string: make `index()` return `?int` instead of `int`/-1

vlib/builtin/string.v

@@ -134,11 +134,8 @@ pub fn cstring_to_vstring(cstr byteptr) string {
 }
 
 pub fn (s string) replace_once(rep, with string) string {
-    index := s.index(rep)
-    if index != -1 {
+	index := s.index(rep) or { return s }
 	return s.substr(0,index) + with + s.substr(index + rep.len, s.len)
-    }
-    return s
 }
 
 pub fn (s string) replace(rep, with string) string {
@@ -151,8 +148,7 @@ pub fn (s string) replace(rep, with string) string {
 	mut rem := s
 	mut rstart := 0
 	for {
-		mut i := rem.index(rep)
-		if i < 0 {break}
+		mut i := rem.index(rep) or { break }
 		idxs << rstart + i
 		i += rep.len
 		rstart += i
@@ -428,7 +424,7 @@ fn (s string) substr(start, end int) string {
 	return res
 }
 
-pub fn (s string) index(p string) int {
+pub fn (s string) index_old(p string) int {
 	if p.len > s.len {
 		return -1
 	}
@@ -446,6 +442,24 @@ pub fn (s string) index(p string) int {
 	return -1
 }
 
+pub fn (s string) index(p string) ?int {
+	if p.len > s.len {
+		return none
+	}
+	mut i := 0
+	for i < s.len {
+		mut j := 0
+		for j < p.len && s[i + j] == p[j] {
+			j++
+		}
+		if j == p.len {
+			return i
+		}
+		i++
+	}
+	return none
+}
+
 // KMP search
 pub fn (s string) index_kmp(p string) int {
         if p.len > s.len {
@@ -480,11 +494,9 @@ pub fn (s string) index_kmp(p string) int {
 
 pub fn (s string) index_any(chars string) int {
 	for c in chars {
-		index := s.index(c.str())
-		if index != -1 {
+		index := s.index(c.str()) or { continue }
 		return index
 	}
-	}
 	return -1
 }
 
@@ -573,13 +585,15 @@ pub fn (s string) count(substr string) int {
 }
 
 pub fn (s string) contains(p string) bool {
-	res := s.index(p) > 0 - 1
-	return res
+	_ = s.index(p) or {
+		return false
+	}
+	return true
 }
 
 pub fn (s string) starts_with(p string) bool {
-	res := s.index(p) == 0
-	return res
+	idx := s.index(p) or { return false }
+	return idx == 0
 }
 
 pub fn (s string) ends_with(p string) bool {
@@ -628,16 +642,10 @@ pub fn (s string) title() string {
 // 'hey [man] how you doin'
 // find_between('[', ']') == 'man'
 pub fn (s string) find_between(start, end string) string {
-	start_pos := s.index(start)
-	if start_pos == -1 {
-		return ''
-	}
+	start_pos := s.index(start) or { return '' }
 	// First get everything to the right of 'start'
 	val := s.right(start_pos + start.len)
-	end_pos := val.index(end)
-	if end_pos == -1 {
-		return val
-	}
+	end_pos := val.index(end) or { return val }
 	return val.left(end_pos)
 }
 
@@ -984,10 +992,7 @@ fn (arr []string) free() {
 
 // all_before('23:34:45.234', '.') == '23:34:45'
 pub fn (s string) all_before(dot string) string {
-	pos := s.index(dot)
-	if pos == -1 {
-		return s
-	}
+	pos := s.index(dot) or { return s }
 	return s.left(pos)
 }
 

vlib/compiler/cflags.v

@@ -84,7 +84,7 @@ fn (table mut Table) parse_cflag(cflag string, mod string) ?bool {
 	mut fos := ''
 	mut name := ''
 	if flag.starts_with('linux') || flag.starts_with('darwin') || flag.starts_with('freebsd') || flag.starts_with('windows') {
-		pos := flag.index(' ')
+		pos := flag.index(' ') or { return none }
 		fos = flag[..pos].trim_space()
 		flag = flag[pos..].trim_space()
 	}
@@ -101,16 +101,21 @@ fn (table mut Table) parse_cflag(cflag string, mod string) ?bool {
 				}
 			}
 		}
-		for i in [flag.index(' '), flag.index(',')] {
-			if index == -1 || (i != -1 && i < index) {
+		if i := flag.index(' ') {
+			if index == -1 || i < index {
+				index = i
+			}
+		}
+		if i := flag.index(',') {
+			if index == -1 || i < index {
 				index = i
 			}
 		}
 		if index != -1 && flag[index] == ` ` && flag[index+1] == `-` {
 			for f in allowed_flags {
-				i := index+f.len
-				if i < flag.len && f == flag[index..i] {
-					index = i
+				j := index+f.len
+				if j < flag.len && f == flag[index..j] {
+					index = j
 					break
 				}
 			}

vlib/compiler/comptime.v

@@ -220,8 +220,8 @@ fn (p mut Parser) chash() {
 	}
 	// TODO remove after ui_mac.m is removed
 	else if hash.contains('embed') {
-		pos := hash.index('embed') + 5
-		file := hash[pos..]
+		pos := hash.index('embed') or { return }
+		file := hash[pos+5..]
 		//if p.pref.build_mode != .default_mode {
 			p.genln('#include $file')
 		//}

vlib/compiler/main.v

@@ -799,8 +799,7 @@ pub fn get_arg(joined_args, arg, def string) string {
 
 pub fn get_param_after(joined_args, arg, def string) string {
 	key := '$arg '
-	mut pos := joined_args.index(key)
-	if pos == -1 {
+	mut pos := joined_args.index(key) or {
 		return def
 	}
 	pos += key.len

vlib/compiler/parser.v

@@ -1068,9 +1068,12 @@ fn (p mut Parser) get_type() string {
 		//}
 		return 'void*'
 	}
+	/*
+	TODO this is not needed?
 	if typ.last_index('__') > typ.index('__') {
 		p.error('2 __ in gettype(): typ="$typ"')
 	}
+	*/
 	return typ
 }
 
@@ -1410,9 +1413,11 @@ fn ($v.name mut $v.typ) $p.cur_fn.name (...) {
 	{
 		line := p.cgen.cur_line
 		vname := line[..pos].replace('=','') // TODO cgen line hack
-		p.cgen.resetln(line.replace(line[..line.index('=')+1], ''))
+		if idx := line.index('=') {
+			p.cgen.resetln(line.replace(line[..idx+1], ''))
 			p.gen_handle_option_or_else(expr_type, vname, ph)
 		}
+	}
 	else if expr_type[0]==`[` {
 		// assignment to a fixed_array `mut a:=[3]int a=[1,2,3]!!`
 		expr := p.cgen.cur_line[pos..].all_after('{').all_before('}') // TODO cgen line hack
@@ -3053,13 +3058,11 @@ fn (p mut Parser) defer_st() {
 }
 
 fn (p mut Parser) check_and_register_used_imported_type(typ_name string) {
-	us_idx := typ_name.index('__')
-	if us_idx != -1 {
+	us_idx := typ_name.index('__') or { return }
 	arg_mod := typ_name[..us_idx]
 	if p.import_table.known_alias(arg_mod) {
 		p.import_table.register_used_import(arg_mod)
 	}
-	}
 }
 
 fn (p mut Parser) check_unused_imports() {

vlib/compiler/parser2.v

@@ -157,8 +157,10 @@ fn (p mut Parser) get_type2() Type {
 		typ = 'Option_$typ'
 		p.table.register_type_with_parent(typ, 'Option')
 	}
+	/*
 	if typ.last_index('__') > typ.index('__') {
 		p.error('2 __ in gettype(): typ="$typ"')
 	}
+	*/
 	return Type{name: typ, cat: cat}
 }

vlib/compiler/table.v

@@ -931,8 +931,8 @@ fn (p &Parser) identify_typo(name string) string {
 // compare just name part, some items are mod prefied
 fn typo_compare_name_mod(a, b, b_mod string) f32 {
 	if a.len - b.len > 2 || b.len - a.len > 2 { return 0 }
-	auidx := a.index('__')
-	buidx := b.index('__')
+	auidx := a.index('__') or { -1 }
+	buidx := b.index('__') or { -1 }
 	a_mod := if auidx != -1 { mod_gen_name_rev(a[..auidx]) } else { '' }
 	a_name := if auidx != -1 { a[auidx+2..] } else { a }
 	b_name := if buidx != -1 { b[buidx+2..] } else { b }

vlib/eventbus/params.v

@@ -115,7 +115,9 @@ pub fn (p mut Params) put_custom(name string, typ string, data voidptr) {
 //HELPERS
 
 fn parse_len(typ, s_tok, e_tok string) int {
-	len := typ[typ.index(s_tok) + 1 .. typ.index(e_tok)].int()
+	start_index := typ.index(s_tok) or { return 0 }
+	end_index := typ.index(e_tok) or { return 0 }
+	len := typ[start_index+1..end_index].int()
 	//t := typ.substr(typ.index(e_tok) + 1, typ.len)
 	return len
 }

vlib/net/urllib/urllib.v

@@ -516,8 +516,8 @@ fn parse_url(rawurl string, via_request bool) ?URL {
 		// RFC 3986, §3.3:
 		// In addition, a URI reference (Section 4.1) may be a relative-path reference,
 		// in which case the first path segment cannot contain a colon (':') character.
-		colon := rest.index(':')
-		slash := rest.index('/')
+		colon := rest.index(':') or { -1 }
+		slash := rest.index('/') or { -1 }
 		if colon >= 0 && (slash < 0 || colon < slash) {
 			// First path segment has colon. Not allowed in relative URL.
 			return error(error_msg('parse_url: first path segment in URL cannot contain colon', ''))
@@ -615,8 +615,7 @@ fn parse_host(host string) ?string {
 		// can only %-encode non-ASCII bytes.
 		// We do impose some restrictions on the zone, to avoid stupidity
 		// like newlines.
-		zone := host[..i].index('%25')
-		if zone >= 0 {
+		if zone := host[..i].index('%25') {
 			host1 := unescape(host[..zone], .encode_host) or {
 				return err
 			}

vlib/time/time.v

@@ -313,8 +313,7 @@ pub fn (t Time) clean12() string {
 // `parse` parses time in the following format: "2018-01-27 12:48:34"
 pub fn parse(s string) Time {
 	// println('parse="$s"')
-	pos := s.index(' ')
-	if pos <= 0 {
+	pos := s.index(' ') or {
 		println('bad time format')
 		return now()
 	}

vlib/vweb/tmpl/tmpl.v

@@ -46,8 +46,8 @@ _ = header
 		}
 		if line.contains('@if ') {
 			s.writeln(STR_END)
-			pos := line.index('@if')
-			s.writeln('if ' + line[pos + 4..] + '{')
+			pos := line.index('@if') or { continue }
+			s.writeln('if ' + line[pos+4..] + '{')
 			s.writeln(STR_START)
 		}
 		else if line.contains('@end') {
@@ -62,8 +62,8 @@ _ = header
 		}
 		else if line.contains('@for') {
 			s.writeln(STR_END)
-			pos := line.index('@for')
-			s.writeln('for ' + line[pos + 4..] + '{')
+			pos := line.index('@for') or { continue }
+			s.writeln('for ' + line[pos+4..] + '{')
 			s.writeln(STR_START)
 		}
 		else if !in_css && line.contains('.') && line.ends_with('{') {