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Description of the helper program stic*/bin/cgen
cgen is copyright 2001 to 2007, Thomas Schmitt <>
and provided under BSD license.
cc -g -o cgen cgen.c ctyp.c smem.c
cgen produces a class stub in C programming language. The data structure of
the class is described by some lines which get read from stdin. The stub will
consist of four files which emerge in the current working directory:
<classname>.h public header file of the class
<classname>.c automatically generated C code of the class
plus a copy of <classname>.c.methods
<classname>_private.h private header file of the class
<classname>.c.methods safe storage for manually created functions.
From here they get copied into the generated stub.
If such a file is missing, a dummy gets created.
It will define a struct <ClassnamE> for representing the class data aspects,
construtor <Classname>_new(), destructor <Classname>_destroy(),
getter <Classname>_<element>_get() for each structure element.
Some more functions get added for particular class and element roles.
cgen normally refuses to overwrite existing files because it supposes that
those contain code added by the human programmer.
Human programmer enhancements may be explanatory comments, class specific
methods, initial element values and other special precautions within the
generated functions.
As long as the modelling phase is going on, one may store such human code
in <classname>.c.methods and may use command line option -overwrite for
modelling development cycles.
At some point of model matureness one may decide to give up cgen and the
.c.method files and to go on only with _private.h , .h and .c files.
Command line options
-no_stic prevents usage of stic_dir/s_tools/*.[ch]
-ansi generates ANSI C function heads and makes file <classname>.h hold
only public definitions: an opaque declaration of the class struct
and a list of function prototypes. The definiton of the class
struct is then in <classname>_private.h .
-global_include filename
sets the name of a file which will contain globally necessary
declarations. Currently it lists the existence of all class
-lowercase generate struct <classname> rather than struct <ClassnamE> and
function names <classname>_func() rather than <Classname>_func() .
-overwrite allows to overwrite files <classname>_private.h, <classname>.h
and <classname>.c, but not <classname>.c.methods.
Input line format:
There are two states of input: class level and element level.
Exampes are shown below with class roles and element roles.
Input starts at class level. A class level line may be one of
- Comment. A line which begins with '#' is ignored on class level.
- Empty. A line with no characters is a comment with empty text (i.e. ignored).
- Class. Options which begin with '-' and finally a word in lowercase letters
which defines the <classname>. The classname leads to a struct ClassnamE
and some class methods implemented as C functions <Classnname>_<func>().
- End of input. Line "@@@" or EOF at stdin end the program run.
After a class line, input switches to element level where a line may be:
- Comment. A line which after some white space begins with '#' is considered
a comment. The preceeding white space is ignored and the text after '#' is
eventuellay trimmed by a single blank at both ends. This text will be part
of the class struct definition within file <classname_private>.h as a single
C comment line /* ... */. The sequence of elements and comments is preserved.
An empty comment text leads to an empty line in <classname_private>.h.
- Empty. A line with no characters is a comment with empty text.
- Element. Options which begin with '-', eventual C keywords "unsigned" or
"volatile", type or "struct <NamE>", element name. This leads to a struct
element which is taken into respect in some class methods. Depending on the
options in this line, some element methods <Classnname>_<func>_<element>()
may get generated.
- End of class. A single '@' marks the end of the element list and brings
input back to class level. I.e. next is expected another class name or
"@@@" or EOF at stdin.
Input semantics:
A class can have one of two roles:
- Standalone class.
Input example:
- Listable class, which has pointers to peer instances: .prev and .next
Such classes get a list destructor <Classname>_destroy_all() which destroys
all members of a list (which is given by any of the list members).
Such a class should have a pointer *boss as first element in which case
the constructor will look like
<Classname>_new(struct <ClassnamE> **o,struct <Some_clasS> *boss,int flag);
There is a function <Classname>_link() which inserts an instance into a list
and a function <Classname>_count() which tells the number of list members.
For pseudo random access there is function <Classname>_by_idx().
Input example:
-l my_class
A modifier is defined for classes:
- Bossless. Disables a special boss-subordinate relationship which is created
if the first element of a class is a struct pointer with the name "boss".
-l <classname>
-v struct Some_clasS *boss
Normally such a parameter *boss becomes part of the constructor method
<Classname>_new(struct <ClassnamE> **o, struct Some_clasS *boss, int flag);
This relationship is typical for a listable class and a single class which
is designed to host instances of that listable class. Therefore one gets a
warning if a listable class does not begin with a struct pointer *boss.
But if -b is given, then CgeN ill not include a parameter *boss into the
constructor. It will rather look normal:
<Classname>_new(struct <ClassnamE> **o, int flag);
It will not warn if the first element of a listable class is not struct
pointer *boss.
Elements have one of the following roles:
- Value. It provides only storage for a C data type (which may be a C pointer
despite the role name "value"), a getter method <Classname>_<element>_get(),
and a setter method <Classname>_<element>_set().
Input examples:
-v int i
-v int a[100]
-v char *cpt
-v struct xyz x
-v struct xyz *xpt
- Managed. This has to be a pointer to a struct <XyZ> or to char. It will not
get attached to an object by the stub's code but its destructor
<Xyz>_destroy() will be called by <Classname>_destruct(). In case of (char *)
it is supposed that a non-NULL value has been allocated by malloc().
Managed (char *) types get a setter function <Classname>_<element>_set()
which allocates memory and copies the textstring from its parameter.
Input examples:
-m struct XyZ *xyzpt
-m char *textstring
- Chainlink. A pair of prev-next-style pointers to the own class struct.
Function <Classname>_destruct() will unlink the affected instance and
put together its link partners.
Input example (there must always be two consequtive -c lines):
-c struct My_clasS *up
-c struct My_clasS *down
- List. A pair of pointers to the struct <XyZ> of a listable class. The first
one <ls> holds the start of the list, the second one <eol> holds the end.
The getter function has an additional argument idx:
<Classname>_get_<ls>(struct <ClassnamE> *o, int idx, struct <XyZ> **pt,
int flag)
idx == 0 is the start of the list, idx=1 the next element, ...
idx == -1 retrieves the last element of the list.
For insertion of list items there is provided method <Classname>_new_<ls>().
The inserted item is reachable via the getter function with idx == -1
<Classname>_destroy() instance calls <Xyz>_destroy_all(). Note that the end
pointer is always generated as private element (-p).
Input example (there must always be a -l and a -v line):
-l struct XyZ *list_start
-v struct XyZ *list_end
The availability of getter method <Classname>_get_<element>(), and setter
method <Classname>_set_<element>_set() can be controled by two modifiers:
- Readonly. Only a getter method.
Input example
-r -v int broadcasted_status
- Private. Neither getter nor setter method.
Input example
-p -v int private_value
- Bossless listable. This marks elements which are listable objects but do not
expect a boss pointer in their constructor. See above: Listable class and
the bossless modifier for classes.
Input example
-b -l struct XyZ *list
-v struct XyZ *last_in_list
- Initialization free. The class constructor will not initialize this element.
This modifier has to be used if neither NULL nor 0 are suitable
initialization values.
Example run:
rm class_x.c class_x.h class_y.c class_y.h
bin/cgen <<+
-l class_x
-r -v struct Boss_clasS *boss
-v int x
-r -v struct stat stbuf
-m struct Class_Y *y
-m char *text
-c struct Class_X *master
-c struct Class_X *slave
-b -l struct Class_X *provider
-p -v struct Class_X *last_provider
-b -l class_y
-r -v char providername[80]