mirror of https://github.com/prometheus/prometheus
280 lines
7.9 KiB
Go
280 lines
7.9 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.md file.
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package cmp
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import (
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"fmt"
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"reflect"
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"strconv"
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"strings"
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"unicode"
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"github.com/google/go-cmp/cmp/internal/flags"
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"github.com/google/go-cmp/cmp/internal/value"
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)
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type formatValueOptions struct {
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// AvoidStringer controls whether to avoid calling custom stringer
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// methods like error.Error or fmt.Stringer.String.
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AvoidStringer bool
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// ShallowPointers controls whether to avoid descending into pointers.
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// Useful when printing map keys, where pointer comparison is performed
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// on the pointer address rather than the pointed-at value.
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ShallowPointers bool
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// PrintAddresses controls whether to print the address of all pointers,
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// slice elements, and maps.
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PrintAddresses bool
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}
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// FormatType prints the type as if it were wrapping s.
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// This may return s as-is depending on the current type and TypeMode mode.
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func (opts formatOptions) FormatType(t reflect.Type, s textNode) textNode {
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// Check whether to emit the type or not.
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switch opts.TypeMode {
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case autoType:
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switch t.Kind() {
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case reflect.Struct, reflect.Slice, reflect.Array, reflect.Map:
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if s.Equal(textNil) {
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return s
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}
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default:
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return s
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}
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case elideType:
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return s
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}
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// Determine the type label, applying special handling for unnamed types.
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typeName := t.String()
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if t.Name() == "" {
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// According to Go grammar, certain type literals contain symbols that
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// do not strongly bind to the next lexicographical token (e.g., *T).
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switch t.Kind() {
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case reflect.Chan, reflect.Func, reflect.Ptr:
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typeName = "(" + typeName + ")"
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}
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typeName = strings.Replace(typeName, "struct {", "struct{", -1)
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typeName = strings.Replace(typeName, "interface {", "interface{", -1)
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}
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// Avoid wrap the value in parenthesis if unnecessary.
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if s, ok := s.(textWrap); ok {
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hasParens := strings.HasPrefix(s.Prefix, "(") && strings.HasSuffix(s.Suffix, ")")
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hasBraces := strings.HasPrefix(s.Prefix, "{") && strings.HasSuffix(s.Suffix, "}")
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if hasParens || hasBraces {
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return textWrap{typeName, s, ""}
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}
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}
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return textWrap{typeName + "(", s, ")"}
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}
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// FormatValue prints the reflect.Value, taking extra care to avoid descending
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// into pointers already in m. As pointers are visited, m is also updated.
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func (opts formatOptions) FormatValue(v reflect.Value, m visitedPointers) (out textNode) {
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if !v.IsValid() {
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return nil
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}
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t := v.Type()
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// Check whether there is an Error or String method to call.
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if !opts.AvoidStringer && v.CanInterface() {
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// Avoid calling Error or String methods on nil receivers since many
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// implementations crash when doing so.
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if (t.Kind() != reflect.Ptr && t.Kind() != reflect.Interface) || !v.IsNil() {
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switch v := v.Interface().(type) {
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case error:
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return textLine("e" + formatString(v.Error()))
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case fmt.Stringer:
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return textLine("s" + formatString(v.String()))
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}
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}
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}
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// Check whether to explicitly wrap the result with the type.
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var skipType bool
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defer func() {
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if !skipType {
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out = opts.FormatType(t, out)
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}
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}()
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var ptr string
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switch t.Kind() {
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case reflect.Bool:
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return textLine(fmt.Sprint(v.Bool()))
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case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
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return textLine(fmt.Sprint(v.Int()))
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case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
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// Unnamed uints are usually bytes or words, so use hexadecimal.
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if t.PkgPath() == "" || t.Kind() == reflect.Uintptr {
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return textLine(formatHex(v.Uint()))
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}
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return textLine(fmt.Sprint(v.Uint()))
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case reflect.Float32, reflect.Float64:
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return textLine(fmt.Sprint(v.Float()))
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case reflect.Complex64, reflect.Complex128:
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return textLine(fmt.Sprint(v.Complex()))
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case reflect.String:
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return textLine(formatString(v.String()))
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case reflect.UnsafePointer, reflect.Chan, reflect.Func:
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return textLine(formatPointer(v))
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case reflect.Struct:
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var list textList
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for i := 0; i < v.NumField(); i++ {
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vv := v.Field(i)
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if value.IsZero(vv) {
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continue // Elide fields with zero values
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}
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s := opts.WithTypeMode(autoType).FormatValue(vv, m)
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list = append(list, textRecord{Key: t.Field(i).Name, Value: s})
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}
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return textWrap{"{", list, "}"}
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case reflect.Slice:
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if v.IsNil() {
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return textNil
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}
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if opts.PrintAddresses {
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ptr = formatPointer(v)
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}
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fallthrough
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case reflect.Array:
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var list textList
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for i := 0; i < v.Len(); i++ {
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vi := v.Index(i)
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if vi.CanAddr() { // Check for cyclic elements
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p := vi.Addr()
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if m.Visit(p) {
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var out textNode
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out = textLine(formatPointer(p))
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out = opts.WithTypeMode(emitType).FormatType(p.Type(), out)
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out = textWrap{"*", out, ""}
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list = append(list, textRecord{Value: out})
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continue
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}
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}
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s := opts.WithTypeMode(elideType).FormatValue(vi, m)
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list = append(list, textRecord{Value: s})
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}
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return textWrap{ptr + "{", list, "}"}
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case reflect.Map:
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if v.IsNil() {
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return textNil
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}
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if m.Visit(v) {
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return textLine(formatPointer(v))
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}
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var list textList
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for _, k := range value.SortKeys(v.MapKeys()) {
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sk := formatMapKey(k)
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sv := opts.WithTypeMode(elideType).FormatValue(v.MapIndex(k), m)
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list = append(list, textRecord{Key: sk, Value: sv})
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}
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if opts.PrintAddresses {
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ptr = formatPointer(v)
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}
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return textWrap{ptr + "{", list, "}"}
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case reflect.Ptr:
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if v.IsNil() {
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return textNil
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}
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if m.Visit(v) || opts.ShallowPointers {
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return textLine(formatPointer(v))
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}
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if opts.PrintAddresses {
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ptr = formatPointer(v)
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}
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skipType = true // Let the underlying value print the type instead
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return textWrap{"&" + ptr, opts.FormatValue(v.Elem(), m), ""}
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case reflect.Interface:
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if v.IsNil() {
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return textNil
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}
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// Interfaces accept different concrete types,
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// so configure the underlying value to explicitly print the type.
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skipType = true // Print the concrete type instead
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return opts.WithTypeMode(emitType).FormatValue(v.Elem(), m)
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default:
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panic(fmt.Sprintf("%v kind not handled", v.Kind()))
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}
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}
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// formatMapKey formats v as if it were a map key.
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// The result is guaranteed to be a single line.
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func formatMapKey(v reflect.Value) string {
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var opts formatOptions
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opts.TypeMode = elideType
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opts.AvoidStringer = true
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opts.ShallowPointers = true
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s := opts.FormatValue(v, visitedPointers{}).String()
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return strings.TrimSpace(s)
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}
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// formatString prints s as a double-quoted or backtick-quoted string.
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func formatString(s string) string {
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// Use quoted string if it the same length as a raw string literal.
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// Otherwise, attempt to use the raw string form.
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qs := strconv.Quote(s)
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if len(qs) == 1+len(s)+1 {
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return qs
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}
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// Disallow newlines to ensure output is a single line.
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// Only allow printable runes for readability purposes.
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rawInvalid := func(r rune) bool {
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return r == '`' || r == '\n' || !(unicode.IsPrint(r) || r == '\t')
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}
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if strings.IndexFunc(s, rawInvalid) < 0 {
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return "`" + s + "`"
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}
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return qs
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}
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// formatHex prints u as a hexadecimal integer in Go notation.
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func formatHex(u uint64) string {
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var f string
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switch {
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case u <= 0xff:
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f = "0x%02x"
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case u <= 0xffff:
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f = "0x%04x"
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case u <= 0xffffff:
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f = "0x%06x"
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case u <= 0xffffffff:
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f = "0x%08x"
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case u <= 0xffffffffff:
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f = "0x%010x"
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case u <= 0xffffffffffff:
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f = "0x%012x"
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case u <= 0xffffffffffffff:
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f = "0x%014x"
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case u <= 0xffffffffffffffff:
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f = "0x%016x"
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}
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return fmt.Sprintf(f, u)
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}
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// formatPointer prints the address of the pointer.
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func formatPointer(v reflect.Value) string {
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p := v.Pointer()
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if flags.Deterministic {
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p = 0xdeadf00f // Only used for stable testing purposes
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}
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return fmt.Sprintf("⟪0x%x⟫", p)
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}
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type visitedPointers map[value.Pointer]struct{}
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// Visit inserts pointer v into the visited map and reports whether it had
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// already been visited before.
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func (m visitedPointers) Visit(v reflect.Value) bool {
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p := value.PointerOf(v)
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_, visited := m[p]
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m[p] = struct{}{}
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return visited
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}
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