /**
+   * Returns true if this path is a prefix of the given path.
+   *
+   * Empty path is a prefix of any path. Any path is a prefix of itself.
+   */
+  bool IsPrefixOf(const T& rhs) const {
+    return size() <= rhs.size() && std::equal(begin(), end(), rhs.begin());
+  }
+
+  bool operator==(const BasePath& rhs) const {
+    return segments_ == rhs.segments_;
+  }
+  bool operator!=(const BasePath& rhs) const {
+    return segments_ != rhs.segments_;
+  }
+  bool operator<(const BasePath& rhs) const {
+    return segments_ < rhs.segments_;
+  }
+  bool operator>(const BasePath& rhs) const {
+    return segments_ > rhs.segments_;
+  }
+  bool operator<=(const BasePath& rhs) const {
+    return segments_ <= rhs.segments_;
+  }
+  bool operator>=(const BasePath& rhs) const {
+    return segments_ >= rhs.segments_;
+  }
+
+ protected:
+  BasePath() = default;
+  template <typename IterT>
+  BasePath(const IterT begin, const IterT end) : segments_{begin, end} {
+  }
+  BasePath(std::initializer_list<std::string> list) : segments_{list} {
+  }
+  BasePath(SegmentsT&& segments) : segments_{std::move(segments)} {
+  }
+
+ private:
+  SegmentsT segments_;
+};
+
+}  // namespace impl
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_BASE_PATH_H_
diff --git a/Firestore/core/src/firebase/firestore/model/field_path.cc b/Firestore/core/src/firebase/firestore/model/field_path.cc
new file mode 100644
index 0000000..6c40600
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/field_path.cc
@@ -0,0 +1,176 @@
+/*
+ * 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/firebase_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 {
+
+// TODO(varconst): move to C++ equivalent of FSTDocumentKey.{h,cc}
+const char* const kDocumentKeyPath = "__name__";
+
+/**
+ * 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 (int 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());
+
+  // string_view doesn't have a c_str() method, because it might not be
+  // null-terminated. Assertions expect C strings, so construct std::string on
+  // the fly, so that c_str() might be called on it.
+  const auto to_string = [](const absl::string_view view) {
+    return std::string{view.data(), view.data() + view.size()};
+  };
+  const auto finish_segment = [&segments, &segment, &path, &to_string] {
+    FIREBASE_ASSERT_MESSAGE(
+        !segment.empty(),
+        "Invalid field path (%s). Paths must not be empty, begin with "
+        "'.', end with '.', or contain '..'",
+        to_string(path).c_str());
+    // 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;
+  int 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.
+        FIREBASE_ASSERT_MESSAGE(i + 1 != path.size(),
+                                "Trailing escape characters not allowed in %s",
+                                to_string(path).c_str());
+        ++i;
+        segment += path[i];
+        break;
+
+      default:
+        segment += c;
+        break;
+    }
+    ++i;
+  }
+  finish_segment();
+
+  FIREBASE_ASSERT_MESSAGE(!inside_backticks, "Unterminated ` in path %s",
+                          to_string(path).c_str());
+
+  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{kDocumentKeyPath};
+  return key_field_path;
+}
+
+bool FieldPath::IsKeyFieldPath() const {
+  return size() == 1 && first_segment() == 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
diff --git a/Firestore/core/src/firebase/firestore/model/field_path.h b/Firestore/core/src/firebase/firestore/model/field_path.h
new file mode 100644
index 0000000..a8b147e
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/field_path.h
@@ -0,0 +1,94 @@
+/*
+ * 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_PATH_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_PATH_H_
+
+#include <initializer_list>
+#include <string>
+#include <utility>
+
+#include "Firestore/core/src/firebase/firestore/model/base_path.h"
+#include "absl/strings/string_view.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * A dot-separated path for navigating sub-objects within a document.
+ *
+ * Immutable; all instances are fully independent.
+ */
+class FieldPath : public impl::BasePath<FieldPath> {
+ public:
+  FieldPath() = default;
+  /** Constructs the path from segments. */
+  template <typename IterT>
+  FieldPath(const IterT begin, const IterT end) : BasePath{begin, end} {
+  }
+  FieldPath(std::initializer_list<std::string> list) : BasePath{list} {
+  }
+
+  /**
+   * Creates and returns a new path from the server formatted field-path string,
+   * where path segments are separated by a dot "." and optionally encoded using
+   * backticks.
+   */
+  static FieldPath FromServerFormat(absl::string_view path);
+  /** Returns a field path that represents an empty path. */
+  static const FieldPath& EmptyPath();
+  /** Returns a field path that represents a document key. */
+  static const FieldPath& KeyFieldPath();
+
+  /** Returns a standardized string representation of this path. */
+  std::string CanonicalString() const;
+  /** True if this FieldPath represents a document key. */
+  bool IsKeyFieldPath() const;
+
+  bool operator==(const FieldPath& rhs) const {
+    return BasePath::operator==(rhs);
+  }
+  bool operator!=(const FieldPath& rhs) const {
+    return BasePath::operator!=(rhs);
+  }
+  bool operator<(const FieldPath& rhs) const {
+    return BasePath::operator<(rhs);
+  }
+  bool operator>(const FieldPath& rhs) const {
+    return BasePath::operator>(rhs);
+  }
+  bool operator<=(const FieldPath& rhs) const {
+    return BasePath::operator<=(rhs);
+  }
+  bool operator>=(const FieldPath& rhs) const {
+    return BasePath::operator>=(rhs);
+  }
+
+ private:
+  FieldPath(SegmentsT&& segments) : BasePath{std::move(segments)} {
+  }
+
+  // So that methods of base can construct FieldPath using the private
+  // constructor.
+  friend class BasePath;
+};
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif  // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_FIELD_PATH_H_
diff --git a/Firestore/core/src/firebase/firestore/model/resource_path.cc b/Firestore/core/src/firebase/firestore/model/resource_path.cc
new file mode 100644
index 0000000..36218e9
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/resource_path.cc
@@ -0,0 +1,57 @@
+/*
+ * 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/resource_path.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "Firestore/core/src/firebase/firestore/util/firebase_assert.h"
+#include "absl/strings/str_join.h"
+#include "absl/strings/str_split.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+ResourcePath ResourcePath::Parse(const absl::string_view path) {
+  // NOTE: The client is ignorant of any path segments containing escape
+  // sequences (e.g. __id123__) and just passes them through raw (they exist
+  // for legacy reasons and should not be used frequently).
+
+  FIREBASE_ASSERT_MESSAGE(
+      path.find("//") == std::string::npos,
+      "Invalid path (%s). Paths must not contain // in them.",
+      std::string{path.data(), path.data() + path.size()}.c_str());
+
+  // SkipEmpty because we may still have an empty segment at the beginning or
+  // end if they had a leading or trailing slash (which we allow).
+  std::vector<std::string> segments =
+      absl::StrSplit(path, '/', absl::SkipEmpty());
+  return ResourcePath{std::move(segments)};
+}
+
+std::string ResourcePath::CanonicalString() const {
+  // NOTE: The client is ignorant of any path segments containing escape
+  // sequences (e.g. __id123__) and just passes them through raw (they exist
+  // for legacy reasons and should not be used frequently).
+
+  return absl::StrJoin(begin(), end(), "/");
+}
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
diff --git a/Firestore/core/src/firebase/firestore/model/resource_path.h b/Firestore/core/src/firebase/firestore/model/resource_path.h
new file mode 100644
index 0000000..481d32f
--- /dev/null
+++ b/Firestore/core/src/firebase/firestore/model/resource_path.h
@@ -0,0 +1,84 @@
+/*
+ * 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.
+ */
+
+#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_RESOURCE_PATH_H_
+#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_MODEL_RESOURCE_PATH_H_
+
+#include <initializer_list>
+#include <string>
+
+#include "Firestore/core/src/firebase/firestore/model/base_path.h"
+#include "absl/strings/string_view.h"
+
+namespace firebase {
+namespace firestore {
+namespace model {
+
+/**
+ * A slash-separated path for navigating resources (documents and collections)
+ * within Firestore. Immutable; all instances are fully independent.
+ */
+class ResourcePath : public impl::BasePath<ResourcePath> {
+ public:
+  ResourcePath() = default;
+  /** Constructs the path from segments. */
+  template <typename IterT>
+  ResourcePath(const IterT begin, const IterT end) : BasePath{begin, end} {
+  }
+  ResourcePath(std::initializer_list<std::string> list) : BasePath{list} {
+  }
+  /**
+   * Creates and returns a new path from the given resource-path string, where
+   * the path segments are separated by a slash "/".
+   */
+  static ResourcePath Parse(absl::string_view path);
+
+  /** Returns a standardized string representation of this path. */
+  std::string CanonicalString() const;
+
+  bool operator==(const ResourcePath& rhs) const {
+    return BasePath::operator==(rhs);
+  }
+  bool operator!=(const ResourcePath& rhs) const {
+    return BasePath::operator!=(rhs);
+  }
+  bool operator<(const ResourcePath& rhs) const {
+    return BasePath::operator<(rhs);
+  }
+  bool operator>(const ResourcePath& rhs) const {
+    return BasePath::operator>(rhs);
+  }
+  bool operator<=(const ResourcePath& rhs) const {
+    return BasePath::operator<=(rhs);
+  }
+  bool operator>=(const ResourcePath& rhs) const {
+    return BasePath::operator>=(rhs);
+  }
+
+ private:
+  ResourcePath(SegmentsT&& segments) : BasePath{std::move(segments)} {
+  }
+
+  // So that methods of base can construct ResourcePath using the private
+  // constructor.
+  friend class BasePath;
+};
+
+}  // namespace model
+}  // namespace firestore
+}  // namespace firebase
+
+#endif