--- /dev/null
+/*
+ * 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))
+}
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