Adds most of the toolsHEADmaster

1 files changed, 1640 insertions, 0 deletions

diff --git a/v_windows/v/old/vlib/builtin/string.v b/v_windows/v/old/vlib/builtin/string.v
new file mode 100644
index 0000000..169ed2d
--- /dev/null
+++ b/v_windows/v/old/vlib/builtin/string.v
@@ -0,0 +1,1640 @@
+// Copyright (c) 2019-2021 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+module builtin
+
+import strconv
+
+/*
+NB: A V string should be/is immutable from the point of view of
+    V user programs after it is first created. A V string is
+    also slightly larger than the equivalent C string because
+    the V string also has an integer length attached.
+
+    This tradeoff is made, since V strings are created just *once*,
+    but potentially used *many times* over their lifetime.
+
+    The V string implementation uses a struct, that has a .str field,
+    which points to a C style 0 terminated memory block. Although not
+    strictly necessary from the V point of view, that additional 0
+    is *very useful for C interoperability*.
+
+    The V string implementation also has an integer .len field,
+    containing the length of the .str field, excluding the
+    terminating 0 (just like the C's strlen(s) would do).
+
+    The 0 ending of .str, and the .len field, mean that in practice:
+      a) a V string s can be used very easily, wherever a
+         C string is needed, just by passing s.str,
+         without a need for further conversion/copying.
+
+      b) where strlen(s) is needed, you can just pass s.len,
+         without having to constantly recompute the length of s
+         *over and over again* like some C programs do. This is because
+         V strings are immutable and so their length does not change.
+
+    Ordinary V code *does not need* to be concerned with the
+    additional 0 in the .str field. The 0 *must* be put there by the
+    low level string creating functions inside this module.
+
+    Failing to do this will lead to programs that work most of the
+    time, when used with pure V functions, but fail in strange ways,
+    when used with modules using C functions (for example os and so on).
+*/
+pub struct string {
+pub:
+	str &byte = 0 // points to a C style 0 terminated string of bytes.
+	len int   // the length of the .str field, excluding the ending 0 byte. It is always equal to strlen(.str).
+	// NB string.is_lit is an enumeration of the following:
+	// .is_lit == 0 => a fresh string, should be freed by autofree
+	// .is_lit == 1 => a literal string from .rodata, should NOT be freed
+	// .is_lit == -98761234 => already freed string, protects against double frees.
+	// ---------> ^^^^^^^^^ calling free on these is a bug.
+	// Any other value means that the string has been corrupted.
+mut:
+	is_lit int
+}
+
+// vstrlen returns the V length of the C string `s` (0 terminator is not counted).
+[unsafe]
+pub fn vstrlen(s &byte) int {
+	return unsafe { C.strlen(&char(s)) }
+}
+
+pub fn (s string) runes() []rune {
+	mut runes := []rune{cap: s.len}
+	for i := 0; i < s.len; i++ {
+		char_len := utf8_char_len(unsafe { s.str[i] })
+		if char_len > 1 {
+			end := if s.len - 1 >= i + char_len { i + char_len } else { s.len }
+			mut r := unsafe { s[i..end] }
+			runes << r.utf32_code()
+			i += char_len - 1
+		} else {
+			runes << unsafe { s.str[i] }
+		}
+	}
+	return runes
+}
+
+// tos converts a C string to a V string.
+// String data is reused, not copied.
+[unsafe]
+pub fn tos(s &byte, len int) string {
+	// This should never happen.
+	if s == 0 {
+		panic('tos(): nil string')
+	}
+	return string{
+		str: unsafe { s }
+		len: len
+	}
+}
+
+// tos_clone returns a copy of `s`.
+[unsafe]
+pub fn tos_clone(s &byte) string {
+	return unsafe { tos2(s) }.clone()
+}
+
+// tos2 does the same as `tos`, but also calculates the length. Called by `string(bytes)` casts.
+// Used only internally.
+[unsafe]
+pub fn tos2(s &byte) string {
+	if s == 0 {
+		panic('tos2: nil string')
+	}
+	return string{
+		str: unsafe { s }
+		len: unsafe { vstrlen(s) }
+	}
+}
+
+// tos3 does the same as `tos2`, but for char*, to avoid warnings.
+[unsafe]
+pub fn tos3(s &char) string {
+	if s == 0 {
+		panic('tos3: nil string')
+	}
+	return string{
+		str: &byte(s)
+		len: unsafe { C.strlen(s) }
+	}
+}
+
+// tos4 does the same as `tos2`, but returns an empty string on nil ptr.
+[unsafe]
+pub fn tos4(s &byte) string {
+	if s == 0 {
+		return ''
+	}
+	return unsafe { tos2(s) }
+}
+
+// tos5 does the same as `tos4`, but for char*, to avoid warnings.
+[unsafe]
+pub fn tos5(s &char) string {
+	if s == 0 {
+		return ''
+	}
+	return unsafe { tos3(s) }
+}
+
+// vstring converts a C style string to a V string. NB: the string data is reused, NOT copied.
+// strings returned from this function will be normal V strings beside that (i.e. they would be
+// freed by V's -autofree mechanism, when they are no longer used).
+[unsafe]
+pub fn (bp &byte) vstring() string {
+	return string{
+		str: unsafe { bp }
+		len: unsafe { C.strlen(&char(bp)) }
+	}
+}
+
+// vstring_with_len converts a C style string to a V string.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (bp &byte) vstring_with_len(len int) string {
+	return string{
+		str: unsafe { bp }
+		len: len
+		is_lit: 0
+	}
+}
+
+// vstring converts C char* to V string.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp &char) vstring() string {
+	return string{
+		str: &byte(cp)
+		len: unsafe { C.strlen(cp) }
+		is_lit: 0
+	}
+}
+
+// vstring_with_len converts C char* to V string.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp &char) vstring_with_len(len int) string {
+	return string{
+		str: &byte(cp)
+		len: len
+		is_lit: 0
+	}
+}
+
+// vstring_literal converts a C style string to a V string.
+// NB: the string data is reused, NOT copied.
+// NB2: unlike vstring, vstring_literal will mark the string
+// as a literal, so it will not be freed by autofree.
+// This is suitable for readonly strings, C string literals etc,
+// that can be read by the V program, but that should not be
+// managed by it, for example `os.args` is implemented using it.
+[unsafe]
+pub fn (bp &byte) vstring_literal() string {
+	return string{
+		str: unsafe { bp }
+		len: unsafe { C.strlen(&char(bp)) }
+		is_lit: 1
+	}
+}
+
+// vstring_with_len converts a C style string to a V string.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (bp &byte) vstring_literal_with_len(len int) string {
+	return string{
+		str: unsafe { bp }
+		len: len
+		is_lit: 1
+	}
+}
+
+// vstring_literal converts C char* to V string.
+// See also vstring_literal defined on byteptr for more details.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp &char) vstring_literal() string {
+	return string{
+		str: &byte(cp)
+		len: unsafe { C.strlen(cp) }
+		is_lit: 1
+	}
+}
+
+// vstring_literal_with_len converts C char* to V string.
+// See also vstring_literal_with_len defined on byteptr.
+// NB: the string data is reused, NOT copied.
+[unsafe]
+pub fn (cp &char) vstring_literal_with_len(len int) string {
+	return string{
+		str: &byte(cp)
+		len: len
+		is_lit: 1
+	}
+}
+
+// clone_static returns an independent copy of a given array.
+// It should be used only in -autofree generated code.
+fn (a string) clone_static() string {
+	return a.clone()
+}
+
+// clone returns a copy of the V string `a`.
+pub fn (a string) clone() string {
+	if a.len == 0 {
+		return ''
+	}
+	mut b := string{
+		str: unsafe { malloc_noscan(a.len + 1) }
+		len: a.len
+	}
+	unsafe {
+		C.memcpy(b.str, a.str, a.len)
+		b.str[a.len] = 0
+	}
+	return b
+}
+
+// cstring_to_vstring creates a copy of cstr and turns it into a v string.
+[unsafe]
+pub fn cstring_to_vstring(cstr &char) string {
+	return unsafe { tos_clone(&byte(cstr)) }
+}
+
+// replace_once replaces the first occurence of `rep` with the string passed in `with`.
+pub fn (s string) replace_once(rep string, with string) string {
+	idx := s.index_(rep)
+	if idx == -1 {
+		return s.clone()
+	}
+	return s.substr(0, idx) + with + s.substr(idx + rep.len, s.len)
+}
+
+// replace replaces all occurences of `rep` with the string passed in `with`.
+[direct_array_access]
+pub fn (s string) replace(rep string, with string) string {
+	if s.len == 0 || rep.len == 0 || rep.len > s.len {
+		return s.clone()
+	}
+	if !s.contains(rep) {
+		return s.clone()
+	}
+	// TODO PERF Allocating ints is expensive. Should be a stack array
+	// Get locations of all reps within this string
+	mut idxs := []int{cap: s.len / rep.len}
+	defer {
+		unsafe { idxs.free() }
+	}
+	mut idx := 0
+	for {
+		idx = s.index_after(rep, idx)
+		if idx == -1 {
+			break
+		}
+		idxs << idx
+		idx += rep.len
+	}
+	// Dont change the string if there's nothing to replace
+	if idxs.len == 0 {
+		return s.clone()
+	}
+	// Now we know the number of replacements we need to do and we can calc the len of the new string
+	new_len := s.len + idxs.len * (with.len - rep.len)
+	mut b := unsafe { malloc_noscan(new_len + 1) } // add space for the null byte at the end
+	// Fill the new string
+	mut b_i := 0
+	mut s_idx := 0
+	for _, rep_pos in idxs {
+		for i in s_idx .. rep_pos { // copy everything up to piece being replaced
+			unsafe {
+				b[b_i] = s[i]
+			}
+			b_i++
+		}
+		s_idx = rep_pos + rep.len // move string index past replacement
+		for i in 0 .. with.len { // copy replacement piece
+			unsafe {
+				b[b_i] = with[i]
+			}
+			b_i++
+		}
+	}
+	if s_idx < s.len { // if any original after last replacement, copy it
+		for i in s_idx .. s.len {
+			unsafe {
+				b[b_i] = s[i]
+			}
+			b_i++
+		}
+	}
+	unsafe {
+		b[new_len] = 0
+		return tos(b, new_len)
+	}
+}
+
+struct RepIndex {
+	idx     int
+	val_idx int
+}
+
+// compare_rep_index returns the result of comparing RepIndex `a` and `b`.
+fn compare_rep_index(a &RepIndex, b &RepIndex) int {
+	if a.idx < b.idx {
+		return -1
+	}
+	if a.idx > b.idx {
+		return 1
+	}
+	return 0
+}
+
+// sort2 sorts the RepIndex array using `compare_rep_index`.
+fn (mut a []RepIndex) sort2() {
+	a.sort_with_compare(compare_rep_index)
+}
+
+// replace_each replaces all occurences of the string pairs given in `vals`.
+// Example: assert 'ABCD'.replace_each(['B','C/','C','D','D','C']) == 'AC/DC'
+[direct_array_access]
+pub fn (s string) replace_each(vals []string) string {
+	if s.len == 0 || vals.len == 0 {
+		return s.clone()
+	}
+	if vals.len % 2 != 0 {
+		eprintln('string.replace_each(): odd number of strings')
+		return s.clone()
+	}
+	// `rep` - string to replace
+	// `with` - string to replace with
+	// Remember positions of all rep strings, and calculate the length
+	// of the new string to do just one allocation.
+	mut new_len := s.len
+	mut idxs := []RepIndex{}
+	mut idx := 0
+	s_ := s.clone()
+	for rep_i := 0; rep_i < vals.len; rep_i += 2 {
+		// vals: ['rep1, 'with1', 'rep2', 'with2']
+		rep := vals[rep_i]
+		with := vals[rep_i + 1]
+		for {
+			idx = s_.index_after(rep, idx)
+			if idx == -1 {
+				break
+			}
+			// The string already found is set to `/del`, to avoid duplicate searches.
+			for i in 0 .. rep.len {
+				unsafe {
+					s_.str[idx + i] = 127
+				}
+			}
+			// We need to remember both the position in the string,
+			// and which rep/with pair it refers to.
+			idxs << RepIndex{
+				idx: idx
+				val_idx: rep_i
+			}
+			idx += rep.len
+			new_len += with.len - rep.len
+		}
+	}
+	// Dont change the string if there's nothing to replace
+	if idxs.len == 0 {
+		return s.clone()
+	}
+	idxs.sort2()
+	mut b := unsafe { malloc_noscan(new_len + 1) } // add space for 0 terminator
+	// Fill the new string
+	mut idx_pos := 0
+	mut cur_idx := idxs[idx_pos]
+	mut b_i := 0
+	for i := 0; i < s.len; i++ {
+		if i == cur_idx.idx {
+			// Reached the location of rep, replace it with "with"
+			rep := vals[cur_idx.val_idx]
+			with := vals[cur_idx.val_idx + 1]
+			for j in 0 .. with.len {
+				unsafe {
+					b[b_i] = with[j]
+				}
+				b_i++
+			}
+			// Skip the length of rep, since we just replaced it with "with"
+			i += rep.len - 1
+			// Go to the next index
+			idx_pos++
+			if idx_pos < idxs.len {
+				cur_idx = idxs[idx_pos]
+			}
+		} else {
+			// Rep doesnt start here, just copy
+			unsafe {
+				b[b_i] = s.str[i]
+			}
+			b_i++
+		}
+	}
+	unsafe {
+		b[new_len] = 0
+		return tos(b, new_len)
+	}
+}
+
+// bool returns `true` if the string equals the word "true" it will return `false` otherwise.
+pub fn (s string) bool() bool {
+	return s == 'true' || s == 't' // TODO t for pg, remove
+}
+
+// int returns the value of the string as an integer `'1'.int() == 1`.
+pub fn (s string) int() int {
+	return int(strconv.common_parse_int(s, 0, 32, false, false) or { 0 })
+}
+
+// i64 returns the value of the string as i64 `'1'.i64() == i64(1)`.
+pub fn (s string) i64() i64 {
+	return strconv.common_parse_int(s, 0, 64, false, false) or { 0 }
+}
+
+// i8 returns the value of the string as i8 `'1'.i8() == i8(1)`.
+pub fn (s string) i8() i8 {
+	return i8(strconv.common_parse_int(s, 0, 8, false, false) or { 0 })
+}
+
+// i16 returns the value of the string as i16 `'1'.i16() == i16(1)`.
+pub fn (s string) i16() i16 {
+	return i16(strconv.common_parse_int(s, 0, 16, false, false) or { 0 })
+}
+
+// f32 returns the value of the string as f32 `'1.0'.f32() == f32(1)`.
+pub fn (s string) f32() f32 {
+	// return C.atof(&char(s.str))
+	return f32(strconv.atof64(s))
+}
+
+// f64 returns the value of the string as f64 `'1.0'.f64() == f64(1)`.
+pub fn (s string) f64() f64 {
+	// return C.atof(&char(s.str))
+	return strconv.atof64(s)
+}
+
+// u16 returns the value of the string as u16 `'1'.u16() == u16(1)`.
+pub fn (s string) u16() u16 {
+	return u16(strconv.common_parse_uint(s, 0, 16, false, false) or { 0 })
+}
+
+// u32 returns the value of the string as u32 `'1'.u32() == u32(1)`.
+pub fn (s string) u32() u32 {
+	return u32(strconv.common_parse_uint(s, 0, 32, false, false) or { 0 })
+}
+
+// u64 returns the value of the string as u64 `'1'.u64() == u64(1)`.
+pub fn (s string) u64() u64 {
+	return strconv.common_parse_uint(s, 0, 64, false, false) or { 0 }
+}
+
+[direct_array_access]
+fn (s string) == (a string) bool {
+	if s.str == 0 {
+		// should never happen
+		panic('string.eq(): nil string')
+	}
+	if s.len != a.len {
+		return false
+	}
+	if s.len > 0 {
+		last_idx := s.len - 1
+		if s[last_idx] != a[last_idx] {
+			return false
+		}
+	}
+	unsafe {
+		return C.memcmp(s.str, a.str, a.len) == 0
+	}
+}
+
+fn (s string) < (a string) bool {
+	for i in 0 .. s.len {
+		if i >= a.len || s[i] > a[i] {
+			return false
+		} else if s[i] < a[i] {
+			return true
+		}
+	}
+	if s.len < a.len {
+		return true
+	}
+	return false
+}
+
+fn (s string) + (a string) string {
+	new_len := a.len + s.len
+	mut res := string{
+		str: unsafe { malloc_noscan(new_len + 1) }
+		len: new_len
+	}
+	for j in 0 .. s.len {
+		unsafe {
+			res.str[j] = s.str[j]
+		}
+	}
+	for j in 0 .. a.len {
+		unsafe {
+			res.str[s.len + j] = a.str[j]
+		}
+	}
+	unsafe {
+		res.str[new_len] = 0 // V strings are not null terminated, but just in case
+	}
+	return res
+}
+
+// split splits the string to an array by `delim`.
+// Example: assert 'A B C'.split(' ') == ['A','B','C']
+// If `delim` is empty the string is split by it's characters.
+// Example: assert 'DEF'.split('') == ['D','E','F']
+pub fn (s string) split(delim string) []string {
+	return s.split_nth(delim, 0)
+}
+
+// split_nth splits the string based on the passed `delim` substring.
+// It returns the first Nth parts. When N=0, return all the splits.
+// The last returned element has the remainder of the string, even if
+// the remainder contains more `delim` substrings.
+[direct_array_access]
+pub fn (s string) split_nth(delim string, nth int) []string {
+	mut res := []string{}
+	mut i := 0
+
+	match delim.len {
+		0 {
+			i = 1
+			for ch in s {
+				if nth > 0 && i >= nth {
+					res << s[i..]
+					break
+				}
+				res << ch.ascii_str()
+				i++
+			}
+			return res
+		}
+		1 {
+			mut start := 0
+			delim_byte := delim[0]
+
+			for i < s.len {
+				if s[i] == delim_byte {
+					was_last := nth > 0 && res.len == nth - 1
+					if was_last {
+						break
+					}
+					val := s.substr(start, i)
+					res << val
+					start = i + delim.len
+					i = start
+				} else {
+					i++
+				}
+			}
+
+			// Then the remaining right part of the string
+			if nth < 1 || res.len < nth {
+				res << s[start..]
+			}
+			return res
+		}
+		else {
+			mut start := 0
+			// Take the left part for each delimiter occurence
+			for i <= s.len {
+				is_delim := i + delim.len <= s.len && s.substr(i, i + delim.len) == delim
+				if is_delim {
+					was_last := nth > 0 && res.len == nth - 1
+					if was_last {
+						break
+					}
+					val := s.substr(start, i)
+					res << val
+					start = i + delim.len
+					i = start
+				} else {
+					i++
+				}
+			}
+			// Then the remaining right part of the string
+			if nth < 1 || res.len < nth {
+				res << s[start..]
+			}
+			return res
+		}
+	}
+}
+
+// split_into_lines splits the string by newline characters.
+// newlines are stripped.
+// Both `\n` and `\r\n` newline endings are supported.
+[direct_array_access]
+pub fn (s string) split_into_lines() []string {
+	mut res := []string{}
+	if s.len == 0 {
+		return res
+	}
+	mut start := 0
+	mut end := 0
+	for i := 0; i < s.len; i++ {
+		if s[i] == 10 {
+			end = if i > 0 && s[i - 1] == 13 { i - 1 } else { i }
+			res << if start == end { '' } else { s[start..end] }
+			start = i + 1
+		}
+	}
+	if start < s.len {
+		res << s[start..]
+	}
+	return res
+}
+
+// used internally for [2..4]
+fn (s string) substr2(start int, _end int, end_max bool) string {
+	end := if end_max { s.len } else { _end }
+	return s.substr(start, end)
+}
+
+// substr returns the string between index positions `start` and `end`.
+// Example: assert 'ABCD'.substr(1,3) == 'BC'
+pub fn (s string) substr(start int, end int) string {
+	$if !no_bounds_checking ? {
+		if start > end || start > s.len || end > s.len || start < 0 || end < 0 {
+			panic('substr($start, $end) out of bounds (len=$s.len)')
+		}
+	}
+	len := end - start
+	if len == s.len {
+		return s.clone()
+	}
+	mut res := string{
+		str: unsafe { malloc_noscan(len + 1) }
+		len: len
+	}
+	for i in 0 .. len {
+		unsafe {
+			res.str[i] = s.str[start + i]
+		}
+	}
+	unsafe {
+		res.str[len] = 0
+	}
+	return res
+}
+
+// index returns the position of the first character of the input string.
+// It will return `-1` if the input string can't be found.
+fn (s string) index_(p string) int {
+	if p.len > s.len || p.len == 0 {
+		return -1
+	}
+	if p.len > 2 {
+		return s.index_kmp(p)
+	}
+	mut i := 0
+	for i < s.len {
+		mut j := 0
+		for j < p.len && unsafe { s.str[i + j] == p.str[j] } {
+			j++
+		}
+		if j == p.len {
+			return i
+		}
+		i++
+	}
+	return -1
+}
+
+// index returns the position of the first character of the input string.
+// It will return `none` if the input string can't be found.
+pub fn (s string) index(p string) ?int {
+	idx := s.index_(p)
+	if idx == -1 {
+		return none
+	}
+	return idx
+}
+
+// index_kmp does KMP search.
+[direct_array_access; manualfree]
+fn (s string) index_kmp(p string) int {
+	if p.len > s.len {
+		return -1
+	}
+	mut prefix := []int{len: p.len}
+	defer {
+		unsafe { prefix.free() }
+	}
+	mut j := 0
+	for i := 1; i < p.len; i++ {
+		for unsafe { p.str[j] != p.str[i] } && j > 0 {
+			j = prefix[j - 1]
+		}
+		if unsafe { p.str[j] == p.str[i] } {
+			j++
+		}
+		prefix[i] = j
+	}
+	j = 0
+	for i in 0 .. s.len {
+		for unsafe { p.str[j] != s.str[i] } && j > 0 {
+			j = prefix[j - 1]
+		}
+		if unsafe { p.str[j] == s.str[i] } {
+			j++
+		}
+		if j == p.len {
+			return i - p.len + 1
+		}
+	}
+	return -1
+}
+
+// index_any returns the position of any of the characters in the input string - if found.
+pub fn (s string) index_any(chars string) int {
+	for c in chars {
+		idx := s.index_(c.ascii_str())
+		if idx == -1 {
+			continue
+		}
+		return idx
+	}
+	return -1
+}
+
+// last_index returns the position of the last occurence of the input string.
+fn (s string) last_index_(p string) int {
+	if p.len > s.len || p.len == 0 {
+		return -1
+	}
+	mut i := s.len - p.len
+	for i >= 0 {
+		mut j := 0
+		for j < p.len && unsafe { s.str[i + j] == p.str[j] } {
+			j++
+		}
+		if j == p.len {
+			return i
+		}
+		i--
+	}
+	return -1
+}
+
+// last_index returns the position of the last occurence of the input string.
+pub fn (s string) last_index(p string) ?int {
+	idx := s.last_index_(p)
+	if idx == -1 {
+		return none
+	}
+	return idx
+}
+
+// index_after returns the position of the input string, starting search from `start` position.
+pub fn (s string) index_after(p string, start int) int {
+	if p.len > s.len {
+		return -1
+	}
+	mut strt := start
+	if start < 0 {
+		strt = 0
+	}
+	if start >= s.len {
+		return -1
+	}
+	mut i := strt
+	for i < s.len {
+		mut j := 0
+		mut ii := i
+		for j < p.len && unsafe { s.str[ii] == p.str[j] } {
+			j++
+			ii++
+		}
+		if j == p.len {
+			return i
+		}
+		i++
+	}
+	return -1
+}
+
+// index_byte returns the index of byte `c` if found in the string.
+// index_byte returns -1 if the byte can not be found.
+pub fn (s string) index_byte(c byte) int {
+	for i in 0 .. s.len {
+		if unsafe { s.str[i] } == c {
+			return i
+		}
+	}
+	return -1
+}
+
+// last_index_byte returns the index of the last occurence of byte `c` if found in the string.
+// last_index_byte returns -1 if the byte is not found.
+pub fn (s string) last_index_byte(c byte) int {
+	for i := s.len - 1; i >= 0; i-- {
+		if unsafe { s.str[i] == c } {
+			return i
+		}
+	}
+	return -1
+}
+
+// count returns the number of occurrences of `substr` in the string.
+// count returns -1 if no `substr` could be found.
+pub fn (s string) count(substr string) int {
+	if s.len == 0 || substr.len == 0 {
+		return 0
+	}
+	if substr.len > s.len {
+		return 0
+	}
+
+	mut n := 0
+
+	if substr.len == 1 {
+		target := substr[0]
+
+		for letter in s {
+			if letter == target {
+				n++
+			}
+		}
+
+		return n
+	}
+
+	mut i := 0
+	for {
+		i = s.index_after(substr, i)
+		if i == -1 {
+			return n
+		}
+		i += substr.len
+		n++
+	}
+	return 0 // TODO can never get here - v doesn't know that
+}
+
+// contains returns `true` if the string contains `substr`.
+pub fn (s string) contains(substr string) bool {
+	if substr.len == 0 {
+		return true
+	}
+	if s.index_(substr) == -1 {
+		return false
+	}
+	return true
+}
+
+// contains_any returns `true` if the string contains any chars in `chars`.
+pub fn (s string) contains_any(chars string) bool {
+	for c in chars {
+		if s.contains(c.ascii_str()) {
+			return true
+		}
+	}
+	return false
+}
+
+// contains_any_substr returns `true` if the string contains any of the strings in `substrs`.
+pub fn (s string) contains_any_substr(substrs []string) bool {
+	if substrs.len == 0 {
+		return true
+	}
+	for sub in substrs {
+		if s.contains(sub) {
+			return true
+		}
+	}
+	return false
+}
+
+// starts_with returns `true` if the string starts with `p`.
+pub fn (s string) starts_with(p string) bool {
+	if p.len > s.len {
+		return false
+	}
+	for i in 0 .. p.len {
+		if unsafe { s.str[i] != p.str[i] } {
+			return false
+		}
+	}
+	return true
+}
+
+// ends_with returns `true` if the string ends with `p`.
+pub fn (s string) ends_with(p string) bool {
+	if p.len > s.len {
+		return false
+	}
+	for i in 0 .. p.len {
+		if unsafe { p.str[i] != s.str[s.len - p.len + i] } {
+			return false
+		}
+	}
+	return true
+}
+
+// to_lower returns the string in all lowercase characters.
+// TODO only works with ASCII
+pub fn (s string) to_lower() string {
+	unsafe {
+		mut b := malloc_noscan(s.len + 1)
+		for i in 0 .. s.len {
+			if s.str[i] >= `A` && s.str[i] <= `Z` {
+				b[i] = s.str[i] + 32
+			} else {
+				b[i] = s.str[i]
+			}
+		}
+		b[s.len] = 0
+		return tos(b, s.len)
+	}
+}
+
+// is_lower returns `true` if all characters in the string is lowercase.
+// Example: assert 'hello developer'.is_lower() == true
+[direct_array_access]
+pub fn (s string) is_lower() bool {
+	for i in 0 .. s.len {
+		if s[i] >= `A` && s[i] <= `Z` {
+			return false
+		}
+	}
+	return true
+}
+
+// to_upper returns the string in all uppercase characters.
+// Example: assert 'Hello V'.to_upper() == 'HELLO V'
+pub fn (s string) to_upper() string {
+	unsafe {
+		mut b := malloc_noscan(s.len + 1)
+		for i in 0 .. s.len {
+			if s.str[i] >= `a` && s.str[i] <= `z` {
+				b[i] = s.str[i] - 32
+			} else {
+				b[i] = s.str[i]
+			}
+		}
+		b[s.len] = 0
+		return tos(b, s.len)
+	}
+}
+
+// is_upper returns `true` if all characters in the string is uppercase.
+// Example: assert 'HELLO V'.is_upper() == true
+[direct_array_access]
+pub fn (s string) is_upper() bool {
+	for i in 0 .. s.len {
+		if s[i] >= `a` && s[i] <= `z` {
+			return false
+		}
+	}
+	return true
+}
+
+// capitalize returns the string with the first character capitalized.
+// Example: assert 'hello'.capitalize() == 'Hello'
+[direct_array_access]
+pub fn (s string) capitalize() string {
+	if s.len == 0 {
+		return ''
+	}
+	s0 := s[0]
+	letter := s0.ascii_str()
+	uletter := letter.to_upper()
+	if s.len == 1 {
+		return uletter
+	}
+	srest := s[1..]
+	res := uletter + srest
+	return res
+}
+
+// is_capital returns `true` if the first character in the string is a capital letter.
+// Example: assert 'Hello'.is_capital() == true
+[direct_array_access]
+pub fn (s string) is_capital() bool {
+	if s.len == 0 || !(s[0] >= `A` && s[0] <= `Z`) {
+		return false
+	}
+	for i in 1 .. s.len {
+		if s[i] >= `A` && s[i] <= `Z` {
+			return false
+		}
+	}
+	return true
+}
+
+// title returns the string with each word capitalized.
+// Example: assert 'hello v developer'.title() == 'Hello V Developer'
+pub fn (s string) title() string {
+	words := s.split(' ')
+	mut tit := []string{}
+	for word in words {
+		tit << word.capitalize()
+	}
+	title := tit.join(' ')
+	return title
+}
+
+// is_title returns true if all words of the string is capitalized.
+// Example: assert 'Hello V Developer'.is_title() == true
+pub fn (s string) is_title() bool {
+	words := s.split(' ')
+	for word in words {
+		if !word.is_capital() {
+			return false
+		}
+	}
+	return true
+}
+
+// find_between returns the string found between `start` string and `end` string.
+// Example: assert 'hey [man] how you doin'.find_between('[', ']') == 'man'
+pub fn (s string) find_between(start string, end string) string {
+	start_pos := s.index_(start)
+	if start_pos == -1 {
+		return ''
+	}
+	// First get everything to the right of 'start'
+	val := s[start_pos + start.len..]
+	end_pos := val.index_(end)
+	if end_pos == -1 {
+		return val
+	}
+	return val[..end_pos]
+}
+
+// trim_space strips any of ` `, `\n`, `\t`, `\v`, `\f`, `\r` from the start and end of the string.
+// Example: assert ' Hello V '.trim_space() == 'Hello V'
+pub fn (s string) trim_space() string {
+	return s.trim(' \n\t\v\f\r')
+}
+
+// trim strips any of the characters given in `cutset` from the start and end of the string.
+// Example: assert ' ffHello V ffff'.trim(' f') == 'Hello V'
+[direct_array_access]
+pub fn (s string) trim(cutset string) string {
+	if s.len < 1 || cutset.len < 1 {
+		return s.clone()
+	}
+	mut pos_left := 0
+	mut pos_right := s.len - 1
+	mut cs_match := true
+	for pos_left <= s.len && pos_right >= -1 && cs_match {
+		cs_match = false
+		for cs in cutset {
+			if s[pos_left] == cs {
+				pos_left++
+				cs_match = true
+				break
+			}
+		}
+		for cs in cutset {
+			if s[pos_right] == cs {
+				pos_right--
+				cs_match = true
+				break
+			}
+		}
+		if pos_left > pos_right {
+			return ''
+		}
+	}
+	return s.substr(pos_left, pos_right + 1)
+}
+
+// trim_left strips any of the characters given in `cutset` from the left of the string.
+// Example: assert 'd Hello V developer'.trim_left(' d') == 'Hello V developer'
+[direct_array_access]
+pub fn (s string) trim_left(cutset string) string {
+	if s.len < 1 || cutset.len < 1 {
+		return s.clone()
+	}
+	mut pos := 0
+	for pos < s.len {
+		mut found := false
+		for cs in cutset {
+			if s[pos] == cs {
+				found = true
+				break
+			}
+		}
+		if !found {
+			break
+		}
+		pos++
+	}
+	return s[pos..]
+}
+
+// trim_right strips any of the characters given in `cutset` from the right of the string.
+// Example: assert ' Hello V d'.trim_right(' d') == ' Hello V'
+[direct_array_access]
+pub fn (s string) trim_right(cutset string) string {
+	if s.len < 1 || cutset.len < 1 {
+		return s.clone()
+	}
+	mut pos := s.len - 1
+	for pos >= 0 {
+		mut found := false
+		for cs in cutset {
+			if s[pos] == cs {
+				found = true
+			}
+		}
+		if !found {
+			break
+		}
+		pos--
+	}
+	if pos < 0 {
+		return ''
+	}
+	return s[..pos + 1]
+}
+
+// trim_prefix strips `str` from the start of the string.
+// Example: assert 'WorldHello V'.trim_prefix('World') == 'Hello V'
+pub fn (s string) trim_prefix(str string) string {
+	if s.starts_with(str) {
+		return s[str.len..]
+	}
+	return s.clone()
+}
+
+// trim_suffix strips `str` from the end of the string.
+// Example: assert 'Hello VWorld'.trim_suffix('World') == 'Hello V'
+pub fn (s string) trim_suffix(str string) string {
+	if s.ends_with(str) {
+		return s[..s.len - str.len]
+	}
+	return s.clone()
+}
+
+// compare_strings returns `-1` if `a < b`, `1` if `a > b` else `0`.
+pub fn compare_strings(a &string, b &string) int {
+	if a < b {
+		return -1
+	}
+	if a > b {
+		return 1
+	}
+	return 0
+}
+
+// compare_strings_reverse returns `1` if `a < b`, `-1` if `a > b` else `0`.
+fn compare_strings_reverse(a &string, b &string) int {
+	if a < b {
+		return 1
+	}
+	if a > b {
+		return -1
+	}
+	return 0
+}
+
+// compare_strings_by_len returns `-1` if `a.len < b.len`, `1` if `a.len > b.len` else `0`.
+fn compare_strings_by_len(a &string, b &string) int {
+	if a.len < b.len {
+		return -1
+	}
+	if a.len > b.len {
+		return 1
+	}
+	return 0
+}
+
+// compare_lower_strings returns the same as compare_strings but converts `a` and `b` to lower case before comparing.
+fn compare_lower_strings(a &string, b &string) int {
+	aa := a.to_lower()
+	bb := b.to_lower()
+	return compare_strings(&aa, &bb)
+}
+
+// sort sorts the string array.
+pub fn (mut s []string) sort() {
+	s.sort_with_compare(compare_strings)
+}
+
+// sort_ignore_case sorts the string array using case insesitive comparing.
+pub fn (mut s []string) sort_ignore_case() {
+	s.sort_with_compare(compare_lower_strings)
+}
+
+// sort_by_len sorts the the string array by each string's `.len` length.
+pub fn (mut s []string) sort_by_len() {
+	s.sort_with_compare(compare_strings_by_len)
+}
+
+// str returns a copy of the string
+pub fn (s string) str() string {
+	return s.clone()
+}
+
+// at returns the byte at index `idx`.
+// Example: assert 'ABC'.at(1) == byte(`B`)
+fn (s string) at(idx int) byte {
+	$if !no_bounds_checking ? {
+		if idx < 0 || idx >= s.len {
+			panic('string index out of range: $idx / $s.len')
+		}
+	}
+	unsafe {
+		return s.str[idx]
+	}
+}
+
+// version of `at()` that is used in `a[i] or {`
+// return an error when the index is out of range
+fn (s string) at_with_check(idx int) ?byte {
+	if idx < 0 || idx >= s.len {
+		return error('string index out of range')
+	}
+	unsafe {
+		return s.str[idx]
+	}
+}
+
+// is_space returns `true` if the byte is a white space character.
+// The following list is considered white space characters: ` `, `\t`, `\n`, `\v`, `\f`, `\r`, 0x85, 0xa0
+// Example: assert byte(` `).is_space() == true
+[inline]
+pub fn (c byte) is_space() bool {
+	// 0x85 is NEXT LINE (NEL)
+	// 0xa0 is NO-BREAK SPACE
+	return c == 32 || (c > 8 && c < 14) || (c == 0x85) || (c == 0xa0)
+}
+
+// is_digit returns `true` if the byte is in range 0-9 and `false` otherwise.
+// Example: assert byte(`9`) == true
+[inline]
+pub fn (c byte) is_digit() bool {
+	return c >= `0` && c <= `9`
+}
+
+// is_hex_digit returns `true` if the byte is either in range 0-9, a-f or A-F and `false` otherwise.
+// Example: assert byte(`F`) == true
+[inline]
+pub fn (c byte) is_hex_digit() bool {
+	return c.is_digit() || (c >= `a` && c <= `f`) || (c >= `A` && c <= `F`)
+}
+
+// is_oct_digit returns `true` if the byte is in range 0-7 and `false` otherwise.
+// Example: assert byte(`7`) == true
+[inline]
+pub fn (c byte) is_oct_digit() bool {
+	return c >= `0` && c <= `7`
+}
+
+// is_bin_digit returns `true` if the byte is a binary digit (0 or 1) and `false` otherwise.
+// Example: assert byte(`0`) == true
+[inline]
+pub fn (c byte) is_bin_digit() bool {
+	return c == `0` || c == `1`
+}
+
+// is_letter returns `true` if the byte is in range a-z or A-Z and `false` otherwise.
+// Example: assert byte(`V`) == true
+[inline]
+pub fn (c byte) is_letter() bool {
+	return (c >= `a` && c <= `z`) || (c >= `A` && c <= `Z`)
+}
+
+// free allows for manually freeing the memory occupied by the string
+[manualfree; unsafe]
+pub fn (s &string) free() {
+	$if prealloc {
+		return
+	}
+	if s.is_lit == -98761234 {
+		double_free_msg := unsafe { &byte(c'double string.free() detected\n') }
+		double_free_msg_len := unsafe { vstrlen(double_free_msg) }
+		$if freestanding {
+			bare_eprint(double_free_msg, u64(double_free_msg_len))
+		} $else {
+			_write_buf_to_fd(1, double_free_msg, double_free_msg_len)
+		}
+		return
+	}
+	if s.is_lit == 1 || s.str == 0 {
+		return
+	}
+	unsafe {
+		free(s.str)
+	}
+	s.is_lit = -98761234
+}
+
+// before returns the contents before `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.before('.') == '23:34:45'
+// Example: assert 'abcd'.before('.') == 'abcd'
+// TODO: deprecate and remove either .before or .all_before
+pub fn (s string) before(sub string) string {
+	pos := s.index_(sub)
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[..pos]
+}
+
+// all_before returns the contents before `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.all_before('.') == '23:34:45'
+// Example: assert 'abcd'.all_before('.') == 'abcd'
+pub fn (s string) all_before(sub string) string {
+	// TODO remove dup method
+	pos := s.index_(sub)
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[..pos]
+}
+
+// all_before_last returns the contents before the last occurence of `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.all_before_last(':') == '23:34'
+// Example: assert 'abcd'.all_before_last('.') == 'abcd'
+pub fn (s string) all_before_last(sub string) string {
+	pos := s.last_index_(sub)
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[..pos]
+}
+
+// all_after returns the contents after `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.all_after('.') == '234'
+// Example: assert 'abcd'.all_after('z') == 'abcd'
+pub fn (s string) all_after(sub string) string {
+	pos := s.index_(sub)
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[pos + sub.len..]
+}
+
+// all_after_last returns the contents after the last occurence of `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.all_after_last(':') == '45.234'
+// Example: assert 'abcd'.all_after_last('z') == 'abcd'
+pub fn (s string) all_after_last(sub string) string {
+	pos := s.last_index_(sub)
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[pos + sub.len..]
+}
+
+// after returns the contents after the last occurence of `sub` in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.after(':') == '45.234'
+// Example: assert 'abcd'.after('z') == 'abcd'
+// TODO: deprecate either .all_after_last or .after
+pub fn (s string) after(sub string) string {
+	return s.all_after_last(sub)
+}
+
+// after_char returns the contents after the first occurence of `sub` character in the string.
+// If the substring is not found, it returns the full input string.
+// Example: assert '23:34:45.234'.after_char(`:`) == '34:45.234'
+// Example: assert 'abcd'.after_char(`:`) == 'abcd'
+pub fn (s string) after_char(sub byte) string {
+	mut pos := -1
+	for i, c in s {
+		if c == sub {
+			pos = i
+			break
+		}
+	}
+	if pos == -1 {
+		return s.clone()
+	}
+	return s[pos + 1..]
+}
+
+// join joins a string array into a string using `sep` separator.
+// Example: assert ['Hello','V'].join(' ') == 'Hello V'
+pub fn (a []string) join(sep string) string {
+	if a.len == 0 {
+		return ''
+	}
+	mut len := 0
+	for val in a {
+		len += val.len + sep.len
+	}
+	len -= sep.len
+	// Allocate enough memory
+	mut res := string{
+		str: unsafe { malloc_noscan(len + 1) }
+		len: len
+	}
+	mut idx := 0
+	for i, val in a {
+		unsafe {
+			C.memcpy(res.str + idx, val.str, val.len)
+			idx += val.len
+		}
+		// Add sep if it's not last
+		if i != a.len - 1 {
+			unsafe {
+				C.memcpy(res.str + idx, sep.str, sep.len)
+				idx += sep.len
+			}
+		}
+	}
+	unsafe {
+		res.str[res.len] = 0
+	}
+	return res
+}
+
+// join joins a string array into a string using a `\n` newline delimiter.
+pub fn (s []string) join_lines() string {
+	return s.join('\n')
+}
+
+// reverse returns a reversed string.
+// Example: assert 'Hello V'.reverse() == 'V olleH'
+pub fn (s string) reverse() string {
+	if s.len == 0 || s.len == 1 {
+		return s.clone()
+	}
+	mut res := string{
+		str: unsafe { malloc_noscan(s.len + 1) }
+		len: s.len
+	}
+	for i := s.len - 1; i >= 0; i-- {
+		unsafe {
+			res.str[s.len - i - 1] = s[i]
+		}
+	}
+	unsafe {
+		res.str[res.len] = 0
+	}
+	return res
+}
+
+// limit returns a portion of the string, starting at `0` and extending for a given number of characters afterward.
+// 'hello'.limit(2) => 'he'
+// 'hi'.limit(10) => 'hi'
+pub fn (s string) limit(max int) string {
+	u := s.runes()
+	if u.len <= max {
+		return s.clone()
+	}
+	return u[0..max].string()
+}
+
+// hash returns an integer hash of the string.
+pub fn (s string) hash() int {
+	mut h := u32(0)
+	if h == 0 && s.len > 0 {
+		for c in s {
+			h = h * 31 + u32(c)
+		}
+	}
+	return int(h)
+}
+
+// bytes returns the string converted to a byte array.
+pub fn (s string) bytes() []byte {
+	if s.len == 0 {
+		return []
+	}
+	mut buf := []byte{len: s.len}
+	unsafe { C.memcpy(buf.data, s.str, s.len) }
+	return buf
+}
+
+// repeat returns a new string with `count` number of copies of the string it was called on.
+pub fn (s string) repeat(count int) string {
+	if count < 0 {
+		panic('string.repeat: count is negative: $count')
+	} else if count == 0 {
+		return ''
+	} else if count == 1 {
+		return s.clone()
+	}
+	mut ret := unsafe { malloc_noscan(s.len * count + 1) }
+	for i in 0 .. count {
+		for j in 0 .. s.len {
+			unsafe {
+				ret[i * s.len + j] = s[j]
+			}
+		}
+	}
+	new_len := s.len * count
+	unsafe {
+		ret[new_len] = 0
+	}
+	return unsafe { ret.vstring_with_len(new_len) }
+}
+
+// fields returns a string array of the string split by `\t` and ` `
+// Example: assert '\t\tv = v'.fields() == ['v', '=', 'v']
+// Example: assert '  sss   ssss'.fields() == ['sss', 'ssss']
+pub fn (s string) fields() []string {
+	mut res := []string{}
+	mut word_start := 0
+	mut word_len := 0
+	mut is_in_word := false
+	mut is_space := false
+	for i, c in s {
+		is_space = c in [32, 9, 10]
+		if !is_space {
+			word_len++
+		}
+		if !is_in_word && !is_space {
+			word_start = i
+			is_in_word = true
+			continue
+		}
+		if is_space && is_in_word {
+			res << s[word_start..word_start + word_len]
+			is_in_word = false
+			word_len = 0
+			word_start = 0
+			continue
+		}
+	}
+	if is_in_word && word_len > 0 {
+		// collect the remainder word at the end
+		res << s[word_start..s.len]
+	}
+	return res
+}
+
+// strip_margin allows multi-line strings to be formatted in a way that removes white-space
+// before a delimeter. by default `|` is used.
+// Note: the delimiter has to be a byte at this time. That means surrounding
+// the value in ``.
+//
+// Example:
+// st := 'Hello there,
+// |this is a string,
+// |    Everything before the first | is removed'.strip_margin()
+// Returns:
+// Hello there,
+// this is a string,
+// Everything before the first | is removed
+pub fn (s string) strip_margin() string {
+	return s.strip_margin_custom(`|`)
+}
+
+// strip_margin_custom does the same as `strip_margin` but will use `del` as delimiter instead of `|`
+[direct_array_access]
+pub fn (s string) strip_margin_custom(del byte) string {
+	mut sep := del
+	if sep.is_space() {
+		eprintln('Warning: `strip_margin` cannot use white-space as a delimiter')
+		eprintln('    Defaulting to `|`')
+		sep = `|`
+	}
+	// don't know how much space the resulting string will be, but the max it
+	// can be is this big
+	mut ret := unsafe { malloc_noscan(s.len + 1) }
+	mut count := 0
+	for i := 0; i < s.len; i++ {
+		if s[i] in [10, 13] {
+			unsafe {
+				ret[count] = s[i]
+			}
+			count++
+			// CRLF
+			if s[i] == 13 && i < s.len - 1 && s[i + 1] == 10 {
+				unsafe {
+					ret[count] = s[i + 1]
+				}
+				count++
+				i++
+			}
+			for s[i] != sep {
+				i++
+				if i >= s.len {
+					break
+				}
+			}
+		} else {
+			unsafe {
+				ret[count] = s[i]
+			}
+			count++
+		}
+	}
+	unsafe {
+		ret[count] = 0
+		return ret.vstring_with_len(count)
+	}
+}