1 files changed, 85 insertions, 0 deletions
diff --git a/libgo/go/exp/eval/abort.go b/libgo/go/exp/eval/abort.go
new file mode 100644
index 000000000..22e17cec4
--- /dev/null
+++ b/libgo/go/exp/eval/abort.go
@@ -0,0 +1,85 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package eval
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+)
+
+// Abort aborts the thread's current computation,
+// causing the innermost Try to return err.
+func (t *Thread) Abort(err os.Error) {
+	if t.abort == nil {
+		panic("abort: " + err.String())
+	}
+	t.abort <- err
+	runtime.Goexit()
+}
+
+// Try executes a computation; if the computation
+// Aborts, Try returns the error passed to abort.
+func (t *Thread) Try(f func(t *Thread)) os.Error {
+	oc := t.abort
+	c := make(chan os.Error)
+	t.abort = c
+	go func() {
+		f(t)
+		c <- nil
+	}()
+	err := <-c
+	t.abort = oc
+	return err
+}
+
+type DivByZeroError struct{}
+
+func (DivByZeroError) String() string { return "divide by zero" }
+
+type NilPointerError struct{}
+
+func (NilPointerError) String() string { return "nil pointer dereference" }
+
+type IndexError struct {
+	Idx, Len int64
+}
+
+func (e IndexError) String() string {
+	if e.Idx < 0 {
+		return fmt.Sprintf("negative index: %d", e.Idx)
+	}
+	return fmt.Sprintf("index %d exceeds length %d", e.Idx, e.Len)
+}
+
+type SliceError struct {
+	Lo, Hi, Cap int64
+}
+
+func (e SliceError) String() string {
+	return fmt.Sprintf("slice [%d:%d]; cap %d", e.Lo, e.Hi, e.Cap)
+}
+
+type KeyError struct {
+	Key interface{}
+}
+
+func (e KeyError) String() string { return fmt.Sprintf("key '%v' not found in map", e.Key) }
+
+type NegativeLengthError struct {
+	Len int64
+}
+
+func (e NegativeLengthError) String() string {
+	return fmt.Sprintf("negative length: %d", e.Len)
+}
+
+type NegativeCapacityError struct {
+	Len int64
+}
+
+func (e NegativeCapacityError) String() string {
+	return fmt.Sprintf("negative capacity: %d", e.Len)
+}