replace.go

package sr

import "bytes"

// ReplaceSlice replaces b[i:] with the contents of replace, calling Extend if needed.
func ReplaceSlice(b []byte, i int, replace []byte) []byte {
	n := len(b) - i
	m := len(replace)
	o := m - n
	if o > 0 {
		b = Extend(b, o)
	}
	copy(b[i:], replace)
	if o < 0 {
		b = Truncate(b, len(b)+o)
	}
	return b
}

// ReplaceSlice2 replaces b[i:j] with the contents of replace, calling Extend if needed.
func ReplaceSlice2(b []byte, i int, j int, replace []byte) []byte {
	n := j - i
	m := len(replace)
	o := m - n
	if o > 0 {
		b = Extend(b, o)
	}
	copy(b[i+m:], b[j:])
	if o < 0 {
		b = Truncate(b, len(b)+o)
	}
	copy(b[i:], replace)
	return b
}

// ReplaceSlice3 replaces b[:j] with the contents of replace, calling Extend if needed.
func ReplaceSlice3(b []byte, j int, replace []byte) []byte {
	n := j
	m := len(replace)
	o := m - n
	if o > 0 {
		b = Extend(b, o)
	}
	copy(b[j+o:], b[j:])
	if o < 0 {
		b = Truncate(b, len(b)+o)
	}
	copy(b, replace)
	return b
}

func Replace(b, find, replace []byte) []byte {
	i := bytes.Index(b, find)
	if i < 0 {
		return b
	}
	n := len(find)
	b = ReplaceSlice2(b, i, i+n, replace)
	return b
}

func ReplaceAll(b, find, replace []byte) []byte {
	n := len(find)
	m := len(replace)
	o := m - n
	for i := bytes.Index(b, find); i < len(b); {
		b = ReplaceSlice2(b, i, i+n, replace)
		i += o
		idx := bytes.Index(b[i:], find)
		if idx < 0 {
			break
		}
		i += idx
	}
	return b
}

func ReplaceFull(b, replace []byte) []byte { return ReplaceSlice2(b, 0, len(b), replace) }

func ReplacePrefix(b, find, replace []byte) []byte {
	if !bytes.HasPrefix(b, find) {
		return b
	}
	n := len(find)
	b = ReplaceSlice2(b, 0, n, replace)
	return b
}

func ReplaceSuffix(b, find, replace []byte) []byte {
	if !bytes.HasSuffix(b, find) {
		return b
	}
	n := len(b)
	m := len(find)
	b = ReplaceSlice2(b, n-m, n, replace)
	return b
}