mirror of
https://github.com/go-gitea/gitea
synced 2024-11-09 03:34:24 +00:00
212 lines
8.3 KiB
Go
212 lines
8.3 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 implements a deep pretty printer for Go data structures to aid in
|
|
debugging.
|
|
|
|
A quick overview of the additional features spew provides over the built-in
|
|
printing facilities for Go data types are as follows:
|
|
|
|
* 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 (only when using
|
|
Dump style)
|
|
|
|
There are two different approaches spew allows for dumping Go data structures:
|
|
|
|
* Dump style which prints with newlines, customizable indentation,
|
|
and additional debug information such as types and all pointer addresses
|
|
used to indirect to the final value
|
|
* A custom Formatter interface that integrates cleanly with the standard fmt
|
|
package and replaces %v, %+v, %#v, and %#+v to provide inline printing
|
|
similar to the default %v while providing the additional functionality
|
|
outlined above and passing unsupported format verbs such as %x and %q
|
|
along to fmt
|
|
|
|
Quick Start
|
|
|
|
This section demonstrates how to quickly get started with spew. See the
|
|
sections below for further details on formatting and configuration options.
|
|
|
|
To dump a variable with full newlines, indentation, type, and pointer
|
|
information use Dump, Fdump, or Sdump:
|
|
spew.Dump(myVar1, myVar2, ...)
|
|
spew.Fdump(someWriter, myVar1, myVar2, ...)
|
|
str := spew.Sdump(myVar1, myVar2, ...)
|
|
|
|
Alternatively, if you would prefer to use format strings with a compacted inline
|
|
printing style, use the convenience wrappers Printf, Fprintf, etc with
|
|
%v (most compact), %+v (adds pointer addresses), %#v (adds types), or
|
|
%#+v (adds types and pointer addresses):
|
|
spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
|
|
spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
|
|
spew.Fprintf(someWriter, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
|
|
spew.Fprintf(someWriter, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
|
|
|
|
Configuration Options
|
|
|
|
Configuration of spew is handled by fields in the ConfigState type. For
|
|
convenience, all of the top-level functions use a global state available
|
|
via the spew.Config global.
|
|
|
|
It is also possible to create a ConfigState instance that provides methods
|
|
equivalent to the top-level functions. This allows concurrent configuration
|
|
options. See the ConfigState documentation for more details.
|
|
|
|
The following configuration options are available:
|
|
* Indent
|
|
String to use for each indentation level for Dump functions.
|
|
It is a single space by default. A popular alternative is "\t".
|
|
|
|
* MaxDepth
|
|
Maximum number of levels to descend into nested data structures.
|
|
There is no limit by default.
|
|
|
|
* DisableMethods
|
|
Disables invocation of error and Stringer interface methods.
|
|
Method invocation is enabled by default.
|
|
|
|
* DisablePointerMethods
|
|
Disables invocation of error and Stringer interface methods on types
|
|
which only accept pointer receivers from non-pointer variables.
|
|
Pointer method invocation is enabled by default.
|
|
|
|
* DisablePointerAddresses
|
|
DisablePointerAddresses specifies whether to disable the printing of
|
|
pointer addresses. This is useful when diffing data structures in tests.
|
|
|
|
* DisableCapacities
|
|
DisableCapacities specifies whether to disable the printing of
|
|
capacities for arrays, slices, maps and channels. This is useful when
|
|
diffing data structures in tests.
|
|
|
|
* ContinueOnMethod
|
|
Enables recursion into types after invoking error and Stringer interface
|
|
methods. Recursion after method invocation is disabled by default.
|
|
|
|
* SortKeys
|
|
Specifies map keys should be sorted before being printed. Use
|
|
this to have a more deterministic, diffable output. Note that
|
|
only native types (bool, int, uint, floats, uintptr and string)
|
|
and types which implement error or Stringer interfaces are
|
|
supported with other types sorted according to the
|
|
reflect.Value.String() output which guarantees display
|
|
stability. Natural map order is used by default.
|
|
|
|
* SpewKeys
|
|
Specifies that, as a last resort attempt, map keys should be
|
|
spewed to strings and sorted by those strings. This is only
|
|
considered if SortKeys is true.
|
|
|
|
Dump Usage
|
|
|
|
Simply call spew.Dump with a list of variables you want to dump:
|
|
|
|
spew.Dump(myVar1, myVar2, ...)
|
|
|
|
You may also call spew.Fdump if you would prefer to output to an arbitrary
|
|
io.Writer. For example, to dump to standard error:
|
|
|
|
spew.Fdump(os.Stderr, myVar1, myVar2, ...)
|
|
|
|
A third option is to call spew.Sdump to get the formatted output as a string:
|
|
|
|
str := spew.Sdump(myVar1, myVar2, ...)
|
|
|
|
Sample Dump Output
|
|
|
|
See the Dump example for details on the setup of the types and variables being
|
|
shown here.
|
|
|
|
(main.Foo) {
|
|
unexportedField: (*main.Bar)(0xf84002e210)({
|
|
flag: (main.Flag) flagTwo,
|
|
data: (uintptr) <nil>
|
|
}),
|
|
ExportedField: (map[interface {}]interface {}) (len=1) {
|
|
(string) (len=3) "one": (bool) true
|
|
}
|
|
}
|
|
|
|
Byte (and uint8) arrays and slices are displayed uniquely like the hexdump -C
|
|
command as shown.
|
|
([]uint8) (len=32 cap=32) {
|
|
00000000 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 |............... |
|
|
00000010 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 |!"#$%&'()*+,-./0|
|
|
00000020 31 32 |12|
|
|
}
|
|
|
|
Custom Formatter
|
|
|
|
Spew provides a custom formatter that implements the fmt.Formatter interface
|
|
so that it integrates cleanly with standard fmt package printing functions. The
|
|
formatter is useful for inline printing of smaller data types similar to the
|
|
standard %v format specifier.
|
|
|
|
The custom formatter only responds to the %v (most compact), %+v (adds pointer
|
|
addresses), %#v (adds types), or %#+v (adds types and pointer addresses) verb
|
|
combinations. Any other verbs such as %x and %q will be sent to the the
|
|
standard fmt package for formatting. In addition, the custom formatter ignores
|
|
the width and precision arguments (however they will still work on the format
|
|
specifiers not handled by the custom formatter).
|
|
|
|
Custom Formatter Usage
|
|
|
|
The simplest way to make use of the spew custom formatter is to call one of the
|
|
convenience functions such as spew.Printf, spew.Println, or spew.Printf. The
|
|
functions have syntax you are most likely already familiar with:
|
|
|
|
spew.Printf("myVar1: %v -- myVar2: %+v", myVar1, myVar2)
|
|
spew.Printf("myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
|
|
spew.Println(myVar, myVar2)
|
|
spew.Fprintf(os.Stderr, "myVar1: %v -- myVar2: %+v", myVar1, myVar2)
|
|
spew.Fprintf(os.Stderr, "myVar3: %#v -- myVar4: %#+v", myVar3, myVar4)
|
|
|
|
See the Index for the full list convenience functions.
|
|
|
|
Sample Formatter Output
|
|
|
|
Double pointer to a uint8:
|
|
%v: <**>5
|
|
%+v: <**>(0xf8400420d0->0xf8400420c8)5
|
|
%#v: (**uint8)5
|
|
%#+v: (**uint8)(0xf8400420d0->0xf8400420c8)5
|
|
|
|
Pointer to circular struct with a uint8 field and a pointer to itself:
|
|
%v: <*>{1 <*><shown>}
|
|
%+v: <*>(0xf84003e260){ui8:1 c:<*>(0xf84003e260)<shown>}
|
|
%#v: (*main.circular){ui8:(uint8)1 c:(*main.circular)<shown>}
|
|
%#+v: (*main.circular)(0xf84003e260){ui8:(uint8)1 c:(*main.circular)(0xf84003e260)<shown>}
|
|
|
|
See the Printf example for details on the setup of variables being shown
|
|
here.
|
|
|
|
Errors
|
|
|
|
Since it is possible for custom Stringer/error interfaces to panic, spew
|
|
detects them and handles them internally by printing the panic information
|
|
inline with the output. Since spew is intended to provide deep pretty printing
|
|
capabilities on structures, it intentionally does not return any errors.
|
|
*/
|
|
package spew
|