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 english
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\quotes_language english
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\layout Standard

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

New Type Features
\layout Subsection

New Types
\layout List
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integer
\family default 
 32 bit signed integer
\layout List
\labelwidthstring 00.00.0000


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


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


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Protocol
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 protocol object pointer
\layout List
\labelwidthstring 00.00.0000


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Method
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 method pointer
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\labelwidthstring 00.00.0000


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SEL
\family default 
 selector
\layout List
\labelwidthstring 00.00.0000


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IMP
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 message imlementation
\layout Standard


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

Enums
\layout Standard

as per C
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Structures
\layout Verse


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struct foo {
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
integer bar;
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
float baz;
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
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 Verse


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integer [13] array;
\layout Subsection

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

Complex types
\layout Standard

Complex types can be created by nesting type declarations within 
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()
\family default 
s.
 eg:
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(.float) (string name) find_field;
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declares a function (
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find_field
\family default 
) taking a string parameter and returning a float field `offset'.
 Without the 
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()
\family default 
s around the 
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.float
\family default 
, the declaration would be a function field.
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typedef
\layout Standard

By using 
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typedef
\family default 
 complex types can be given symbolic names.
 eg:
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struct foo_s {};
\newline 
typedef foo_s [] foo_t;
\layout Standard

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

vararg functions
\layout Standard

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

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


\series bold 
\emph on 
Warning: attempting to pass 
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@argv
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 to another non-engine function will not work due to the 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 missmatch
 error.
 Similar for pointers to various types.
\layout Section

Variables
\layout Subsection

Local variables
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Initialization
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Local variables of basic types can now be initialized when declared.
 eg
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local integer elite = 31337;
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Unused variables
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Local variables that are declared but not used produce a warning.
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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.
 Occurances of false negatives are not known, but the possibility of their
 existance 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 
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= { 
\emph on 
elementlist
\emph default 
 };
\family default 
.
 Element lists may be nested using 
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{}
\family default 
.
 Structures cannot currently be initialized, but this is a FIXME :)
\layout Subsection

Magic variables
\layout List
\labelwidthstring 00.00.0000

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

@this Automagicly declared 
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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 
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self
\family default 
 parameter to 
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touch
\family default 
 and 
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think
\family default 
 methods (the engine assumes it's calling a method rather than a function
 if the @this field is used.
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\labelwidthstring 00.00.0000

@argc Number of parameters passed through 
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...

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

@argv Array of vectors representing the parameters passed through 
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...

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

Code constructs
\layout Subsection


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break
\layout Standard

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


\family typewriter 
continue
\layout Standard

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


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for
\layout Standard

The 
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for
\family default 
 loop is:
\layout Verse


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for (
\emph on 
initialization expression
\emph default 
; 
\emph on 
test expression
\emph default 
; 
\emph on 
post expression
\emph default 
)
\emph on 

\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
statement
\layout Standard

and is equivalent to
\layout Verse


\family typewriter 
\emph on 
initialization expression
\emph default 

\newline 
while (
\emph on 
test expression
\emph default 
) {
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~

\emph on 
statement
\emph default 

\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~

\emph on 
post expression
\emph default 

\newline 
}
\layout Subsection


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switch
\layout Standard

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


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switch (
\emph on 
test expression
\emph default 
) {
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
case
\emph on 
 value
\emph default 
:
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
optional statements
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
case
\emph on 
 value
\emph default 
:
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
optional statements
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
default:
\newline 
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
\SpecialChar ~
optional statements
\newline 
}
\layout Standard

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


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\emph on 
test expression
\layout Standard

The test expression may result in a float, string or integer value.
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case 
\emph on 
value
\layout Verse


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

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


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default
\layout Standard

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

Expressions
\layout Subsection

Binary
\layout List
\labelwidthstring 00.00.0000


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


\family typewriter 
^
\family default 
 bitwise exclusive or
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\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 
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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
\the_end