Update dependencies

vendor/go4.org/mem/fields.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2020 The Go4 AUTHORS
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package mem
+
+import (
+	"unicode"
+	"unicode/utf8"
+)
+
+var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
+
+// AppendFields is like strings.Fields, but is append-like and uses a mem.RO instead of a string.
+func AppendFields(dst []RO, m RO) []RO {
+	s := m.m
+
+	// Copied from the Go standard library (BSD license).
+
+	// First count the fields.
+	// This is an exact count if s is ASCII, otherwise it is an approximation.
+	n := 0
+	wasSpace := 1
+	// setBits is used to track which bits are set in the bytes of s.
+	setBits := uint8(0)
+	for i := 0; i < len(s); i++ {
+		r := s[i]
+		setBits |= r
+		isSpace := int(asciiSpace[r])
+		n += wasSpace & ^isSpace
+		wasSpace = isSpace
+	}
+
+	if setBits >= utf8.RuneSelf {
+		// Some runes in the input string are not ASCII.
+		return AppendFieldsFunc(dst, m, unicode.IsSpace)
+	}
+	// ASCII fast path
+	fieldStart := 0
+	i := 0
+	// Skip spaces in the front of the input.
+	for i < len(s) && asciiSpace[s[i]] != 0 {
+		i++
+	}
+	fieldStart = i
+	for i < len(s) {
+		if asciiSpace[s[i]] == 0 {
+			i++
+			continue
+		}
+		dst = append(dst, RO{m: s[fieldStart:i]})
+		i++
+		// Skip spaces in between fields.
+		for i < len(s) && asciiSpace[s[i]] != 0 {
+			i++
+		}
+		fieldStart = i
+	}
+	if fieldStart < len(s) { // Last field might end at EOF.
+		dst = append(dst, RO{m: s[fieldStart:]})
+	}
+	return dst
+}
+
+// AppendFieldsFunc is like strings.FieldsFunc, but is append-like and uses a mem.RO instead of a string.
+func AppendFieldsFunc(dst []RO, m RO, f func(rune) bool) []RO {
+	s := string(m.m)
+
+	// Find the field start and end indices.
+	wasField := false
+	fromIndex := 0
+	for i, rune := range s {
+		if f(rune) {
+			if wasField {
+				dst = append(dst, RO{m: unsafeString(s[fromIndex:i])})
+				wasField = false
+			}
+		} else {
+			if !wasField {
+				fromIndex = i
+				wasField = true
+			}
+		}
+	}
+
+	// Last field might end at EOF.
+	if wasField {
+		dst = append(dst, RO{m: unsafeString(s[fromIndex:len(s)])})
+	}
+	return dst
+}