vendor.github.com.pkg.errors.stack.go Maven / Gradle / Ivy
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package errors
import (
"fmt"
"io"
"path"
"runtime"
"strconv"
"strings"
)
// Frame represents a program counter inside a stack frame.
// For historical reasons if Frame is interpreted as a uintptr
// its value represents the program counter + 1.
type Frame uintptr
// pc returns the program counter for this frame;
// multiple frames may have the same PC value.
func (f Frame) pc() uintptr { return uintptr(f) - 1 }
// file returns the full path to the file that contains the
// function for this Frame's pc.
func (f Frame) file() string {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return "unknown"
}
file, _ := fn.FileLine(f.pc())
return file
}
// line returns the line number of source code of the
// function for this Frame's pc.
func (f Frame) line() int {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return 0
}
_, line := fn.FileLine(f.pc())
return line
}
// name returns the name of this function, if known.
func (f Frame) name() string {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return "unknown"
}
return fn.Name()
}
// Format formats the frame according to the fmt.Formatter interface.
//
// %s source file
// %d source line
// %n function name
// %v equivalent to %s:%d
//
// Format accepts flags that alter the printing of some verbs, as follows:
//
// %+s function name and path of source file relative to the compile time
// GOPATH separated by \n\t (\n\t)
// %+v equivalent to %+s:%d
func (f Frame) Format(s fmt.State, verb rune) {
switch verb {
case 's':
switch {
case s.Flag('+'):
io.WriteString(s, f.name())
io.WriteString(s, "\n\t")
io.WriteString(s, f.file())
default:
io.WriteString(s, path.Base(f.file()))
}
case 'd':
io.WriteString(s, strconv.Itoa(f.line()))
case 'n':
io.WriteString(s, funcname(f.name()))
case 'v':
f.Format(s, 's')
io.WriteString(s, ":")
f.Format(s, 'd')
}
}
// MarshalText formats a stacktrace Frame as a text string. The output is the
// same as that of fmt.Sprintf("%+v", f), but without newlines or tabs.
func (f Frame) MarshalText() ([]byte, error) {
name := f.name()
if name == "unknown" {
return []byte(name), nil
}
return []byte(fmt.Sprintf("%s %s:%d", name, f.file(), f.line())), nil
}
// StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
type StackTrace []Frame
// Format formats the stack of Frames according to the fmt.Formatter interface.
//
// %s lists source files for each Frame in the stack
// %v lists the source file and line number for each Frame in the stack
//
// Format accepts flags that alter the printing of some verbs, as follows:
//
// %+v Prints filename, function, and line number for each Frame in the stack.
func (st StackTrace) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
switch {
case s.Flag('+'):
for _, f := range st {
io.WriteString(s, "\n")
f.Format(s, verb)
}
case s.Flag('#'):
fmt.Fprintf(s, "%#v", []Frame(st))
default:
st.formatSlice(s, verb)
}
case 's':
st.formatSlice(s, verb)
}
}
// formatSlice will format this StackTrace into the given buffer as a slice of
// Frame, only valid when called with '%s' or '%v'.
func (st StackTrace) formatSlice(s fmt.State, verb rune) {
io.WriteString(s, "[")
for i, f := range st {
if i > 0 {
io.WriteString(s, " ")
}
f.Format(s, verb)
}
io.WriteString(s, "]")
}
// stack represents a stack of program counters.
type stack []uintptr
func (s *stack) Format(st fmt.State, verb rune) {
switch verb {
case 'v':
switch {
case st.Flag('+'):
for _, pc := range *s {
f := Frame(pc)
fmt.Fprintf(st, "\n%+v", f)
}
}
}
}
func (s *stack) StackTrace() StackTrace {
f := make([]Frame, len(*s))
for i := 0; i < len(f); i++ {
f[i] = Frame((*s)[i])
}
return f
}
func callers() *stack {
const depth = 32
var pcs [depth]uintptr
n := runtime.Callers(3, pcs[:])
var st stack = pcs[0:n]
return &st
}
// funcname removes the path prefix component of a function's name reported by func.Name().
func funcname(name string) string {
i := strings.LastIndex(name, "/")
name = name[i+1:]
i = strings.Index(name, ".")
return name[i+1:]
}