"fmt"
"go/token"
"io"
- "os"
"sort"
)
-// An implementation of an ErrorHandler may be provided to the Scanner.
-// If a syntax error is encountered and a handler was installed, Error
-// is called with a position and an error message. The position points
-// to the beginning of the offending token.
-//
-type ErrorHandler interface {
- Error(pos token.Position, msg string)
-}
-
-// ErrorVector implements the ErrorHandler interface. It maintains a list
-// of errors which can be retrieved with GetErrorList and GetError. The
-// zero value for an ErrorVector is an empty ErrorVector ready to use.
-//
-// A common usage pattern is to embed an ErrorVector alongside a
-// scanner in a data structure that uses the scanner. By passing a
-// reference to an ErrorVector to the scanner's Init call, default
-// error handling is obtained.
-//
-type ErrorVector struct {
- errors []*Error
-}
-
-// Reset resets an ErrorVector to no errors.
-func (h *ErrorVector) Reset() { h.errors = h.errors[:0] }
-
-// ErrorCount returns the number of errors collected.
-func (h *ErrorVector) ErrorCount() int { return len(h.errors) }
-
-// Within ErrorVector, an error is represented by an Error node. The
-// position Pos, if valid, points to the beginning of the offending
-// token, and the error condition is described by Msg.
+// In an ErrorList, an error is represented by an *Error.
+// The position Pos, if valid, points to the beginning of
+// the offending token, and the error condition is described
+// by Msg.
//
type Error struct {
Pos token.Position
Msg string
}
-func (e *Error) String() string {
+// Error implements the error interface.
+func (e Error) Error() string {
if e.Pos.Filename != "" || e.Pos.IsValid() {
// don't print "<unknown position>"
// TODO(gri) reconsider the semantics of Position.IsValid
return e.Msg
}
-// An ErrorList is a (possibly sorted) list of Errors.
+// ErrorList is a list of *Errors.
+// The zero value for an ErrorList is an empty ErrorList ready to use.
+//
type ErrorList []*Error
+// Add adds an Error with given position and error message to an ErrorList.
+func (p *ErrorList) Add(pos token.Position, msg string) {
+ *p = append(*p, &Error{pos, msg})
+}
+
+// Reset resets an ErrorList to no errors.
+func (p *ErrorList) Reset() { *p = (*p)[0:0] }
+
// ErrorList implements the sort Interface.
func (p ErrorList) Len() int { return len(p) }
func (p ErrorList) Swap(i, j int) { p[i], p[j] = p[j], p[i] }
return false
}
-func (p ErrorList) String() string {
- switch len(p) {
- case 0:
- return "unspecified error"
- case 1:
- return p[0].String()
- }
- return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
-}
-
-// These constants control the construction of the ErrorList
-// returned by GetErrors.
+// Sort sorts an ErrorList. *Error entries are sorted by position,
+// other errors are sorted by error message, and before any *Error
+// entry.
//
-const (
- Raw = iota // leave error list unchanged
- Sorted // sort error list by file, line, and column number
- NoMultiples // sort error list and leave only the first error per line
-)
-
-// GetErrorList returns the list of errors collected by an ErrorVector.
-// The construction of the ErrorList returned is controlled by the mode
-// parameter. If there are no errors, the result is nil.
-//
-func (h *ErrorVector) GetErrorList(mode int) ErrorList {
- if len(h.errors) == 0 {
- return nil
- }
-
- list := make(ErrorList, len(h.errors))
- copy(list, h.errors)
-
- if mode >= Sorted {
- sort.Sort(list)
- }
+func (p ErrorList) Sort() {
+ sort.Sort(p)
+}
- if mode >= NoMultiples {
- var last token.Position // initial last.Line is != any legal error line
- i := 0
- for _, e := range list {
- if e.Pos.Filename != last.Filename || e.Pos.Line != last.Line {
- last = e.Pos
- list[i] = e
- i++
- }
+// RemoveMultiples sorts an ErrorList and removes all but the first error per line.
+func (p *ErrorList) RemoveMultiples() {
+ sort.Sort(p)
+ var last token.Position // initial last.Line is != any legal error line
+ i := 0
+ for _, e := range *p {
+ if e.Pos.Filename != last.Filename || e.Pos.Line != last.Line {
+ last = e.Pos
+ (*p)[i] = e
+ i++
}
- list = list[0:i]
}
-
- return list
+ (*p) = (*p)[0:i]
}
-// GetError is like GetErrorList, but it returns an os.Error instead
-// so that a nil result can be assigned to an os.Error variable and
-// remains nil.
-//
-func (h *ErrorVector) GetError(mode int) os.Error {
- if len(h.errors) == 0 {
- return nil
+// An ErrorList implements the error interface.
+func (p ErrorList) Error() string {
+ switch len(p) {
+ case 0:
+ return "no errors"
+ case 1:
+ return p[0].Error()
}
-
- return h.GetErrorList(mode)
+ return fmt.Sprintf("%s (and %d more errors)", p[0], len(p)-1)
}
-// ErrorVector implements the ErrorHandler interface.
-func (h *ErrorVector) Error(pos token.Position, msg string) {
- h.errors = append(h.errors, &Error{pos, msg})
+// Err returns an error equivalent to this error list.
+// If the list is empty, Err returns nil.
+func (p ErrorList) Err() error {
+ if len(p) == 0 {
+ return nil
+ }
+ return p
}
// PrintError is a utility function that prints a list of errors to w,
// one error per line, if the err parameter is an ErrorList. Otherwise
// it prints the err string.
//
-func PrintError(w io.Writer, err os.Error) {
+func PrintError(w io.Writer, err error) {
if list, ok := err.(ErrorList); ok {
for _, e := range list {
fmt.Fprintf(w, "%s\n", e)
}
- } else {
+ } else if err != nil {
fmt.Fprintf(w, "%s\n", err)
}
}
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