| 1 | %%% -*-latex-*- |
| 2 | %%% |
| 3 | %%% Output machinery |
| 4 | %%% |
| 5 | %%% (c) 2015 Straylight/Edgeware |
| 6 | %%% |
| 7 | |
| 8 | %%%----- Licensing notice --------------------------------------------------- |
| 9 | %%% |
| 10 | %%% This file is part of the Sensible Object Design, an object system for C. |
| 11 | %%% |
| 12 | %%% SOD is free software; you can redistribute it and/or modify |
| 13 | %%% it under the terms of the GNU General Public License as published by |
| 14 | %%% the Free Software Foundation; either version 2 of the License, or |
| 15 | %%% (at your option) any later version. |
| 16 | %%% |
| 17 | %%% SOD is distributed in the hope that it will be useful, |
| 18 | %%% but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | %%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | %%% GNU General Public License for more details. |
| 21 | %%% |
| 22 | %%% You should have received a copy of the GNU General Public License |
| 23 | %%% along with SOD; if not, write to the Free Software Foundation, |
| 24 | %%% Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 25 | |
| 26 | \chapter{The output system} \label{ch:output} |
| 27 | |
| 28 | This chapter deals with actually generating output files. It will be of |
| 29 | interest to programmers introducing new layout object classes, or new kinds |
| 30 | of output files. An understanding of the material in |
| 31 | \xref{sec:structures.layout} will prove valuable. |
| 32 | |
| 33 | %%%-------------------------------------------------------------------------- |
| 34 | \section{Output sequencing} \label{sec:output.sequencer} |
| 35 | |
| 36 | C compilers are picky about the order in which things are presented to them |
| 37 | in their input; but information about the structure of our classes is |
| 38 | scattered among a variety of different layout objects. It's not the case |
| 39 | that a layout object only contributes to a single localized portion of the |
| 40 | output: for example, a @|vtmsgs| layout object is responsible for declaring |
| 41 | both the appropriate @|struct $C$__vtmsgs_$a$| structure in the header file, |
| 42 | populated with method entry pointers, but also declaring its member in the |
| 43 | enclosing @|struct $C$__vt_$i$| structure. |
| 44 | |
| 45 | One approach would be to have the various layout objects just know how to |
| 46 | call each other in the right order so as to have everything come out |
| 47 | properly. That would make extending the translator, e.g., to add new kinds |
| 48 | of layout objects, rather difficult. And it doesn't let users insert custom |
| 49 | C fragments in flexible ways. |
| 50 | |
| 51 | Instead, there's a clear separation between which things need to be output, |
| 52 | and the order in which they're produced. |
| 53 | |
| 54 | Ordering is handled by a \emph{sequencer} object. A sequencer doesn't know |
| 55 | anything particular about output: its job is simply to do things in a |
| 56 | particular order. It's described here because Sod only uses it for output |
| 57 | scheduling. |
| 58 | |
| 59 | A sequencer maintains a collection of named \emph{items}, each of which has a |
| 60 | name and a list of functions associated with it. A name can be any Lisp |
| 61 | object. Names are compared using @|equal|, so lists can be used to construct |
| 62 | a hierarchical namespace. |
| 63 | |
| 64 | The sequencer also maintains a collection of \emph{constraints}, which take |
| 65 | the form of lists of item names. A constraint of the form @|($N_1$, $N_2$, |
| 66 | $\ldots$, $N_k$)| requires that the item named $N_1$ must be scheduled before |
| 67 | the item named $N_2$, and so on, all of which must be scheduled before the |
| 68 | item named $N_k$. Items with these names do not need to exist or be known to |
| 69 | the sequencer. An item name may appear in any number of constraints, all of |
| 70 | which apply. |
| 71 | |
| 72 | It might be that a collection of constraints is impossible to satisfy: for |
| 73 | example, the set |
| 74 | \begin{center} \codeface |
| 75 | (alice bob) \qquad (bob carol) \qquad (carol alice) |
| 76 | \end{center} |
| 77 | can't be satisfied, since the first constraint requires that @|alice| |
| 78 | precedes @|bob|, but the third says that @|alice| must come after @|carol|, |
| 79 | and the second that @|carol| comes after @|bob|: it's not possible that |
| 80 | @|alice| comes before @|bob| and after @|bob|. In this case, the sequencer |
| 81 | fails and signals an error of type @|inconsistent-merge-error|. |
| 82 | |
| 83 | It is possible, but tedious, to explicitly order an entire collection of |
| 84 | items by adding constraints. In the absence of explicit constraints to order |
| 85 | them, items are ordered according to the order in which constraints naming |
| 86 | them were first added to the sequencer. Items not named in any constraint |
| 87 | are not processed at all. |
| 88 | |
| 89 | For example, suppose we have the following constraints. |
| 90 | \begin{center} \codeface |
| 91 | (perl java) \qquad |
| 92 | (lisp java) \qquad |
| 93 | (python icon) \qquad |
| 94 | (icon perl) |
| 95 | \end{center} |
| 96 | The constraints give us that $@|python| < @|icon| < @|perl| < @|java|$, and |
| 97 | also $@|lisp| < @|java|$. In this case, @|lisp| precedes @|python| because |
| 98 | @|lisp| is mentioned in the second constraint while @|python| isn't mentioned |
| 99 | until the third. So the final processing order is |
| 100 | \begin{center} |
| 101 | @|lisp|, \quad |
| 102 | @|python|, \quad |
| 103 | @|icon|, \quad |
| 104 | @|perl|, \quad |
| 105 | @|java| |
| 106 | \end{center} |
| 107 | |
| 108 | |
| 109 | \begin{describe}{cls}{sequencer-item} |
| 110 | An object of class @|sequencer-item| represents a sequencer item. |
| 111 | Sequencer items maintain a \emph{name} and a list of \emph{functions}. |
| 112 | Names are compared using @|equal|. |
| 113 | |
| 114 | The functions are maintained in \emph{reverse order}, because it's |
| 115 | convenient to be able to add new functions using @|push|. |
| 116 | \end{describe} |
| 117 | |
| 118 | \begin{describe}{fun}{sequencer-item-p @<object> @> @<generalized-boolean>} |
| 119 | Return non-nil if and only if @<object> is a @|sequencer-item|. |
| 120 | \end{describe} |
| 121 | |
| 122 | \begin{describe}{fun} |
| 123 | {make-sequencer-item @<name> \&optional @<functions> @> @<item>} |
| 124 | Create and return a new sequencer item with the given @<name> and list of |
| 125 | @<functions>; the list of functions defaults to nil if omitted. |
| 126 | \end{describe} |
| 127 | |
| 128 | \begin{describe*} |
| 129 | {\dhead{fun}{sequencer-item-name @<item> @> @<name>} |
| 130 | \dhead{fun}{sequencer-item-functions @<item> @> @<list>} |
| 131 | \dhead{fun}{setf (sequencer-item-functions @<item>) @<list>}} |
| 132 | These functions read or modify the state of a sequencer @<item>, as |
| 133 | originally established by @|make-sequencer-item|. |
| 134 | |
| 135 | It is an error to modify an item's list of functions during a call to |
| 136 | @|invoke-sequencer-items| on the item's owning sequencer. |
| 137 | \end{describe*} |
| 138 | |
| 139 | \begin{describe}{cls}{sequencer () \&key :constraints} |
| 140 | \end{describe} |
| 141 | |
| 142 | \begin{describe}{fun}{ensure-sequencer-item @<sequencer> @<name> @> @<item>} |
| 143 | \end{describe} |
| 144 | |
| 145 | \begin{describe}{fun}{add-sequencer-constraint @<sequencer> @<constraint>} |
| 146 | \end{describe} |
| 147 | |
| 148 | \begin{describe}{fun} |
| 149 | {invoke-sequencer-items @<sequencer> \&rest @<arguments>} |
| 150 | \end{describe} |
| 151 | |
| 152 | \begin{describe}{gf}{hook-output progn @<object> @<reason> @<sequencer>} |
| 153 | \begin{describe}{meth}{t,t} |
| 154 | {hook-output progn (@<object> t) (@<reason> t) @<sequencer>} |
| 155 | \end{describe} |
| 156 | \end{describe} |
| 157 | |
| 158 | \begin{describe}{mac} |
| 159 | {sequence-output (@<stream-var> @<sequencer>) \\ \ind |
| 160 | @{ :constraint (@<item-name>^*) @} \\ |
| 161 | @{ (@<item-name> @<form>^*) @}^*} |
| 162 | \end{describe} |
| 163 | |
| 164 | %%%-------------------------------------------------------------------------- |
| 165 | \section{Module output} \label{output.module} |
| 166 | |
| 167 | \subsection{Producing output} |
| 168 | |
| 169 | \begin{describe}{fun}{output-module @<module> @<reason> @<stream>} |
| 170 | \end{describe} |
| 171 | |
| 172 | |
| 173 | \subsection{Managing output types} \label{output.module.manage} |
| 174 | |
| 175 | \begin{describe}{fun}{declare-output-type @<reason> @<pathname>} |
| 176 | \end{describe} |
| 177 | |
| 178 | \begin{describe}{fun}{output-type-pathname @<reason> @> @<pathname>} |
| 179 | \end{describe} |
| 180 | |
| 181 | |
| 182 | \subsection{Utilities} \label{output.module.utilities} |
| 183 | |
| 184 | \begin{describe}{fun}{banner @<title> @<output> \&key :blank-line-p} |
| 185 | \end{describe} |
| 186 | |
| 187 | \begin{describe}{fun}{guard-name @<filename> @> @<string>} |
| 188 | \end{describe} |
| 189 | |
| 190 | \begin{describe}{fun} |
| 191 | {one-off-output @<token> @<sequencer> @<item-name> @<function>} |
| 192 | \end{describe} |
| 193 | |
| 194 | %%%-------------------------------------------------------------------------- |
| 195 | \section{Class output} \label{output.class} |
| 196 | |
| 197 | \begin{describe}{var}{*instance-class*} |
| 198 | \end{describe} |
| 199 | |
| 200 | %% output for `h' files |
| 201 | %% |
| 202 | %% prologue |
| 203 | %% guard start |
| 204 | %% typedefs start |
| 205 | %% typedefs |
| 206 | %% typedefs end |
| 207 | %% includes start |
| 208 | %% includes |
| 209 | %% includes end |
| 210 | %% classes start |
| 211 | %% early-user start |
| 212 | %% early-user |
| 213 | %% early-user end |
| 214 | %% CLASS banner |
| 215 | %% CLASS islots start |
| 216 | %% CLASS islots slots |
| 217 | %% CLASS islots end |
| 218 | %% CLASS vtmsgs start |
| 219 | %% CLASS vtmsgs CLASS start |
| 220 | %% CLASS vtmsgs CLASS slots |
| 221 | %% CLASS vtmsgs CLASS end |
| 222 | %% CLASS vtmsgs end |
| 223 | %% CLASS vtables start |
| 224 | %% CLASS vtables CHAIN-HEAD start |
| 225 | %% CLASS vtables CHAIN-HEAD slots |
| 226 | %% CLASS vtables CHAIN-HEAD end |
| 227 | %% CLASS vtables end |
| 228 | %% CLASS vtable-externs |
| 229 | %% CLASS vtable-externs-after |
| 230 | %% CLASS methods start |
| 231 | %% CLASS methods |
| 232 | %% CLASS methods end |
| 233 | %% CLASS ichains start |
| 234 | %% CLASS ichains CHAIN-HEAD start |
| 235 | %% CLASS ichains CHAIN-HEAD slots |
| 236 | %% CLASS ichains CHAIN-HEAD end |
| 237 | %% CLASS ichains end |
| 238 | %% CLASS ilayout start |
| 239 | %% CLASS ilayout slots |
| 240 | %% CLASS ilayout end |
| 241 | %% CLASS conversions |
| 242 | %% CLASS object |
| 243 | %% classes end |
| 244 | %% user start |
| 245 | %% user |
| 246 | %% user end |
| 247 | %% guard end |
| 248 | %% epilogue |
| 249 | |
| 250 | %% output for `c' files |
| 251 | %% |
| 252 | %% prologue |
| 253 | %% includes start |
| 254 | %% includes |
| 255 | %% includes end |
| 256 | %% early-user start |
| 257 | %% early-user |
| 258 | %% early-user end |
| 259 | %% classes start |
| 260 | %% CLASS banner |
| 261 | %% CLASS direct-methods start |
| 262 | %% CLASS direct-methods METHOD start |
| 263 | %% CLASS direct-methods METHOD body |
| 264 | %% CLASS direct-methods METHOD end |
| 265 | %% CLASS direct-methods end |
| 266 | %% CLASS effective-methods |
| 267 | %% CLASS vtables start |
| 268 | %% CLASS vtables CHAIN-HEAD start |
| 269 | %% CLASS vtables CHAIN-HEAD class-pointer METACLASS |
| 270 | %% CLASS vtables CHAIN-HEAD base-offset |
| 271 | %% CLASS vtables CHAIN-HEAD chain-offset TARGET-HEAD |
| 272 | %% CLASS vtables CHAIN-HEAD vtmsgs CLASS start |
| 273 | %% CLASS vtables CHAIN-HEAD vtmsgs CLASS slots |
| 274 | %% CLASS vtables CHAIN-HEAD vtmsgs CLASS end |
| 275 | %% CLASS vtables CHAIN-HEAD end |
| 276 | %% CLASS vtables end |
| 277 | %% CLASS object prepare |
| 278 | %% CLASS object start |
| 279 | %% CLASS object CHAIN-HEAD ichain start |
| 280 | %% CLASS object SUPER slots start |
| 281 | %% CLASS object SUPER slots |
| 282 | %% CLASS object SUPER vtable |
| 283 | %% CLASS object SUPER slots end |
| 284 | %% CLASS object CHAIN-HEAD ichain end |
| 285 | %% CLASS object end |
| 286 | %% classes end |
| 287 | %% user start |
| 288 | %% user |
| 289 | %% user end |
| 290 | %% epilogue |
| 291 | |
| 292 | %%%----- That's all, folks -------------------------------------------------- |
| 293 | |
| 294 | %%% Local variables: |
| 295 | %%% mode: LaTeX |
| 296 | %%% TeX-master: "sod.tex" |
| 297 | %%% TeX-PDF-mode: t |
| 298 | %%% End: |