Initial distributor implementation

appengine/cmd/dm/distributor/impl/jobsim/parser/range_slice.go

+// Copyright 2015 The Chromium 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 parser
+
+import (
+        "bytes"
+        "fmt"
+)
+
+type Range [2]uint64
+
+func (r Range) Low() uint64            { return r[0] }
+func (r Range) Single() (uint64, bool) { return r[0], r[1] == 0 }
+func (r Range) High() uint64 {
+        if r[1] == 0 {
+                return r[0]
+        }
+        return r[1]
+}
+
+func (r Range) Iter(cb func(uint64) error) error {
+        if s, ok := r.Single(); ok {
+                return cb(s)
+        }
+        for i := r.Low(); i < r.High(); i++ {
+                if err := cb(i); err != nil {
+                        return err
+                }
+        }
+        return nil
+}
+
+func (r Range) String() string {
+        if s, ok := r.Single(); ok {
+                return fmt.Sprintf("%d", s)
+        }
+        return fmt.Sprintf("%d-%d", r.Low(), r.High())
+}
+
+type RangeSlice []Range
+
+func (rs RangeSlice) String() string {
+        b := bytes.Buffer{}
+        for i, r := range rs {
+                if i != 0 {
+                        b.WriteRune(',')
+                }
+                b.WriteString(r.String())
+        }
+        return b.String()
+}
+
+func (rs RangeSlice) Iter(cb func(uint64) error) error {
+        for _, rng := range rs {
+                if err := rng.Iter(cb); err != nil {
+                        return err
+                }
+        }
+        return nil
+}