mojom: Add associative arrays to the mojom language.

mojo/public/cpp/bindings/lib/map_data_internal.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_DATA_INTERNAL_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_DATA_INTERNAL_H_
+
+#include "mojo/public/cpp/bindings/lib/array_internal.h"
+#include "mojo/public/cpp/bindings/lib/validate_params.h"
+#include "mojo/public/cpp/bindings/lib/validation_errors.h"
+
+namespace mojo {
+namespace internal {
+
+// Data types for keys.
+template <typename MapKey>
+struct MapKeyValidateParams {
+ public:
+  typedef NoValidateParams ElementValidateParams;
+  static const uint32_t expected_num_elements = 0;
+  static const bool element_is_nullable = false;
+};
+
+// For non-nullable strings only. (Which is OK; map keys can't be null.)
+template <>
+struct MapKeyValidateParams<mojo::internal::Array_Data<char>*> {
+ public:
+  typedef ArrayValidateParams<0, false, NoValidateParams> ElementValidateParams;
+  static const uint32_t expected_num_elements = 0;
+  static const bool element_is_nullable = false;
+};
+
+// Map serializes into a struct which has two arrays as struct fields, the keys
+// and the values.
+template <typename Key, typename Value>
+class Map_Data {
+ public:
+  static Map_Data* New(Buffer* buf) {
+    return new (buf->Allocate(sizeof(Map_Data))) Map_Data();
+  }
+
+  template <typename ValueParams>
+  static bool Validate(const void* data, BoundsChecker* bounds_checker) {
+    if (!data)
+      return true;
+
+    if (!ValidateStructHeader(data, sizeof(Map_Data), 2, bounds_checker))
+      return false;
+
+    const Map_Data* object = static_cast<const Map_Data*>(data);
+    if (!ValidateEncodedPointer(&object->keys.offset)) {
+      ReportValidationError(VALIDATION_ERROR_ILLEGAL_POINTER);
+      return false;
+    }
+    if (!object->keys.offset) {
+      ReportValidationError(VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
+                            "null key array in map struct");
+      return false;
+    }
+    if (!Array_Data<Key>::template Validate<MapKeyValidateParams<Key>>(
+            DecodePointerRaw(&object->keys.offset), bounds_checker)) {
+      return false;
+    }
+
+    if (!ValidateEncodedPointer(&object->values.offset)) {
+      ReportValidationError(VALIDATION_ERROR_ILLEGAL_POINTER);
+      return false;
+    }
+    if (!object->values.offset) {
+      ReportValidationError(VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
+                            "null value array in map struct");
+      return false;
+    }
+    if (!Array_Data<Value>::template Validate<ValueParams>(
+            DecodePointerRaw(&object->values.offset), bounds_checker)) {
+      return false;
+    }
+
+    const ArrayHeader* key_header =
+        static_cast<const ArrayHeader*>(DecodePointerRaw(&object->keys.offset));
+    const ArrayHeader* value_header = static_cast<const ArrayHeader*>(
+        DecodePointerRaw(&object->values.offset));
+    if (key_header->num_elements != value_header->num_elements) {
+      ReportValidationError(VALIDATION_ERROR_DIFFERENT_SIZED_ARRAYS_IN_MAP);
+      return false;
+    }
+
+    return true;
+  }
+
+  StructHeader header_;
+
+  ArrayPointer<Key> keys;
+  ArrayPointer<Value> values;
+
+  void EncodePointersAndHandles(std::vector<mojo::Handle>* handles) {
+    Encode(&keys, handles);
+    Encode(&values, handles);
+  }
+
+  void DecodePointersAndHandles(std::vector<mojo::Handle>* handles) {
+    Decode(&keys, handles);
+    Decode(&values, handles);
+  }
+
+ private:
+  Map_Data() {
+    header_.num_bytes = sizeof(*this);
+    header_.num_fields = 2;
+  }
+  ~Map_Data() = delete;
+};
+static_assert(sizeof(Map_Data<char, char>) == 24, "Bad sizeof(Map_Data)");
+
+}  // namespace internal
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MAP_DATA_INTERNAL_H_