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| package godog | |
| import ( | |
| "fmt" | |
| "go/build" | |
| "io" | |
| "path" | |
| "path/filepath" | |
| "runtime" | |
| "strings" | |
| ) | |
| // Frame represents a program counter inside a stack frame. | |
| type stackFrame uintptr | |
| // pc returns the program counter for this frame; | |
| // multiple frames may have the same PC value. | |
| func (f stackFrame) 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 stackFrame) file() string { | |
| fn := runtime.FuncForPC(f.pc()) | |
| if fn == nil { | |
| return "unknown" | |
| } | |
| file, _ := fn.FileLine(f.pc()) | |
| return file | |
| } | |
| func trimGoPath(file string) string { | |
| for _, p := range filepath.SplitList(build.Default.GOPATH) { | |
| file = strings.Replace(file, filepath.Join(p, "src")+string(filepath.Separator), "", 1) | |
| } | |
| return file | |
| } | |
| // line returns the line number of source code of the | |
| // function for this Frame's pc. | |
| func (f stackFrame) line() int { | |
| fn := runtime.FuncForPC(f.pc()) | |
| if fn == nil { | |
| return 0 | |
| } | |
| _, line := fn.FileLine(f.pc()) | |
| return line | |
| } | |
| // 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 path of source file relative to the compile time GOPATH | |
| // %+v equivalent to %+s:%d | |
| func (f stackFrame) Format(s fmt.State, verb rune) { | |
| funcname := func(name string) string { | |
| i := strings.LastIndex(name, "/") | |
| name = name[i+1:] | |
| i = strings.Index(name, ".") | |
| return name[i+1:] | |
| } | |
| switch verb { | |
| case 's': | |
| switch { | |
| case s.Flag('+'): | |
| pc := f.pc() | |
| fn := runtime.FuncForPC(pc) | |
| if fn == nil { | |
| io.WriteString(s, "unknown") | |
| } else { | |
| file, _ := fn.FileLine(pc) | |
| fmt.Fprintf(s, "%s\n\t%s", fn.Name(), trimGoPath(file)) | |
| } | |
| default: | |
| io.WriteString(s, path.Base(f.file())) | |
| } | |
| case 'd': | |
| fmt.Fprintf(s, "%d", f.line()) | |
| case 'n': | |
| name := runtime.FuncForPC(f.pc()).Name() | |
| io.WriteString(s, funcname(name)) | |
| case 'v': | |
| f.Format(s, 's') | |
| io.WriteString(s, ":") | |
| f.Format(s, 'd') | |
| } | |
| } | |
| // 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 := stackFrame(pc) | |
| fmt.Fprintf(st, "\n%+v", f) | |
| } | |
| } | |
| } | |
| } | |
| func callStack() *stack { | |
| const depth = 32 | |
| var pcs [depth]uintptr | |
| n := runtime.Callers(3, pcs[:]) | |
| var st stack = pcs[0:n] | |
| return &st | |
| } | |
| // fundamental is an error that has a message and a stack, but no caller. | |
| type traceError struct { | |
| msg string | |
| *stack | |
| } | |
| func (f *traceError) Error() string { return f.msg } | |
| func (f *traceError) Format(s fmt.State, verb rune) { | |
| switch verb { | |
| case 'v': | |
| if s.Flag('+') { | |
| io.WriteString(s, f.msg) | |
| f.stack.Format(s, verb) | |
| return | |
| } | |
| fallthrough | |
| case 's': | |
| io.WriteString(s, f.msg) | |
| case 'q': | |
| fmt.Fprintf(s, "%q", f.msg) | |
| } | |
| } |