aboutsummaryrefslogtreecommitdiff
path: root/vendor/github.com/davecgh/go-spew/spew/dump.go
blob: f78d89fc1f6c454df58cd1e346817db6e30c4299 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
/*
 * 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"
	"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:
		d.w.Write(nilAngleBytes)

	case cycleFound:
		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...)
}