Index: mojo/public/c/bindings/lib/type_table.h |
diff --git a/mojo/public/c/bindings/lib/type_table.h b/mojo/public/c/bindings/lib/type_table.h |
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+// Copyright 2016 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. |
+ |
+// This file contains structs used for constructing type tables for generated |
+// mojom types. A type table for a mojom struct is a table describing the |
+// byte-offsets of all the pointers and handles in the struct, and has |
+// references to the type tables that further describe the pointers. This table |
+// is used for doing all computations for the struct -- determining serialized |
+// size, encoding and decoding recursively, etc. A type table is generated for |
+// each struct, union, array and map. |
+// |
+// The user is not expected to construct type tables -- a bindings generator |
+// will do this when it generates bindings for a mojom file. |
+// |
+// A type table for a mojom struct and a mojom union is a |MojomTypeTable| with |
+// containing an array of entries of types of |MojomTypeTableStructEntry| and |
+// |MojomTypeTableUnionEntry|, respectively. |
+// Since arrays only have one type, they are described by |
+// |MojomTypeTableArrayEntry|, not contained inside a |MojomTypeTable|. |
+ |
+#ifndef MOJO_PUBLIC_C_BINDINGS_LIB_TYPE_TABLE_H_ |
+#define MOJO_PUBLIC_C_BINDINGS_LIB_TYPE_TABLE_H_ |
+ |
+#include <stdbool.h> |
+#include <stdint.h> |
+ |
+#include "mojo/public/c/system/macros.h" |
+ |
+MOJO_BEGIN_EXTERN_C |
+ |
+// This enum is used in a type table entry for the |elem_type| field, and |
+// indicates which type the accompanying |elem_table| is describing. |
+enum MojomTypeTableElemType { |
+ // A map is a struct with 2 arrays. |
+ MOJOM_ELEMENT_TYPE_STRUCT = 0, |
+ MOJOM_ELEMENT_TYPE_ARRAY = 1, |
+ MOJOM_ELEMENT_TYPE_UNION = 2, |
+ MOJOM_ELEMENT_TYPE_HANDLE = 3, |
+ MOJOM_ELEMENT_TYPE_INTERFACE = 4, |
+ // This is only used in an array table entry, and serves as a way to terminate |
+ // a chain of array entries; the last entry in the chain always contains a |
+ // plain-old-data type. |
+ MOJOM_ELEMENT_TYPE_POD = 5, |
+}; |
+ |
+// Structs and unions are described using this struct; |entries| is of type |
viettrungluu
2016/06/21 18:08:30
I suggest you just make two separate structs (with
vardhan
2016/06/21 22:42:58
Done.
|
+// |MojomTypeTableStructEntry| for mojom structs, and |MojomTypeTableUnion| |
+// for mojom unions. |
+struct MojomTypeTable { |
+ size_t num_entries; |
+ const void* entries; |
+}; |
+ |
+// This struct is used to describe each entry in a mojom struct. Each entry |
+// indicates whether it is describing a reference type, or a handle type through |
+// the field |elem_type|. |elem_table| points to the type table describing the |
+// field, if the type has one (handles don't have type tables). |offset| |
+// indicates the starting byte offset of the element within the struct. |
+struct MojomTypeTableStructEntry { |
+ // The type that |elem_table| points to. |
+ // - If MOJOM_ELEMENT_TYPE_STRUCT, then |elem_table| points to a |
+ // |MojomTypeTable|, with its |entries| field pointing to an array of |
+ // |MojomTypeTableStructEntry|. |
+ // - If MOJOM_ELEMENT_TYPE_UNION, then |elem_table| points to a |
+ // |MojomTypeTable|, with its |entries| field pointing to an array of |
+ // |MojomTypeTableUnionEntry|. |
+ // - If MOJOM_ELEMENT_TYPE_ARRAY, then |elem_table| points to a |
+ // |MojomTypeTableArrayEntry|. |
+ // - For any other value, |elem_table| is NULL. |
+ enum MojomTypeTableElemType elem_type; |
+ // |elem_table| can be |MojomTypeTable|, MojomTypeTableArrayEntry|, or NULL. |
viettrungluu
2016/06/21 18:08:30
I think you should rationalize the names of things
vardhan
2016/06/21 22:42:58
Done.
|
+ // Use |elem_type| to decide which it is. |
+ const void* elem_table; |
+ // |offset| does not account for the struct header. Offset 0 always refers to |
+ // the first element. |
+ uint32_t offset; |
+ // Corresponds to the '[MinVersion]' attribute in mojom IDL. This determines |
+ // if this field should be ignored if its min_version < version of the struct |
+ // we are dealing with. |
+ uint32_t min_version; |
+ // Is this field nullable? |
+ bool nullable; |
+}; |
+ |
+// Like |MojomTypeTableStructEntry|, this variant is used to construct a type |
+// table for a union. Instead of an offset, it describes a union field by the |
+// |tag|. |
+struct MojomTypeTableUnionEntry { |
+ // The behaviour of |elem_type| and |elem_table| is the same as |
+ // |MojomTypeTableStructEntry|. |
+ enum MojomTypeTableElemType elem_type; |
+ const void* elem_table; |
+ // The tag of the union field. |
+ uint32_t tag; |
+ bool nullable; |
+}; |
+ |
+// Describes a mojom array. To describe an array, we don't need a type table of |
+// entries, since arrays can only describe 1 type. However, that one type can |
+// recursively be an array (e.g, array<array<int>>), in which case a |
+// chain of array entries are constructed. |
+struct MojomTypeTableArrayEntry { |
+ enum MojomTypeTableElemType elem_type; |
+ const void* elem_table; |
+ // How many elements is this array expected to hold? |
+ // 0 means unspecified. |
+ uint32_t num_elements; |
+ bool nullable; |
+}; |
+ |
+// This describes a mojom string. |
+// A mojom string is a mojom array of chars without a fixed-sized. |
+extern const struct MojomTypeTableArrayEntry MojomTypeTableStringEntry; |
viettrungluu
2016/06/21 18:08:30
It's very odd that MojomTypeTableStringEntry is no
vardhan
2016/06/21 22:42:58
Renamed to MojomStringTypeDescription.
|
+ |
+MOJO_END_EXTERN_C |
+ |
+#endif // MOJO_PUBLIC_C_BINDINGS_LIB_TYPE_TABLE_H_ |