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authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /web/noweb/src/c/getline.nw
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+% Copyright 1991 by Norman Ramsey. All rights reserved.
+% See file COPYRIGHT for more information.
+@
+\section{Utility functions}
+
+\subsection{Line-oriented input}
+[[getline_nw]] is reads in the next line, no matter
+how long it is, expanding tabs.
+I allocate more and more space for the line, until I've
+read a whole line or until I run out of space, whichever comes first.
+The buffer grows in size exponentially, so the cost in overhead is roughly the logarithm
+of the length of the longest line.
+@
+[[getline_nw]] reuses the same internal buffers over and over, so subsequent
+calls destroy the results of previous calls.
+<<*>>=
+static char rcsid[] = "$Id: getline.nw,v 2.24 2008/10/06 01:03:05 nr Exp nr $";
+static char rcsname[] = "$Name: v2_12 $";
+#define START_SIZE 128 /* initial buffer size */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "columns.h"
+#include "errors.h"
+#include "getline.h"
+
+static char *buf1 = NULL, *buf2 = NULL; /* lines without, with tabs expanded */
+static int buf_size = START_SIZE; /* size of both buffers if non-NULL */
+
+<<C functions>>
+@
+<<header>>=
+char *getline_expand (FILE *fp);
+ /* grab a line in buffer, return new buffer or NULL for eof
+ tabs in line are expanded according to tabsize */
+char *getline_nw (FILE *fp);
+ /* grab a line in the buffer, return a new buffer or NULL for eof
+ no expansion of tabs */
+@ N.B. In 2008, [[getline]] became part of a POSIX standard,
+so Noweb's version (which is 20 years old) is now [[getline_nw]].
+@
+<<C functions>>=
+void new_buffers(void) {
+ checkptr(buf1 = (char *) realloc(buf1, buf_size));
+ checkptr(buf2 = (char *) realloc(buf2, buf_size));
+}
+<<C functions>>=
+char *getline_nw (FILE *fp) {
+
+ <<if [[buf1==NULL]], allocate initial buffers>>
+
+ buf1=fgets(buf1, buf_size, fp);
+ if (buf1==NULL) return buf1; /* end of file */
+ while (buf1[strlen(buf1)-1] != '\n') { /* failed to get whole line */
+ buf_size *= 2;
+ new_buffers();
+ if (fgets(buf1+strlen(buf1),buf_size-strlen(buf1),fp)==NULL)
+ return buf1; /* end of file */
+ }
+ (void)rcsid; /* avoid a warning */
+ (void)rcsname; /* avoid a warning */
+ return buf1;
+}
+<<C functions>>=
+char *getline_expand (FILE *fp) {
+ char *s, *t;
+ int width;
+
+ if (getline_nw(fp)==NULL) return NULL;
+ <<if [[columnwidth(buf1) > buf_size - 1]], allocate new buffers>>
+ s = buf1; t = buf2; width=0;
+ while (*s)
+ if (*s=='\t' && tabsize > 0) {
+ do {
+ *t++ = ' '; width++;
+ } while (width % tabsize != 0);
+ s++;
+ } else {
+ *t++ = *s++; width++;
+ }
+ *t='\0';
+ return buf2;
+}
+<<if [[buf1==NULL]], allocate initial buffers>>=
+if (buf1==NULL) {
+ checkptr(buf1 = (char *) malloc (buf_size));
+ checkptr(buf2 = (char *) malloc (buf_size));
+}
+<<if [[columnwidth(buf1) > buf_size - 1]], allocate new buffers>>=
+if (columnwidth(buf1) > buf_size - 1) {
+ while (columnwidth(buf1) > buf_size - 1) buf_size *= 2;
+ new_buffers();
+}