From dc2c62807ab7e741599255f7eb5ed6eff0c5cad4 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Fri, 25 Oct 2019 23:41:18 +0300
Subject: [PATCH] string: faster int()

---
 vlib/builtin/cfns.v        |  1 +
 vlib/builtin/string.v      | 20 ++++++++++++++++++++
 vlib/builtin/string_test.v | 10 ++++++++++
 3 files changed, 31 insertions(+)

diff --git a/vlib/builtin/cfns.v b/vlib/builtin/cfns.v
index e5f973af86..39bd9bdac8 100644
--- a/vlib/builtin/cfns.v
+++ b/vlib/builtin/cfns.v
@@ -10,6 +10,7 @@ fn C.qsort(voidptr, int, int, voidptr)
 
 fn C.sprintf(a ...voidptr) byteptr
 fn C.strlen(s byteptr) int
+fn C.isdigit(s byteptr) bool
 
 
 
diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index bb51dfb8e5..4418a77215 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -176,9 +176,29 @@ pub fn (s string) replace(rep, with string) string {
 	return tos(b, new_len)
 }
 
+/*
 pub fn (s string) int() int {
 	return strconv.parse_int(s, 0, 32)
 }
+*/
+
+pub fn (s string) int() int {
+	mut neg := false
+	mut i := 0
+	if s[0] == `-` {
+		neg = true
+		i++
+	}
+	else if s[0] == `+` {
+		i++
+	}
+	mut n := 0
+	for C.isdigit(s[i]) {
+		n = 10 * n - int(s[i] - `0`)
+		i++
+	}
+	return if neg { n } else { -n }
+}
 
 
 pub fn (s string) i64() i64 {
diff --git a/vlib/builtin/string_test.v b/vlib/builtin/string_test.v
index 4145aba5cb..7619027940 100644
--- a/vlib/builtin/string_test.v
+++ b/vlib/builtin/string_test.v
@@ -482,3 +482,13 @@ fn test_escape() {
 	//println("\"$a")
 }	
 
+fn test_atoi() {
+	assert '234232'.int() == 234232
+	assert '-9009'.int() == -9009
+	assert '0'.int() == 0
+	for n in -10000 .. 100000 {
+		s := n.str()
+		assert s.int() == n
+	}	
+}	
+