Mojo C++ bindings: expose public <struct>DataView and StringDataView.

mojo/public/tools/bindings/generators/cpp_templates/struct_data_view_declaration.tmpl

Index: mojo/public/tools/bindings/generators/cpp_templates/struct_data_view_declaration.tmpl
diff --git a/mojo/public/tools/bindings/generators/cpp_templates/struct_data_view_declaration.tmpl b/mojo/public/tools/bindings/generators/cpp_templates/struct_data_view_declaration.tmpl
new file mode 100644
index 0000000000000000000000000000000000000000..be7043a4f51a9b842fb8c9ac4f44b98bdc9c7e5f
--- /dev/null
+++ b/mojo/public/tools/bindings/generators/cpp_templates/struct_data_view_declaration.tmpl
@@ -0,0 +1,41 @@
+class {{struct.name}}DataView {
+ public:
+  {{struct.name}}DataView(
+      internal::{{struct.name}}_Data* data,
+      mojo::internal::SerializationContext* context);
+
+  // Whether the data represents a null struct.
+  // Note: Must not access the following methods if is_null() returns true.
+  bool is_null() const { return !data_; }
+
+{%- for pf in struct.packed.packed_fields_in_ordinal_order %}
+{%-   set kind = pf.field.kind -%}
+{%-   set name = pf.field.name -%}
+{%-   if kind|is_struct_kind or kind|is_array_kind or kind|is_string_kind %}
+  template <typename UserType>
+  bool Read{{name|under_to_camel}}(UserType* value) {
+    DCHECK(!is_null());
+
+{%-  if pf.min_version != 0 %}
+    auto pointer = data_->header_.version >= {{pf.min_version}}
+                   ? data_->{{name}}.ptr : nullptr;
+{%-  else %}
+    auto pointer = data_->{{name}}.ptr;
+{%-  endif %}
+    return mojo::internal::Deserialize<{{kind|unmapped_type_for_serializer}}>(
+        pointer, value, context_);
+  }
+{%-   elif kind|is_map_kind or kind|is_union_kind %}
+  bool Read{{name|under_to_camel}}({{kind|cpp_wrapper_type}}* value);
+{%-   elif kind|is_interface_kind or kind|is_any_handle_kind or
+           kind|is_associated_kind %}
+  {{kind|cpp_wrapper_type}} Take{{name|under_to_camel}}();
+{%-   else %}
+  {{kind|cpp_wrapper_type}} {{name}}() const;
+{%-   endif %}
+{%- endfor %}
+ private:
+  internal::{{struct.name}}_Data* data_;
+  mojo::internal::SerializationContext* context_;
+};
+