prometheus/vendor/github.com/google/go-cmp/cmp/report_reflect.go

280 lines
7.9 KiB
Go

// Copyright 2019, 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.md file.
package cmp
import (
"fmt"
"reflect"
"strconv"
"strings"
"unicode"
"github.com/google/go-cmp/cmp/internal/flags"
"github.com/google/go-cmp/cmp/internal/value"
)
type formatValueOptions struct {
// AvoidStringer controls whether to avoid calling custom stringer
// methods like error.Error or fmt.Stringer.String.
AvoidStringer bool
// ShallowPointers controls whether to avoid descending into pointers.
// Useful when printing map keys, where pointer comparison is performed
// on the pointer address rather than the pointed-at value.
ShallowPointers bool
// PrintAddresses controls whether to print the address of all pointers,
// slice elements, and maps.
PrintAddresses bool
}
// FormatType prints the type as if it were wrapping s.
// This may return s as-is depending on the current type and TypeMode mode.
func (opts formatOptions) FormatType(t reflect.Type, s textNode) textNode {
// Check whether to emit the type or not.
switch opts.TypeMode {
case autoType:
switch t.Kind() {
case reflect.Struct, reflect.Slice, reflect.Array, reflect.Map:
if s.Equal(textNil) {
return s
}
default:
return s
}
case elideType:
return s
}
// Determine the type label, applying special handling for unnamed types.
typeName := t.String()
if t.Name() == "" {
// According to Go grammar, certain type literals contain symbols that
// do not strongly bind to the next lexicographical token (e.g., *T).
switch t.Kind() {
case reflect.Chan, reflect.Func, reflect.Ptr:
typeName = "(" + typeName + ")"
}
typeName = strings.Replace(typeName, "struct {", "struct{", -1)
typeName = strings.Replace(typeName, "interface {", "interface{", -1)
}
// Avoid wrap the value in parenthesis if unnecessary.
if s, ok := s.(textWrap); ok {
hasParens := strings.HasPrefix(s.Prefix, "(") && strings.HasSuffix(s.Suffix, ")")
hasBraces := strings.HasPrefix(s.Prefix, "{") && strings.HasSuffix(s.Suffix, "}")
if hasParens || hasBraces {
return textWrap{typeName, s, ""}
}
}
return textWrap{typeName + "(", s, ")"}
}
// FormatValue prints the reflect.Value, taking extra care to avoid descending
// into pointers already in m. As pointers are visited, m is also updated.
func (opts formatOptions) FormatValue(v reflect.Value, m visitedPointers) (out textNode) {
if !v.IsValid() {
return nil
}
t := v.Type()
// Check whether there is an Error or String method to call.
if !opts.AvoidStringer && v.CanInterface() {
// Avoid calling Error or String methods on nil receivers since many
// implementations crash when doing so.
if (t.Kind() != reflect.Ptr && t.Kind() != reflect.Interface) || !v.IsNil() {
switch v := v.Interface().(type) {
case error:
return textLine("e" + formatString(v.Error()))
case fmt.Stringer:
return textLine("s" + formatString(v.String()))
}
}
}
// Check whether to explicitly wrap the result with the type.
var skipType bool
defer func() {
if !skipType {
out = opts.FormatType(t, out)
}
}()
var ptr string
switch t.Kind() {
case reflect.Bool:
return textLine(fmt.Sprint(v.Bool()))
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return textLine(fmt.Sprint(v.Int()))
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
// Unnamed uints are usually bytes or words, so use hexadecimal.
if t.PkgPath() == "" || t.Kind() == reflect.Uintptr {
return textLine(formatHex(v.Uint()))
}
return textLine(fmt.Sprint(v.Uint()))
case reflect.Float32, reflect.Float64:
return textLine(fmt.Sprint(v.Float()))
case reflect.Complex64, reflect.Complex128:
return textLine(fmt.Sprint(v.Complex()))
case reflect.String:
return textLine(formatString(v.String()))
case reflect.UnsafePointer, reflect.Chan, reflect.Func:
return textLine(formatPointer(v))
case reflect.Struct:
var list textList
for i := 0; i < v.NumField(); i++ {
vv := v.Field(i)
if value.IsZero(vv) {
continue // Elide fields with zero values
}
s := opts.WithTypeMode(autoType).FormatValue(vv, m)
list = append(list, textRecord{Key: t.Field(i).Name, Value: s})
}
return textWrap{"{", list, "}"}
case reflect.Slice:
if v.IsNil() {
return textNil
}
if opts.PrintAddresses {
ptr = formatPointer(v)
}
fallthrough
case reflect.Array:
var list textList
for i := 0; i < v.Len(); i++ {
vi := v.Index(i)
if vi.CanAddr() { // Check for cyclic elements
p := vi.Addr()
if m.Visit(p) {
var out textNode
out = textLine(formatPointer(p))
out = opts.WithTypeMode(emitType).FormatType(p.Type(), out)
out = textWrap{"*", out, ""}
list = append(list, textRecord{Value: out})
continue
}
}
s := opts.WithTypeMode(elideType).FormatValue(vi, m)
list = append(list, textRecord{Value: s})
}
return textWrap{ptr + "{", list, "}"}
case reflect.Map:
if v.IsNil() {
return textNil
}
if m.Visit(v) {
return textLine(formatPointer(v))
}
var list textList
for _, k := range value.SortKeys(v.MapKeys()) {
sk := formatMapKey(k)
sv := opts.WithTypeMode(elideType).FormatValue(v.MapIndex(k), m)
list = append(list, textRecord{Key: sk, Value: sv})
}
if opts.PrintAddresses {
ptr = formatPointer(v)
}
return textWrap{ptr + "{", list, "}"}
case reflect.Ptr:
if v.IsNil() {
return textNil
}
if m.Visit(v) || opts.ShallowPointers {
return textLine(formatPointer(v))
}
if opts.PrintAddresses {
ptr = formatPointer(v)
}
skipType = true // Let the underlying value print the type instead
return textWrap{"&" + ptr, opts.FormatValue(v.Elem(), m), ""}
case reflect.Interface:
if v.IsNil() {
return textNil
}
// Interfaces accept different concrete types,
// so configure the underlying value to explicitly print the type.
skipType = true // Print the concrete type instead
return opts.WithTypeMode(emitType).FormatValue(v.Elem(), m)
default:
panic(fmt.Sprintf("%v kind not handled", v.Kind()))
}
}
// formatMapKey formats v as if it were a map key.
// The result is guaranteed to be a single line.
func formatMapKey(v reflect.Value) string {
var opts formatOptions
opts.TypeMode = elideType
opts.AvoidStringer = true
opts.ShallowPointers = true
s := opts.FormatValue(v, visitedPointers{}).String()
return strings.TrimSpace(s)
}
// formatString prints s as a double-quoted or backtick-quoted string.
func formatString(s string) string {
// Use quoted string if it the same length as a raw string literal.
// Otherwise, attempt to use the raw string form.
qs := strconv.Quote(s)
if len(qs) == 1+len(s)+1 {
return qs
}
// Disallow newlines to ensure output is a single line.
// Only allow printable runes for readability purposes.
rawInvalid := func(r rune) bool {
return r == '`' || r == '\n' || !(unicode.IsPrint(r) || r == '\t')
}
if strings.IndexFunc(s, rawInvalid) < 0 {
return "`" + s + "`"
}
return qs
}
// formatHex prints u as a hexadecimal integer in Go notation.
func formatHex(u uint64) string {
var f string
switch {
case u <= 0xff:
f = "0x%02x"
case u <= 0xffff:
f = "0x%04x"
case u <= 0xffffff:
f = "0x%06x"
case u <= 0xffffffff:
f = "0x%08x"
case u <= 0xffffffffff:
f = "0x%010x"
case u <= 0xffffffffffff:
f = "0x%012x"
case u <= 0xffffffffffffff:
f = "0x%014x"
case u <= 0xffffffffffffffff:
f = "0x%016x"
}
return fmt.Sprintf(f, u)
}
// formatPointer prints the address of the pointer.
func formatPointer(v reflect.Value) string {
p := v.Pointer()
if flags.Deterministic {
p = 0xdeadf00f // Only used for stable testing purposes
}
return fmt.Sprintf("⟪0x%x⟫", p)
}
type visitedPointers map[value.Pointer]struct{}
// Visit inserts pointer v into the visited map and reports whether it had
// already been visited before.
func (m visitedPointers) Visit(v reflect.Value) bool {
p := value.PointerOf(v)
_, visited := m[p]
m[p] = struct{}{}
return visited
}