excontext.c

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/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/
 
/*
 * Glenn Fowler
 * AT&T Research
 *
 * expression library
 */
 
#include <expr/exlib.h>
#include <util/gv_ctype.h>
 
/*
 * copy input token error context into buf of n chars and reset the context
 * end of buf returned
 */
 
char*
excontext(Expr_t* p, char* buf, int n)
{
        char*   s;
        char*   t;
        char*   e;
 
        s = buf;
        if (p->linep > p->line || p->linewrap)
        {
                e = buf + n - 5;
                if (p->linewrap)
                {
                        t = p->linep + 1;
                        while (t < &p->line[sizeof(p->line)] && gv_isspace(*t))
                                t++;
                        if ((n = (sizeof(p->line) - (t - (p->linep + 1))) - (e - s)) > 0)
                        {
                                if (n > &p->line[sizeof(p->line)] - t)
                                        t = &p->line[sizeof(p->line)];
                                else t += n;
                        }
                        while (t < &p->line[sizeof(p->line)])
                                *s++ = *t++;
                }
                t = p->line;
                if (p->linewrap)
                        p->linewrap = 0;
                else while (t < p->linep && gv_isspace(*t))
                        t++;
                if ((n = (p->linep - t) - (e - s)) > 0)
                        t += n;
                while (t < p->linep)
                        *s++ = *t++;
                p->linep = p->line;
                t = "<<< ";
                while ((*s = *t++))
                        s++;
        }
        *s = 0;
        return s;
}