special case buffer_get_token with token length 1 through memccpy

buffer/buffer_get_token.c

@@ -2,16 +2,35 @@
 #include "buffer.h"
 #include "scan.h"
 
+#include <string.h>	/* for memccpy */
+
 ssize_t buffer_get_token(buffer* b,char* x,size_t len,const char* charset,size_t setlen) {
   size_t blen;
 
   if ((ssize_t)len<0) len=(ssize_t)(((size_t)-1)>>1);
-  for (blen=0;blen<len;++blen) {
-    register ssize_t r;
-    if ((r=buffer_getc(b,x))<0) return r;
-    if (r==0) { *x=0; break; }
-    if (byte_chr(charset,setlen,*x)<setlen) break;
-    ++x;
+  if (setlen==1) {
+    for (blen=0; blen<len; ) {
+      ssize_t n=buffer_feed(b);
+      char* d;
+      if (n<=0) return blen;
+      if (n>(ssize_t)(len-blen)) n=len-blen;
+      if ((d=memccpy(x+blen,b->x+b->p,(unsigned char)charset[0],n))) {
+	/* memccpy returns a pointer to the next char after matching
+	 * char or NULL if it copied all bytes it was asked for */
+	b->p+=(d-(x+blen));
+	return d-x-1;
+      }
+      blen+=n;
+      b->p+=n;
+    }
+  } else {
+    for (blen=0;blen<len;++blen) {
+      register ssize_t r;
+      if ((r=buffer_getc(b,x))<0) return r;
+      if (r==0) { *x=0; break; }
+      if (byte_chr(charset,setlen,*x)<setlen) break;
+      ++x;
+    }
   }
   return (ssize_t)blen;
 }