431 lines
12 KiB
Go
431 lines
12 KiB
Go
// Copyright 2019, The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package cmp
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import (
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"bytes"
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"fmt"
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"math/rand"
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"strings"
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"time"
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"unicode/utf8"
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"github.com/google/go-cmp/cmp/internal/flags"
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)
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var randBool = rand.New(rand.NewSource(time.Now().Unix())).Intn(2) == 0
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const maxColumnLength = 80
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type indentMode int
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func (n indentMode) appendIndent(b []byte, d diffMode) []byte {
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// The output of Diff is documented as being unstable to provide future
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// flexibility in changing the output for more humanly readable reports.
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// This logic intentionally introduces instability to the exact output
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// so that users can detect accidental reliance on stability early on,
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// rather than much later when an actual change to the format occurs.
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if flags.Deterministic || randBool {
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// Use regular spaces (U+0020).
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switch d {
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case diffUnknown, diffIdentical:
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b = append(b, " "...)
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case diffRemoved:
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b = append(b, "- "...)
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case diffInserted:
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b = append(b, "+ "...)
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}
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} else {
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// Use non-breaking spaces (U+00a0).
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switch d {
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case diffUnknown, diffIdentical:
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b = append(b, " "...)
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case diffRemoved:
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b = append(b, "- "...)
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case diffInserted:
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b = append(b, "+ "...)
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}
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}
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return repeatCount(n).appendChar(b, '\t')
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}
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type repeatCount int
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func (n repeatCount) appendChar(b []byte, c byte) []byte {
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for ; n > 0; n-- {
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b = append(b, c)
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}
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return b
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}
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// textNode is a simplified tree-based representation of structured text.
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// Possible node types are textWrap, textList, or textLine.
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type textNode interface {
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// Len reports the length in bytes of a single-line version of the tree.
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// Nested textRecord.Diff and textRecord.Comment fields are ignored.
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Len() int
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// Equal reports whether the two trees are structurally identical.
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// Nested textRecord.Diff and textRecord.Comment fields are compared.
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Equal(textNode) bool
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// String returns the string representation of the text tree.
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// It is not guaranteed that len(x.String()) == x.Len(),
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// nor that x.String() == y.String() implies that x.Equal(y).
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String() string
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// formatCompactTo formats the contents of the tree as a single-line string
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// to the provided buffer. Any nested textRecord.Diff and textRecord.Comment
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// fields are ignored.
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//
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// However, not all nodes in the tree should be collapsed as a single-line.
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// If a node can be collapsed as a single-line, it is replaced by a textLine
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// node. Since the top-level node cannot replace itself, this also returns
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// the current node itself.
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//
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// This does not mutate the receiver.
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formatCompactTo([]byte, diffMode) ([]byte, textNode)
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// formatExpandedTo formats the contents of the tree as a multi-line string
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// to the provided buffer. In order for column alignment to operate well,
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// formatCompactTo must be called before calling formatExpandedTo.
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formatExpandedTo([]byte, diffMode, indentMode) []byte
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}
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// textWrap is a wrapper that concatenates a prefix and/or a suffix
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// to the underlying node.
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type textWrap struct {
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Prefix string // e.g., "bytes.Buffer{"
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Value textNode // textWrap | textList | textLine
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Suffix string // e.g., "}"
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Metadata interface{} // arbitrary metadata; has no effect on formatting
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}
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func (s *textWrap) Len() int {
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return len(s.Prefix) + s.Value.Len() + len(s.Suffix)
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}
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func (s1 *textWrap) Equal(s2 textNode) bool {
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if s2, ok := s2.(*textWrap); ok {
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return s1.Prefix == s2.Prefix && s1.Value.Equal(s2.Value) && s1.Suffix == s2.Suffix
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}
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return false
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}
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func (s *textWrap) String() string {
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var d diffMode
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var n indentMode
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_, s2 := s.formatCompactTo(nil, d)
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b := n.appendIndent(nil, d) // Leading indent
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b = s2.formatExpandedTo(b, d, n) // Main body
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b = append(b, '\n') // Trailing newline
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return string(b)
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}
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func (s *textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
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n0 := len(b) // Original buffer length
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b = append(b, s.Prefix...)
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b, s.Value = s.Value.formatCompactTo(b, d)
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b = append(b, s.Suffix...)
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if _, ok := s.Value.(textLine); ok {
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return b, textLine(b[n0:])
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}
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return b, s
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}
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func (s *textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
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b = append(b, s.Prefix...)
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b = s.Value.formatExpandedTo(b, d, n)
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b = append(b, s.Suffix...)
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return b
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}
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// textList is a comma-separated list of textWrap or textLine nodes.
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// The list may be formatted as multi-lines or single-line at the discretion
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// of the textList.formatCompactTo method.
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type textList []textRecord
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type textRecord struct {
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Diff diffMode // e.g., 0 or '-' or '+'
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Key string // e.g., "MyField"
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Value textNode // textWrap | textLine
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ElideComma bool // avoid trailing comma
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Comment fmt.Stringer // e.g., "6 identical fields"
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}
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// AppendEllipsis appends a new ellipsis node to the list if none already
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// exists at the end. If cs is non-zero it coalesces the statistics with the
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// previous diffStats.
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func (s *textList) AppendEllipsis(ds diffStats) {
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hasStats := !ds.IsZero()
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if len(*s) == 0 || !(*s)[len(*s)-1].Value.Equal(textEllipsis) {
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if hasStats {
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*s = append(*s, textRecord{Value: textEllipsis, ElideComma: true, Comment: ds})
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} else {
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*s = append(*s, textRecord{Value: textEllipsis, ElideComma: true})
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}
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return
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}
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if hasStats {
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(*s)[len(*s)-1].Comment = (*s)[len(*s)-1].Comment.(diffStats).Append(ds)
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}
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}
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func (s textList) Len() (n int) {
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for i, r := range s {
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n += len(r.Key)
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if r.Key != "" {
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n += len(": ")
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}
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n += r.Value.Len()
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if i < len(s)-1 {
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n += len(", ")
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}
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}
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return n
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}
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func (s1 textList) Equal(s2 textNode) bool {
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if s2, ok := s2.(textList); ok {
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if len(s1) != len(s2) {
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return false
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}
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for i := range s1 {
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r1, r2 := s1[i], s2[i]
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if !(r1.Diff == r2.Diff && r1.Key == r2.Key && r1.Value.Equal(r2.Value) && r1.Comment == r2.Comment) {
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return false
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}
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}
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return true
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}
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return false
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}
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func (s textList) String() string {
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return (&textWrap{Prefix: "{", Value: s, Suffix: "}"}).String()
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}
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func (s textList) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
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s = append(textList(nil), s...) // Avoid mutating original
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// Determine whether we can collapse this list as a single line.
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n0 := len(b) // Original buffer length
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var multiLine bool
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for i, r := range s {
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if r.Diff == diffInserted || r.Diff == diffRemoved {
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multiLine = true
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}
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b = append(b, r.Key...)
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if r.Key != "" {
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b = append(b, ": "...)
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}
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b, s[i].Value = r.Value.formatCompactTo(b, d|r.Diff)
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if _, ok := s[i].Value.(textLine); !ok {
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multiLine = true
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}
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if r.Comment != nil {
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multiLine = true
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}
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if i < len(s)-1 {
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b = append(b, ", "...)
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}
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}
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// Force multi-lined output when printing a removed/inserted node that
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// is sufficiently long.
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if (d == diffInserted || d == diffRemoved) && len(b[n0:]) > maxColumnLength {
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multiLine = true
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}
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if !multiLine {
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return b, textLine(b[n0:])
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}
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return b, s
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}
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func (s textList) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte {
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alignKeyLens := s.alignLens(
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func(r textRecord) bool {
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_, isLine := r.Value.(textLine)
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return r.Key == "" || !isLine
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},
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func(r textRecord) int { return utf8.RuneCountInString(r.Key) },
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)
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alignValueLens := s.alignLens(
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func(r textRecord) bool {
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_, isLine := r.Value.(textLine)
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return !isLine || r.Value.Equal(textEllipsis) || r.Comment == nil
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},
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func(r textRecord) int { return utf8.RuneCount(r.Value.(textLine)) },
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)
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// Format lists of simple lists in a batched form.
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// If the list is sequence of only textLine values,
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// then batch multiple values on a single line.
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var isSimple bool
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for _, r := range s {
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_, isLine := r.Value.(textLine)
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isSimple = r.Diff == 0 && r.Key == "" && isLine && r.Comment == nil
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if !isSimple {
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break
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}
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}
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if isSimple {
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n++
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var batch []byte
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emitBatch := func() {
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if len(batch) > 0 {
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b = n.appendIndent(append(b, '\n'), d)
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b = append(b, bytes.TrimRight(batch, " ")...)
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batch = batch[:0]
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}
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}
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for _, r := range s {
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line := r.Value.(textLine)
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if len(batch)+len(line)+len(", ") > maxColumnLength {
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emitBatch()
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}
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batch = append(batch, line...)
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batch = append(batch, ", "...)
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}
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emitBatch()
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n--
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return n.appendIndent(append(b, '\n'), d)
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}
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// Format the list as a multi-lined output.
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n++
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for i, r := range s {
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b = n.appendIndent(append(b, '\n'), d|r.Diff)
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if r.Key != "" {
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b = append(b, r.Key+": "...)
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}
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b = alignKeyLens[i].appendChar(b, ' ')
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b = r.Value.formatExpandedTo(b, d|r.Diff, n)
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if !r.ElideComma {
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b = append(b, ',')
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}
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b = alignValueLens[i].appendChar(b, ' ')
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if r.Comment != nil {
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b = append(b, " // "+r.Comment.String()...)
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}
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}
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n--
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return n.appendIndent(append(b, '\n'), d)
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}
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func (s textList) alignLens(
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skipFunc func(textRecord) bool,
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lenFunc func(textRecord) int,
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) []repeatCount {
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var startIdx, endIdx, maxLen int
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lens := make([]repeatCount, len(s))
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for i, r := range s {
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if skipFunc(r) {
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for j := startIdx; j < endIdx && j < len(s); j++ {
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lens[j] = repeatCount(maxLen - lenFunc(s[j]))
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}
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startIdx, endIdx, maxLen = i+1, i+1, 0
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} else {
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if maxLen < lenFunc(r) {
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maxLen = lenFunc(r)
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}
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endIdx = i + 1
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}
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}
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for j := startIdx; j < endIdx && j < len(s); j++ {
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lens[j] = repeatCount(maxLen - lenFunc(s[j]))
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}
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return lens
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}
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// textLine is a single-line segment of text and is always a leaf node
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// in the textNode tree.
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type textLine []byte
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var (
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textNil = textLine("nil")
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textEllipsis = textLine("...")
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)
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func (s textLine) Len() int {
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return len(s)
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}
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func (s1 textLine) Equal(s2 textNode) bool {
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if s2, ok := s2.(textLine); ok {
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return bytes.Equal([]byte(s1), []byte(s2))
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}
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return false
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}
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func (s textLine) String() string {
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return string(s)
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}
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func (s textLine) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) {
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return append(b, s...), s
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}
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func (s textLine) formatExpandedTo(b []byte, _ diffMode, _ indentMode) []byte {
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return append(b, s...)
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}
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type diffStats struct {
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Name string
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NumIgnored int
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NumIdentical int
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NumRemoved int
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NumInserted int
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NumModified int
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}
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func (s diffStats) IsZero() bool {
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s.Name = ""
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return s == diffStats{}
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}
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func (s diffStats) NumDiff() int {
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return s.NumRemoved + s.NumInserted + s.NumModified
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}
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func (s diffStats) Append(ds diffStats) diffStats {
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assert(s.Name == ds.Name)
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s.NumIgnored += ds.NumIgnored
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s.NumIdentical += ds.NumIdentical
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s.NumRemoved += ds.NumRemoved
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s.NumInserted += ds.NumInserted
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s.NumModified += ds.NumModified
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return s
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}
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// String prints a humanly-readable summary of coalesced records.
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//
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// Example:
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// diffStats{Name: "Field", NumIgnored: 5}.String() => "5 ignored fields"
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func (s diffStats) String() string {
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var ss []string
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var sum int
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labels := [...]string{"ignored", "identical", "removed", "inserted", "modified"}
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counts := [...]int{s.NumIgnored, s.NumIdentical, s.NumRemoved, s.NumInserted, s.NumModified}
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for i, n := range counts {
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if n > 0 {
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ss = append(ss, fmt.Sprintf("%d %v", n, labels[i]))
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}
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sum += n
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}
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// Pluralize the name (adjusting for some obscure English grammar rules).
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name := s.Name
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if sum > 1 {
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name += "s"
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if strings.HasSuffix(name, "ys") {
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name = name[:len(name)-2] + "ies" // e.g., "entrys" => "entries"
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}
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}
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// Format the list according to English grammar (with Oxford comma).
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switch n := len(ss); n {
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case 0:
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return ""
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case 1, 2:
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return strings.Join(ss, " and ") + " " + name
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default:
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return strings.Join(ss[:n-1], ", ") + ", and " + ss[n-1] + " " + name
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}
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}
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type commentString string
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func (s commentString) String() string { return string(s) }
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