OOP In Ficl
Upgrading To 4.0
A Ficl dictionary is equivalent to the FORTH "dictionary"; it is where words are stored.
A single dictionary has a single
A Ficl system information structure is used to change default values used
in initializing a Ficl system.
A Ficl system contains a single dictionary, and one or more virtual machines.
A Ficl stack is equivalent to a FORTH "stack". Ficl has three stacks:
The data stack, where integer arguments are stored.
The return stack, where locals and return addresses for subroutine returns are stored.
The float stack, where floating-point arguments are stored. (This stack
is only enabled when
FICL_WANT_FLOAT is nonzero.)
A Ficl virtual machine (or vm) represents a single running instance of the Ficl interpreter.
All virtual machines in a single Ficl system see the same dictionary.
Though Ficl's API offers a great deal of flexibility, most programs
incorporating Ficl simply use it as follows:
Create a single
Add native functions as necessary with
Add constants as necessary with
Create one (or more) virtual machine(s) with
Add one or more scripted functions with
Execute code in a Ficl virtual machine, usually with
but perhaps with
At shutdown, call
ficlSystemDestroy() on the single Ficl system.
The following is a partial listing of functions that interface your
system or program to Ficl. For a complete listing, see
(which is heavily commented). For a simple example, see
Note that as of Ficl 4, the API is internally consistent.
Every external entry point starts with the word
ficl, and the word after that also corresponds
with the first argument. For instance, a word that operates
ficlSystem * will be called
void ficlSystemInformationInitialize(ficlSystemInformation *fsi)
ficlSystemInformation structure to all zeros.
(Actually implemented as a macro.) Use this to initialize a
structure before initializing its members and passing it
ficlSystem *ficlSystemCreate(ficlSystemInformation *fsi)
Initializes Ficl's shared system data structures, and creates the
dictionary allocating the specified number of cells from the heap
(by a call to
ficlMalloc()). If you pass in a
pointer, you will recieve a
ficlSystem using the default
sizes for the dictionary and stacks.
void ficlSystemDestroy(ficlSystem *system)
Reclaims memory allocated for the Ficl system including all
dictionaries and all virtual machines created by
ficlSystemCreateVm(). Note that this will not
automatically free memory allocated by the FORTH memory allocation
ficlWord *ficlDictionarySetPrimitive(ficlDictionary *dictionary, char *name, ficlCode code, ficlUnsigned8 flags)
Adds a new word to the dictionary with the given
name, code pointer, and flags. To add
flags parameter is a bitfield. The valid
For more information on these flags, see
ficlVm *ficlSystemCreateVm(ficlSystem *system)
Creates a new virtual machine in the specified system.
int ficlVmEvaluate(ficlVm *vm, char *text)
the specified C string (zero-terminated) to the given
virtual machine for evaluation. Returns various exception codes (VM_XXXX
in ficl.h) to indicate the reason for returning. Normal exit
condition is VM_OUTOFTEXT, indicating that the VM consumed the string
successfully and is back for more. Calls to
can be nested, and
the function itself is re-entrant, but note that a VM is
static, so you have to take reasonable precautions (for example, use one
VM per thread in a multithreaded system if you want multiple threads to
be able to execute commands).
int ficlVmExecuteXT(ficlVm *vm, ficlWord *pFW)
Same as ficlExec, but takes a pointer to a ficlWord instead of a
string. Executes the word and returns after it has finished. If
executing the word results in an exception, this function will
re-throw the same code if it is nested under another ficlExec family
function, or return the exception code directly if not. This function
is useful if you need to execute the same word repeatedly—you
save the dictionary search and outer interpreter overhead.
void ficlFreeVM(ficlVm *vm)
Removes the VM in question from the system VM list and deletes
the memory allocated to it. This is an optional call, since
ficlTermSystem will do this cleanup for you. This function is
handy if you're going to do a lot of dynamic creation of VMs.
ficlVm *ficlNewVM(ficlSystem *system)
Create, initialize, and return a VM from the heap using
ficlMalloc. Links the VM into the system VM list for later reclamation
ficlWord *ficlSystemLookup(ficlSystem *system, char *name)
Returns the address of the specified word in the main dictionary.
If no such word is found, it returns
The address is also a valid execution token, and can be used in a call to
ficlDictionary *ficlSystemGetDictionary(ficlSystem *system)
ficlDictionary *ficlVmGetDictionary(ficlVm *system)
Returns a pointer to the main system dictionary.
ficlDictionary *ficlSystemGetEnvironment(ficlSystem *system)
Returns a pointer to the environment dictionary. This dictionary
stores information that describes this implementation as required by the
ficlDictionary *ficlSystemGetLocals(ficlSystem *system)
Returns a pointer to the locals dictionary. This function is
defined only if
FICL_WANT_LOCALS is non-zero (see
The locals dictionary is the symbol table for
There are a lot of preprocessor constants you can set at compile-time
to modify Ficl's runtime behavior. Some are required, such as telling
Ficl whether or not the local platform supports double-width integers
some are optional, such as telling Ficl whether or not to use the
extended set of "prefixes" (
The best way to find out more about these constants is to read
yourself. The settings that turn on or off Ficl modules all start with
FICL_WANT. The settings relating to functionality available
on the current platform all start with
One more note about constants. Ficl now ships with a standard place for
you to tweak the Ficl compile-time preprocessor constants.
It's a file called
ficllocal.h, and we guarantee that it
will always ship empty (or with only comments). We suggest that you
put all your local changes there, rather than editing
or editing the makefile. That should make it much easier to integrate
future Ficl releases into your product—all you need do is preserve
your tweaked copy of
ficllocal.h and replace the rest.