libgo/go/exp/eval/abort.go

   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 eval
   6
   7 import (
   8         "fmt"
   9         "os"
  10         "runtime"
  11 )
  12
  13 // Abort aborts the thread's current computation,
  14 // causing the innermost Try to return err.
  15 func (t *Thread) Abort(err os.Error) {
  16         if t.abort == nil {
  17                 panic("abort: " + err.String())
  18         }
  19         t.abort <- err
  20         runtime.Goexit()
  21 }
  22
  23 // Try executes a computation; if the computation
  24 // Aborts, Try returns the error passed to abort.
  25 func (t *Thread) Try(f func(t *Thread)) os.Error {
  26         oc := t.abort
  27         c := make(chan os.Error)
  28         t.abort = c
  29         go func() {
  30                 f(t)
  31                 c <- nil
  32         }()
  33         err := <-c
  34         t.abort = oc
  35         return err
  36 }
  37
  38 type DivByZeroError struct{}
  39
  40 func (DivByZeroError) String() string { return "divide by zero" }
  41
  42 type NilPointerError struct{}
  43
  44 func (NilPointerError) String() string { return "nil pointer dereference" }
  45
  46 type IndexError struct {
  47         Idx, Len int64
  48 }
  49
  50 func (e IndexError) String() string {
  51         if e.Idx < 0 {
  52                 return fmt.Sprintf("negative index: %d", e.Idx)
  53         }
  54         return fmt.Sprintf("index %d exceeds length %d", e.Idx, e.Len)
  55 }
  56
  57 type SliceError struct {
  58         Lo, Hi, Cap int64
  59 }
  60
  61 func (e SliceError) String() string {
  62         return fmt.Sprintf("slice [%d:%d]; cap %d", e.Lo, e.Hi, e.Cap)
  63 }
  64
  65 type KeyError struct {
  66         Key interface{}
  67 }
  68
  69 func (e KeyError) String() string { return fmt.Sprintf("key '%v' not found in map", e.Key) }
  70
  71 type NegativeLengthError struct {
  72         Len int64
  73 }
  74
  75 func (e NegativeLengthError) String() string {
  76         return fmt.Sprintf("negative length: %d", e.Len)
  77 }
  78
  79 type NegativeCapacityError struct {
  80         Len int64
  81 }
  82
  83 func (e NegativeCapacityError) String() string {
  84         return fmt.Sprintf("negative capacity: %d", e.Len)
  85 }