Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 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 true |
| 59 | } |
| 60 | if e.Filename == f.Filename { |
| 61 | if e.Line < f.Line { |
| 62 | return true |
| 63 | } |
| 64 | if e.Line == f.Line { |
| 65 | return e.Column < f.Column |
| 66 | } |
| 67 | } |
| 68 | return false |
| 69 | } |
| 70 | |
| 71 | // Sort sorts an ErrorList. *Error entries are sorted by position, |
| 72 | // other errors are sorted by error message, and before any *Error |
| 73 | // entry. |
| 74 | // |
| 75 | func (p ErrorList) Sort() { |
| 76 | sort.Sort(p) |
| 77 | } |
| 78 | |
| 79 | // RemoveMultiples sorts an ErrorList and removes all but the first error per line. |
| 80 | func (p *ErrorList) RemoveMultiples() { |
| 81 | sort.Sort(p) |
| 82 | var last token.Position // initial last.Line is != any legal error line |
| 83 | i := 0 |
| 84 | for _, e := range *p { |
| 85 | if e.Pos.Filename != last.Filename || e.Pos.Line != last.Line { |
| 86 | last = e.Pos |
| 87 | (*p)[i] = e |
| 88 | i++ |
| 89 | } |
| 90 | } |
| 91 | (*p) = (*p)[0:i] |
| 92 | } |
| 93 | |
| 94 | // An ErrorList implements the error interface. |
| 95 | func (p ErrorList) Error() string { |
| 96 | switch len(p) { |
| 97 | case 0: |
| 98 | return "no errors" |
| 99 | case 1: |
| 100 | return p[0].Error() |
| 101 | } |
| 102 | return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1) |
| 103 | } |
| 104 | |
| 105 | // Err returns an error equivalent to this error list. |
| 106 | // If the list is empty, Err returns nil. |
| 107 | func (p ErrorList) Err() error { |
| 108 | if len(p) == 0 { |
| 109 | return nil |
| 110 | } |
| 111 | return p |
| 112 | } |
| 113 | |
| 114 | // PrintError is a utility function that prints a list of errors to w, |
| 115 | // one error per line, if the err parameter is an ErrorList. Otherwise |
| 116 | // it prints the err string. |
| 117 | // |
| 118 | func PrintError(w io.Writer, err error) { |
| 119 | if list, ok := err.(ErrorList); ok { |
| 120 | for _, e := range list { |
| 121 | fmt.Fprintf(w, "%s\n", e) |
| 122 | } |
Bernhard Rosenkraenzer | ee2ec6d | 2012-10-10 01:40:27 +0159 | [diff] [blame^] | 123 | } else if err != nil { |
Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 124 | fmt.Fprintf(w, "%s\n", err) |
| 125 | } |
| 126 | } |