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70ee43f1e9
Add SPDX license (but not copyright) headers to all files which follow a certain pattern in their existing non-machine-readable header comment. This commit was entirely generated using the command: ``` git ls-files glib/*.[ch] | xargs perl -0777 -pi -e 's/\n \*\n \* This library is free software; you can redistribute it and\/or\n \* modify it under the terms of the GNU Lesser General Public/\n \*\n \* SPDX-License-Identifier: LGPL-2.1-or-later\n \*\n \* This library is free software; you can redistribute it and\/or\n \* modify it under the terms of the GNU Lesser General Public/igs' ``` Signed-off-by: Philip Withnall <pwithnall@endlessos.org> Helps: #1415
164 lines
7.1 KiB
C
164 lines
7.1 KiB
C
/*
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* Copyright © 2008 Ryan Lortie
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* Copyright © 2010 Codethink Limited
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Ryan Lortie <desrt@desrt.ca>
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*/
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#ifndef __G_VARIANT_TYPE_INFO_H__
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#define __G_VARIANT_TYPE_INFO_H__
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#include <glib/gvarianttype.h>
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#define G_VARIANT_TYPE_INFO_CHAR_MAYBE 'm'
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#define G_VARIANT_TYPE_INFO_CHAR_ARRAY 'a'
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#define G_VARIANT_TYPE_INFO_CHAR_TUPLE '('
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#define G_VARIANT_TYPE_INFO_CHAR_DICT_ENTRY '{'
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#define G_VARIANT_TYPE_INFO_CHAR_VARIANT 'v'
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#define g_variant_type_info_get_type_char(info) \
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(g_variant_type_info_get_type_string(info)[0])
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typedef struct _GVariantTypeInfo GVariantTypeInfo;
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/* < private >
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* GVariantMemberInfo:
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*
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* This structure describes how to construct a GVariant instance
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* corresponding to a given child of a tuple or dictionary entry in a
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* very short constant time. It contains the typeinfo of the child,
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* along with 4 constants that allow the bounds of the child's
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* serialized data within the container's serialized data to be found
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* very efficiently.
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*
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* Since dictionary entries are serialized as if they were tuples of 2
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* items, the term "tuple" will be used here in the general sense to
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* refer to tuples and dictionary entries.
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*
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* BACKGROUND:
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* The serialized data for a tuple contains an array of "offsets" at
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* the end. There is one "offset" in this array for each
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* variable-sized item in the tuple (except for the last one). The
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* offset points to the end point of that item's serialized data. The
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* procedure for finding the start point is described below. An
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* offset is not needed for the last item because the end point of the
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* last item is merely the end point of the container itself (after
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* the offsets array has been accounted for). An offset is not needed
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* for fixed-sized items (like integers) because, due to their fixed
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* size, the end point is a constant addition to the start point.
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*
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* It is clear that the starting point of a given item in the tuple is
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* determined by the items that precede it in the tuple. Logically,
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* the start point of a particular item in a given type of tuple can
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* be determined entirely by the end point of the nearest
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* variable-sized item that came before it (or from the start of the
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* container itself in case there is no preceding variable-sized
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* item). In the case of "(isis)" for example, in order to find out
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* the start point of the last string, one must start at the end point
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* of the first string, align to 4 (for the integer's alignment) and
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* then add 4 (for storing the integer). That's the point where the
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* string starts (since no special alignment is required for strings).
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*
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* Of course, this process requires iterating over the types in the
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* tuple up to the item of interest. As it turns out, it is possible
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* to determine 3 constants 'a', 'b', and 'c' for each item in the
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* tuple, such that, given the ending offset of the nearest previous
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* variable-sized item (prev_end), a very simple calculation can be
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* performed to determine the start of the item of interest.
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*
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* The constants in this structure are used as follows:
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*
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* First, among the array of offsets contained in the tuple, 'i' is the
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* index of the offset that refers to the end of the variable-sized item
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* preceding the item of interest. If no variable-sized items precede
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* this item, then 'i' will be -1.
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*
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* Let 'prev_end' be the end offset of the previous item (or 0 in the
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* case that there was no such item). The start address of this item
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* can then be calculate using 'a', 'b', and 'c':
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*
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* item_start = ((prev_end + a) & b) | c;
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*
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* For details about how 'a', 'b' and 'c' are calculated, see the
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* comments at the point of the implementation in gvariantypeinfo.c.
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*
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* The end address of the item is then determined in one of three ways,
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* according to the 'end_type' field.
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*
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* - FIXED: For fixed sized items, the end address is equal to the
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* start address plus the fixed size.
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*
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* - LAST: For the last variable sized item in the tuple, the end
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* address is equal to the end address of the tuple, minus the size
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* of the offset array.
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*
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* - OFFSET: For other variable sized items, the next index past 'i'
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* (ie: 'i + 1') must be consulted to find the end of this item.
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*/
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typedef struct
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{
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GVariantTypeInfo *type_info;
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gsize i, a;
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gint8 b, c;
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guint8 ending_type;
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} GVariantMemberInfo;
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#define G_VARIANT_MEMBER_ENDING_FIXED 0
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#define G_VARIANT_MEMBER_ENDING_LAST 1
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#define G_VARIANT_MEMBER_ENDING_OFFSET 2
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/* query */
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GLIB_AVAILABLE_IN_ALL
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const gchar * g_variant_type_info_get_type_string (GVariantTypeInfo *typeinfo);
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GLIB_AVAILABLE_IN_ALL
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void g_variant_type_info_query (GVariantTypeInfo *typeinfo,
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guint *alignment,
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gsize *size);
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GLIB_AVAILABLE_IN_2_60
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gsize g_variant_type_info_query_depth (GVariantTypeInfo *typeinfo);
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/* array */
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GLIB_AVAILABLE_IN_ALL
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GVariantTypeInfo * g_variant_type_info_element (GVariantTypeInfo *typeinfo);
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GLIB_AVAILABLE_IN_ALL
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void g_variant_type_info_query_element (GVariantTypeInfo *typeinfo,
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guint *alignment,
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gsize *size);
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/* structure */
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GLIB_AVAILABLE_IN_ALL
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gsize g_variant_type_info_n_members (GVariantTypeInfo *typeinfo);
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GLIB_AVAILABLE_IN_ALL
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const GVariantMemberInfo * g_variant_type_info_member_info (GVariantTypeInfo *typeinfo,
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gsize index);
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/* new/ref/unref */
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GLIB_AVAILABLE_IN_ALL
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GVariantTypeInfo * g_variant_type_info_get (const GVariantType *type);
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GLIB_AVAILABLE_IN_ALL
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GVariantTypeInfo * g_variant_type_info_ref (GVariantTypeInfo *typeinfo);
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GLIB_AVAILABLE_IN_ALL
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void g_variant_type_info_unref (GVariantTypeInfo *typeinfo);
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GLIB_AVAILABLE_IN_ALL
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void g_variant_type_info_assert_no_infos (void);
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#endif /* __G_VARIANT_TYPE_INFO_H__ */
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