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dnscrypt-proxy/vendor/github.com/davecgh/go-spew/spew/common.go
William Elwood af0629856c Add unit tests for sources.go
Tests cover most of the cache and download related code paths and specify the expected result of various starting states and external failure modes.
Where the current code's behaviour doesn't match a test's expectations, the test is disabled and annotated with a TODO until it can be fixed.
Added dependency on `github.com/powerman/check` and ran `go mod vendor`.
2019-11-08 10:17:12 +01:00

342 lines
10 KiB
Go

/*
* Copyright (c) 2013-2016 Dave Collins <dave@davec.name>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package spew
import (
"bytes"
"fmt"
"io"
"reflect"
"sort"
"strconv"
)
// Some constants in the form of bytes to avoid string overhead. This mirrors
// the technique used in the fmt package.
var (
panicBytes = []byte("(PANIC=")
plusBytes = []byte("+")
iBytes = []byte("i")
trueBytes = []byte("true")
falseBytes = []byte("false")
interfaceBytes = []byte("(interface {})")
commaNewlineBytes = []byte(",\n")
newlineBytes = []byte("\n")
openBraceBytes = []byte("{")
openBraceNewlineBytes = []byte("{\n")
closeBraceBytes = []byte("}")
asteriskBytes = []byte("*")
colonBytes = []byte(":")
colonSpaceBytes = []byte(": ")
openParenBytes = []byte("(")
closeParenBytes = []byte(")")
spaceBytes = []byte(" ")
pointerChainBytes = []byte("->")
nilAngleBytes = []byte("<nil>")
maxNewlineBytes = []byte("<max depth reached>\n")
maxShortBytes = []byte("<max>")
circularBytes = []byte("<already shown>")
circularShortBytes = []byte("<shown>")
invalidAngleBytes = []byte("<invalid>")
openBracketBytes = []byte("[")
closeBracketBytes = []byte("]")
percentBytes = []byte("%")
precisionBytes = []byte(".")
openAngleBytes = []byte("<")
closeAngleBytes = []byte(">")
openMapBytes = []byte("map[")
closeMapBytes = []byte("]")
lenEqualsBytes = []byte("len=")
capEqualsBytes = []byte("cap=")
)
// hexDigits is used to map a decimal value to a hex digit.
var hexDigits = "0123456789abcdef"
// catchPanic handles any panics that might occur during the handleMethods
// calls.
func catchPanic(w io.Writer, v reflect.Value) {
if err := recover(); err != nil {
w.Write(panicBytes)
fmt.Fprintf(w, "%v", err)
w.Write(closeParenBytes)
}
}
// handleMethods attempts to call the Error and String methods on the underlying
// type the passed reflect.Value represents and outputes the result to Writer w.
//
// It handles panics in any called methods by catching and displaying the error
// as the formatted value.
func handleMethods(cs *ConfigState, w io.Writer, v reflect.Value) (handled bool) {
// We need an interface to check if the type implements the error or
// Stringer interface. However, the reflect package won't give us an
// interface on certain things like unexported struct fields in order
// to enforce visibility rules. We use unsafe, when it's available,
// to bypass these restrictions since this package does not mutate the
// values.
if !v.CanInterface() {
if UnsafeDisabled {
return false
}
v = unsafeReflectValue(v)
}
// Choose whether or not to do error and Stringer interface lookups against
// the base type or a pointer to the base type depending on settings.
// Technically calling one of these methods with a pointer receiver can
// mutate the value, however, types which choose to satisify an error or
// Stringer interface with a pointer receiver should not be mutating their
// state inside these interface methods.
if !cs.DisablePointerMethods && !UnsafeDisabled && !v.CanAddr() {
v = unsafeReflectValue(v)
}
if v.CanAddr() {
v = v.Addr()
}
// Is it an error or Stringer?
switch iface := v.Interface().(type) {
case error:
defer catchPanic(w, v)
if cs.ContinueOnMethod {
w.Write(openParenBytes)
w.Write([]byte(iface.Error()))
w.Write(closeParenBytes)
w.Write(spaceBytes)
return false
}
w.Write([]byte(iface.Error()))
return true
case fmt.Stringer:
defer catchPanic(w, v)
if cs.ContinueOnMethod {
w.Write(openParenBytes)
w.Write([]byte(iface.String()))
w.Write(closeParenBytes)
w.Write(spaceBytes)
return false
}
w.Write([]byte(iface.String()))
return true
}
return false
}
// printBool outputs a boolean value as true or false to Writer w.
func printBool(w io.Writer, val bool) {
if val {
w.Write(trueBytes)
} else {
w.Write(falseBytes)
}
}
// printInt outputs a signed integer value to Writer w.
func printInt(w io.Writer, val int64, base int) {
w.Write([]byte(strconv.FormatInt(val, base)))
}
// printUint outputs an unsigned integer value to Writer w.
func printUint(w io.Writer, val uint64, base int) {
w.Write([]byte(strconv.FormatUint(val, base)))
}
// printFloat outputs a floating point value using the specified precision,
// which is expected to be 32 or 64bit, to Writer w.
func printFloat(w io.Writer, val float64, precision int) {
w.Write([]byte(strconv.FormatFloat(val, 'g', -1, precision)))
}
// printComplex outputs a complex value using the specified float precision
// for the real and imaginary parts to Writer w.
func printComplex(w io.Writer, c complex128, floatPrecision int) {
r := real(c)
w.Write(openParenBytes)
w.Write([]byte(strconv.FormatFloat(r, 'g', -1, floatPrecision)))
i := imag(c)
if i >= 0 {
w.Write(plusBytes)
}
w.Write([]byte(strconv.FormatFloat(i, 'g', -1, floatPrecision)))
w.Write(iBytes)
w.Write(closeParenBytes)
}
// printHexPtr outputs a uintptr formatted as hexadecimal with a leading '0x'
// prefix to Writer w.
func printHexPtr(w io.Writer, p uintptr) {
// Null pointer.
num := uint64(p)
if num == 0 {
w.Write(nilAngleBytes)
return
}
// Max uint64 is 16 bytes in hex + 2 bytes for '0x' prefix
buf := make([]byte, 18)
// It's simpler to construct the hex string right to left.
base := uint64(16)
i := len(buf) - 1
for num >= base {
buf[i] = hexDigits[num%base]
num /= base
i--
}
buf[i] = hexDigits[num]
// Add '0x' prefix.
i--
buf[i] = 'x'
i--
buf[i] = '0'
// Strip unused leading bytes.
buf = buf[i:]
w.Write(buf)
}
// valuesSorter implements sort.Interface to allow a slice of reflect.Value
// elements to be sorted.
type valuesSorter struct {
values []reflect.Value
strings []string // either nil or same len and values
cs *ConfigState
}
// newValuesSorter initializes a valuesSorter instance, which holds a set of
// surrogate keys on which the data should be sorted. It uses flags in
// ConfigState to decide if and how to populate those surrogate keys.
func newValuesSorter(values []reflect.Value, cs *ConfigState) sort.Interface {
vs := &valuesSorter{values: values, cs: cs}
if canSortSimply(vs.values[0].Kind()) {
return vs
}
if !cs.DisableMethods {
vs.strings = make([]string, len(values))
for i := range vs.values {
b := bytes.Buffer{}
if !handleMethods(cs, &b, vs.values[i]) {
vs.strings = nil
break
}
vs.strings[i] = b.String()
}
}
if vs.strings == nil && cs.SpewKeys {
vs.strings = make([]string, len(values))
for i := range vs.values {
vs.strings[i] = Sprintf("%#v", vs.values[i].Interface())
}
}
return vs
}
// canSortSimply tests whether a reflect.Kind is a primitive that can be sorted
// directly, or whether it should be considered for sorting by surrogate keys
// (if the ConfigState allows it).
func canSortSimply(kind reflect.Kind) bool {
// This switch parallels valueSortLess, except for the default case.
switch kind {
case reflect.Bool:
return true
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
return true
case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
return true
case reflect.Float32, reflect.Float64:
return true
case reflect.String:
return true
case reflect.Uintptr:
return true
case reflect.Array:
return true
}
return false
}
// Len returns the number of values in the slice. It is part of the
// sort.Interface implementation.
func (s *valuesSorter) Len() int {
return len(s.values)
}
// Swap swaps the values at the passed indices. It is part of the
// sort.Interface implementation.
func (s *valuesSorter) Swap(i, j int) {
s.values[i], s.values[j] = s.values[j], s.values[i]
if s.strings != nil {
s.strings[i], s.strings[j] = s.strings[j], s.strings[i]
}
}
// valueSortLess returns whether the first value should sort before the second
// value. It is used by valueSorter.Less as part of the sort.Interface
// implementation.
func valueSortLess(a, b reflect.Value) bool {
switch a.Kind() {
case reflect.Bool:
return !a.Bool() && b.Bool()
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
return a.Int() < b.Int()
case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
return a.Uint() < b.Uint()
case reflect.Float32, reflect.Float64:
return a.Float() < b.Float()
case reflect.String:
return a.String() < b.String()
case reflect.Uintptr:
return a.Uint() < b.Uint()
case reflect.Array:
// Compare the contents of both arrays.
l := a.Len()
for i := 0; i < l; i++ {
av := a.Index(i)
bv := b.Index(i)
if av.Interface() == bv.Interface() {
continue
}
return valueSortLess(av, bv)
}
}
return a.String() < b.String()
}
// Less returns whether the value at index i should sort before the
// value at index j. It is part of the sort.Interface implementation.
func (s *valuesSorter) Less(i, j int) bool {
if s.strings == nil {
return valueSortLess(s.values[i], s.values[j])
}
return s.strings[i] < s.strings[j]
}
// sortValues is a sort function that handles both native types and any type that
// can be converted to error or Stringer. Other inputs are sorted according to
// their Value.String() value to ensure display stability.
func sortValues(values []reflect.Value, cs *ConfigState) {
if len(values) == 0 {
return
}
sort.Sort(newValuesSorter(values, cs))
}