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1 | /* |
2 | * Copyright (c) 2013-2016 Dave Collins <dave@davec.name> | |
3 | * | |
4 | * Permission to use, copy, modify, and distribute this software for any | |
5 | * purpose with or without fee is hereby granted, provided that the above | |
6 | * copyright notice and this permission notice appear in all copies. | |
7 | * | |
8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES | |
9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
15 | */ | |
16 | ||
17 | package spew | |
18 | ||
19 | import ( | |
20 | "bytes" | |
21 | "fmt" | |
22 | "reflect" | |
23 | "strconv" | |
24 | "strings" | |
25 | ) | |
26 | ||
27 | // supportedFlags is a list of all the character flags supported by fmt package. | |
28 | const supportedFlags = "0-+# " | |
29 | ||
30 | // formatState implements the fmt.Formatter interface and contains information | |
31 | // about the state of a formatting operation. The NewFormatter function can | |
32 | // be used to get a new Formatter which can be used directly as arguments | |
33 | // in standard fmt package printing calls. | |
34 | type formatState struct { | |
35 | value interface{} | |
36 | fs fmt.State | |
37 | depth int | |
38 | pointers map[uintptr]int | |
39 | ignoreNextType bool | |
40 | cs *ConfigState | |
41 | } | |
42 | ||
43 | // buildDefaultFormat recreates the original format string without precision | |
44 | // and width information to pass in to fmt.Sprintf in the case of an | |
45 | // unrecognized type. Unless new types are added to the language, this | |
46 | // function won't ever be called. | |
47 | func (f *formatState) buildDefaultFormat() (format string) { | |
48 | buf := bytes.NewBuffer(percentBytes) | |
49 | ||
50 | for _, flag := range supportedFlags { | |
51 | if f.fs.Flag(int(flag)) { | |
52 | buf.WriteRune(flag) | |
53 | } | |
54 | } | |
55 | ||
56 | buf.WriteRune('v') | |
57 | ||
58 | format = buf.String() | |
59 | return format | |
60 | } | |
61 | ||
62 | // constructOrigFormat recreates the original format string including precision | |
63 | // and width information to pass along to the standard fmt package. This allows | |
64 | // automatic deferral of all format strings this package doesn't support. | |
65 | func (f *formatState) constructOrigFormat(verb rune) (format string) { | |
66 | buf := bytes.NewBuffer(percentBytes) | |
67 | ||
68 | for _, flag := range supportedFlags { | |
69 | if f.fs.Flag(int(flag)) { | |
70 | buf.WriteRune(flag) | |
71 | } | |
72 | } | |
73 | ||
74 | if width, ok := f.fs.Width(); ok { | |
75 | buf.WriteString(strconv.Itoa(width)) | |
76 | } | |
77 | ||
78 | if precision, ok := f.fs.Precision(); ok { | |
79 | buf.Write(precisionBytes) | |
80 | buf.WriteString(strconv.Itoa(precision)) | |
81 | } | |
82 | ||
83 | buf.WriteRune(verb) | |
84 | ||
85 | format = buf.String() | |
86 | return format | |
87 | } | |
88 | ||
89 | // unpackValue returns values inside of non-nil interfaces when possible and | |
90 | // ensures that types for values which have been unpacked from an interface | |
91 | // are displayed when the show types flag is also set. | |
92 | // This is useful for data types like structs, arrays, slices, and maps which | |
93 | // can contain varying types packed inside an interface. | |
94 | func (f *formatState) unpackValue(v reflect.Value) reflect.Value { | |
95 | if v.Kind() == reflect.Interface { | |
96 | f.ignoreNextType = false | |
97 | if !v.IsNil() { | |
98 | v = v.Elem() | |
99 | } | |
100 | } | |
101 | return v | |
102 | } | |
103 | ||
104 | // formatPtr handles formatting of pointers by indirecting them as necessary. | |
105 | func (f *formatState) formatPtr(v reflect.Value) { | |
106 | // Display nil if top level pointer is nil. | |
107 | showTypes := f.fs.Flag('#') | |
108 | if v.IsNil() && (!showTypes || f.ignoreNextType) { | |
109 | f.fs.Write(nilAngleBytes) | |
110 | return | |
111 | } | |
112 | ||
113 | // Remove pointers at or below the current depth from map used to detect | |
114 | // circular refs. | |
115 | for k, depth := range f.pointers { | |
116 | if depth >= f.depth { | |
117 | delete(f.pointers, k) | |
118 | } | |
119 | } | |
120 | ||
121 | // Keep list of all dereferenced pointers to possibly show later. | |
122 | pointerChain := make([]uintptr, 0) | |
123 | ||
124 | // Figure out how many levels of indirection there are by derferencing | |
125 | // pointers and unpacking interfaces down the chain while detecting circular | |
126 | // references. | |
127 | nilFound := false | |
128 | cycleFound := false | |
129 | indirects := 0 | |
130 | ve := v | |
131 | for ve.Kind() == reflect.Ptr { | |
132 | if ve.IsNil() { | |
133 | nilFound = true | |
134 | break | |
135 | } | |
136 | indirects++ | |
137 | addr := ve.Pointer() | |
138 | pointerChain = append(pointerChain, addr) | |
139 | if pd, ok := f.pointers[addr]; ok && pd < f.depth { | |
140 | cycleFound = true | |
141 | indirects-- | |
142 | break | |
143 | } | |
144 | f.pointers[addr] = f.depth | |
145 | ||
146 | ve = ve.Elem() | |
147 | if ve.Kind() == reflect.Interface { | |
148 | if ve.IsNil() { | |
149 | nilFound = true | |
150 | break | |
151 | } | |
152 | ve = ve.Elem() | |
153 | } | |
154 | } | |
155 | ||
156 | // Display type or indirection level depending on flags. | |
157 | if showTypes && !f.ignoreNextType { | |
158 | f.fs.Write(openParenBytes) | |
159 | f.fs.Write(bytes.Repeat(asteriskBytes, indirects)) | |
160 | f.fs.Write([]byte(ve.Type().String())) | |
161 | f.fs.Write(closeParenBytes) | |
162 | } else { | |
163 | if nilFound || cycleFound { | |
164 | indirects += strings.Count(ve.Type().String(), "*") | |
165 | } | |
166 | f.fs.Write(openAngleBytes) | |
167 | f.fs.Write([]byte(strings.Repeat("*", indirects))) | |
168 | f.fs.Write(closeAngleBytes) | |
169 | } | |
170 | ||
171 | // Display pointer information depending on flags. | |
172 | if f.fs.Flag('+') && (len(pointerChain) > 0) { | |
173 | f.fs.Write(openParenBytes) | |
174 | for i, addr := range pointerChain { | |
175 | if i > 0 { | |
176 | f.fs.Write(pointerChainBytes) | |
177 | } | |
178 | printHexPtr(f.fs, addr) | |
179 | } | |
180 | f.fs.Write(closeParenBytes) | |
181 | } | |
182 | ||
183 | // Display dereferenced value. | |
184 | switch { | |
15c0b25d | 185 | case nilFound: |
bae9f6d2 JC |
186 | f.fs.Write(nilAngleBytes) |
187 | ||
15c0b25d | 188 | case cycleFound: |
bae9f6d2 JC |
189 | f.fs.Write(circularShortBytes) |
190 | ||
191 | default: | |
192 | f.ignoreNextType = true | |
193 | f.format(ve) | |
194 | } | |
195 | } | |
196 | ||
197 | // format is the main workhorse for providing the Formatter interface. It | |
198 | // uses the passed reflect value to figure out what kind of object we are | |
199 | // dealing with and formats it appropriately. It is a recursive function, | |
200 | // however circular data structures are detected and handled properly. | |
201 | func (f *formatState) format(v reflect.Value) { | |
202 | // Handle invalid reflect values immediately. | |
203 | kind := v.Kind() | |
204 | if kind == reflect.Invalid { | |
205 | f.fs.Write(invalidAngleBytes) | |
206 | return | |
207 | } | |
208 | ||
209 | // Handle pointers specially. | |
210 | if kind == reflect.Ptr { | |
211 | f.formatPtr(v) | |
212 | return | |
213 | } | |
214 | ||
215 | // Print type information unless already handled elsewhere. | |
216 | if !f.ignoreNextType && f.fs.Flag('#') { | |
217 | f.fs.Write(openParenBytes) | |
218 | f.fs.Write([]byte(v.Type().String())) | |
219 | f.fs.Write(closeParenBytes) | |
220 | } | |
221 | f.ignoreNextType = false | |
222 | ||
223 | // Call Stringer/error interfaces if they exist and the handle methods | |
224 | // flag is enabled. | |
225 | if !f.cs.DisableMethods { | |
226 | if (kind != reflect.Invalid) && (kind != reflect.Interface) { | |
227 | if handled := handleMethods(f.cs, f.fs, v); handled { | |
228 | return | |
229 | } | |
230 | } | |
231 | } | |
232 | ||
233 | switch kind { | |
234 | case reflect.Invalid: | |
235 | // Do nothing. We should never get here since invalid has already | |
236 | // been handled above. | |
237 | ||
238 | case reflect.Bool: | |
239 | printBool(f.fs, v.Bool()) | |
240 | ||
241 | case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int: | |
242 | printInt(f.fs, v.Int(), 10) | |
243 | ||
244 | case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint: | |
245 | printUint(f.fs, v.Uint(), 10) | |
246 | ||
247 | case reflect.Float32: | |
248 | printFloat(f.fs, v.Float(), 32) | |
249 | ||
250 | case reflect.Float64: | |
251 | printFloat(f.fs, v.Float(), 64) | |
252 | ||
253 | case reflect.Complex64: | |
254 | printComplex(f.fs, v.Complex(), 32) | |
255 | ||
256 | case reflect.Complex128: | |
257 | printComplex(f.fs, v.Complex(), 64) | |
258 | ||
259 | case reflect.Slice: | |
260 | if v.IsNil() { | |
261 | f.fs.Write(nilAngleBytes) | |
262 | break | |
263 | } | |
264 | fallthrough | |
265 | ||
266 | case reflect.Array: | |
267 | f.fs.Write(openBracketBytes) | |
268 | f.depth++ | |
269 | if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) { | |
270 | f.fs.Write(maxShortBytes) | |
271 | } else { | |
272 | numEntries := v.Len() | |
273 | for i := 0; i < numEntries; i++ { | |
274 | if i > 0 { | |
275 | f.fs.Write(spaceBytes) | |
276 | } | |
277 | f.ignoreNextType = true | |
278 | f.format(f.unpackValue(v.Index(i))) | |
279 | } | |
280 | } | |
281 | f.depth-- | |
282 | f.fs.Write(closeBracketBytes) | |
283 | ||
284 | case reflect.String: | |
285 | f.fs.Write([]byte(v.String())) | |
286 | ||
287 | case reflect.Interface: | |
288 | // The only time we should get here is for nil interfaces due to | |
289 | // unpackValue calls. | |
290 | if v.IsNil() { | |
291 | f.fs.Write(nilAngleBytes) | |
292 | } | |
293 | ||
294 | case reflect.Ptr: | |
295 | // Do nothing. We should never get here since pointers have already | |
296 | // been handled above. | |
297 | ||
298 | case reflect.Map: | |
299 | // nil maps should be indicated as different than empty maps | |
300 | if v.IsNil() { | |
301 | f.fs.Write(nilAngleBytes) | |
302 | break | |
303 | } | |
304 | ||
305 | f.fs.Write(openMapBytes) | |
306 | f.depth++ | |
307 | if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) { | |
308 | f.fs.Write(maxShortBytes) | |
309 | } else { | |
310 | keys := v.MapKeys() | |
311 | if f.cs.SortKeys { | |
312 | sortValues(keys, f.cs) | |
313 | } | |
314 | for i, key := range keys { | |
315 | if i > 0 { | |
316 | f.fs.Write(spaceBytes) | |
317 | } | |
318 | f.ignoreNextType = true | |
319 | f.format(f.unpackValue(key)) | |
320 | f.fs.Write(colonBytes) | |
321 | f.ignoreNextType = true | |
322 | f.format(f.unpackValue(v.MapIndex(key))) | |
323 | } | |
324 | } | |
325 | f.depth-- | |
326 | f.fs.Write(closeMapBytes) | |
327 | ||
328 | case reflect.Struct: | |
329 | numFields := v.NumField() | |
330 | f.fs.Write(openBraceBytes) | |
331 | f.depth++ | |
332 | if (f.cs.MaxDepth != 0) && (f.depth > f.cs.MaxDepth) { | |
333 | f.fs.Write(maxShortBytes) | |
334 | } else { | |
335 | vt := v.Type() | |
336 | for i := 0; i < numFields; i++ { | |
337 | if i > 0 { | |
338 | f.fs.Write(spaceBytes) | |
339 | } | |
340 | vtf := vt.Field(i) | |
341 | if f.fs.Flag('+') || f.fs.Flag('#') { | |
342 | f.fs.Write([]byte(vtf.Name)) | |
343 | f.fs.Write(colonBytes) | |
344 | } | |
345 | f.format(f.unpackValue(v.Field(i))) | |
346 | } | |
347 | } | |
348 | f.depth-- | |
349 | f.fs.Write(closeBraceBytes) | |
350 | ||
351 | case reflect.Uintptr: | |
352 | printHexPtr(f.fs, uintptr(v.Uint())) | |
353 | ||
354 | case reflect.UnsafePointer, reflect.Chan, reflect.Func: | |
355 | printHexPtr(f.fs, v.Pointer()) | |
356 | ||
357 | // There were not any other types at the time this code was written, but | |
358 | // fall back to letting the default fmt package handle it if any get added. | |
359 | default: | |
360 | format := f.buildDefaultFormat() | |
361 | if v.CanInterface() { | |
362 | fmt.Fprintf(f.fs, format, v.Interface()) | |
363 | } else { | |
364 | fmt.Fprintf(f.fs, format, v.String()) | |
365 | } | |
366 | } | |
367 | } | |
368 | ||
369 | // Format satisfies the fmt.Formatter interface. See NewFormatter for usage | |
370 | // details. | |
371 | func (f *formatState) Format(fs fmt.State, verb rune) { | |
372 | f.fs = fs | |
373 | ||
374 | // Use standard formatting for verbs that are not v. | |
375 | if verb != 'v' { | |
376 | format := f.constructOrigFormat(verb) | |
377 | fmt.Fprintf(fs, format, f.value) | |
378 | return | |
379 | } | |
380 | ||
381 | if f.value == nil { | |
382 | if fs.Flag('#') { | |
383 | fs.Write(interfaceBytes) | |
384 | } | |
385 | fs.Write(nilAngleBytes) | |
386 | return | |
387 | } | |
388 | ||
389 | f.format(reflect.ValueOf(f.value)) | |
390 | } | |
391 | ||
392 | // newFormatter is a helper function to consolidate the logic from the various | |
393 | // public methods which take varying config states. | |
394 | func newFormatter(cs *ConfigState, v interface{}) fmt.Formatter { | |
395 | fs := &formatState{value: v, cs: cs} | |
396 | fs.pointers = make(map[uintptr]int) | |
397 | return fs | |
398 | } | |
399 | ||
400 | /* | |
401 | NewFormatter returns a custom formatter that satisfies the fmt.Formatter | |
402 | interface. As a result, it integrates cleanly with standard fmt package | |
403 | printing functions. The formatter is useful for inline printing of smaller data | |
404 | types similar to the standard %v format specifier. | |
405 | ||
406 | The custom formatter only responds to the %v (most compact), %+v (adds pointer | |
407 | addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb | |
408 | combinations. Any other verbs such as %x and %q will be sent to the the | |
409 | standard fmt package for formatting. In addition, the custom formatter ignores | |
410 | the width and precision arguments (however they will still work on the format | |
411 | specifiers not handled by the custom formatter). | |
412 | ||
413 | Typically this function shouldn't be called directly. It is much easier to make | |
414 | use of the custom formatter by calling one of the convenience functions such as | |
415 | Printf, Println, or Fprintf. | |
416 | */ | |
417 | func NewFormatter(v interface{}) fmt.Formatter { | |
418 | return newFormatter(&Config, v) | |
419 | } |