FEAT: new truncate native for shortening a series

Author: Oldes

src/core/n-data.c

@@ -1023,6 +1023,36 @@ static int Do_Ordinal(REBVAL *ds, REBINT n)
 }
 
 
+/***********************************************************************
+**
+*/	REBNATIVE(truncate)
+/*
+//	truncate: native [
+//		"Removes all bytes/values from series' head to its current index position"
+//		series [series!] "Series to be truncated"
+//      /part   "Also shorten resulted series to a length or end position"
+//       range  [number! series!]
+//	]
+***********************************************************************/
+{
+	REBVAL *arg = D_ARG(1);
+	REBINT index = VAL_INDEX(arg);
+	REBINT len = -1;
+	
+	if (D_REF(2)) {
+		len = Partial(arg, 0, D_ARG(3), 0);
+	}
+	if (index > 0) {
+		Remove_Series(VAL_SERIES(arg), 0, index);
+		VAL_INDEX(arg) = 0;
+	}
+	if (len >= 0) {
+		VAL_TAIL(arg) = len;
+	}
+	return R_ARG1;
+}
+
+
 #ifdef not_fast_enough
 /***********************************************************************
 **

src/modules/httpd.reb

@@ -736,6 +736,8 @@ sys/make-scheme [
 						len:    data/2 & 127
 						data: skip data 2
 						;? final? ? opcode ? len
+
+						;@@ Not removing bytes until we make sure, that there is enough data!
 						case [
 							len = 126 [
 								if 2 >= length? data [break]
@@ -749,8 +751,7 @@ sys/make-scheme [
 							]
 						]
 						if (4 + length? data) < len [break]
-						remove/part head data data
-						data: head data
+						data: truncate data ;; removes already processed bytes from the head
 						either mask? [
 							request-data: make binary! len
 							masks:   take/part data 4
@@ -761,9 +762,8 @@ sys/make-scheme [
 						][
 							request-data: take/part data len
 						]
-						ready?: true						
-						clear skip request-data len
-						ctx/inp/content: request-data
+						ready?: true
+						ctx/inp/content: truncate/part request-data len
 						if opcode = 8 [
 							sys/log/more 'HTTPD "WS Connection Close Frame!"
 							code: 0

src/tests/units/series-test.r3

@@ -392,6 +392,19 @@ Rebol [
 ===end-group===
 
 
+===start-group=== "TRUNCATE"
+--test-- "TRUNCATE"
+	--assert "23"  = truncate next "123"
+	--assert [2 3] = truncate next [1 2 3]
+	--assert "2"   = truncate/part next "123" 1
+	--assert [2]   = truncate/part next [1 2 3] 1
+	--assert "23"  = head truncate next "123"
+	--assert [2 3] = head truncate next [1 2 3]
+	--assert "2"   = head truncate/part next "123" 1
+	--assert [2]   = head truncate/part next [1 2 3] 1
+===end-group===
+
+
 
 ===start-group=== "REPLACE string!"
 	;@@ https://github.com/Oldes/Rebol-issues/issues/54