Source: frame.go in package golang.org/x/xerrors

Source File
	frame.go

Belonging Package
	golang.org/x/xerrors


package xerrors

import (
	"runtime"
)

A Frame contains part of a call stack.

Make room for three PCs: the one we were asked for, what it called, and possibly a PC for skipPleaseUseCallersFrames. See: https://go.googlesource.com/go/+/032678e0fb/src/runtime/extern.go#169

	frames [3]uintptr
}

Caller returns a Frame that describes a frame on the caller's stack. The argument skip is the number of frames to skip over. Caller(0) returns the frame for the caller of Caller.

func Caller(skip int) Frame {
	var s Frame
	runtime.Callers(skip+1, s.frames[:])
	return s
}

location reports the file, line, and function of a frame. The returned function may be "" even if file and line are not.

func (f Frame) location() (function, file string, line int) {
	frames := runtime.CallersFrames(f.frames[:])
	if _, ok := frames.Next(); !ok {
		return "", "", 0
	}
	fr, ok := frames.Next()
	if !ok {
		return "", "", 0
	}
	return fr.Function, fr.File, fr.Line
}

Format prints the stack as error detail. It should be called from an error's Format implementation after printing any other error detail.

func (f Frame) Format(p Printer) {
	if p.Detail() {
		function, file, line := f.location()
		if function != "" {
			p.Printf("%s\n    ", function)
		}
		if file != "" {
			p.Printf("%s:%d\n", file, line)
		}
	}


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