add buffer_fromsa (make virtual buffer from stralloc)

CHANGES

@@ -1,3 +1,6 @@
+0.16:
+  add buffer_fromsa (make buffer from stralloc)
+
 0.15:
   man page update (document stralloc return values)
   add stralloc_chop and stralloc_chomp

buffer.h

@@ -102,6 +102,10 @@ typedef int (*sa_predicate)(stralloc* sa);
 
 /* like buffer_get_token_sa but the token ends when your predicate says so */
 extern int buffer_get_token_sa_pred(buffer* b,stralloc* sa,sa_predicate p);
+
+/* make a buffer from a stralloc.
+ * Do not change the stralloc after this! */
+void buffer_fromsa(buffer* b,stralloc* sa);
 #endif
 
 #endif

buffer/buffer_fromsa.3

@@ -0,0 +1,19 @@
+.TH buffer_fromsa 3
+.SH NAME
+buffer_fromsa \- initialize buffer structure from stralloc
+.SH SYNTAX
+.B #include <buffer.h>
+
+int \fBbuffer_fromsa\fR(buffer* \fIb\fR,stralloc* \fIsa\fR);
+.SH DESCRIPTION
+buffer_fromsa makes a virtual read buffer from a stralloc.  The buffer
+reading functions will be able to read until the end of the data in the
+stralloc, then signal EOF.  The buffer does not have its own buffer
+space, it reuses the one in the stralloc.
+
+Do not touch the stralloc until your are done with the buffer!  In
+particular, do not call stralloc_free on it!
+
+Reading data from the buffer will not change the stralloc.
+.SH "SEE ALSO"
+buffer_init(3), buffer(3)

buffer/buffer_fromsa.c

@@ -0,0 +1,15 @@
+#include "stralloc.h"
+#include "buffer.h"
+
+static int dummyreadwrite(int fd,char* buf,unsigned long int len) {
+  return 0;
+}
+
+void buffer_fromsa(buffer* b,stralloc* sa) {
+  b->x=sa->s;
+  b->p=0;
+  b->n=sa->len;
+  b->a=sa->a;
+  b->fd=0;
+  b->op=dummyreadwrite;
+}

test/buffer_fromsa.c

@@ -0,0 +1,21 @@
+#include "stralloc.h"
+#include "buffer.h"
+
+int main() {
+  stralloc sa;
+  buffer b;
+  stralloc line;
+
+  stralloc_init(&sa);
+  stralloc_init(&line);
+  stralloc_copys(&sa,"this is a test\nline 2\n");
+  buffer_fromsa(&b,&sa);
+
+  while (buffer_getline_sa(&b,&line)==0) {
+    buffer_puts(buffer_1,"got line: \"");
+    if (stralloc_chop(&line)!='\n') break;
+    buffer_putsa(buffer_1,&line);
+    buffer_putsflush(buffer_1,"\"\n");
+    stralloc_copys(&line,"");
+  }
+}