From fb76e02c59b1502c3be557d6c8c94dba2bf2c829 Mon Sep 17 00:00:00 2001
From: Nick Treleaven <n@trelsoft.com>
Date: Mon, 20 Jul 2020 15:44:35 +0100
Subject: [PATCH] builtin: speed up string.clone() by using C.memcpy (#5837)

---
 vlib/builtin/string.v | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index 1e2bdb7131..b87f04f11e 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -85,9 +85,6 @@ pub fn tos(s byteptr, len int) string {
 }
 
 pub fn tos_clone(s byteptr) string {
-	if s == 0 {
-		panic('tos: nil string')
-	}
 	return tos2(s).clone()
 }
 
@@ -131,13 +128,11 @@ fn (a string) clone_static() string {
 
 pub fn (a string) clone() string {
 	mut b := string{
-		str: malloc(a.len + 1)
+		str: unsafe {malloc(a.len + 1)}
 		len: a.len
 	}
-	for i in 0..a.len {
-		b.str[i] = a.str[i]
-	}
 	unsafe {
+		C.memcpy(b.str, a.str, a.len)
 		b.str[a.len] = `\0`
 	}
 	return b
@@ -152,12 +147,7 @@ pub fn (s string) cstr() byteptr {
 
 // cstring_to_vstring creates a copy of cstr and turns it into a v string
 pub fn cstring_to_vstring(cstr byteptr) string {
-	unsafe {
-		slen := C.strlen(charptr(cstr))
-		mut s := byteptr(memdup(cstr, slen + 1))
-		s[slen] = `\0`
-		return tos(s, slen)
-	}
+	return tos_clone(cstr)
 }
 
 pub fn (s string) replace_once(rep, with string) string {