1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package scanner 6 7 import ( 8 "fmt" 9 "go/token" 10 "io" 11 "sort" 12 ) 13 14 // In an ErrorList, an error is represented by an *Error. 15 // The position Pos, if valid, points to the beginning of 16 // the offending token, and the error condition is described 17 // by Msg. 18 // 19 type Error struct { 20 Pos token.Position 21 Msg string 22 } 23 24 // Error implements the error interface. 25 func (e Error) Error() string { 26 if e.Pos.Filename != "" || e.Pos.IsValid() { 27 // don't print "<unknown position>" 28 // TODO(gri) reconsider the semantics of Position.IsValid 29 return e.Pos.String() + ": " + e.Msg 30 } 31 return e.Msg 32 } 33 34 // ErrorList is a list of *Errors. 35 // The zero value for an ErrorList is an empty ErrorList ready to use. 36 // 37 type ErrorList []*Error 38 39 // Add adds an Error with given position and error message to an ErrorList. 40 func (p *ErrorList) Add(pos token.Position, msg string) { 41 *p = append(*p, &Error{pos, msg}) 42 } 43 44 // Reset resets an ErrorList to no errors. 45 func (p *ErrorList) Reset() { *p = (*p)[0:0] } 46 47 // ErrorList implements the sort Interface. 48 func (p ErrorList) Len() int { return len(p) } 49 func (p ErrorList) Swap(i, j int) { p[i], p[j] = p[j], p[i] } 50 51 func (p ErrorList) Less(i, j int) bool { 52 e := &p[i].Pos 53 f := &p[j].Pos 54 // Note that it is not sufficient to simply compare file offsets because 55 // the offsets do not reflect modified line information (through //line 56 // comments). 57 if e.Filename != f.Filename { 58 return e.Filename < f.Filename 59 } 60 if e.Line != f.Line { 61 return e.Line < f.Line 62 } 63 if e.Column != f.Column { 64 return e.Column < f.Column 65 } 66 return p[i].Msg < p[j].Msg 67 } 68 69 // Sort sorts an ErrorList. *Error entries are sorted by position, 70 // other errors are sorted by error message, and before any *Error 71 // entry. 72 // 73 func (p ErrorList) Sort() { 74 sort.Sort(p) 75 } 76 77 // RemoveMultiples sorts an ErrorList and removes all but the first error per line. 78 func (p *ErrorList) RemoveMultiples() { 79 sort.Sort(p) 80 var last token.Position // initial last.Line is != any legal error line 81 i := 0 82 for _, e := range *p { 83 if e.Pos.Filename != last.Filename || e.Pos.Line != last.Line { 84 last = e.Pos 85 (*p)[i] = e 86 i++ 87 } 88 } 89 (*p) = (*p)[0:i] 90 } 91 92 // An ErrorList implements the error interface. 93 func (p ErrorList) Error() string { 94 switch len(p) { 95 case 0: 96 return "no errors" 97 case 1: 98 return p[0].Error() 99 } 100 return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1) 101 } 102 103 // Err returns an error equivalent to this error list. 104 // If the list is empty, Err returns nil. 105 func (p ErrorList) Err() error { 106 if len(p) == 0 { 107 return nil 108 } 109 return p 110 } 111 112 // PrintError is a utility function that prints a list of errors to w, 113 // one error per line, if the err parameter is an ErrorList. Otherwise 114 // it prints the err string. 115 // 116 func PrintError(w io.Writer, err error) { 117 if list, ok := err.(ErrorList); ok { 118 for _, e := range list { 119 fmt.Fprintf(w, "%s\n", e) 120 } 121 } else if err != nil { 122 fmt.Fprintf(w, "%s\n", err) 123 } 124 } 125
