quakeforge/tools/qfcc/doc/qfcc.lyx

#LyX 1.1 created this file. For more info see http://www.lyx.org/
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\language american
\inputencoding latin1
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\papersize letterpaper
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\use_geometry 1
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\secnumdepth 2
\tocdepth 2
\paragraph_separation skip
\defskip medskip
\quotes_language english
\quotes_times 2
\papercolumns 1
\papersides 2
\paperpagestyle headings

\layout Title

The Ruamoko Programming Language
\layout Author

Bill Currie 
\begin_inset Formula \( \bullet  \)
\end_inset 

 Jeff Teunissen
\layout Publishers

QuakeForge Press
\newline 
;-)
\layout Uppertitleback

This manual is free; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 2 of the License, or (at your option) any later
 version.
\newline 

\newline 
This manual is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.
 See the GNU General Public License for more details.
\newline 

\newline 
You should have received a copy of the GNU General Public License along
 with this manual: if not, write to:
\newline 

\newline 
Free Software Foundation, Inc.
\newline 
59 Temple Place - Suite 330
\newline 
Boston MA 02111-1307
\newline 
USA
\layout Lowertitleback

Copyright © 2002 Bill Currie and Jeff Teunissen
\layout Standard


\begin_inset LatexCommand \tableofcontents{}

\end_inset 


\layout Addchap

Preface
\layout Standard

In December 1996, Id Software released 
\emph on 
Quake
\emph default 
 to the world.
 It's doubtful that they knew at the time that it would spark a revolution
 -- but such a revolution happened.
 To the game industry's surprise, people were getting the game not just
 to play it, but to 
\emph on 
change
\emph default 
 it\SpecialChar \@.
 For the first time, people could make whole new games based on the Quake
 engine without having to rewrite the whole game -- and in fact you couldn't
 rewrite the whole game, because the main source code wasn't available to
 the general public.
 What 
\series bold 
was
\series default 
 available was something new -- the game wasn't just a game, it was a virtual
 machine that had a byte-code instruction set -- and it had a compiler that
 you could use to make new games to run inside that engine.
 The language (called 
\emph on 
QuakeC
\emph default 
) was kind of crude, and the compiler was even more crude -- but it was
 a revolutionary development.
\layout Standard

Now, let's fast-forward to another December -- this time, December 1999.
 In another revolutionary move, Id Software released the source code to
 the complete Quake engine.
 This gave many people the opportunity to do a lot more than just make 
\begin_inset Quotes eld
\end_inset 

mods
\begin_inset Quotes erd
\end_inset 

 for Quake.
 Instead, people could make all-new games without using Quake itself.
 Many projects started up around this source code, with many aims\SpecialChar \ldots{}
but one
 project grew to be the most dominant: That project is 
\emph on 
QuakeForge
\emph default 
.
\layout Standard

QuakeForge has developed a number of interesting things involving the Quake
 engine, but most of them are beyond the scope of this manual.
 This manual documents the 
\emph on 
Ruamoko
\begin_float footnote 
\layout Standard

The name Ruamoko comes from the Maori name for their god of volcanoes and
 earthquakes.
 According to myth, Ruamoko is not yet born, and when he shakes inside the
 Earth-mother, the world shakes.
\end_float 
 language, a language based on Id Software's QuakeC, but which has been
 expanded in ways far beyond the original language.
\layout Chapter

A Tutorial Introduction
\layout Standard

Let us begin with a quick introduction to Ruamoko.
 Our aim here is to show the basic elements of the language in real programs,
 but without getting bogged down in details or rules.
 At this point, we're not even trying to be complete, or even precise (except
 that the examples are meant to be correct).
 We want to get you as quickly as possible to the point where you can write
 useful programs, and to do that we have to concentrate on the basics: variables
 and constants, arithmetic, flow control, functions, and the rudiments of
 input and output.
 We are intentionally leaving out of this chapter features of Ruamoko that
 are important for writing bigger programs, or programs to run in an actual
 Quake engine.
 These include entities, structures, pointers, most of the operators, objects,
 and the standard builtin library.
\layout Standard

This approach has its drawbacks.
 Most notable is that the complete story on any particular language feature
 is not found here, and the brief tutorial, just by being brief, may be
 misleading.
 And because the examples don't use the full power of Ruamoko, they may
 not be as elegant or concise as they could be; we 
\series bold 
have
\series default 
 tried to minimize these effects, but be warned.
 Another drawback is that later chapters will repeat some of what's presented
 here.
 We hope that the repetition will help more than it annoys.
\layout Standard

In any case, experienced programmers should be able to get an idea, from
 this chapter, of some of the things that can be done in Ruamoko, for their
 own needs.
 Beginners should supplement it by writing small, similar programs of their
 own.
 Both groups can use it as a framework on which to hang the more detailed
 descriptions that begin in later chapters.
\layout Section

Getting Started
\layout Standard

The best way to learn a new programming language is by writing programs
 in it.
 The first program one writes is almost always the same for all new languages:
 print the phrase 
\begin_inset Quotes eld
\end_inset 

Hello, world!
\begin_inset Quotes erd
\end_inset 

 on the screen.
\layout Standard

This is the big hurdle.
 To get past it, you have to be able to create the program text somewhere,
 compile it, load it successfully, load it, run it, and find out where the
 output went.
 With these mechanical details mastered, everything else is relatively easy.
\layout Standard

In Ruamoko, the program to print 
\begin_inset Quotes eld
\end_inset 

Hello, world!
\begin_inset Quotes erd
\end_inset 

 is:
\layout LyX-Code

#include <qwaq/globals.rh>
\newline 
#include <qwaq/fields.rh>
\newline 
#include <qwaq/builtins.rh>
\newline 

\newline 
void () main =
\newline 
{
\newline 
    printf ("Hello, world!
\backslash 
n");
\newline 
};
\layout Standard

To run this program, you first have to compile it.
 To compile it, you need to save the source code into a file (for example,
 
\family typewriter 
hello.r
\family default 
), and create a 
\family typewriter 
progs.src
\family default 
 file to tell the compiler how to compile it.
 Here is an example 
\family typewriter 
progs.src
\family default 
 file:
\layout LyX-Code

qwaq.dat
\newline 
hello.r
\layout Standard

The first line of 
\family typewriter 
progs.src
\family default 
 tells the compiler the name of the compiled object file that it is supposed
 to save to disk after compilation.
 Following lines tell it the names of files that are to be used to compile
 that object file.
 To compile the source, issue the command
\layout LyX-Code

qfcc
\layout Standard

If you haven't screwed anything up, such as omitting a character or misspelling
 something, the compilation will proceed silently.
 You should be rewarded with something that looks something like the following:
\layout LyX-Code

   208 strofs
\newline 
     4 statements
\newline 
    14 functions
\newline 
    30 globaldefs
\newline 
     0 locals size ((null))
\newline 
     8 fielddefs
\newline 
    52 pr_globals
\newline 
     6 entityfields
\newline 
  1316 TOTAL SIZE
\newline 
Compilation time: 0.0365 seconds.
\layout Standard

You run 
\family typewriter 
qwaq.dat
\family default 
 by issuing the command
\layout LyX-Code

qwaq
\layout Standard

the program should print
\layout LyX-Code

Hello, world!
\layout Standard

to your screen.
\layout Standard

Now, for some explanations regarding the program itself.
 All Ruamoko programs, regardless of size, consist mainly of 
\emph on 
functions
\emph default 
 and 
\emph on 
variables
\emph default 
.
 A function contains statements that tell the compiler what computing operations
 you want to do, and variables store values used during the operation of
 the program.
 Ruamoko functions are roughly equivalent to C's functions, or Pascal's
 procedures and functions.
 Our example is a function called 
\family typewriter 
main
\family default 
.
 You can create functions with just about any name you like, but 
\begin_inset Quotes eld
\end_inset 


\family typewriter 
main
\family default 

\begin_inset Quotes erd
\end_inset 

 is special -- program execution begins there
\begin_float footnote 
\layout Standard

This is not precisely true.
 When used in a game engine, there are certain other functions that are
 called by the engine during the course of a game.
\end_float 
.
 This means that every program must have a 
\family typewriter 
main
\family default 
 function somewhere.
\layout Standard

Main will usually call other functions to do its job -- some of them you
 write, and some of them are provided by the virtual machine your program
 runs inside.
 The first lines of the program,
\layout LyX-Code

#include <qwaq/globals.rh>
\newline 
#include <qwaq/fields.rh>
\newline 
#include <qwaq/builtins.rh>
\layout Standard

tell the compiler to include information about the standard variables, constants
, 
\emph on 
fields
\emph default 
, and 
\emph on 
builtins
\emph default 
 (also known as 
\emph on 
engine functions
\emph default 
) provided by the environment
\begin_float footnote 
\layout Standard

The environment will be described later.
\end_float 
.
\layout Standard

One way of communicating data between functions is for the calling function
 to provide a list of values, called arguments, to the function it calls.
 The parentheses after the function's name surround the argument list.
 In this example, main is defined to be a function that expects no arguments,
 which is indicated by an empty list:\SpecialChar ~

\family typewriter 
()
\family default 
.
\layout Standard

The statements of a function are enclosed in curly braces,\SpecialChar ~

\family typewriter 
{}
\family default 
.
 The function 
\family typewriter 
main
\family default 
 contains only one statement,
\layout LyX-Code

printf ("Hello, world!
\backslash 
n");
\layout Standard

A function is called by giving its name, followed by a list of arguments
 enclosed by parentheses, so this calls the function 
\family typewriter 
printf
\family default 
 with the argument 
\family typewriter 
"Hello, world!
\backslash 
n"
\family default 
.
 
\family typewriter 
printf
\family default 
 is a builtin function that prints output, in this case the string of characters
 between the quotes.
\layout Standard

A sequence of characters between double quotes, like 
\family typewriter 
"Hello, world!
\backslash 
n"
\family default 
, is called a 
\emph on 
string constant
\emph default 
 or simply a 
\emph on 
string
\emph default 
.
 For the moment, our only use of strings will be as arguments for 
\family typewriter 
printf
\family default 
 and other functions.
\layout Standard

The sequence 
\family typewriter 

\backslash 
n
\family default 
 in the string is Ruamoko notation for the 
\emph on 
newline character
\emph default 
, which when printed tells the terminal (or a game client) to advance to
 the next line in the output.
 If you leave out the 
\family typewriter 

\backslash 
n
\family default 
, you will find that there is no advance after the character string is printed.
 You must use 
\family typewriter 

\backslash 
n
\family default 
 to include a newline character in the printf argument; if you try something
 like
\layout LyX-Code

printf ("Hello, world!
\newline 
");
\layout Standard

the Ruamoko compiler will give you an error message.
\layout Standard


\family typewriter 
printf
\family default 
 never supplies a newline automatically, so several calls may be used to
 build up an output line in stages.
 Our first program could just as easily been written as
\layout LyX-Code

#include <qwaq/globals.rh>
\newline 
#include <qwaq/fields.rh>
\newline 
#include <qwaq/builtins.rh>
\newline 

\newline 
void () main =
\newline 
{
\newline 
    printf ("Hello, ");
\newline 
    printf ("world!");
\newline 
    printf ("
\backslash 
n");
\newline 
};
\layout Standard

and it would have produced identical output.
\layout Standard

Note that 
\backslash 
n represents only a single character.
 An escape character like 
\backslash 
n gives you a general way to express hard-to-type or invisible characters.
 Among the others are 
\backslash 
t for a tab, 
\backslash 
b for a backspace, 
\backslash 
" for a double-quote, and 
\backslash 

\backslash 
 for the backslash character itself.
 There is a complete list in [section]
\layout Section

Variables and Mathematical Expressions
\layout Chapter

Language Reference
\layout Standard

This is currently just new stuff in 
\family typewriter 
\series bold 
qfcc
\family default 
\series default 
.
\layout Section

New Type Features
\layout Subsection

New Types
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
integer
\family default 
 32 bit signed integer
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
id
\family default 
 generic object pointer
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
Class
\family default 
 class object pointer
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
Protocol
\family default 
 protocol object pointer
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
Method
\family default 
 method pointer
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
SEL
\family default 
 selector
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
IMP
\family default 
 message implementation
\layout Standard


\family typewriter 
id
\family default 
, 
\family typewriter 
Class
\family default 
, 
\family typewriter 
Protocol
\family default 
, 
\family typewriter 
Method
\family default 
, 
\family typewriter 
SEL
\family default 
 and 
\family typewriter 
IMP
\family default 
 are part of 
\family typewriter 
\series bold 
qfcc
\family default 
\series default 
's Objective-QC extensions.
\layout Subsection

Enumerators
\layout Standard

as per C
\layout Subsection

Structures
\layout LyX-Code

struct foo {
\newline 
    integer bar;
\newline 
    float baz;
\newline 
    void () func;
\newline 
};
\layout Standard

Structures with no elements can be declared for making opaque types (particularl
y useful for engine interface functions).
\layout Subsection

Arrays
\layout LyX-Code

integer [13] array;
\layout Subsection

Pointers
\layout Standard

Pointers are declared the same way as arrays, but with no number in the
 
\family typewriter 
[]
\family default 
s.
 In fact, arrays are just pointers with limited (compile-time) bounds checking
 (constant indices).
\layout Subsection

Complex types
\layout Standard

Complex types can be created by nesting type declarations within 
\family typewriter 
()
\family default 
s.
 e.g.:
\layout LyX-Code

(.float) (string name) find_field;
\layout Standard

declares a function (
\family typewriter 
find_field
\family default 
) taking a string parameter and returning a float field `offset'.
 Without the 
\family typewriter 
()
\family default 
s around the 
\family typewriter 
.float
\family default 
, the declaration would be a function field.
\layout Subsection


\family typewriter 
typedef
\layout Standard

By using 
\family typewriter 
typedef
\family default 
 complex types can be given symbolic names.
 e.g.:
\layout LyX-Code

struct foo_s {};
\newline 
typedef foo_s [] foo_t;
\layout Standard

creates type 
\family typewriter 
foo_t
\family default 
 which is a pointer to the structure 
\family typewriter 
foo_s
\family default 
 (which happens to be opaque).
\layout Subsection

Variable-argument functions
\layout Standard

Typed parameters preceding the ellipsis are allowed, e.g.: 
\family typewriter 
void (string fmt, ...) printf;
\layout Standard

More importantly, it is now possible to write vararg functions in QC.
 
\family typewriter 
@argc
\family default 
 gives the number of parameters passed through the ellipsis and 
\family typewriter 
@argv
\family default 
 is an array of vectors representing the parameters passed through 
\family typewriter 
...
\family default 
.
\layout Standard


\series bold 
\emph on 
Warning: attempting to pass 
\family typewriter 
@argv
\family default 
 to a non-engine function will not work.
 This is because of changes in how local variables are handled by the compiler.
\layout Subsection

Improved type checking
\layout Standard

Function parameters and return types are are fully checked, including the
 number of parameters passed to a function.
 Functions with different return types and/or different parameter types
 or counts are distinct types and mixing them up will cause a type mismatch
 error.
 Similar for pointers to various types.
\layout Section

Variables
\layout Subsection

Local variables
\layout Subsubsection

Initialization
\layout Standard

Local variables of basic types can now be initialized when declared.
 e,g,
\layout Verse


\family typewriter 
local integer elite = 31337;
\layout Subsubsection

Unused variables
\layout Standard

Local variables that are declared but not used produce a warning.
\layout Subsubsection

Uninitialized variables
\layout Standard

Checks are done to ensure that local variables have been initialized before
 being used.
 However, these checks are not perfect and false positives are very likely
 in complex code.
 Occurrences of false negatives are not known, but the possibility of their
 existence remains and any examples of false negatives should be reported
 as bugs.
\layout Subsection

Complex global variables
\layout Standard

Global array variables can be initialized using 
\family typewriter 
= { 
\emph on 
element-list
\emph default 
 };
\family default 
.
 Element lists may be nested using 
\family typewriter 
{}
\family default 
.
 Structures cannot currently be initialized, but this is a FIXME :)
\layout Subsection

Magic variables
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@self
\family default 
 Automagically declared entity variable the engine will use for 
\family typewriter 
touch
\family default 
 and 
\family typewriter 
think
\family default 
 functions.
 This allows 
\family typewriter 
self
\family default 
 to be used as the object hidden parameter in methods.
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@this
\family default 
 Automagically declared 
\family typewriter 
id
\family default 
 field that the engine expects to point to the object associated with the
 entity.
 The engine will use this field, if it exists, to set the 
\family typewriter 
self
\family default 
 parameter to 
\family typewriter 
touch
\family default 
 and 
\family typewriter 
think
\family default 
 methods (the engine assumes it's calling a method rather than a function
 if the @this field is used.
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@argc
\family default 
 Number of parameters passed through 
\family typewriter 
...

\family default 
 in vararg functions.
 Not valid elsewhere.
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@argv
\family default 
 Array of vectors representing the parameters passed through 
\family typewriter 
...

\family default 
 in vararg functions.
 Not valid elsewhere.
\layout Section

Code constructs
\layout Subsection


\family typewriter 
break
\layout Standard

The 
\family typewriter 
break
\family default 
 statement can be used to leave a loop (
\family typewriter 
while
\family default 
, 
\family typewriter 
do
\family default 
 ...
 
\family typewriter 
while
\family default 
, or 
\family typewriter 
for
\family default 
) prematurely.
 The 
\family typewriter 
break
\family default 
 statement is also used to leave a 
\family typewriter 
switch
\family default 
 statement.
\layout Subsection


\family typewriter 
continue
\layout Standard

The 
\family typewriter 
continue
\family default 
 statement is used to jump to the beginning of a loop.
 In 
\family typewriter 
for
\family default 
 loops, the test and post expressions are evaluated before continuing with
 the loop.
\layout Subsection


\family typewriter 
for
\layout Standard

The 
\family typewriter 
for
\family default 
 loop is:
\layout LyX-Code

for (
\emph on 
initialization-expression
\emph default 
; 
\emph on 
test-expression
\emph default 
; 
\emph on 
post-expression
\emph default 
)
\layout LyX-Code


\emph on 
    statement
\layout Standard

and is equivalent to
\layout LyX-Code


\emph on 
initialization expression
\layout LyX-Code

while (
\emph on 
test expression
\emph default 
) {
\layout LyX-Code


\emph on 
    statement
\layout LyX-Code


\emph on 
    post expression
\layout LyX-Code

}
\layout Subsection


\family typewriter 
switch
\layout Standard

The 
\family typewriter 
switch
\family default 
 statement is used to select between multiple code blocks based on the value
 of an expression.
\layout LyX-Code

switch (
\emph on 
test expression
\emph default 
) {
\newline 
   case
\emph on 
 value
\emph default 
:
\newline 

\emph on 
        optional statements
\newline 

\emph default 
   case
\emph on 
 value
\emph default 
:
\newline 

\emph on 
        optional statements
\emph default 

\newline 
    default:
\newline 

\emph on 
        optional statements
\emph default 

\newline 
}
\layout Standard

Code execution starts at the selected 
\family typewriter 
case
\family default 
 and continues on to the end of the switch block.
 Following 
\family typewriter 
case
\family default 
s do 
\emph on 
not
\emph default 
 affect code execution.
 If this behavior is not desired, as is usual, then a 
\family typewriter 
break
\family default 
 statement is required to cause the code to jump to the end of the 
\family typewriter 
switch
\family default 
, skipping any intervening code.
 That is, just like C.
\layout Subsubsection


\family typewriter 
\emph on 
test expression
\layout Standard

The test expression may result in a float, string or integer value.
\layout Subsubsection


\family typewriter 
case 
\emph on 
value
\layout Verse


\family typewriter 
case 
\emph on 
value
\emph default 
:
\layout Standard

The case value may be of any constant type consistent with the test expression
 of the 
\family typewriter 
switch
\family default 
.
\layout Subsubsection


\family typewriter 
default
\layout Standard

If specified, this is where execution will go when no 
\family typewriter 
case
\family default 
 has been selected by the test expression.
 If not specified, and no 
\family typewriter 
case
\family default 
 has been selected by the test expression, the 
\family typewriter 
switch
\family default 
 does not execute any code within the block.
\layout Section

Expressions
\layout Subsection

Binary
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
<<\SpecialChar ~
>>
\family default 
 bit shift left and right
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
^
\family default 
 bitwise exclusive or
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
%
\family default 
 modulus
\layout Subsubsection

Assignment
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
\emph on 
op
\emph default 
= 
\family default 
equivalent to 
\family typewriter 
a = a 
\emph on 
op 
\emph default 
b
\family default 
.
\layout Subsection

Unary
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
~
\family default 
 bitwise not
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
&
\family default 
 address
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
++
\emph on 
e
\emph default 
\SpecialChar ~
--
\emph on 
e
\family default 
\emph default 
 pre-increment and decrement
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
\emph on 
e
\emph default 
++\SpecialChar ~

\emph on 
e
\emph default 
--
\family default 
 post-increment and decrement
\layout Subsection

Other
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
\emph on 
type\SpecialChar ~

\emph default 
(
\emph on 
expr
\emph default 
)
\family default 
 cast expression.
 Only works for converting between integer and float types and between pointer
 types.
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
\emph on 
expr
\emph default 
[
\emph on 
expr
\emph default 
] 
\family default 
array indexing.
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
\emph on 
expr
\emph default 
?
\emph on 
expr
\emph default 
:
\emph on 
expr 
\family default 
\emph default 
C's trinary expression
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
[
\emph on 
expr
\emph default 
\SpecialChar ~

\emph on 
exprs
\emph default 
]
\family default 
 Objective-QC message
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@selector(
\emph on 
exprs
\emph default 
)
\family default 
 Objective-QC selector expression
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@protocol(
\emph on 
name
\emph default 
)
\family default 
 Objective-QC protocol expression
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@encode(
\emph on 
type
\emph default 
)
\family default 
 Objective-QC type encoding expression
\layout List
\labelwidthstring 00.00.0000


\family typewriter 
@
\emph on 
string
\family default 
\emph default 
 Objective-QC string object.
 Currently identical to a normal QC string.
\the_end