57 lines
1.5 KiB
Go
57 lines
1.5 KiB
Go
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package xerrors
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import (
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"runtime"
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)
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// A Frame contains part of a call stack.
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type Frame struct {
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// Make room for three PCs: the one we were asked for, what it called,
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// and possibly a PC for skipPleaseUseCallersFrames. See:
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// https://go.googlesource.com/go/+/032678e0fb/src/runtime/extern.go#169
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frames [3]uintptr
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}
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// Caller returns a Frame that describes a frame on the caller's stack.
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// The argument skip is the number of frames to skip over.
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// Caller(0) returns the frame for the caller of Caller.
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func Caller(skip int) Frame {
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var s Frame
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runtime.Callers(skip+1, s.frames[:])
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return s
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}
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// location reports the file, line, and function of a frame.
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//
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// The returned function may be "" even if file and line are not.
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func (f Frame) location() (function, file string, line int) {
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frames := runtime.CallersFrames(f.frames[:])
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if _, ok := frames.Next(); !ok {
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return "", "", 0
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}
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fr, ok := frames.Next()
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if !ok {
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return "", "", 0
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}
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return fr.Function, fr.File, fr.Line
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}
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// Format prints the stack as error detail.
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// It should be called from an error's Format implementation
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// after printing any other error detail.
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func (f Frame) Format(p Printer) {
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if p.Detail() {
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function, file, line := f.location()
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if function != "" {
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p.Printf("%s\n ", function)
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}
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if file != "" {
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p.Printf("%s:%d\n", file, line)
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}
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}
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}
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