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