_BOB AS A MACRO PROCESSOR LIBRARY_
by Brett Dutton


Listing One

/* initialize the bob interface language */
if ( ( bobSock = BobInitialize ( ) ) < 0 ){
   fprintf (stderr,"Unable to initialize Bob\n" );
   exit(1);
}
/* add this socket to the event loop for listening */
XtAppAddInput ( app_context, bobSock, (XtPointer)XtInputReadMask, AppCheckBob, NULL );
/* register the external functions with BOB */
BobAddFunction ( "message", Message );
BobAddFunction ( "error", Error );
/* load up the application defaults macros */
BobLoadFile ( "." APPNAME "rc" ); 
/* create windows for widgets and map them */
XtRealizeWidget ( topLevel );
/* loop for events */
XtAppMainLoop ( app_context );  


Listing Two

int Message ( int argc, VALUE *arg, VALUE *retval  )
{
   char   msg[500]; /* message to put in dialog */
   Arg    xargs[1]; /* New value */
    
   /* make sure that there is 1 args */
   /* make sure that it is a string */
   if ( ! BobExtArgs ( argc, 1, 1, retval ) ) 
      return ( FALSE );
   if ( ! BobExtCheckType ( &arg[0], DT_STRING, retval))
      return ( FALSE );
   BobGetString ( msg, sizeof ( msg ), &arg[0] );
   XtSetArg ( xargs[0], XtNvalue, (XtArgVal)msg );
   XtSetValues ( message, xargs, 1 );
   return ( BobReturnValue ( retval, DT_INTEGER, TRUE));
}   


Listing Three

/* example.c: Exemplifies the use of the Bob macro processor library
 * Copyright (c) 1994 Brett Dutton
 *** Revision History:  * 13-Dec-1994 Dutton      Initial coding
 */

/* Description: */
/* includes */
#include <stdio.h>
#include <stdlib.h>
#include "bob/bob.h"
#include <X11/Intrinsic.h>
#include <X11/StringDefs.h>
#include <X11/Xaw/Label.h>
#include <X11/Xaw/Command.h>
#include <X11/Xaw/Box.h>
#include <X11/Xaw/Dialog.h>

/* macros */
#define APPNAME "example"
#define VERSION APPNAME " 1.0 By Brett Dutton"

/* typedefs */

/* prototypes */
void AppCheckBob ( XtPointer cl_data, int *fid, XtInputId *id );
void Quit ( Widget w, XtPointer cl_data, XtPointer call_data );
void Break ( Widget w, XtPointer cl_data, XtPointer call_data );
void LoadOk ( Widget w, XtPointer cl_data, XtPointer call_data );
void ExecuteOk ( Widget w, XtPointer cl_data, XtPointer call_data );
int Message ( int argc, VALUE *arg, VALUE *retval );
int Error ( int argc, VALUE *arg, VALUE *retval );
void ShowError ( char *msg );

/* variables */
/* these resources are usually external */
static String resources[] = {
    "*example.width: 300",
    "*example.height: 400",
    "*quit*label: Quit",
    "*break*label: Break",
    "*Command*background: green",
    "*message*label: Message:",
    "*message*width: 275",
    "*error*label: Error:",
    "*error*width: 275",
    "*value: ",
    "*load*label: Load file:",
    "*load*loadok*label: Ok",
    "*load*width: 275",
    "*execute*label: Execute function:",
    "*execute*executeok*label: Ok",
    "*execute*width: 275",
};

/* global widgets */
Widget message, errordia, load, loadok, executedia, executeok;

/* functions */
/******************************************************************************
 * Function: main -- main function
 * Returns: Nothing   
 */
void main ( int argc, char *argv[] ) 
{
    XtAppContext        app_context;
    Widget              topLevel;
    Widget              box, quit, brkwid;
    int                 bobSock;
    /* create a application */
    topLevel = XtVaAppInitialize ( &app_context, APPNAME, NULL, 0, 
                                  &argc, argv, resources, NULL ); 
    /* create all the buttons and dialogs for the application */
    box = XtVaCreateManagedWidget ( "box", boxWidgetClass, topLevel, NULL ); 
    quit = XtVaCreateManagedWidget ( "quit", commandWidgetClass, box, NULL ); 
    brkwid = XtVaCreateManagedWidget ("break", commandWidgetClass, box, NULL); 
    message = XtVaCreateManagedWidget ( "message",dialogWidgetClass,box,NULL );
    errordia = XtVaCreateManagedWidget ("error", dialogWidgetClass,box, NULL );
    load = XtVaCreateManagedWidget ( "load", dialogWidgetClass, box, NULL ); 
    loadok = XtVaCreateManagedWidget ( "loadok",commandWidgetClass,load,NULL );
    executedia = XtVaCreateManagedWidget ( "execute", dialogWidgetClass, box, NULL );
    executeok = XtVaCreateManagedWidget ( "executeok", commandWidgetClass, executedia, NULL );
    /* set up all the callbacks for the buttons */
    XtAddCallback ( quit, XtNcallback, Quit, 0 );
    XtAddCallback ( brkwid, XtNcallback, Break, 0 );
    XtAddCallback ( loadok, XtNcallback, LoadOk, 0 );
    XtAddCallback ( executeok, XtNcallback, ExecuteOk, 0 );
    /* initialize the bob interface language */
    if ( ( bobSock = BobInitialize ( ) ) < 0 ) {
        fprintf (stderr,"Unable to initialize Bob\n" );
        exit(1);
    }
    /* add this socket to the event loop for monitoring */
    XtAppAddInput ( app_context, bobSock, (XtPointer)XtInputReadMask, 
                    AppCheckBob, NULL );
    /* register the external functions with BOB */
    BobAddFunction ( "message", Message );
    BobAddFunction ( "error", Error );
    /* load up the application defaults macros */
    BobLoadFile ( "." APPNAME "rc" );  /* user definitions */
    /* this has just been put in to demonstrate calling BOB functions */
    BobExecute ( "print", 4, DT_STRING, "Hi ", DT_INTEGER, 20,
                 DT_NIL, DT_STRING, " World\n" );
    /* create windows for widgets and map them */
    XtRealizeWidget ( topLevel );
    /* loop for events */
    XtAppMainLoop ( app_context );
}
/******************************************************************************
 * Function: AppCheckBob -- The is the work proc called when there is  
 * input from Bob
 * Returns: Nothing   
 */
void AppCheckBob ( XtPointer cl_data, int *fid, XtInputId *id )
{
    /* Call bob to get the events of the Bob comms socket */
    BobCheckClient ( );
}
/******************************************************************************
 * Function: Quit -- Exits from the windows system
 * Returns: Nothing   
 */
void Quit ( Widget w, XtPointer cl_data, XtPointer call_data )
{
    BobTalkTerm ();     /* shutdown comms with Bob */
    exit ( 0 );
}
/******************************************************************************
 * Function: Break -- Exits from the windows system
 * Returns: Nothing   
 */
void Break ( Widget w, XtPointer cl_data, XtPointer call_data )
{
    BobBreak ( "BOB Inturrupted" );
}
/******************************************************************************
 * Function: LoadOk -- The load dialog is complete and to load up file
 * Returns: Nothing   
 */
void LoadOk ( Widget w, XtPointer cl_data, XtPointer call_data )
{
    String      str;            /* filename to load */
    char        msg[500];       /* Error message */
    Arg         xargs[1];       /* New value */
    /* get the string and try to load it */
    str = XawDialogGetValueString ( load );
    if ( BobLoadFile ( str ) ) {
        /* clear the box if no error */
        XtSetArg ( xargs[0], XtNvalue, (XtArgVal)"" );
        XtSetValues ( load, xargs, 1 );
    } else {
        /* send an error to the error box */
        sprintf ( msg, "Unable to load file: %s", str );
        ShowError ( msg );
    }
}
/******************************************************************************
 * Function: ExecuteOk -- Execute dialog is complete 
 * Returns: Nothing   
 */
void ExecuteOk ( Widget w, XtPointer cl_data, XtPointer call_data )
{
    String      str;            /* function to execute */
    char        msg[500];       /* error message */
    Arg         xargs[1];       /* New value */
    /* get the string and try to load it */
    str = XawDialogGetValueString ( executedia );
    if ( BobExecute ( str, 0 ) ) {
        /* clear the box if no error */
        XtSetArg ( xargs[0], XtNvalue, (XtArgVal)"" );
        XtSetValues ( executedia, xargs, 1 );
    } else {
        /* send an error to the error box */
        sprintf ( msg, "Unable to execute function: %s", str );
        ShowError ( msg );
    }
}
/******************************************************************************
 * Function: Message --  Displays a message in the dialog boc
 * Returns: Tells Bob if it is an error or not
 */
int Message ( int argc, VALUE *arg, VALUE *retval  )
{
    char                msg[500]; /* message to put in dialog */
    Arg                 xargs[1]; /* New value */
    /* make sure that there is 1 args */
    /* make sure that it is a string */
    if ( ! BobExtArgs ( argc, 1, 1, retval ) ) return ( FALSE );
    if ( ! BobExtCheckType ( &arg[0], DT_STRING, retval ) ) return ( FALSE );
    
    BobGetString ( msg, sizeof ( msg ), &arg[0] );
    XtSetArg ( xargs[0], XtNvalue, (XtArgVal)msg );
    XtSetValues ( message, xargs, 1 );
    return ( BobReturnValue ( retval, DT_INTEGER, TRUE ) );
}
/******************************************************************************
 * Function: Error --  Displays a error in the dialog boc
 * Returns: Tells Bob is there is an error or not
 */
int Error ( int argc, VALUE *arg, VALUE *retval  )
{
    char                msg[500]; /* error to put in dialog */
    Arg                 xargs[1]; /* New value */
    /* make sure that there is 1 args */
    /* make sure that it is a string */
    if ( ! BobExtArgs ( argc, 1, 1, retval ) ) return ( FALSE );
    if ( ! BobExtCheckType ( &arg[0], DT_STRING, retval ) ) return ( FALSE );
    BobGetString ( msg, sizeof ( msg ), &arg[0] );
    ShowError ( msg );
    return ( BobReturnValue ( retval, DT_INTEGER, TRUE ) );
}
/******************************************************************************
 * Function: ShowError --  Displays the passed message in the error dialog box
 * Description:
 * Returns: Nothing   
 */
void ShowError ( char *msg )
{
    Arg                 xargs[1]; /* New value */
    XtSetArg ( xargs[0], XtNvalue, (XtArgVal)msg );
    XtSetValues ( errordia, xargs, 1 );
}


Example 1:

(a)

InterpreterContext *ic = NewInterpreterContext(16384,1024);
ic->errorHandler = ErrorHandler;


(b)

EnterLibrarySymbols(ic);
ic->findFunctionHandler = FindLibraryFunctionHandler;


(c)

CompilerContext *c = InitCompiler(ic,4096,256);


(d)

ObjectPtr val;
ProtectPointer(ic,&val);


Example 2:

for (;;) {
    printf("\nExpr> ");
    if (gets(lineBuffer)) {
        Stream *s = CreateStringStream(lineBuffer,
                                       strlen(lineBuffer));
        if (s) {
            val = CompileExpr(c,s);
            val = CallFunction(ic,val,0);
            printf("Value: ");
            PrintValue(ic,val,ic->standardOutput);
            CloseStream(s);
        }
    }
    else
        break;
}


Example 3:

(a)

ObjectPtr CallFunction(InterpreterContext ic,
                       ObjectPtr function,
                       int argumentCount,...);



(b)

ObjectPtr CallFunctionByName(InterpreterContext ic,
                             char *functionName,
                             int argumentCount,...);