t.Fatal("read did not panic")
case error:
if !strings.Contains(err.Error(), "reader returned negative count from Read") {
- t.Fatal("wrong panic: %v", err)
+ t.Fatalf("wrong panic: %v", err)
}
default:
t.Fatalf("unexpected panic value: %T(%v)", err, err)
--- /dev/null
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bufio
+
+// Exported for testing only.
+import (
+ "unicode/utf8"
+)
+
+var IsSpace = isSpace
+
+func (s *Scanner) MaxTokenSize(n int) {
+ if n < utf8.UTFMax || n > 1e9 {
+ panic("bad max token size")
+ }
+ if n < len(s.buf) {
+ s.buf = make([]byte, n)
+ }
+ s.maxTokenSize = n
+}
+
+// ErrOrEOF is like Err, but returns EOF. Used to test a corner case.
+func (s *Scanner) ErrOrEOF() error {
+ return s.err
+}
--- /dev/null
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bufio
+
+import (
+ "bytes"
+ "errors"
+ "io"
+ "unicode/utf8"
+)
+
+// Scanner provides a convenient interface for reading data such as
+// a file of newline-delimited lines of text. Successive calls to
+// the Scan method will step through the 'tokens' of a file, skipping
+// the bytes between the tokens. The specification of a token is
+// defined by a split function of type SplitFunc; the default split
+// function breaks the input into lines with newlines stripped. Split
+// functions are defined in this package for scanning a file into
+// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
+// client may instead provide a custom split function.
+//
+// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
+// large to fit in the buffer. When a scan stops, the reader may have
+// advanced arbitrarily far past the last token. Programs that need more
+// control over error handling or large tokens, or must run sequential scans
+// on a reader, should use bufio.Reader instead.
+//
+// TODO(r): Provide executable examples.
+//
+type Scanner struct {
+ r io.Reader // The reader provided by the client.
+ split SplitFunc // The function to split the tokens.
+ maxTokenSize int // Maximum size of a token; modified by tests.
+ token []byte // Last token returned by split.
+ buf []byte // Buffer used as argument to split.
+ start int // First non-processed byte in buf.
+ end int // End of data in buf.
+ err error // Sticky error.
+}
+
+// SplitFunc is the signature of the split function used to tokenize the
+// input. The arguments are an initial substring of the remaining unprocessed
+// data and a flag, atEOF, that reports whether the Reader has no more data
+// to give. The return values are the number of bytes to advance the input
+// and the next token to return to the user, plus an error, if any. If the
+// data does not yet hold a complete token, for instance if it has no newline
+// while scanning lines, SplitFunc can return (0, nil) to signal the Scanner
+// to read more data into the slice and try again with a longer slice
+// starting at the same point in the input.
+//
+// If the returned error is non-nil, scanning stops and the error
+// is returned to the client.
+//
+// The function is never called with an empty data slice unless atEOF
+// is true. If atEOF is true, however, data may be non-empty and,
+// as always, holds unprocessed text.
+type SplitFunc func(data []byte, atEOF bool) (advance int, token []byte, err error)
+
+// Errors returned by Scanner.
+var (
+ ErrTooLong = errors.New("bufio.Scanner: token too long")
+ ErrNegativeAdvance = errors.New("bufio.Scanner: SplitFunc returns negative advance count")
+ ErrAdvanceTooFar = errors.New("bufio.Scanner: SplitFunc returns advance count beyond input")
+)
+
+const (
+ // Maximum size used to buffer a token. The actual maximum token size
+ // may be smaller as the buffer may need to include, for instance, a newline.
+ MaxScanTokenSize = 64 * 1024
+)
+
+// NewScanner returns a new Scanner to read from r.
+func NewScanner(r io.Reader) *Scanner {
+ return &Scanner{
+ r: r,
+ split: ScanLines,
+ maxTokenSize: MaxScanTokenSize,
+ buf: make([]byte, 4096), // Plausible starting size; needn't be large.
+ }
+}
+
+// Err returns the first non-EOF error that was encountered by the Scanner.
+func (s *Scanner) Err() error {
+ if s.err == io.EOF {
+ return nil
+ }
+ return s.err
+}
+
+// Bytes returns the most recent token generated by a call to Scan.
+// The underlying array may point to data that will be overwritten
+// by a subsequent call to Scan. It does no allocation.
+func (s *Scanner) Bytes() []byte {
+ return s.token
+}
+
+// Text returns the most recent token generated by a call to Scan
+// as a newly allocated string holding its bytes.
+func (s *Scanner) Text() string {
+ return string(s.token)
+}
+
+// Scan advances the Scanner to the next token, which will then be
+// available through the Bytes or Text method. It returns false when the
+// scan stops, either by reaching the end of the input or an error.
+// After Scan returns false, the Err method will return any error that
+// occurred during scanning, except that if it was io.EOF, Err
+// will return nil.
+func (s *Scanner) Scan() bool {
+ // Loop until we have a token.
+ for {
+ // See if we can get a token with what we already have.
+ if s.end > s.start {
+ advance, token, err := s.split(s.buf[s.start:s.end], s.err != nil)
+ if err != nil {
+ s.setErr(err)
+ return false
+ }
+ if !s.advance(advance) {
+ return false
+ }
+ s.token = token
+ if token != nil {
+ return true
+ }
+ }
+ // We cannot generate a token with what we are holding.
+ // If we've already hit EOF or an I/O error, we are done.
+ if s.err != nil {
+ // Shut it down.
+ s.start = 0
+ s.end = 0
+ return false
+ }
+ // Must read more data.
+ // First, shift data to beginning of buffer if there's lots of empty space
+ // or space is neded.
+ if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
+ copy(s.buf, s.buf[s.start:s.end])
+ s.end -= s.start
+ s.start = 0
+ }
+ // Is the buffer full? If so, resize.
+ if s.end == len(s.buf) {
+ if len(s.buf) >= s.maxTokenSize {
+ s.setErr(ErrTooLong)
+ return false
+ }
+ newSize := len(s.buf) * 2
+ if newSize > s.maxTokenSize {
+ newSize = s.maxTokenSize
+ }
+ newBuf := make([]byte, newSize)
+ copy(newBuf, s.buf[s.start:s.end])
+ s.buf = newBuf
+ s.end -= s.start
+ s.start = 0
+ continue
+ }
+ // Finally we can read some input.
+ n, err := s.r.Read(s.buf[s.end:len(s.buf)])
+ if err != nil {
+ s.setErr(err)
+ }
+ if n == 0 { // Don't loop forever if Reader doesn't deliver EOF.
+ s.err = io.EOF
+ }
+ s.end += n
+ }
+ panic("not reached")
+}
+
+// advance consumes n bytes of the buffer. It reports whether the advance was legal.
+func (s *Scanner) advance(n int) bool {
+ if n < 0 {
+ s.setErr(ErrNegativeAdvance)
+ return false
+ }
+ if n > s.end-s.start {
+ s.setErr(ErrAdvanceTooFar)
+ return false
+ }
+ s.start += n
+ return true
+}
+
+// setErr records the first error encountered.
+func (s *Scanner) setErr(err error) {
+ if s.err == nil || s.err == io.EOF {
+ s.err = err
+ }
+}
+
+// Split sets the split function for the Scanner. If called, it must be
+// called before Scan. The default split function is ScanLines.
+func (s *Scanner) Split(split SplitFunc) {
+ s.split = split
+}
+
+// Split functions
+
+// ScanBytes is a split function for a Scanner that returns each byte as a token.
+func ScanBytes(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ if atEOF && len(data) == 0 {
+ return 0, nil, nil
+ }
+ return 1, data[0:1], nil
+}
+
+var errorRune = []byte(string(utf8.RuneError))
+
+// ScanRunes is a split function for a Scanner that returns each
+// UTF-8-encoded rune as a token. The sequence of runes returned is
+// equivalent to that from a range loop over the input as a string, which
+// means that erroneous UTF-8 encodings translate to U+FFFD = "\xef\xbf\xbd".
+// Because of the Scan interface, this makes it impossible for the client to
+// distinguish correctly encoded replacement runes from encoding errors.
+func ScanRunes(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ if atEOF && len(data) == 0 {
+ return 0, nil, nil
+ }
+
+ // Fast path 1: ASCII.
+ if data[0] < utf8.RuneSelf {
+ return 1, data[0:1], nil
+ }
+
+ // Fast path 2: Correct UTF-8 decode without error.
+ _, width := utf8.DecodeRune(data)
+ if width > 1 {
+ // It's a valid encoding. Width cannot be one for a correctly encoded
+ // non-ASCII rune.
+ return width, data[0:width], nil
+ }
+
+ // We know it's an error: we have width==1 and implicitly r==utf8.RuneError.
+ // Is the error because there wasn't a full rune to be decoded?
+ // FullRune distinguishes correctly between erroneous and incomplete encodings.
+ if !atEOF && !utf8.FullRune(data) {
+ // Incomplete; get more bytes.
+ return 0, nil, nil
+ }
+
+ // We have a real UTF-8 encoding error. Return a properly encoded error rune
+ // but advance only one byte. This matches the behavior of a range loop over
+ // an incorrectly encoded string.
+ return 1, errorRune, nil
+}
+
+// dropCR drops a terminal \r from the data.
+func dropCR(data []byte) []byte {
+ if len(data) > 0 && data[len(data)-1] == '\r' {
+ return data[0 : len(data)-1]
+ }
+ return data
+}
+
+// ScanLines is a split function for a Scanner that returns each line of
+// text, stripped of any trailing end-of-line marker. The returned line may
+// be empty. The end-of-line marker is one optional carriage return followed
+// by one mandatory newline. In regular expression notation, it is `\r?\n'.
+// The last non-empty line of input will be returned even if it has no
+// newline.
+func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ if atEOF && len(data) == 0 {
+ return 0, nil, nil
+ }
+ if i := bytes.IndexByte(data, '\n'); i >= 0 {
+ // We have a full newline-terminated line.
+ return i + 1, dropCR(data[0:i]), nil
+ }
+ // If we're at EOF, we have a final, non-terminated line. Return it.
+ if atEOF {
+ return len(data), dropCR(data), nil
+ }
+ // Request more data.
+ return 0, nil, nil
+}
+
+// isSpace returns whether the character is a Unicode white space character.
+// We avoid dependency on the unicode package, but check validity of the implementation
+// in the tests.
+func isSpace(r rune) bool {
+ if r <= '\u00FF' {
+ // Obvious ASCII ones: \t through \r plus space. Plus two Latin-1 oddballs.
+ switch r {
+ case ' ', '\t', '\n', '\v', '\f', '\r':
+ return true
+ case '\u0085', '\u00A0':
+ return true
+ }
+ return false
+ }
+ // High-valued ones.
+ if '\u2000' <= r && r <= '\u200a' {
+ return true
+ }
+ switch r {
+ case '\u1680', '\u180e', '\u2028', '\u2029', '\u202f', '\u205f', '\u3000':
+ return true
+ }
+ return false
+}
+
+// ScanWords is a split function for a Scanner that returns each
+// space-separated word of text, with surrounding spaces deleted. It will
+// never return an empty string. The definition of space is set by
+// unicode.IsSpace.
+func ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ // Skip leading spaces.
+ start := 0
+ for width := 0; start < len(data); start += width {
+ var r rune
+ r, width = utf8.DecodeRune(data[start:])
+ if !isSpace(r) {
+ break
+ }
+ }
+ if atEOF && len(data) == 0 {
+ return 0, nil, nil
+ }
+ // Scan until space, marking end of word.
+ for width, i := 0, start; i < len(data); i += width {
+ var r rune
+ r, width = utf8.DecodeRune(data[i:])
+ if isSpace(r) {
+ return i + width, data[start:i], nil
+ }
+ }
+ // If we're at EOF, we have a final, non-empty, non-terminated word. Return it.
+ if atEOF && len(data) > start {
+ return len(data), data[start:], nil
+ }
+ // Request more data.
+ return 0, nil, nil
+}
--- /dev/null
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package bufio_test
+
+import (
+ . "bufio"
+ "bytes"
+ "errors"
+ "io"
+ "strings"
+ "testing"
+ "unicode"
+ "unicode/utf8"
+)
+
+// Test white space table matches the Unicode definition.
+func TestSpace(t *testing.T) {
+ for r := rune(0); r <= utf8.MaxRune; r++ {
+ if IsSpace(r) != unicode.IsSpace(r) {
+ t.Fatalf("white space property disagrees: %#U should be %t", r, unicode.IsSpace(r))
+ }
+ }
+}
+
+var scanTests = []string{
+ "",
+ "a",
+ "¼",
+ "☹",
+ "\x81", // UTF-8 error
+ "\uFFFD", // correctly encoded RuneError
+ "abcdefgh",
+ "abc def\n\t\tgh ",
+ "abc¼☹\x81\uFFFD日本語\x82abc",
+}
+
+func TestScanByte(t *testing.T) {
+ for n, test := range scanTests {
+ buf := bytes.NewBufferString(test)
+ s := NewScanner(buf)
+ s.Split(ScanBytes)
+ var i int
+ for i = 0; s.Scan(); i++ {
+ if b := s.Bytes(); len(b) != 1 || b[0] != test[i] {
+ t.Errorf("#%d: %d: expected %q got %q", n, i, test, b)
+ }
+ }
+ if i != len(test) {
+ t.Errorf("#%d: termination expected at %d; got %d", n, len(test), i)
+ }
+ err := s.Err()
+ if err != nil {
+ t.Errorf("#%d: %v", n, err)
+ }
+ }
+}
+
+// Test that the rune splitter returns same sequence of runes (not bytes) as for range string.
+func TestScanRune(t *testing.T) {
+ for n, test := range scanTests {
+ buf := bytes.NewBufferString(test)
+ s := NewScanner(buf)
+ s.Split(ScanRunes)
+ var i, runeCount int
+ var expect rune
+ // Use a string range loop to validate the sequence of runes.
+ for i, expect = range string(test) {
+ if !s.Scan() {
+ break
+ }
+ runeCount++
+ got, _ := utf8.DecodeRune(s.Bytes())
+ if got != expect {
+ t.Errorf("#%d: %d: expected %q got %q", n, i, expect, got)
+ }
+ }
+ if s.Scan() {
+ t.Errorf("#%d: scan ran too long, got %q", n, s.Text())
+ }
+ testRuneCount := utf8.RuneCountInString(test)
+ if runeCount != testRuneCount {
+ t.Errorf("#%d: termination expected at %d; got %d", n, testRuneCount, runeCount)
+ }
+ err := s.Err()
+ if err != nil {
+ t.Errorf("#%d: %v", n, err)
+ }
+ }
+}
+
+var wordScanTests = []string{
+ "",
+ " ",
+ "\n",
+ "a",
+ " a ",
+ "abc def",
+ " abc def ",
+ " abc\tdef\nghi\rjkl\fmno\vpqr\u0085stu\u00a0\n",
+}
+
+// Test that the word splitter returns the same data as strings.Fields.
+func TestScanWords(t *testing.T) {
+ for n, test := range wordScanTests {
+ buf := bytes.NewBufferString(test)
+ s := NewScanner(buf)
+ s.Split(ScanWords)
+ words := strings.Fields(test)
+ var wordCount int
+ for wordCount = 0; wordCount < len(words); wordCount++ {
+ if !s.Scan() {
+ break
+ }
+ got := s.Text()
+ if got != words[wordCount] {
+ t.Errorf("#%d: %d: expected %q got %q", n, wordCount, words[wordCount], got)
+ }
+ }
+ if s.Scan() {
+ t.Errorf("#%d: scan ran too long, got %q", n, s.Text())
+ }
+ if wordCount != len(words) {
+ t.Errorf("#%d: termination expected at %d; got %d", n, len(words), wordCount)
+ }
+ err := s.Err()
+ if err != nil {
+ t.Errorf("#%d: %v", n, err)
+ }
+ }
+}
+
+// slowReader is a reader that returns only a few bytes at a time, to test the incremental
+// reads in Scanner.Scan.
+type slowReader struct {
+ max int
+ buf *bytes.Buffer
+}
+
+func (sr *slowReader) Read(p []byte) (n int, err error) {
+ if len(p) > sr.max {
+ p = p[0:sr.max]
+ }
+ return sr.buf.Read(p)
+}
+
+// genLine writes to buf a predictable but non-trivial line of text of length
+// n, including the terminal newline and an occasional carriage return.
+// If addNewline is false, the \r and \n are not emitted.
+func genLine(buf *bytes.Buffer, lineNum, n int, addNewline bool) {
+ buf.Reset()
+ doCR := lineNum%5 == 0
+ if doCR {
+ n--
+ }
+ for i := 0; i < n-1; i++ { // Stop early for \n.
+ c := 'a' + byte(lineNum+i)
+ if c == '\n' || c == '\r' { // Don't confuse us.
+ c = 'N'
+ }
+ buf.WriteByte(c)
+ }
+ if addNewline {
+ if doCR {
+ buf.WriteByte('\r')
+ }
+ buf.WriteByte('\n')
+ }
+ return
+}
+
+// Test the line splitter, including some carriage returns but no long lines.
+func TestScanLongLines(t *testing.T) {
+ const smallMaxTokenSize = 256 // Much smaller for more efficient testing.
+ // Build a buffer of lots of line lengths up to but not exceeding smallMaxTokenSize.
+ tmp := new(bytes.Buffer)
+ buf := new(bytes.Buffer)
+ lineNum := 0
+ j := 0
+ for i := 0; i < 2*smallMaxTokenSize; i++ {
+ genLine(tmp, lineNum, j, true)
+ if j < smallMaxTokenSize {
+ j++
+ } else {
+ j--
+ }
+ buf.Write(tmp.Bytes())
+ lineNum++
+ }
+ s := NewScanner(&slowReader{1, buf})
+ s.Split(ScanLines)
+ s.MaxTokenSize(smallMaxTokenSize)
+ j = 0
+ for lineNum := 0; s.Scan(); lineNum++ {
+ genLine(tmp, lineNum, j, false)
+ if j < smallMaxTokenSize {
+ j++
+ } else {
+ j--
+ }
+ line := tmp.String() // We use the string-valued token here, for variety.
+ if s.Text() != line {
+ t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Text(), line)
+ }
+ }
+ err := s.Err()
+ if err != nil {
+ t.Fatal(err)
+ }
+}
+
+// Test that the line splitter errors out on a long line.
+func TestScanLineTooLong(t *testing.T) {
+ const smallMaxTokenSize = 256 // Much smaller for more efficient testing.
+ // Build a buffer of lots of line lengths up to but not exceeding smallMaxTokenSize.
+ tmp := new(bytes.Buffer)
+ buf := new(bytes.Buffer)
+ lineNum := 0
+ j := 0
+ for i := 0; i < 2*smallMaxTokenSize; i++ {
+ genLine(tmp, lineNum, j, true)
+ j++
+ buf.Write(tmp.Bytes())
+ lineNum++
+ }
+ s := NewScanner(&slowReader{3, buf})
+ s.Split(ScanLines)
+ s.MaxTokenSize(smallMaxTokenSize)
+ j = 0
+ for lineNum := 0; s.Scan(); lineNum++ {
+ genLine(tmp, lineNum, j, false)
+ if j < smallMaxTokenSize {
+ j++
+ } else {
+ j--
+ }
+ line := tmp.Bytes()
+ if !bytes.Equal(s.Bytes(), line) {
+ t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Bytes(), line)
+ }
+ }
+ err := s.Err()
+ if err != ErrTooLong {
+ t.Fatalf("expected ErrTooLong; got %s", err)
+ }
+}
+
+// Test that the line splitter handles a final line without a newline.
+func testNoNewline(text string, lines []string, t *testing.T) {
+ buf := bytes.NewBufferString(text)
+ s := NewScanner(&slowReader{7, buf})
+ s.Split(ScanLines)
+ for lineNum := 0; s.Scan(); lineNum++ {
+ line := lines[lineNum]
+ if s.Text() != line {
+ t.Errorf("%d: bad line: %d %d\n%.100q\n%.100q\n", lineNum, len(s.Bytes()), len(line), s.Bytes(), line)
+ }
+ }
+ err := s.Err()
+ if err != nil {
+ t.Fatal(err)
+ }
+}
+
+var noNewlineLines = []string{
+ "abcdefghijklmn\nopqrstuvwxyz",
+}
+
+// Test that the line splitter handles a final line without a newline.
+func TestScanLineNoNewline(t *testing.T) {
+ const text = "abcdefghijklmn\nopqrstuvwxyz"
+ lines := []string{
+ "abcdefghijklmn",
+ "opqrstuvwxyz",
+ }
+ testNoNewline(text, lines, t)
+}
+
+// Test that the line splitter handles a final line with a carriage return but nonewline.
+func TestScanLineReturnButNoNewline(t *testing.T) {
+ const text = "abcdefghijklmn\nopqrstuvwxyz\r"
+ lines := []string{
+ "abcdefghijklmn",
+ "opqrstuvwxyz",
+ }
+ testNoNewline(text, lines, t)
+}
+
+// Test that the line splitter handles a final empty line.
+func TestScanLineEmptyFinalLine(t *testing.T) {
+ const text = "abcdefghijklmn\nopqrstuvwxyz\n\n"
+ lines := []string{
+ "abcdefghijklmn",
+ "opqrstuvwxyz",
+ "",
+ }
+ testNoNewline(text, lines, t)
+}
+
+// Test that the line splitter handles a final empty line with a carriage return but no newline.
+func TestScanLineEmptyFinalLineWithCR(t *testing.T) {
+ const text = "abcdefghijklmn\nopqrstuvwxyz\n\r"
+ lines := []string{
+ "abcdefghijklmn",
+ "opqrstuvwxyz",
+ "",
+ }
+ testNoNewline(text, lines, t)
+}
+
+var testError = errors.New("testError")
+
+// Test the correct error is returned when the split function errors out.
+func TestSplitError(t *testing.T) {
+ // Create a split function that delivers a little data, then a predictable error.
+ numSplits := 0
+ const okCount = 7
+ errorSplit := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ if atEOF {
+ panic("didn't get enough data")
+ }
+ if numSplits >= okCount {
+ return 0, nil, testError
+ }
+ numSplits++
+ return 1, data[0:1], nil
+ }
+ // Read the data.
+ const text = "abcdefghijklmnopqrstuvwxyz"
+ buf := bytes.NewBufferString(text)
+ s := NewScanner(&slowReader{1, buf})
+ s.Split(errorSplit)
+ var i int
+ for i = 0; s.Scan(); i++ {
+ if len(s.Bytes()) != 1 || text[i] != s.Bytes()[0] {
+ t.Errorf("#%d: expected %q got %q", i, text[i], s.Bytes()[0])
+ }
+ }
+ // Check correct termination location and error.
+ if i != okCount {
+ t.Errorf("unexpected termination; expected %d tokens got %d", okCount, i)
+ }
+ err := s.Err()
+ if err != testError {
+ t.Fatalf("expected %q got %v", testError, err)
+ }
+}
+
+// Test that an EOF is overridden by a user-generated scan error.
+func TestErrAtEOF(t *testing.T) {
+ s := NewScanner(strings.NewReader("1 2 33"))
+ // This spitter will fail on last entry, after s.err==EOF.
+ split := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
+ advance, token, err = ScanWords(data, atEOF)
+ if len(token) > 1 {
+ if s.ErrOrEOF() != io.EOF {
+ t.Fatal("not testing EOF")
+ }
+ err = testError
+ }
+ return
+ }
+ s.Split(split)
+ for s.Scan() {
+ }
+ if s.Err() != testError {
+ t.Fatal("wrong error:", s.Err())
+ }
+}
}
// Fields splits the string s around each instance of one or more consecutive white space
-// characters, returning an array of substrings of s or an empty list if s contains only white space.
+// characters, as defined by unicode.IsSpace, returning an array of substrings of s or an
+// empty list if s contains only white space.
func Fields(s string) []string {
return FieldsFunc(s, unicode.IsSpace)
}