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/*++
/* NAME
/* vs_alloc(), VS_ADDCH()
/* SUMMARY
/* auto-resizing string library
/* PACKAGE
/* vstring
/* SYNOPSIS
/* #include "vstring.h"
/*
/* struct vstring *vs_alloc(len)
/* int len;
/*
/* int VS_ADDCH(vs, wp, ch)
/* struct vstring *vs;
/* char *wp;
/* int ch;
/* DESCRIPTION
/* These functions and macros implement a small library for
/* arbitrary-length strings that grow automatically when
/* they fill up. The allocation strategy is such that there
/* will always be place for the terminating null character.
/*
/* vs_alloc() allocates storage for a variable-length string.
/*
/* VS_ADDCH() adds a character to a variable-length string
/* and automagically extends the string if fills up.
/* \fIvs\fP is a pointer to a vstring structure; \fIwp\fP
/* the current write position in the corresponding character
/* array; \fIch\fP the character value to be written.
/* Note that VS_ADDCH() is a macro that evaluates some
/* arguments more than once.
/* DIAGNOSTICS
/* VS_ADDCH() returns zero if it was unable to dynamically
/* resize a string.
/*
/* vs_alloc() returns a null pointer in case of problems.
/* BUGS
/* Auto-resizing may change the address of the string data in
/* a vstring structure. Beware of dangling pointers.
/* AUTHOR(S)
/* Wietse Venema
/* Eindhoven University of Technology
/* Department of Mathematics and Computer Science
/* Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
/* LAST MODIFICATION
/* 91/09/22 21:21:38
/* VERSION/RELEASE
/* 1.2
/*--*/
static char vstring_sccsid[] = "@(#) vstring.c 1.2 91/09/22 21:21:38";
/* C library */
extern char *malloc();
extern char *realloc();
/* Application-specific stuff */
#include "vstring.h"
/* vs_alloc - initial string allocation */
struct vstring *vs_alloc(len)
int len;
{
register struct vstring *vp;
if (len < 1
|| (vp = (struct vstring *) malloc(sizeof(struct vstring))) == 0
|| (vp->str = malloc(len)) == 0)
return (0);
vp->last = vp->str + len - 1;
return (vp);
}
/* vs_realloc - extend string, update write pointer */
char *vs_realloc(vp, cp)
register struct vstring *vp;
char *cp;
{
int where = cp - vp->str;
int len = vp->last - vp->str + 1;
if ((vp->str = realloc(vp->str, len *= 2)) == 0)
return (0);
vp->last = vp->str + len - 1;
return (vp->str + where);
}
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