| 1 | \documentclass[noarticle]{strayman} |
| 2 | |
| 3 | \usepackage[T1]{fontenc} |
| 4 | \usepackage[utf8]{inputenc} |
| 5 | \usepackage[palatino, helvetica, courier, maths=cmr]{mdwfonts} |
| 6 | \usepackage{syntax} |
| 7 | \usepackage{sverb} |
| 8 | \usepackage{mdwtab} |
| 9 | \usepackage{footnote} |
| 10 | \usepackage{at} |
| 11 | \usepackage{mdwref} |
| 12 | |
| 13 | \title{A Sensible Object Design for C} |
| 14 | \author{Mark Wooding} |
| 15 | |
| 16 | \makeatletter |
| 17 | |
| 18 | \errorcontextlines999 |
| 19 | |
| 20 | \def\syntleft{\normalfont\itshape} |
| 21 | \let\syntright\empty |
| 22 | |
| 23 | \let\codeface\sffamily |
| 24 | |
| 25 | \def\ulitleft{\normalfont\codeface} |
| 26 | \let\ulitright\empty |
| 27 | |
| 28 | \let\listingsize\relax |
| 29 | |
| 30 | \let\epsilon\varepsilon |
| 31 | |
| 32 | \atdef <#1>{\synt{#1}\@scripts} |
| 33 | \atdef "#1"{\lit*{#1}\@scripts} |
| 34 | \atdef `#1'{\lit{#1}\@scripts} |
| 35 | \atdef |#1|{\textsf{#1}\@scripts} |
| 36 | \def\dbl@maybe#1{\let\@tempa#1\futurelet\@ch\dbl@maybe@i} |
| 37 | \def\dbl@maybe@i{\m@maybe\ifx\@ch\@tempa\@tempa\!\@tempa% |
| 38 | \expandafter\@firstoftwo\expandafter\@scripts% |
| 39 | \else\@tempa\expandafter\@scripts\fi} |
| 40 | \atdef [{\dbl@maybe[} |
| 41 | \atdef ]{\dbl@maybe]} |
| 42 | \atdef {{\m@maybe\{\@scripts} |
| 43 | \atdef }{\m@maybe\}\@scripts} |
| 44 | \atdef ({\m@maybe(\@scripts} |
| 45 | \atdef ){\m@maybe)\@scripts} |
| 46 | \atdef !{\m@maybe|\@scripts} |
| 47 | \atdef to{\leavevmode\unskip\quad\m@maybe\longrightarrow\m@maybe@end\quad} |
| 48 | \let\m@maybe@end\relax |
| 49 | \def\m@maybe{\ifmmode\else$\let\m@maybe@end$\fi} |
| 50 | \def\@scripts{\futurelet\@ch\@scripts@i} |
| 51 | |
| 52 | \atdef ;#1\\{\normalfont\itshape;#1\\} |
| 53 | \let\@@grammar\grammar |
| 54 | \def\grammar{\def\textbar{\hbox{$|$}}\@@grammar} |
| 55 | |
| 56 | \begingroup\lccode`\~=`\_\lowercase{\endgroup |
| 57 | \def\@scripts@i{\if1\ifx\@ch~1\else\ifx\@ch^1\else0\fi\fi% |
| 58 | \expandafter\@scripts@ii\else\expandafter\m@maybe@end\fi}} |
| 59 | \def\@scripts@ii#1#2{\m@maybe#1{#2}\@scripts} |
| 60 | |
| 61 | \def\Cplusplus{C\kern-\p@++} |
| 62 | \def\Csharp{C\#} |
| 63 | \def\man#1#2{\textbf{#1}(#2)} |
| 64 | |
| 65 | \begingroup\lccode`\~=`\ |
| 66 | \lowercase{ |
| 67 | \endgroup |
| 68 | \def\prog{% |
| 69 | \codeface% |
| 70 | \quote% |
| 71 | \let\old@nl\\% |
| 72 | \obeylines% |
| 73 | \tabbing% |
| 74 | \global\let~\\% |
| 75 | \global\let\\\textbackslash% |
| 76 | } |
| 77 | \def\endprog{% |
| 78 | \endtabbing% |
| 79 | \global\let\\\old@nl% |
| 80 | \endquote% |
| 81 | }} |
| 82 | |
| 83 | \newenvironment{boxy}[1][\q@]{% |
| 84 | \dimen@\linewidth\advance\dimen@-1.2pt\advance\dimen@-2ex% |
| 85 | \medskip% |
| 86 | \vbox\bgroup\hrule\hbox\bgroup\vrule% |
| 87 | \vbox\bgroup\vskip1ex\hbox\bgroup\hskip1ex\minipage\dimen@% |
| 88 | \def\@temp{#1}\ifx\@temp\q@\else\leavevmode{\headfam\bfseries#1\quad}\fi% |
| 89 | }{% |
| 90 | \endminipage\hskip1ex\egroup\vskip1ex\egroup% |
| 91 | \vrule\egroup\hrule\egroup% |
| 92 | \medskip% |
| 93 | } |
| 94 | |
| 95 | \def\definedescribecategory#1#2{\@namedef{cat!#1}{#2}} |
| 96 | \def\describecategoryname#1{% |
| 97 | \expandafter\let\expandafter\@tempa\csname cat!#1\endcsname% |
| 98 | \ifx\@tempa\relax#1\else\@tempa\fi} |
| 99 | \definedescribecategory{fun}{function} |
| 100 | \definedescribecategory{gf}{generic function} |
| 101 | \definedescribecategory{var}{variable} |
| 102 | \definedescribecategory{const}{constant} |
| 103 | \definedescribecategory{meth}{primary method} |
| 104 | \definedescribecategory{ar-meth}{around-method} |
| 105 | \definedescribecategory{be-meth}{before-method} |
| 106 | \definedescribecategory{af-meth}{after-method} |
| 107 | \definedescribecategory{cls}{class} |
| 108 | \definedescribecategory{ty}{type} |
| 109 | \definedescribecategory{mac}{macro} |
| 110 | |
| 111 | \def\q@{\q@} |
| 112 | \newenvironment{describe}[3][\q@]{% |
| 113 | \normalfont% |
| 114 | \par\goodbreak% |
| 115 | \vspace{\bigskipamount}% |
| 116 | \setbox\z@\hbox{\bfseries[\describecategoryname{#2}]}% |
| 117 | \dimen@\linewidth\advance\dimen@-\wd\z@% |
| 118 | \def\@temp##1 ##2\q@{\message{#2:##1}\label{#2:##1}}% |
| 119 | \def\@tempa{#1}\ifx\@tempa\q@\@temp#3 \q@\else\@temp{#1} \\\fi% |
| 120 | \edef\@temp{{\the\linewidth}{@{}p{\the\dimen@}% |
| 121 | @{\extracolsep{\fill}}l@{\extracolsep{0pt}}}}% |
| 122 | \noindent\csname tabular*\expandafter\endcsname\@temp% |
| 123 | \tabbing\codeface#3\endtabbing&\unhbox\z@\\\endtabular% |
| 124 | % \@afterheading% |
| 125 | \list{}{\rightmargin\z@}\item% |
| 126 | }{% |
| 127 | \endlist% |
| 128 | } |
| 129 | |
| 130 | \def\push{\quad\=\+\kill} |
| 131 | |
| 132 | \begin{document} |
| 133 | |
| 134 | \maketitle |
| 135 | |
| 136 | \include{sod-tut} |
| 137 | |
| 138 | %%%-------------------------------------------------------------------------- |
| 139 | \chapter{Internals} |
| 140 | |
| 141 | \section{Generated names} |
| 142 | |
| 143 | The generated names for functions and objects related to a class are |
| 144 | constructed systematically so as not to interfere with each other. The rules |
| 145 | on class, slot and message naming exist so as to ensure that the generated |
| 146 | names don't collide with each other. |
| 147 | |
| 148 | The following notation is used in this section. |
| 149 | \begin{description} |
| 150 | \item[@<class>] The full name of the `focus' class: the one for which we are |
| 151 | generating name. |
| 152 | \item[@<super-nick>] The nickname of a superclass. |
| 153 | \item[@<head-nick>] The nickname of the chain-head class of the chain |
| 154 | in question. |
| 155 | \end{description} |
| 156 | |
| 157 | \subsection{Instance layout} |
| 158 | |
| 159 | %%%-------------------------------------------------------------------------- |
| 160 | \section{Syntax} |
| 161 | \label{sec:syntax} |
| 162 | |
| 163 | Fortunately, Sod is syntactically quite simple. I've used a little slightly |
| 164 | unusual notation in order to make the presentation easier to read. |
| 165 | \begin{itemize} |
| 166 | \item $\epsilon$ denotes the empty nonterminal: |
| 167 | \begin{quote} |
| 168 | $\epsilon$ ::= |
| 169 | \end{quote} |
| 170 | \item @[@<item>@] means an optional @<item>: |
| 171 | \begin{quote} |
| 172 | \syntax{@[<item>@] ::= $\epsilon$ @! <item>} |
| 173 | \end{quote} |
| 174 | \item @<item>^* means a sequence of zero or more @<item>s: |
| 175 | \begin{quote} |
| 176 | \syntax{@<item>^* ::= $\epsilon$ @! @<item>^* <item>} |
| 177 | \end{quote} |
| 178 | \item @<item>^+ means a sequence of one or more @<item>s: |
| 179 | \begin{quote} |
| 180 | \syntax{@<item>^+ ::= <item> @<item>^*} |
| 181 | \end{quote} |
| 182 | \item @<item-list> means a sequence of one or more @<item>s separated |
| 183 | by commas: |
| 184 | \begin{quote} |
| 185 | \syntax{<item-list> ::= <item> @! <item-list> "," <item>} |
| 186 | \end{quote} |
| 187 | \end{itemize} |
| 188 | |
| 189 | \subsection{Lexical syntax} |
| 190 | \label{sec:syntax.lex} |
| 191 | |
| 192 | Whitespace and comments are discarded. The remaining characters are |
| 193 | collected into tokens according to the following syntax. |
| 194 | |
| 195 | \begin{grammar} |
| 196 | <token> ::= <identifier> |
| 197 | \alt <reserved-word> |
| 198 | \alt <string-literal> |
| 199 | \alt <char-literal> |
| 200 | \alt <integer-literal> |
| 201 | \alt <punctuation> |
| 202 | \end{grammar} |
| 203 | |
| 204 | This syntax is slightly ambiguous. The following two rules serve to |
| 205 | disambiguate: |
| 206 | \begin{enumerate} |
| 207 | \item Reserved words take precedence. All @<reserved-word>s are |
| 208 | syntactically @<identifier>s; Sod resolves the ambiguity in favour of |
| 209 | @<reserved-word>. |
| 210 | \item `Maximal munch'. In other cases, at each stage we take the longest |
| 211 | sequence of characters which could be a token. |
| 212 | \end{enumerate} |
| 213 | |
| 214 | \subsubsection{Identifiers} \label{sec:syntax.lex.id} |
| 215 | |
| 216 | \begin{grammar} |
| 217 | <identifier> ::= <id-start-char> @<id-body-char>^* |
| 218 | |
| 219 | <id-start-char> ::= <alpha-char> | "_" |
| 220 | |
| 221 | <id-body-char> ::= <id-start-char> @! <digit-char> |
| 222 | |
| 223 | <alpha-char> ::= "A" | "B" | \dots\ | "Z" |
| 224 | \alt "a" | "b" | \dots\ | "z" |
| 225 | \alt <extended-alpha-char> |
| 226 | |
| 227 | <digit-char> ::= "0" | <nonzero-digit-char> |
| 228 | |
| 229 | <nonzero-digit-char> ::= "1" | "2" $| \cdots |$ "9" |
| 230 | \end{grammar} |
| 231 | |
| 232 | The precise definition of @<alpha-char> is left to the function |
| 233 | \textsf{alpha-char-p} in the hosting Lisp system. For portability, |
| 234 | programmers are encouraged to limit themselves to the standard ASCII letters. |
| 235 | |
| 236 | \subsubsection{Reserved words} \label{sec:syntax.lex.reserved} |
| 237 | |
| 238 | \begin{grammar} |
| 239 | <reserved-word> ::= |
| 240 | "char" | "class" | "code" | "const" | "double" | "enum" | |
| 241 | "extern" | "float" | "import" | "int" | "lisp" | "load" | "long" |
| 242 | | "restrict" | "short" | "signed" | "struct" | "typename" | |
| 243 | "union" | "unsigned" | "void" | "volatile" |
| 244 | \end{grammar} |
| 245 | |
| 246 | Many of these are borrowed from~C; however, some (e.g., @"import" and |
| 247 | @"lisp") are not, and some C reserved words are not reserved (e.g., |
| 248 | @"static"). |
| 249 | |
| 250 | \subsubsection{String and character literals} \label{sec:syntax.lex.string} |
| 251 | |
| 252 | \begin{grammar} |
| 253 | <string-literal> ::= "\"" @<string-literal-char>^* "\"" |
| 254 | |
| 255 | <char-literal> ::= "'" <char-literal-char> "'" |
| 256 | |
| 257 | <string-literal-char> ::= any character other than "\\" or "\"" |
| 258 | \alt "\\" <char> |
| 259 | |
| 260 | <char-literal-char> ::= any character other than "\\" or "'" |
| 261 | \alt "\\" <char> |
| 262 | |
| 263 | <char> ::= any single character |
| 264 | \end{grammar} |
| 265 | |
| 266 | The syntax for string and character literals differs from~C. In particular, |
| 267 | escape sequences such as @`\textbackslash n' are not recognized. The use |
| 268 | of string and character literals in Sod, outside of C~fragments, is limited, |
| 269 | and the simple syntax seems adequate. For the sake of future compatibility, |
| 270 | the use of character sequences which resemble C escape sequences is |
| 271 | discouraged. |
| 272 | |
| 273 | \subsubsection{Integer literals} \label{sec:syntax.lex.int} |
| 274 | |
| 275 | \begin{grammar} |
| 276 | <integer-literal> ::= <decimal-integer> |
| 277 | \alt <binary-integer> |
| 278 | \alt <octal-integer> |
| 279 | \alt <hex-integer> |
| 280 | |
| 281 | <decimal-integer> ::= <nonzero-digit-char> @<digit-char>^* |
| 282 | |
| 283 | <binary-integer> ::= "0" @("b"|"B"@) @<binary-digit-char>^+ |
| 284 | |
| 285 | <binary-digit-char> ::= "0" | "1" |
| 286 | |
| 287 | <octal-integer> ::= "0" @["o"|"O"@] @<octal-digit-char>^+ |
| 288 | |
| 289 | <octal-digit-char> ::= "0" | "1" $| \cdots |$ "7" |
| 290 | |
| 291 | <hex-integer> ::= "0" @("x"|"X"@) @<hex-digit-char>^+ |
| 292 | |
| 293 | <hex-digit-char> ::= <digit-char> |
| 294 | \alt "A" | "B" | "C" | "D" | "E" | "F" |
| 295 | \alt "a" | "b" | "c" | "d" | "e" | "f" |
| 296 | \end{grammar} |
| 297 | |
| 298 | Sod understands only integers, not floating-point numbers; its integer syntax |
| 299 | goes slightly beyond C in allowing a @`0o' prefix for octal and @`0b' for |
| 300 | binary. However, length and signedness indicators are not permitted. |
| 301 | |
| 302 | \subsubsection{Punctuation} \label{sec:syntax.lex.punct} |
| 303 | |
| 304 | \begin{grammar} |
| 305 | <punctuation> ::= any character other than "\"" or "'" |
| 306 | \end{grammar} |
| 307 | |
| 308 | Due to the `maximal munch' rule, @<punctuation> tokens cannot be |
| 309 | alphanumeric. |
| 310 | |
| 311 | \subsubsection{Comments} \label{sec:lex-comment} |
| 312 | |
| 313 | \begin{grammar} |
| 314 | <comment> ::= <block-comment> |
| 315 | \alt <line-comment> |
| 316 | |
| 317 | <block-comment> ::= |
| 318 | "/*" |
| 319 | @<not-star>^* @(@<star>^+ <not-star-or-slash> @<not-star>^*@)^* |
| 320 | @<star>^* |
| 321 | "*/" |
| 322 | |
| 323 | <star> ::= "*" |
| 324 | |
| 325 | <not-star> ::= any character other than "*" |
| 326 | |
| 327 | <not-star-or-slash> ::= any character other than "*" or "/" |
| 328 | |
| 329 | <line-comment> ::= "//" @<not-newline>^* <newline> |
| 330 | |
| 331 | <newline> ::= a newline character |
| 332 | |
| 333 | <not-newline> ::= any character other than newline |
| 334 | \end{grammar} |
| 335 | |
| 336 | Comments are exactly as in C99: both traditional block comments `\texttt{/*} |
| 337 | \dots\ \texttt{*/}' and \Cplusplus-style `\texttt{//} \dots' comments are |
| 338 | permitted and ignored. |
| 339 | |
| 340 | \subsection{Special nonterminals} |
| 341 | \label{sec:special-nonterminals} |
| 342 | |
| 343 | Aside from the lexical syntax presented above (\xref{sec:lexical-syntax}), |
| 344 | two special nonterminals occur in the module syntax. |
| 345 | |
| 346 | \subsubsection{S-expressions} \label{sec:syntax-sexp} |
| 347 | |
| 348 | \begin{grammar} |
| 349 | <s-expression> ::= an S-expression, as parsed by the Lisp reader |
| 350 | \end{grammar} |
| 351 | |
| 352 | When an S-expression is expected, the Sod parser simply calls the host Lisp |
| 353 | system's \textsf{read} function. Sod modules are permitted to modify the |
| 354 | read table to extend the S-expression syntax. |
| 355 | |
| 356 | S-expressions are self-delimiting, so no end-marker is needed. |
| 357 | |
| 358 | \subsubsection{C fragments} \label{sec:syntax.lex.cfrag} |
| 359 | |
| 360 | \begin{grammar} |
| 361 | <c-fragment> ::= a sequence of C tokens, with matching brackets |
| 362 | \end{grammar} |
| 363 | |
| 364 | Sequences of C code are simply stored and written to the output unchanged |
| 365 | during translation. They are read using a simple scanner which nonetheless |
| 366 | understands C comments and string and character literals. |
| 367 | |
| 368 | A C fragment is terminated by one of a small number of delimiter characters |
| 369 | determined by the immediately surrounding context -- usually a closing brace |
| 370 | or bracket. The first such delimiter character which is not enclosed in |
| 371 | brackets, braces or parenthesis ends the fragment. |
| 372 | |
| 373 | \subsection{Module syntax} \label{sec:syntax-module} |
| 374 | |
| 375 | \begin{grammar} |
| 376 | <module> ::= @<definition>^* |
| 377 | |
| 378 | <definition> ::= <import-definition> |
| 379 | \alt <load-definition> |
| 380 | \alt <lisp-definition> |
| 381 | \alt <code-definition> |
| 382 | \alt <typename-definition> |
| 383 | \alt <class-definition> |
| 384 | \end{grammar} |
| 385 | |
| 386 | A module is the top-level syntactic item. A module consists of a sequence of |
| 387 | definitions. |
| 388 | |
| 389 | \subsection{Simple definitions} \label{sec:syntax.defs} |
| 390 | |
| 391 | \subsubsection{Importing modules} \label{sec:syntax.defs.import} |
| 392 | |
| 393 | \begin{grammar} |
| 394 | <import-definition> ::= "import" <string> ";" |
| 395 | \end{grammar} |
| 396 | |
| 397 | The module named @<string> is processed and its definitions made available. |
| 398 | |
| 399 | A search is made for a module source file as follows. |
| 400 | \begin{itemize} |
| 401 | \item The module name @<string> is converted into a filename by appending |
| 402 | @`.sod', if it has no extension already.\footnote{% |
| 403 | Technically, what happens is \textsf{(merge-pathnames name (make-pathname |
| 404 | :type "SOD" :case :common))}, so exactly what this means varies |
| 405 | according to the host system.} % |
| 406 | \item The file is looked for relative to the directory containing the |
| 407 | importing module. |
| 408 | \item If that fails, then the file is looked for in each directory on the |
| 409 | module search path in turn. |
| 410 | \item If the file still isn't found, an error is reported and the import |
| 411 | fails. |
| 412 | \end{itemize} |
| 413 | At this point, if the file has previously been imported, nothing further |
| 414 | happens.\footnote{% |
| 415 | This check is done using \textsf{truename}, so it should see through simple |
| 416 | tricks like symbolic links. However, it may be confused by fancy things |
| 417 | like bind mounts and so on.} % |
| 418 | |
| 419 | Recursive imports, either direct or indirect, are an error. |
| 420 | |
| 421 | \subsubsection{Loading extensions} \label{sec:syntax.defs.load} |
| 422 | |
| 423 | \begin{grammar} |
| 424 | <load-definition> ::= "load" <string> ";" |
| 425 | \end{grammar} |
| 426 | |
| 427 | The Lisp file named @<string> is loaded and evaluated. |
| 428 | |
| 429 | A search is made for a Lisp source file as follows. |
| 430 | \begin{itemize} |
| 431 | \item The name @<string> is converted into a filename by appending @`.lisp', |
| 432 | if it has no extension already.\footnote{% |
| 433 | Technically, what happens is \textsf{(merge-pathnames name (make-pathname |
| 434 | :type "LISP" :case :common))}, so exactly what this means varies |
| 435 | according to the host system.} % |
| 436 | \item A search is then made in the same manner as for module imports |
| 437 | (\xref{sec:syntax-module}). |
| 438 | \end{itemize} |
| 439 | If the file is found, it is loaded using the host Lisp's \textsf{load} |
| 440 | function. |
| 441 | |
| 442 | Note that Sod doesn't attempt to compile Lisp files, or even to look for |
| 443 | existing compiled files. The right way to package a substantial extension to |
| 444 | the Sod translator is to provide the extension as a standard ASDF system (or |
| 445 | similar) and leave a dropping @"foo-extension.lisp" in the module path saying |
| 446 | something like |
| 447 | \begin{listing} |
| 448 | (asdf:operate 'asdf:load-op :foo-extension) |
| 449 | \end{listing} |
| 450 | which will arrange for the extension to be compiled if necessary. |
| 451 | |
| 452 | (This approach means that the language doesn't need to depend on any |
| 453 | particular system definition facility. It's bad enough already that it |
| 454 | depends on Common Lisp.) |
| 455 | |
| 456 | \subsubsection{Lisp escapes} \label{sec:syntax.defs.lisp} |
| 457 | |
| 458 | \begin{grammar} |
| 459 | <lisp-definition> ::= "lisp" <s-expression> ";" |
| 460 | \end{grammar} |
| 461 | |
| 462 | The @<s-expression> is evaluated immediately. It can do anything it likes. |
| 463 | |
| 464 | \textbf{Warning!} This means that hostile Sod modules are a security hazard. |
| 465 | Lisp code can read and write files, start other programs, and make network |
| 466 | connections. Don't install Sod modules from sources that you don't |
| 467 | trust.\footnote{% |
| 468 | Presumably you were going to run the corresponding code at some point, so |
| 469 | this isn't as unusually scary as it sounds. But please be careful.} % |
| 470 | |
| 471 | \subsubsection{Declaring type names} \label{sec:syntax.defs.typename} |
| 472 | |
| 473 | \begin{grammar} |
| 474 | <typename-definition> ::= |
| 475 | "typename" <identifier-list> ";" |
| 476 | \end{grammar} |
| 477 | |
| 478 | Each @<identifier> is declared as naming a C type. This is important because |
| 479 | the C type syntax -- which Sod uses -- is ambiguous, and disambiguation is |
| 480 | done by distinguishing type names from other identifiers. |
| 481 | |
| 482 | Don't declare class names using @"typename"; use @"class" forward |
| 483 | declarations instead. |
| 484 | |
| 485 | \subsection{Literal code} \label{sec:syntax-code} |
| 486 | |
| 487 | \begin{grammar} |
| 488 | <code-definition> ::= |
| 489 | "code" <identifier> ":" <identifier> @[<constraints>@] |
| 490 | "{" <c-fragment> "}" |
| 491 | |
| 492 | <constraints> ::= "[" <constraint-list> "]" |
| 493 | |
| 494 | <constraint> ::= @<identifier>^+ |
| 495 | \end{grammar} |
| 496 | |
| 497 | The @<c-fragment> will be output unchanged to one of the output files. |
| 498 | |
| 499 | The first @<identifier> is the symbolic name of an output file. Predefined |
| 500 | output file names are @"c" and @"h", which are the implementation code and |
| 501 | header file respectively; other output files can be defined by extensions. |
| 502 | |
| 503 | The second @<identifier> provides a name for the output item. Several C |
| 504 | fragments can have the same name: they will be concatenated together in the |
| 505 | order in which they were encountered. |
| 506 | |
| 507 | The @<constraints> provide a means for specifying where in the output file |
| 508 | the output item should appear. (Note the two kinds of square brackets shown |
| 509 | in the syntax: square brackets must appear around the constraints if they are |
| 510 | present, but that they may be omitted.) Each comma-separated @<constraint> |
| 511 | is a sequence of identifiers naming output items, and indicates that the |
| 512 | output items must appear in the order given -- though the translator is free |
| 513 | to insert additional items in between them. (The particular output items |
| 514 | needn't be defined already -- indeed, they needn't be defined ever.) |
| 515 | |
| 516 | There is a predefined output item @"includes" in both the @"c" and @"h" |
| 517 | output files which is a suitable place for inserting @"\#include" |
| 518 | preprocessor directives in order to declare types and functions for use |
| 519 | elsewhere in the generated output files. |
| 520 | |
| 521 | \subsection{Property sets} \label{sec:syntax.propset} |
| 522 | |
| 523 | \begin{grammar} |
| 524 | <properties> ::= "[" <property-list> "]" |
| 525 | |
| 526 | <property> ::= <identifier> "=" <expression> |
| 527 | \end{grammar} |
| 528 | |
| 529 | Property sets are a means for associating miscellaneous information with |
| 530 | classes and related items. By using property sets, additional information |
| 531 | can be passed to extensions without the need to introduce idiosyncratic |
| 532 | syntax. |
| 533 | |
| 534 | A property has a name, given as an @<identifier>, and a value computed by |
| 535 | evaluating an @<expression>. The value can be one of a number of types, |
| 536 | though the only operators currently defined act on integer values only. |
| 537 | |
| 538 | \subsubsection{The expression evaluator} \label{sec:syntax.propset.expr} |
| 539 | |
| 540 | \begin{grammar} |
| 541 | <expression> ::= <term> | <expression> "+" <term> | <expression> "-" <term> |
| 542 | |
| 543 | <term> ::= <factor> | <term> "*" <factor> | <term> "/" <factor> |
| 544 | |
| 545 | <factor> ::= <primary> | "+" <factor> | "-" <factor> |
| 546 | |
| 547 | <primary> ::= |
| 548 | <integer-literal> | <string-literal> | <char-literal> | <identifier> |
| 549 | \alt "?" <s-expression> |
| 550 | \alt "(" <expression> ")" |
| 551 | \end{grammar} |
| 552 | |
| 553 | The arithmetic expression syntax is simple and standard; there are currently |
| 554 | no bitwise, logical, or comparison operators. |
| 555 | |
| 556 | A @<primary> expression may be a literal or an identifier. Note that |
| 557 | identifiers stand for themselves: they \emph{do not} denote values. For more |
| 558 | fancy expressions, the syntax |
| 559 | \begin{quote} |
| 560 | @"?" @<s-expression> |
| 561 | \end{quote} |
| 562 | causes the @<s-expression> to be evaluated using the Lisp \textsf{eval} |
| 563 | function. |
| 564 | %%% FIXME crossref to extension docs |
| 565 | |
| 566 | \subsection{C types} \label{sec:syntax.c-types} |
| 567 | |
| 568 | Sod's syntax for C types closely mirrors the standard C syntax. A C type has |
| 569 | two parts: a sequence of @<declaration-specifier>s and a @<declarator>. In |
| 570 | Sod, a type must contain at least one @<declaration-specifier> (i.e., |
| 571 | `implicit @"int"' is forbidden), and storage-class specifiers are not |
| 572 | recognized. |
| 573 | |
| 574 | \subsubsection{Declaration specifiers} \label{sec:syntax.c-types.declspec} |
| 575 | |
| 576 | \begin{grammar} |
| 577 | <declaration-specifier> ::= <type-name> |
| 578 | \alt "struct" <identifier> | "union" <identifier> | "enum" <identifier> |
| 579 | \alt "void" | "char" | "int" | "float" | "double" |
| 580 | \alt "short" | "long" |
| 581 | \alt "signed" | "unsigned" |
| 582 | \alt <qualifier> |
| 583 | |
| 584 | <qualifier> ::= "const" | "volatile" | "restrict" |
| 585 | |
| 586 | <type-name> ::= <identifier> |
| 587 | \end{grammar} |
| 588 | |
| 589 | A @<type-name> is an identifier which has been declared as being a type name, |
| 590 | using the @"typename" or @"class" definitions. |
| 591 | |
| 592 | Declaration specifiers may appear in any order. However, not all |
| 593 | combinations are permitted. A declaration specifier must consist of zero or |
| 594 | more @<qualifiers>, and one of the following, up to reordering. |
| 595 | \begin{itemize} |
| 596 | \item @<type-name> |
| 597 | \item @"struct" @<identifier>, @"union" @<identifier>, @"enum" @<identifier> |
| 598 | \item @"void" |
| 599 | \item @"char", @"unsigned char", @"signed char" |
| 600 | \item @"short", @"unsigned short", @"signed short" |
| 601 | \item @"short int", @"unsigned short int", @"signed short int" |
| 602 | \item @"int", @"unsigned int", @"signed int", @"unsigned", @"signed" |
| 603 | \item @"long", @"unsigned long", @"signed long" |
| 604 | \item @"long int", @"unsigned long int", @"signed long int" |
| 605 | \item @"long long", @"unsigned long long", @"signed long long" |
| 606 | \item @"long long int", @"unsigned long long int", @"signed long long int" |
| 607 | \item @"float", @"double", @"long double" |
| 608 | \end{itemize} |
| 609 | All of these have their usual C meanings. |
| 610 | |
| 611 | \subsubsection{Declarators} \label{sec:syntax.c-types.declarator} |
| 612 | |
| 613 | \begin{grammar} |
| 614 | <declarator>$[k]$ ::= @<pointer>^* <primary-declarator>$[k]$ |
| 615 | |
| 616 | <primary-declarator>$[k]$ ::= $k$ |
| 617 | \alt "(" <primary-declarator>$[k]$ ")" |
| 618 | \alt <primary-declarator>$[k]$ @<declarator-suffix>^* |
| 619 | |
| 620 | <pointer> ::= "*" @<qualifier>^* |
| 621 | |
| 622 | <declarator-suffix> ::= "[" <c-fragment> "]" |
| 623 | \alt "(" <arguments> ")" |
| 624 | |
| 625 | <arguments> ::= $\epsilon$ | "..." |
| 626 | \alt <argument-list> @["," "..."@] |
| 627 | |
| 628 | <argument> ::= @<declaration-specifier>^+ <argument-declarator> |
| 629 | |
| 630 | <argument-declarator> ::= <declarator>@[<identifier> @! $\epsilon$@] |
| 631 | |
| 632 | <simple-declarator> ::= <declarator>@[<identifier>@] |
| 633 | |
| 634 | <dotted-name> ::= <identifier> "." <identifier> |
| 635 | |
| 636 | <dotted-declarator> ::= <declarator>@[<dotted-name>@] |
| 637 | \end{grammar} |
| 638 | |
| 639 | The declarator syntax is taken from C, but with some differences. |
| 640 | \begin{itemize} |
| 641 | \item Array dimensions are uninterpreted @<c-fragments>, terminated by a |
| 642 | closing square bracket. This allows array dimensions to contain arbitrary |
| 643 | constant expressions. |
| 644 | \item A declarator may have either a single @<identifier> at its centre or a |
| 645 | pair of @<identifier>s separated by a @`.'; this is used to refer to |
| 646 | slots or messages defined in superclasses. |
| 647 | \end{itemize} |
| 648 | The remaining differences are (I hope) a matter of presentation rather than |
| 649 | substance. |
| 650 | |
| 651 | \subsection{Defining classes} \label{sec:syntax.class} |
| 652 | |
| 653 | \begin{grammar} |
| 654 | <class-definition> ::= <class-forward-declaration> |
| 655 | \alt <full-class-definition> |
| 656 | \end{grammar} |
| 657 | |
| 658 | \subsubsection{Forward declarations} \label{sec:class.class.forward} |
| 659 | |
| 660 | \begin{grammar} |
| 661 | <class-forward-declaration> ::= "class" <identifier> ";" |
| 662 | \end{grammar} |
| 663 | |
| 664 | A @<class-forward-declaration> informs Sod that an @<identifier> will be used |
| 665 | to name a class which is currently undefined. Forward declarations are |
| 666 | necessary in order to resolve certain kinds of circularity. For example, |
| 667 | \begin{listing} |
| 668 | class Sub; |
| 669 | |
| 670 | class Super : SodObject { |
| 671 | Sub *sub; |
| 672 | }; |
| 673 | |
| 674 | class Sub : Super { |
| 675 | /* ... */ |
| 676 | }; |
| 677 | \end{listing} |
| 678 | |
| 679 | \subsubsection{Full class definitions} \label{sec:class.class.full} |
| 680 | |
| 681 | \begin{grammar} |
| 682 | <full-class-definition> ::= |
| 683 | @[<properties>@] |
| 684 | "class" <identifier> ":" <identifier-list> |
| 685 | "{" @<class-item>^* "}" |
| 686 | |
| 687 | <class-item> ::= <slot-item> ";" |
| 688 | \alt <message-item> |
| 689 | \alt <method-item> |
| 690 | \alt <initializer-item> ";" |
| 691 | \end{grammar} |
| 692 | |
| 693 | A full class definition provides a complete description of a class. |
| 694 | |
| 695 | The first @<identifier> gives the name of the class. It is an error to |
| 696 | give the name of an existing class (other than a forward-referenced class), |
| 697 | or an existing type name. It is conventional to give classes `MixedCase' |
| 698 | names, to distinguish them from other kinds of identifiers. |
| 699 | |
| 700 | The @<identifier-list> names the direct superclasses for the new class. It |
| 701 | is an error if any of these @<identifier>s does not name a defined class. |
| 702 | |
| 703 | The @<properties> provide additional information. The standard class |
| 704 | properties are as follows. |
| 705 | \begin{description} |
| 706 | \item[@"lisp_class"] The name of the Lisp class to use within the translator |
| 707 | to represent this class. The property value must be an identifier; the |
| 708 | default is @"sod_class". Extensions may define classes with additional |
| 709 | behaviour, and may recognize additional class properties. |
| 710 | \item[@"metaclass"] The name of the Sod metaclass for this class. In the |
| 711 | generated code, a class is itself an instance of another class -- its |
| 712 | \emph{metaclass}. The metaclass defines which slots the class will have, |
| 713 | which messages it will respond to, and what its behaviour will be when it |
| 714 | receives them. The property value must be an identifier naming a defined |
| 715 | subclass of @"SodClass". The default metaclass is @"SodClass". |
| 716 | %%% FIXME xref to theory |
| 717 | \item[@"nick"] A nickname for the class, to be used to distinguish it from |
| 718 | other classes in various limited contexts. The property value must be an |
| 719 | identifier; the default is constructed by forcing the class name to |
| 720 | lower-case. |
| 721 | \end{description} |
| 722 | |
| 723 | The class body consists of a sequence of @<class-item>s enclosed in braces. |
| 724 | These items are discussed on the following sections. |
| 725 | |
| 726 | \subsubsection{Slot items} \label{sec:sntax.class.slot} |
| 727 | |
| 728 | \begin{grammar} |
| 729 | <slot-item> ::= |
| 730 | @[<properties>@] |
| 731 | @<declaration-specifier>^+ <init-declarator-list> |
| 732 | |
| 733 | <init-declarator> ::= <declarator> @["=" <initializer>@] |
| 734 | \end{grammar} |
| 735 | |
| 736 | A @<slot-item> defines one or more slots. All instances of the class and any |
| 737 | subclass will contain these slot, with the names and types given by the |
| 738 | @<declaration-specifiers> and the @<declarators>. Slot declarators may not |
| 739 | contain qualified identifiers. |
| 740 | |
| 741 | It is not possible to declare a slot with function type: such an item is |
| 742 | interpreted as being a @<message-item> or @<method-item>. Pointers to |
| 743 | functions are fine. |
| 744 | |
| 745 | An @<initializer>, if present, is treated as if a separate |
| 746 | @<initializer-item> containing the slot name and initializer were present. |
| 747 | For example, |
| 748 | \begin{listing} |
| 749 | [nick = eg] |
| 750 | class Example : Super { |
| 751 | int foo = 17; |
| 752 | }; |
| 753 | \end{listing} |
| 754 | means the same as |
| 755 | \begin{listing} |
| 756 | [nick = eg] |
| 757 | class Example : Super { |
| 758 | int foo; |
| 759 | eg.foo = 17; |
| 760 | }; |
| 761 | \end{listing} |
| 762 | |
| 763 | \subsubsection{Initializer items} \label{sec:syntax.class.init} |
| 764 | |
| 765 | \begin{grammar} |
| 766 | <initializer-item> ::= @["class"@] <slot-initializer-list> |
| 767 | |
| 768 | <slot-initializer> ::= <qualified-identifier> "=" <initializer> |
| 769 | |
| 770 | <initializer> :: "{" <c-fragment> "}" | <c-fragment> |
| 771 | \end{grammar} |
| 772 | |
| 773 | An @<initializer-item> provides an initial value for one or more slots. If |
| 774 | prefixed by @"class", then the initial values are for class slots (i.e., |
| 775 | slots of the class object itself); otherwise they are for instance slots. |
| 776 | |
| 777 | The first component of the @<qualified-identifier> must be the nickname of |
| 778 | one of the class's superclasses (including itself); the second must be the |
| 779 | name of a slot defined in that superclass. |
| 780 | |
| 781 | The initializer has one of two forms. |
| 782 | \begin{itemize} |
| 783 | \item A @<c-fragment> enclosed in braces denotes an aggregate initializer. |
| 784 | This is suitable for initializing structure, union or array slots. |
| 785 | \item A @<c-fragment> \emph{not} beginning with an open brace is a `bare' |
| 786 | initializer, and continues until the next @`,' or @`;' which is not within |
| 787 | nested brackets. Bare initializers are suitable for initializing scalar |
| 788 | slots, such as pointers or integers, and strings. |
| 789 | \end{itemize} |
| 790 | |
| 791 | \subsubsection{Message items} \label{sec:syntax.class.message} |
| 792 | |
| 793 | \begin{grammar} |
| 794 | <message-item> ::= |
| 795 | @[<properties>@] |
| 796 | @<declaration-specifier>^+ <declarator> @[<method-body>@] |
| 797 | \end{grammar} |
| 798 | |
| 799 | \subsubsection{Method items} \label{sec:syntax.class.method} |
| 800 | |
| 801 | \begin{grammar} |
| 802 | <method-item> ::= |
| 803 | @[<properties>@] |
| 804 | @<declaration-specifier>^+ <declarator> <method-body> |
| 805 | |
| 806 | <method-body> ::= "{" <c-fragment> "}" | "extern" ";" |
| 807 | \end{grammar} |
| 808 | |
| 809 | %%%-------------------------------------------------------------------------- |
| 810 | \section{Class objects} |
| 811 | |
| 812 | \begin{listing} |
| 813 | typedef struct SodClass__ichain_obj SodClass; |
| 814 | |
| 815 | struct sod_chain { |
| 816 | size_t n_classes; /* Number of classes in chain */ |
| 817 | const SodClass *const *classes; /* Vector of classes, head first */ |
| 818 | size_t off_ichain; /* Offset of ichain from instance base */ |
| 819 | const struct sod_vtable *vt; /* Vtable pointer for chain */ |
| 820 | size_t ichainsz; /* Size of the ichain structure */ |
| 821 | }; |
| 822 | |
| 823 | struct sod_vtable { |
| 824 | SodClass *_class; /* Pointer to instance's class */ |
| 825 | size_t _base; /* Offset to instance base */ |
| 826 | }; |
| 827 | |
| 828 | struct SodClass__islots { |
| 829 | |
| 830 | /* Basic information */ |
| 831 | const char *name; /* The class's name as a string */ |
| 832 | const char *nick; /* The nickname as a string */ |
| 833 | |
| 834 | /* Instance allocation and initialization */ |
| 835 | size_t instsz; /* Instance layout size in bytes */ |
| 836 | void *(*imprint)(void *); /* Stamp instance with vtable ptrs */ |
| 837 | void *(*init)(void *); /* Initialize instance */ |
| 838 | |
| 839 | /* Superclass structure */ |
| 840 | size_t n_supers; /* Number of direct superclasses */ |
| 841 | const SodClass *const *supers; /* Vector of direct superclasses */ |
| 842 | size_t n_cpl; /* Length of class precedence list */ |
| 843 | const SodClass *const *cpl; /* Vector for class precedence list */ |
| 844 | |
| 845 | /* Chain structure */ |
| 846 | const SodClass *link; /* Link to next class in chain */ |
| 847 | const SodClass *head; /* Pointer to head of chain */ |
| 848 | size_t level; /* Index of class in its chain */ |
| 849 | size_t n_chains; /* Number of superclass chains */ |
| 850 | const sod_chain *chains; /* Vector of chain structures */ |
| 851 | |
| 852 | /* Layout */ |
| 853 | size_t off_islots; /* Offset of islots from ichain base */ |
| 854 | size_t islotsz; /* Size of instance slots */ |
| 855 | }; |
| 856 | |
| 857 | struct SodClass__ichain_obj { |
| 858 | const SodClass__vt_obj *_vt; |
| 859 | struct SodClass__islots cls; |
| 860 | }; |
| 861 | |
| 862 | struct sod_instance { |
| 863 | struct sod_vtable *_vt; |
| 864 | }; |
| 865 | \end{listing} |
| 866 | |
| 867 | \begin{listing} |
| 868 | void *sod_convert(const SodClass *cls, const void *obj) |
| 869 | { |
| 870 | const struct sod_instance *inst = obj; |
| 871 | const SodClass *real = inst->_vt->_cls; |
| 872 | const struct sod_chain *chain; |
| 873 | size_t i, index; |
| 874 | |
| 875 | for (i = 0; i < real->cls.n_chains; i++) { |
| 876 | chain = &real->cls.chains[i]; |
| 877 | if (chain->classes[0] == cls->cls.head) { |
| 878 | index = cls->cls.index; |
| 879 | if (index < chain->n_classes && chain->classes[index] == cls) |
| 880 | return ((char *)cls - inst->_vt._base + chain->off_ichain); |
| 881 | else |
| 882 | return (0); |
| 883 | } |
| 884 | } |
| 885 | return (0); |
| 886 | } |
| 887 | \end{listing} |
| 888 | |
| 889 | %%%-------------------------------------------------------------------------- |
| 890 | \section{Classes} |
| 891 | |
| 892 | \subsection{Classes and superclasses} |
| 893 | |
| 894 | A @<full-class-definition> must list one or more existing classes to be the |
| 895 | \emph{direct superclasses} for the new class being defined. We make the |
| 896 | following definitions. |
| 897 | \begin{itemize} |
| 898 | \item The \emph{superclasses} of a class consist of the class itself together |
| 899 | with the superclasses of its direct superclasses. |
| 900 | \item The \emph{proper superclasses} of a class are its superclasses other |
| 901 | than itself. |
| 902 | \item If $C$ is a (proper) superclass of $D$ then $D$ is a (\emph{proper}) |
| 903 | \emph{subclass} of $C$. |
| 904 | \end{itemize} |
| 905 | The predefined class @|SodObject| has no direct superclasses; it is unique in |
| 906 | this respect. All classes are subclasses of @|SodObject|. |
| 907 | |
| 908 | \subsection{The class precedence list} |
| 909 | |
| 910 | Let $C$ be a class. The superclasses of $C$ form a directed graph, with an |
| 911 | edge from each class to each of its direct superclasses. This is the |
| 912 | \emph{superclass graph of $C$}. |
| 913 | |
| 914 | In order to resolve inheritance of items, we define a \emph{class precedence |
| 915 | list} (or CPL) for each class, which imposes a total order on that class's |
| 916 | superclasses. The default algorithm for computing the CPL is the \emph{C3} |
| 917 | algorithm \cite{fixme-c3}, though extensions may implement other algorithms. |
| 918 | |
| 919 | The default algorithm works as follows. Let $C$ be the class whose CPL we |
| 920 | are to compute. Let $X$ and $Y$ be two of $C$'s superclasses. |
| 921 | \begin{itemize} |
| 922 | \item $C$ must appear first in the CPL. |
| 923 | \item If $X$ appears before $Y$ in the CPL of one of $C$'s direct |
| 924 | superclasses, then $X$ appears before $Y$ in the $C$'s CPL. |
| 925 | \item If the above rules don't suffice to order $X$ and $Y$, then whichever |
| 926 | of $X$ and $Y$ has a subclass which appears further left in the list of |
| 927 | $C$'s direct superclasses will appear earlier in the CPL. |
| 928 | \end{itemize} |
| 929 | This last rule is sufficient to disambiguate because if both $X$ and $Y$ are |
| 930 | superclasses of the same direct superclass of $C$ then that direct |
| 931 | superclass's CPL will order $X$ and $Y$. |
| 932 | |
| 933 | We say that \emph{$X$ is more specific than $Y$ as a superclass of $C$} if |
| 934 | $X$ is earlier than $Y$ in $C$'s class precedence list. If $C$ is clear from |
| 935 | context then we omit it, saying simply that $X$ is more specific than $Y$. |
| 936 | |
| 937 | \subsection{Instances and metaclasses} |
| 938 | |
| 939 | A class defines the structure and behaviour of its \emph{instances}: run-time |
| 940 | objects created (possibly) dynamically. An instance is an instance of only |
| 941 | one class, though structurally it may be used in place of an instance of any |
| 942 | of that class's superclasses. It is possible, with care, to change the class |
| 943 | of an instance at run-time. |
| 944 | |
| 945 | Classes are themselves represented as instances -- called \emph{class |
| 946 | objects} -- in the running program. Being instances, they have a class, |
| 947 | called the \emph{metaclass}. The metaclass defines the structure and |
| 948 | behaviour of the class object. |
| 949 | |
| 950 | The predefined class @|SodClass| is the default metaclass for new classes. |
| 951 | @|SodClass| has @|SodObject| as its only direct superclass. @|SodClass| is |
| 952 | its own metaclass. |
| 953 | |
| 954 | \subsection{Items and inheritance} |
| 955 | |
| 956 | A class definition also declares \emph{slots}, \emph{messages}, |
| 957 | \emph{initializers} and \emph{methods} -- collectively referred to as |
| 958 | \emph{items}. In addition to the items declared in the class definition -- |
| 959 | the class's \emph{direct items} -- a class also \emph{inherits} items from |
| 960 | its superclasses. |
| 961 | |
| 962 | The precise rules for item inheritance vary according to the kinds of items |
| 963 | involved. |
| 964 | |
| 965 | Some object systems have a notion of `repeated inheritance': if there are |
| 966 | multiple paths in the superclass graph from a class to one of its |
| 967 | superclasses then items defined in that superclass may appear duplicated in |
| 968 | the subclass. Sod does not have this notion. |
| 969 | |
| 970 | \subsubsection{Slots} |
| 971 | A \emph{slot} is a unit of state. In other object systems, slots may be |
| 972 | called `fields', `member variables', or `instance variables'. |
| 973 | |
| 974 | A slot has a \emph{name} and a \emph{type}. The name serves only to |
| 975 | distinguish the slot from other direct slots defined by the same class. A |
| 976 | class inherits all of its proper superclasses' slots. Slots inherited from |
| 977 | superclasses do not conflict with each other or with direct slots, even if |
| 978 | they have the same names. |
| 979 | |
| 980 | At run-time, each instance of the class holds a separate value for each slot, |
| 981 | whether direct or inherited. Changing the value of an instance's slot |
| 982 | doesn't affect other instances. |
| 983 | |
| 984 | \subsubsection{Initializers} |
| 985 | Mumble. |
| 986 | |
| 987 | \subsubsection{Messages} |
| 988 | A \emph{message} is the stimulus for behaviour. In Sod, a class must define, |
| 989 | statically, the name and format of the messages it is able to receive and the |
| 990 | values it will return in reply. In this respect, a message is similar to |
| 991 | `abstract member functions' or `interface member functions' in other object |
| 992 | systems. |
| 993 | |
| 994 | Like slots, a message has a \emph{name} and a \emph{type}. Again, the name |
| 995 | serves only to distinguish the message from other direct messages defined by |
| 996 | the same class. Messages inherited from superclasses do not conflict with |
| 997 | each other or with direct messages, even if they have the same name. |
| 998 | |
| 999 | At run-time, one sends a message to an instance by invoking a function |
| 1000 | obtained from the instance's \emph{vtable}: \xref{sec:fixme-vtable}. |
| 1001 | |
| 1002 | \subsubsection{Methods} |
| 1003 | A \emph{method} is a unit of behaviour. In other object systems, methods may |
| 1004 | be called `member functions'. |
| 1005 | |
| 1006 | A method is associated with a message. When a message is received by an |
| 1007 | instance, all of the methods associated with that message on the instance's |
| 1008 | class or any of its superclasses are \emph{applicable}. The details of how |
| 1009 | the applicable methods are invoked are described fully in |
| 1010 | \xref{sec:fixme-method-combination}. |
| 1011 | |
| 1012 | \subsection{Chains and instance layout} |
| 1013 | |
| 1014 | \include{sod-backg} |
| 1015 | \include{sod-protocol} |
| 1016 | |
| 1017 | \end{document} |
| 1018 | \f |
| 1019 | %%% Local variables: |
| 1020 | %%% mode: LaTeX |
| 1021 | %%% TeX-PDF-mode: t |
| 1022 | %%% End: |