X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/fa548bb16473fff2f7bb9715e3bdf25e41464bf6..4b3a72700ae8799ba6ba07969e2677f2168d32a9:/doc/syntax.tex

diff --git a/doc/syntax.tex b/doc/syntax.tex
index 5e17ff3..6c05acc 100644
--- a/doc/syntax.tex
+++ b/doc/syntax.tex
@@ -51,20 +51,20 @@ could be a token.
 
 <id-start-char> ::= <alpha-char> | "_"
 
-<id-body-char> ::= <id-start-char> @! <digit-char>
+<id-body-char> ::= <id-start-char> | <digit-char>
 
-<alpha-char> ::= "A" | "B" | \dots\ | "Z"
-\alt "a" | "b" | \dots\ | "z"
-\alt <extended-alpha-char>
+<alpha-char> ::= "A" | "B" | $\cdots$ | "Z"
+  | "a" | "b" | $\cdots$ | "z"
+  | <extended-alpha-char>
 
 <digit-char> ::= "0" | <nonzero-digit-char>
 
-<nonzero-digit-char> ::= "1" | "2" $| \ldots |$ "9"
+<nonzero-digit-char> ::= "1" | "2" | $\cdots$ | "9"
 \end{grammar}
 
 The precise definition of @<alpha-char> is left to the function
-\textsf{alpha-char-p} in the hosting Lisp system.  For portability,
-programmers are encouraged to limit themselves to the standard ASCII letters.
+@|alpha-char-p| in the hosting Lisp system.  For portability, programmers are
+encouraged to limit themselves to the standard ASCII letters.
 
 There are no reserved words at the lexical level, but the higher-level syntax
 recognizes certain identifiers as \emph{keywords} in some contexts.  There is
@@ -80,11 +80,11 @@ level.
 
 <char-literal> ::= "'" <char-literal-char> "'"
 
-<string-literal-char> ::= any character other than "\\" or "\""
-\alt "\\" <char>
+<string-literal-char> :: "\\" <char>
+  | any character other than "\\" or "\""
 
-<char-literal-char> ::= any character other than "\\" or "'"
-\alt "\\" <char>
+<char-literal-char> :: "\\" <char>
+  | any character other than "\\" or "'"
 
 <char> ::= any single character
 \end{grammar}
@@ -101,25 +101,25 @@ discouraged.
 
 \begin{grammar}
 <integer-literal> ::= <decimal-integer>
-\alt <binary-integer>
-\alt <octal-integer>
-\alt <hex-integer>
+  | <binary-integer>
+  | <octal-integer>
+  | <hex-integer>
 
 <decimal-integer> ::= "0" | <nonzero-digit-char> @<digit-char>^*
 
-<binary-integer> ::= "0" @("b"|"B"@) @<binary-digit-char>^+
+<binary-integer> ::= "0" @("b" | "B"@) @<binary-digit-char>^+
 
 <binary-digit-char> ::= "0" | "1"
 
-<octal-integer> ::= "0" @["o"|"O"@] @<octal-digit-char>^+
+<octal-integer> ::= "0" @["o" | "O"@] @<octal-digit-char>^+
 
-<octal-digit-char> ::= "0" | "1" $| \ldots |$ "7"
+<octal-digit-char> ::= "0" | "1" | $\cdots$ | "7"
 
-<hex-integer> ::= "0" @("x"|"X"@) @<hex-digit-char>^+
+<hex-integer> ::= "0" @("x" | "X"@) @<hex-digit-char>^+
 
 <hex-digit-char> ::= <digit-char>
-\alt "A" | "B" | "C" | "D" | "E" | "F"
-\alt "a" | "b" | "c" | "d" | "e" | "f"
+  | "A" | "B" | "C" | "D" | "E" | "F"
+  | "a" | "b" | "c" | "d" | "e" | "f"
 \end{grammar}
 
 Sod understands only integers, not floating-point numbers; its integer syntax
@@ -130,15 +130,16 @@ binary.  However, length and signedness indicators are not permitted.
 \subsection{Punctuation} \label{sec:syntax.lex.punct}
 
 \begin{grammar}
-<punctuation> ::= any nonalphanumeric character other than "_", "\"" or "'"
+<punctuation> ::= "<<" | ">>" | "||" | "&&"
+  | "<=" | ">=" | "==" | "!=" | "\dots"
+\alt any nonalphanumeric character other than "_", "\"", or "'"
 \end{grammar}
 
 
 \subsection{Comments} \label{sec:syntax.lex.comment}
 
 \begin{grammar}
-<comment> ::= <block-comment>
-\alt <line-comment>
+<comment> ::= <block-comment> | <line-comment>
 
 <block-comment> ::=
   "/*"
@@ -190,9 +191,9 @@ during translation.  They are read using a simple scanner which nonetheless
 understands C comments and string and character literals.
 
 A C fragment is terminated by one of a small number of delimiter characters
-determined by the immediately surrounding context -- usually a closing brace
-or bracket.  The first such delimiter character which is not enclosed in
-brackets, braces or parenthesis ends the fragment.
+determined by the immediately surrounding context -- usually some kind of
+bracket.  The first such delimiter character which is not enclosed in
+brackets, braces or parentheses ends the fragment.
 
 %%%--------------------------------------------------------------------------
 \section{C types} \label{sec:syntax.type}
@@ -323,7 +324,7 @@ defined in the built-in module.
 <abstract-declarator> ::= <declarator>$[\epsilon, \mbox{@<argument-list>}]$
 
 <argument-declarator> ::=
-  <declarator>$[\mbox{@<identifier> @! $\epsilon$}, \mbox{@<argument-list>}]$
+  <declarator>$[\mbox{@<identifier> | $\epsilon$}, \mbox{@<argument-list>}]$
 
 <simple-declarator> ::=
   <declarator>$[\mbox{@<identifier>}, \mbox{@<argument-list>}]$
@@ -351,7 +352,7 @@ keyword arguments.
   @[<list>$[\mbox{@<argument>}]$@]
   "?" @[<list>$[\mbox{@<keyword-argument>}]$@]
 
-<method-argument-list> ::= <argument-list> @! <keyword-argument-list>
+<method-argument-list> ::= <argument-list> | <keyword-argument-list>
 
 <dotted-name> ::= <identifier> "." <identifier>
 
@@ -367,18 +368,53 @@ keyword arguments.
 
 <property> ::= <identifier> "=" <expression>
 
-<expression> ::= <term> | <expression> "+" <term> | <expression> "--" <term>
+<expression> ::= <logical-or>
 
-<term> ::= <factor> | <term> "*" <factor> | <term> "/" <factor>
+<logical-or> ::= <logical-and>
+  | <logical-or> "||" <logical-and>
 
-<factor> ::= <primary> | "+" <factor> | "--" <factor>
+<logical-and> ::= <bitwise-or>
+  | <logical-and> "&&" <bitwise-or>
+
+<bitwise-or> ::= <bitwise-xor>
+  | <bitwise-or> "|" <bitwise-xor>
+
+<bitwise-xor> ::= <bitwise-and>
+  | <bitwise-xor> "^" <bitwise-and>
+
+<bitwise-and> ::= <equality>
+  | <bitwise-and> "&" <equality>
+
+<equality> ::= <ordering>
+  | <equality> "==" <ordering>
+  | <equality> "!=" <ordering>
+
+<ordering> ::= <shift>
+  | <ordering> "<" <shift>
+  | <ordering> "<=" <shift>
+  | <ordering> ">=" <shift>
+  | <ordering> ">" <shift>
+
+<shift> ::= <additive>
+  | <shift> "<<" <additive>
+  | <shift> ">>" <additive>
+
+<additive> ::= <term>
+  | <additive> "+" <term>
+  | <additive> "--" <term>
+
+<term> ::= <factor>
+  | <term> "*" <factor>
+  | <term> "/" <factor>
+
+<factor> ::= <primary>
+  | "!" <factor> | "~" factor
+  | "+" <factor> | "--" <factor>
 
 <primary> ::=
      <integer-literal> | <string-literal> | <char-literal> | <identifier>
-\alt "<" <plain-type> ">"
-\alt "{" <c-fragment> "}"
-\alt "?" <s-expression>
-\alt "(" <expression> ")"
+\alt "<" <plain-type> ">" | "{" <c-fragment> "}" | "?" <s-expression>
+  | "(" <expression> ")"
 \end{grammar}
 
 \emph{Property sets} are a means for associating miscellaneous information
@@ -431,8 +467,8 @@ operators.
 Finally, an S-expression preceded by @|?| causes the expression to be read in
 the current package (which is always @|sod-user| at the start of a module)
 and immediately evaluated (using @|eval|); the resulting value is converted
-into a property value using the \descref{decode-property}[generic
-function]{gf}.
+into a property value using the \descref{gf}{decode-property}[generic
+function].
 
 
 \subsection{Property output types and coercions}
@@ -440,8 +476,8 @@ function]{gf}.
 
 When a property value is inspected by the Sod translator, or an extension, it
 is \emph{coerced} so as to conform to a requested output type.  This coercion
-process is performed by the \descref{coerce-property-value}[generic
-function]{gf}, and additional output types and coercions can be defined by
+process is performed by the \descref{gf}{coerce-property-value}[generic
+function], and additional output types and coercions can be defined by
 extensions.  The built-in output types coercions, from the value types listed
 above, are as follows.
 
@@ -462,10 +498,10 @@ above, are as follows.
 
 \item The @|boolean| output type denotes a boolean value, which may be either
   true or false.  A value of type @|id| is considered true if it is @|true|,
-  @|t|, @|yes|, @|on|, or @|verily|; or false if it is @|false|, @|nil|,
-  @|no|, @|off|, or @|nowise|; it is erroneous to provide any other
-  identifier where a boolean value is wanted.  A value of type @|int| is
-  considered true if it is nonzero, or false if it is zero.
+  @|t|, @|yes|, @|on|, @|yup|, or @|verily|; or false if it is @|false|,
+  @|nil|, @|no|, @|off|, @|nope|, or @|nowise|; it is erroneous to provide
+  any other identifier where a boolean value is wanted.  A value of type
+  @|int| is considered true if it is nonzero, or false if it is zero.
 
 \item The @|symbol| output type denotes a Lisp symbol.
 
@@ -476,7 +512,7 @@ above, are as follows.
   upper; if the name contains letters of both cases, then it is not changed.
   For example, @|foo45| becomes @|FOO45|, or \emph{vice-versa}; but @|Splat|
   remains as it is.  Second, the name is subjected to \emph{separator
-    switching}: all underscores in the name are replaced with hyphens (and
+  switching}: all underscores in the name are replaced with hyphens (and
   \emph{vice-versa}, though hyphens aren't permitted in identifiers in the
   first place).  Finally, the resulting name is interned in the current
   package, which will usually be @|sod-user| unless changed explicitly by the
@@ -512,7 +548,8 @@ above, are as follows.
 \begin{grammar}
 <module> ::= @<definition>^*
 
-<definition> ::= <import-definition>
+<definition> ::= <property-definition> \fixme{undefined}
+\alt <import-definition>
 \alt <load-definition>
 \alt <lisp-definition>
 \alt <code-definition>
@@ -549,9 +586,9 @@ A search is made for a module source file as follows.
 \begin{itemize}
 \item The module name @<string> is converted into a filename by appending
   @`.sod', if it has no extension already.\footnote{%
-    Technically, what happens is \textsf{(merge-pathnames name (make-pathname
-    :type "SOD" :case :common))}, so exactly what this means varies
-    according to the host system.} %
+    Technically, what happens is @|(merge-pathnames name (make-pathname :type
+    "SOD" :case :common))|, so exactly what this means varies according to
+    the host system.} %
 \item The file is looked for relative to the directory containing the
   importing module.
 \item If that fails, then the file is looked for in each directory on the
@@ -561,7 +598,7 @@ A search is made for a module source file as follows.
 \end{itemize}
 At this point, if the file has previously been imported, nothing further
 happens.\footnote{%
-  This check is done using \textsf{truename}, so it should see through simple
+  This check is done using @|truename|, so it should see through simple
   tricks like symbolic links.  However, it may be confused by fancy things
   like bind mounts and so on.} %
 
@@ -578,23 +615,22 @@ A search is made for a Lisp source file as follows.
 \begin{itemize}
 \item The name @<string> is converted into a filename by appending @`.lisp',
   if it has no extension already.\footnote{%
-    Technically, what happens is \textsf{(merge-pathnames name (make-pathname
-    :type "LISP" :case :common))}, so exactly what this means varies
-    according to the host system.} %
+    Technically, what happens is @|(merge-pathnames name (make-pathname :type
+    "LISP" :case :common))|, so exactly what this means varies according to
+    the host system.} %
 \item A search is then made in the same manner as for module imports
   (\xref{sec:syntax-module}).
 \end{itemize}
-If the file is found, it is loaded using the host Lisp's \textsf{load}
-function.
+If the file is found, it is loaded using the host Lisp's @|load| function.
 
 Note that Sod doesn't attempt to compile Lisp files, or even to look for
 existing compiled files.  The right way to package a substantial extension to
 the Sod translator is to provide the extension as a standard ASDF system (or
 similar) and leave a dropping @|foo-extension.lisp| in the module path saying
 something like
-\begin{quote}
-  \textsf{(asdf:load-system :foo-extension)}
-\end{quote}
+\begin{prog}
+  (asdf:load-system :foo-extension)
+\end{prog}
 which will arrange for the extension to be compiled if necessary.
 
 (This approach means that the language doesn't need to depend on any
@@ -634,14 +670,18 @@ declarations instead.
 
 \begin{grammar}
 <code-definition> ::=
-  "code" <identifier> ":" <item-name> @[<constraints>@]
+  "code" <reason> ":" <item-name> @[<constraints>@]
   "{" <c-fragment> "}"
+\alt
+  "code" <reason> ":" <constraints> ";"
+
+<reason> ::= <identifier>
 
 <constraints> ::= "[" <list>$[\mbox{@<constraint>}]$ "]"
 
 <constraint> ::= @<item-name>^+
 
-<item-name> ::= <identifier> @! "(" @<identifier>^+ ")"
+<item-name> ::= <identifier> | "(" @<identifier>^+ ")"
 \end{grammar}
 
 The @<c-fragment> will be output unchanged to one of the output files.
@@ -670,6 +710,27 @@ preprocessor directives in order to declare types and functions for use
 elsewhere in the generated output files.
 
 
+\subsection{Static instance definitions} \label{sec:syntax.module.instance}
+
+\begin{grammar}
+<static-instance-definition> ::=
+  "instance" <identifier> <identifier>
+  @[":" <list>$[\mbox{@<instance-initializer>}]$@] ";"
+
+<instance-initializer> ::= <identifier> "." <identifier> "=" <c-fragment>
+\end{grammar}
+
+Properties:
+\begin{description}
+\item[@"extern"] A boolean flag: if true, then the instance is public, and
+  will be declared in the output header file; if false (the default), then
+  the instance is only available to code defined within the module.
+\item[@"const"] A boolean flag: if true (the default), then the instance is
+  read-only, and may end up in write-protected storage at run-time; if false,
+  then the instance will be writable.
+\end{description}
+
+
 \subsection{Class definitions} \label{sec:syntax.module.class}
 
 \begin{grammar}
@@ -726,8 +787,9 @@ The @<list>$[\mbox{@<identifier>}]$ names the direct superclasses for the new
 class.  It is an error if any of these @<identifier>s does not name a defined
 class.  The superclass list is required, and must not be empty; listing
 @|SodObject| as your class's superclass is a good choice if nothing else
-seems suitable.  It's not possible to define a \emph{root class} in the Sod
-language: you must use Lisp to do this, and it's quite involved.
+seems suitable.  A class with no direct superclasses is called a \emph{root
+class}.  It is not possible to define a root class in the Sod language: you
+must use Lisp to do this, and it's quite involved.
 
 The @<properties> provide additional information.  The standard class
 properties are as follows.
@@ -862,6 +924,9 @@ Properties:
 \begin{description}
 \item[@|message_class|] A symbol naming the Lisp class to use to represent
   the message.
+\item[@|readonly|] A boolean indicating whether the message guarantees not to
+  modify its receiver.  If this is true, the receiver will be declared
+  @"const".
 \item[@|combination|] A keyword naming the aggregating method combination to
   use.
 \item[@|most_specific|] A keyword, either @`first' or @`last', according to
