summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/source/latex/l3kernel/l3alloc.dtx
blob: 6079cba82746301b7fc55675eb449abe6e8239ee (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
% \iffalse meta-comment
%
%% File: l3alloc.dtx Copyright (C) 1990-2012,2014-2017 The LaTeX3 Project
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version.  The latest version
% of this license is in the file
%
%    https://www.latex-project.org/lppl.txt
%
% This file is part of the "l3kernel bundle" (The Work in LPPL)
% and all files in that bundle must be distributed together.
%
% -----------------------------------------------------------------------
%
% The development version of the bundle can be found at
%
%    https://github.com/latex3/latex3
%
% for those people who are interested.
%
%<*driver>
\documentclass[full,kernel]{l3doc}
\begin{document}
  \DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
%
% \title{^^A
%   The \pkg{l3alloc} package\\ Register allocation^^A
% }
%
% \author{^^A
%  The \LaTeX3 Project\thanks
%    {^^A
%      E-mail:
%        \href{mailto:latex-team@latex-project.org}
%          {latex-team@latex-project.org}^^A
%    }^^A
% }
%
% \date{Released 2017/12/16}
%
% \maketitle
%
% \begin{documentation}
%
% This module provides the basic mechanism for allocating \TeX{}'s
% registers when operating in format mode. When loaded as a package on
% an existing format, the mechanisms from the latter are used.
%
% The approach used here is informed by the mechanisms used in plain
% \TeX{}/\LaTeX{} but noting that newer engines provide us much more
% flexibility. In addition to this, we do not need allocators for all
% register types: for example \texttt{toks} are not used by \LaTeX3 whilst
% reads/writes are handled using a pool and thus do not need a classical
% allocator.
%
% In classical (non-\LuaTeX{}) engines, there are various restriction on
% registers, for example |\box255| is hard-coded as the output box and
% inserts have to be allocated below this (not in the extended pool). Rather
% than worry about this, allocations for the registers affected (\TeX{}
% |box|, |count|, |dimen| and |skip| types) are simply made only from the
% extended pool. (There is a performance impact in engines other than
% \LuaTeX{} but the free use of registers in \pkg{expl3} means that code
% cannot be sure of obtaining a low-numbered register in any case.)
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3alloc} implementation}
%
%    \begin{macrocode}
%<*initex>
%    \end{macrocode}
%
%    \begin{macrocode}
%<@@=alloc>
%    \end{macrocode}
%
% \begin{variable}
%   {
%     \g_@@_int_int    ,
%     \g_@@_dim_int    ,
%     \g_@@_muskip_int ,
%     \g_@@_int_int    ,
%     \g_@@_box_int
%   }
%   The core register tracking is done using the same raw \TeX{} count
%   registers as reserved by plain \TeX{} and \LaTeXe{}, as there may be the
%   odd piece of generic code that needs to work by number. However, as not
%   all of our variables work the same way, some of the older registers are
%   simply ignored. For the same reason, there is no special status for the
%   low-numbers registers other than counts. To avoid having to worry about
%   inserts and reflecting the register availability in \eTeX{}, the lower
%   register space is unused here (though is available for hard-coded
%   use).
%    \begin{macrocode}
\tex_countdef:D \g_@@_int_int    = 10 ~
\tex_countdef:D \g_@@_dim_int    = 11 ~
\tex_countdef:D \g_@@_skip_int   = 12 ~
\tex_countdef:D \g_@@_muskip_int = 13 ~
\tex_countdef:D \g_@@_box_int    = 14 ~
\g_@@_int_int    = 255 ~
\g_@@_dim_int    = 255 ~
\g_@@_skip_int   = 255 ~
\g_@@_muskip_int =   0 ~
\g_@@_box_int    = 255 ~
%    \end{macrocode}
% \end{variable}
%
% \begin{variable}
%   {
%     \g_@@_attribute_int ,
%     \g_@@_bytecode_int  ,
%     \g_@@_chunkname_int ,
%     \g_@@_whatsit_int
%   }
%   To allow \LuaTeX{} to load |ltluatex.lua| for generic \Lua{} support, a
%   small number of counts have to be correctly named at the \TeX{} level.
%   At present there are no \pkg{expl3} allocators for these concepts so the
%   names and numbers of the tracking variables may change.
%    \begin{macrocode}
\etex_ifdefined:D \luatex_luatexversion:D
  \tex_global:D \tex_countdef:D \g_@@_attribute_int  = 21 ~
  \tex_global:D \tex_countdef:D \g_@@_bytecode_int   = 22 ~
  \tex_global:D \tex_countdef:D \g_@@_chunkname_int  = 23 ~
  \tex_global:D \tex_countdef:D \g_@@_whatsit_int    = 24 ~
\tex_fi:D
%    \end{macrocode}
% \end{variable}
%
% \begin{macro}
%   {\box_new:N, \dim_new:N, \int_new:N, \muskip_new:N \skip_new:N}
%   Each of the public allocators is a wrapper around the one internal
%   function needed here.
%    \begin{macrocode}
\cs_new_protected:Npx \box_new:N #1
  {
    \exp_not:N \@@_reg:nNnN { box }
      \cs_if_exist:NTF \luatex_luatexversion:D
        { \tex_chardef:D }
        { \tex_mathchardef:D }
      \c_max_register_int
      #1
  }
\cs_new_protected:Npn \dim_new:N #1
  { \@@_reg:nNnN { dim } \tex_dimendef:D \c_max_register_int #1 }
\cs_new_protected:Npn \int_new:N #1
  { \@@_reg:nNnN { int } \tex_countdef:D \c_max_register_int #1 }
\cs_new_protected:Npn \muskip_new:N #1
  { \@@_reg:nNnN { muskip } \tex_muskipdef:D \c_max_register_int #1 }
\cs_new_protected:Npn \skip_new:N #1
  { \@@_reg:nNnN { skip } \tex_skipdef:D \c_max_register_int #1 }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_reg:nNNN}
%   The allocator itself is modelled somewhat on \LaTeXe{}'s \tn{e@alloc},
%   though there is no need to set \tn{allocationnumber}.
%    \begin{macrocode}
\cs_new_protected:Npn \@@_reg:nNnN #1#2#3#4
  {
    \__chk_if_free_cs:N #4
    \int_compare:nNnTF { \int_use:c { g_@@_ #1 _int } } < {#3}
      {
        \int_gincr:c { g_@@_ #1 _int }
        \tex_global:D #2 #4 \int_use:c { g_@@_ #1 _int }
        \iow_log:x
          {
            \token_to_str:N #4 ~=~ #1 ~register~
            \int_use:c { g_@@_ #1 _int }
          }
      }
      { \__msg_kernel_fatal:nnx { kernel } { out-of-registers } {#1} }
  }
%    \end{macrocode}
% \end{macro}
%
%    \begin{macrocode}
%</initex>
%    \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex