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/* elk-eval.c
*
* $Id$
*
* Copyright 1990, 1991, 1992, 1993, 1994, 1995, Oliver Laumann, Berlin
* Copyright 2002, 2003 Sam Hocevar <sam@hocevar.net>, Paris
*
* This software was derived from Elk 1.2, which was Copyright 1987, 1988,
* 1989, Nixdorf Computer AG and TELES GmbH, Berlin (Elk 1.2 has been written
* by Oliver Laumann for TELES Telematic Services, Berlin, in a joint project
* between TELES and Nixdorf Microprocessor Engineering, Berlin).
*
* Oliver Laumann, TELES GmbH, Nixdorf Computer AG and Sam Hocevar, as co-
* owners or individual owners of copyright in this software, grant to any
* person or company a worldwide, royalty free, license to
*
* i) copy this software,
* ii) prepare derivative works based on this software,
* iii) distribute copies of this software or derivative works,
* iv) perform this software, or
* v) display this software,
*
* provided that this notice is not removed and that neither Oliver Laumann
* nor Teles nor Nixdorf are deemed to have made any representations as to
* the suitability of this software for any purpose nor are held responsible
* for any defects of this software.
*
* THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
*/
/* The function
*
* char *Elk_Eval(char *expr);
*
* is similar to Tcl_Eval() in Tcl. It is called with a Scheme expression
* encoded as a C string and returns the result of evaluating the expression
* (as another C string), or a null pointer if an error has occured
* during evaluation.
*
* Elk_Eval() stores its result in a static buffer of fixed size; this
* can be improved easily by passing a buffer and a length as additional
* arguments.
*/
#include "config.h"
#include <string.h>
#include "scheme.h"
static Object in, out;
static char *String_Eval(char *expr) {
Object str, res;
char *p;
GC_Node;
static char buf[1024];
str = Make_String(expr, strlen(expr));
PORT(in)->name = str;
PORT(in)->ptr = 0;
res = General_Read(in, 0);
GC_Link(res);
res = Eval(res);
(void)General_Print_Object(res, out, 1);
str = P_Get_Output_String(out);
p = Get_String(str);
if (strlen(p) > sizeof buf - 1)
p = "too long";
strcpy(buf, p);
GC_Unlink;
return buf;
}
char *Elk_Eval(char *expr) {
char *s;
s = String_Eval("\
(call-with-current-continuation (lambda (c)\
(set! error-handler (lambda a (print a) (c #f))) #t))\
");
if (strcmp(s, "#f") == 0)
return 0;
return String_Eval(expr);
}
void elk_init_eval() {
in = P_Open_Input_String(Make_String("", 0));
Global_GC_Link(in);
out = P_Open_Output_String();
Global_GC_Link(out);
}
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