--- /dev/null
+/*
+ * Copyright (c) 2013 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"
+ "encoding/hex"
+ "fmt"
+ "io"
+ "os"
+ "reflect"
+ "regexp"
+ "strconv"
+ "strings"
+)
+
+var (
+ // uint8Type is a reflect.Type representing a uint8. It is used to
+ // convert cgo types to uint8 slices for hexdumping.
+ uint8Type = reflect.TypeOf(uint8(0))
+
+ // cCharRE is a regular expression that matches a cgo char.
+ // It is used to detect character arrays to hexdump them.
+ cCharRE = regexp.MustCompile("^.*\\._Ctype_char$")
+
+ // cUnsignedCharRE is a regular expression that matches a cgo unsigned
+ // char. It is used to detect unsigned character arrays to hexdump
+ // them.
+ cUnsignedCharRE = regexp.MustCompile("^.*\\._Ctype_unsignedchar$")
+
+ // cUint8tCharRE is a regular expression that matches a cgo uint8_t.
+ // It is used to detect uint8_t arrays to hexdump them.
+ cUint8tCharRE = regexp.MustCompile("^.*\\._Ctype_uint8_t$")
+)
+
+// dumpState contains information about the state of a dump operation.
+type dumpState struct {
+ w io.Writer
+ depth int
+ pointers map[uintptr]int
+ ignoreNextType bool
+ ignoreNextIndent bool
+ cs *ConfigState
+}
+
+// indent performs indentation according to the depth level and cs.Indent
+// option.
+func (d *dumpState) indent() {
+ if d.ignoreNextIndent {
+ d.ignoreNextIndent = false
+ return
+ }
+ d.w.Write(bytes.Repeat([]byte(d.cs.Indent), d.depth))
+}
+
+// unpackValue returns values inside of non-nil interfaces when possible.
+// This is useful for data types like structs, arrays, slices, and maps which
+// can contain varying types packed inside an interface.
+func (d *dumpState) unpackValue(v reflect.Value) reflect.Value {
+ if v.Kind() == reflect.Interface && !v.IsNil() {
+ v = v.Elem()
+ }
+ return v
+}
+
+// dumpPtr handles formatting of pointers by indirecting them as necessary.
+func (d *dumpState) dumpPtr(v reflect.Value) {
+ // Remove pointers at or below the current depth from map used to detect
+ // circular refs.
+ for k, depth := range d.pointers {
+ if depth >= d.depth {
+ delete(d.pointers, k)
+ }
+ }
+
+ // Keep list of all dereferenced pointers to show later.
+ pointerChain := make([]uintptr, 0)
+
+ // Figure out how many levels of indirection there are by dereferencing
+ // pointers and unpacking interfaces down the chain while detecting circular
+ // references.
+ nilFound := false
+ cycleFound := false
+ indirects := 0
+ ve := v
+ for ve.Kind() == reflect.Ptr {
+ if ve.IsNil() {
+ nilFound = true
+ break
+ }
+ indirects++
+ addr := ve.Pointer()
+ pointerChain = append(pointerChain, addr)
+ if pd, ok := d.pointers[addr]; ok && pd < d.depth {
+ cycleFound = true
+ indirects--
+ break
+ }
+ d.pointers[addr] = d.depth
+
+ ve = ve.Elem()
+ if ve.Kind() == reflect.Interface {
+ if ve.IsNil() {
+ nilFound = true
+ break
+ }
+ ve = ve.Elem()
+ }
+ }
+
+ // Display type information.
+ d.w.Write(openParenBytes)
+ d.w.Write(bytes.Repeat(asteriskBytes, indirects))
+ d.w.Write([]byte(ve.Type().String()))
+ d.w.Write(closeParenBytes)
+
+ // Display pointer information.
+ if !d.cs.DisablePointerAddresses && len(pointerChain) > 0 {
+ d.w.Write(openParenBytes)
+ for i, addr := range pointerChain {
+ if i > 0 {
+ d.w.Write(pointerChainBytes)
+ }
+ printHexPtr(d.w, addr)
+ }
+ d.w.Write(closeParenBytes)
+ }
+
+ // Display dereferenced value.
+ d.w.Write(openParenBytes)
+ switch {
+ case nilFound == true:
+ d.w.Write(nilAngleBytes)
+
+ case cycleFound == true:
+ d.w.Write(circularBytes)
+
+ default:
+ d.ignoreNextType = true
+ d.dump(ve)
+ }
+ d.w.Write(closeParenBytes)
+}
+
+// dumpSlice handles formatting of arrays and slices. Byte (uint8 under
+// reflection) arrays and slices are dumped in hexdump -C fashion.
+func (d *dumpState) dumpSlice(v reflect.Value) {
+ // Determine whether this type should be hex dumped or not. Also,
+ // for types which should be hexdumped, try to use the underlying data
+ // first, then fall back to trying to convert them to a uint8 slice.
+ var buf []uint8
+ doConvert := false
+ doHexDump := false
+ numEntries := v.Len()
+ if numEntries > 0 {
+ vt := v.Index(0).Type()
+ vts := vt.String()
+ switch {
+ // C types that need to be converted.
+ case cCharRE.MatchString(vts):
+ fallthrough
+ case cUnsignedCharRE.MatchString(vts):
+ fallthrough
+ case cUint8tCharRE.MatchString(vts):
+ doConvert = true
+
+ // Try to use existing uint8 slices and fall back to converting
+ // and copying if that fails.
+ case vt.Kind() == reflect.Uint8:
+ // We need an addressable interface to convert the type
+ // to a byte slice. 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 available, to
+ // bypass these restrictions since this package does not
+ // mutate the values.
+ vs := v
+ if !vs.CanInterface() || !vs.CanAddr() {
+ vs = unsafeReflectValue(vs)
+ }
+ if !UnsafeDisabled {
+ vs = vs.Slice(0, numEntries)
+
+ // Use the existing uint8 slice if it can be
+ // type asserted.
+ iface := vs.Interface()
+ if slice, ok := iface.([]uint8); ok {
+ buf = slice
+ doHexDump = true
+ break
+ }
+ }
+
+ // The underlying data needs to be converted if it can't
+ // be type asserted to a uint8 slice.
+ doConvert = true
+ }
+
+ // Copy and convert the underlying type if needed.
+ if doConvert && vt.ConvertibleTo(uint8Type) {
+ // Convert and copy each element into a uint8 byte
+ // slice.
+ buf = make([]uint8, numEntries)
+ for i := 0; i < numEntries; i++ {
+ vv := v.Index(i)
+ buf[i] = uint8(vv.Convert(uint8Type).Uint())
+ }
+ doHexDump = true
+ }
+ }
+
+ // Hexdump the entire slice as needed.
+ if doHexDump {
+ indent := strings.Repeat(d.cs.Indent, d.depth)
+ str := indent + hex.Dump(buf)
+ str = strings.Replace(str, "\n", "\n"+indent, -1)
+ str = strings.TrimRight(str, d.cs.Indent)
+ d.w.Write([]byte(str))
+ return
+ }
+
+ // Recursively call dump for each item.
+ for i := 0; i < numEntries; i++ {
+ d.dump(d.unpackValue(v.Index(i)))
+ if i < (numEntries - 1) {
+ d.w.Write(commaNewlineBytes)
+ } else {
+ d.w.Write(newlineBytes)
+ }
+ }
+}
+
+// dump is the main workhorse for dumping a value. It uses the passed reflect
+// value to figure out what kind of object we are dealing with and formats it
+// appropriately. It is a recursive function, however circular data structures
+// are detected and handled properly.
+func (d *dumpState) dump(v reflect.Value) {
+ // Handle invalid reflect values immediately.
+ kind := v.Kind()
+ if kind == reflect.Invalid {
+ d.w.Write(invalidAngleBytes)
+ return
+ }
+
+ // Handle pointers specially.
+ if kind == reflect.Ptr {
+ d.indent()
+ d.dumpPtr(v)
+ return
+ }
+
+ // Print type information unless already handled elsewhere.
+ if !d.ignoreNextType {
+ d.indent()
+ d.w.Write(openParenBytes)
+ d.w.Write([]byte(v.Type().String()))
+ d.w.Write(closeParenBytes)
+ d.w.Write(spaceBytes)
+ }
+ d.ignoreNextType = false
+
+ // Display length and capacity if the built-in len and cap functions
+ // work with the value's kind and the len/cap itself is non-zero.
+ valueLen, valueCap := 0, 0
+ switch v.Kind() {
+ case reflect.Array, reflect.Slice, reflect.Chan:
+ valueLen, valueCap = v.Len(), v.Cap()
+ case reflect.Map, reflect.String:
+ valueLen = v.Len()
+ }
+ if valueLen != 0 || !d.cs.DisableCapacities && valueCap != 0 {
+ d.w.Write(openParenBytes)
+ if valueLen != 0 {
+ d.w.Write(lenEqualsBytes)
+ printInt(d.w, int64(valueLen), 10)
+ }
+ if !d.cs.DisableCapacities && valueCap != 0 {
+ if valueLen != 0 {
+ d.w.Write(spaceBytes)
+ }
+ d.w.Write(capEqualsBytes)
+ printInt(d.w, int64(valueCap), 10)
+ }
+ d.w.Write(closeParenBytes)
+ d.w.Write(spaceBytes)
+ }
+
+ // Call Stringer/error interfaces if they exist and the handle methods flag
+ // is enabled
+ if !d.cs.DisableMethods {
+ if (kind != reflect.Invalid) && (kind != reflect.Interface) {
+ if handled := handleMethods(d.cs, d.w, v); handled {
+ return
+ }
+ }
+ }
+
+ switch kind {
+ case reflect.Invalid:
+ // Do nothing. We should never get here since invalid has already
+ // been handled above.
+
+ case reflect.Bool:
+ printBool(d.w, v.Bool())
+
+ case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
+ printInt(d.w, v.Int(), 10)
+
+ case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint:
+ printUint(d.w, v.Uint(), 10)
+
+ case reflect.Float32:
+ printFloat(d.w, v.Float(), 32)
+
+ case reflect.Float64:
+ printFloat(d.w, v.Float(), 64)
+
+ case reflect.Complex64:
+ printComplex(d.w, v.Complex(), 32)
+
+ case reflect.Complex128:
+ printComplex(d.w, v.Complex(), 64)
+
+ case reflect.Slice:
+ if v.IsNil() {
+ d.w.Write(nilAngleBytes)
+ break
+ }
+ fallthrough
+
+ case reflect.Array:
+ d.w.Write(openBraceNewlineBytes)
+ d.depth++
+ if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+ d.indent()
+ d.w.Write(maxNewlineBytes)
+ } else {
+ d.dumpSlice(v)
+ }
+ d.depth--
+ d.indent()
+ d.w.Write(closeBraceBytes)
+
+ case reflect.String:
+ d.w.Write([]byte(strconv.Quote(v.String())))
+
+ case reflect.Interface:
+ // The only time we should get here is for nil interfaces due to
+ // unpackValue calls.
+ if v.IsNil() {
+ d.w.Write(nilAngleBytes)
+ }
+
+ case reflect.Ptr:
+ // Do nothing. We should never get here since pointers have already
+ // been handled above.
+
+ case reflect.Map:
+ // nil maps should be indicated as different than empty maps
+ if v.IsNil() {
+ d.w.Write(nilAngleBytes)
+ break
+ }
+
+ d.w.Write(openBraceNewlineBytes)
+ d.depth++
+ if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+ d.indent()
+ d.w.Write(maxNewlineBytes)
+ } else {
+ numEntries := v.Len()
+ keys := v.MapKeys()
+ if d.cs.SortKeys {
+ sortValues(keys, d.cs)
+ }
+ for i, key := range keys {
+ d.dump(d.unpackValue(key))
+ d.w.Write(colonSpaceBytes)
+ d.ignoreNextIndent = true
+ d.dump(d.unpackValue(v.MapIndex(key)))
+ if i < (numEntries - 1) {
+ d.w.Write(commaNewlineBytes)
+ } else {
+ d.w.Write(newlineBytes)
+ }
+ }
+ }
+ d.depth--
+ d.indent()
+ d.w.Write(closeBraceBytes)
+
+ case reflect.Struct:
+ d.w.Write(openBraceNewlineBytes)
+ d.depth++
+ if (d.cs.MaxDepth != 0) && (d.depth > d.cs.MaxDepth) {
+ d.indent()
+ d.w.Write(maxNewlineBytes)
+ } else {
+ vt := v.Type()
+ numFields := v.NumField()
+ for i := 0; i < numFields; i++ {
+ d.indent()
+ vtf := vt.Field(i)
+ d.w.Write([]byte(vtf.Name))
+ d.w.Write(colonSpaceBytes)
+ d.ignoreNextIndent = true
+ d.dump(d.unpackValue(v.Field(i)))
+ if i < (numFields - 1) {
+ d.w.Write(commaNewlineBytes)
+ } else {
+ d.w.Write(newlineBytes)
+ }
+ }
+ }
+ d.depth--
+ d.indent()
+ d.w.Write(closeBraceBytes)
+
+ case reflect.Uintptr:
+ printHexPtr(d.w, uintptr(v.Uint()))
+
+ case reflect.UnsafePointer, reflect.Chan, reflect.Func:
+ printHexPtr(d.w, v.Pointer())
+
+ // There were not any other types at the time this code was written, but
+ // fall back to letting the default fmt package handle it in case any new
+ // types are added.
+ default:
+ if v.CanInterface() {
+ fmt.Fprintf(d.w, "%v", v.Interface())
+ } else {
+ fmt.Fprintf(d.w, "%v", v.String())
+ }
+ }
+}
+
+// fdump is a helper function to consolidate the logic from the various public
+// methods which take varying writers and config states.
+func fdump(cs *ConfigState, w io.Writer, a ...interface{}) {
+ for _, arg := range a {
+ if arg == nil {
+ w.Write(interfaceBytes)
+ w.Write(spaceBytes)
+ w.Write(nilAngleBytes)
+ w.Write(newlineBytes)
+ continue
+ }
+
+ d := dumpState{w: w, cs: cs}
+ d.pointers = make(map[uintptr]int)
+ d.dump(reflect.ValueOf(arg))
+ d.w.Write(newlineBytes)
+ }
+}
+
+// Fdump formats and displays the passed arguments to io.Writer w. It formats
+// exactly the same as Dump.
+func Fdump(w io.Writer, a ...interface{}) {
+ fdump(&Config, w, a...)
+}
+
+// Sdump returns a string with the passed arguments formatted exactly the same
+// as Dump.
+func Sdump(a ...interface{}) string {
+ var buf bytes.Buffer
+ fdump(&Config, &buf, a...)
+ return buf.String()
+}
+
+/*
+Dump displays the passed parameters to standard out with newlines, customizable
+indentation, and additional debug information such as complete types and all
+pointer addresses used to indirect to the final value. It provides the
+following features over the built-in printing facilities provided by the fmt
+package:
+
+ * Pointers are dereferenced and followed
+ * Circular data structures are detected and handled properly
+ * Custom Stringer/error interfaces are optionally invoked, including
+ on unexported types
+ * Custom types which only implement the Stringer/error interfaces via
+ a pointer receiver are optionally invoked when passing non-pointer
+ variables
+ * Byte arrays and slices are dumped like the hexdump -C command which
+ includes offsets, byte values in hex, and ASCII output
+
+The configuration options are controlled by an exported package global,
+spew.Config. See ConfigState for options documentation.
+
+See Fdump if you would prefer dumping to an arbitrary io.Writer or Sdump to
+get the formatted result as a string.
+*/
+func Dump(a ...interface{}) {
+ fdump(&Config, os.Stdout, a...)
+}
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