From 69134311380f70cd95d072fbf0832bc7f0cc54e6 Mon Sep 17 00:00:00 2001
From: Tom Wilkie <tom.wilkie@gmail.com>
Date: Tue, 27 Oct 2015 13:12:37 +0000
Subject: [PATCH] Make IDList an alias for StringSet

---
 report/id_list.go  | 57 ++++------------------------------------------
 report/topology.go |  1 +
 2 files changed, 6 insertions(+), 52 deletions(-)

diff --git a/report/id_list.go b/report/id_list.go
index c69ed6e5f..a530d3c92 100644
--- a/report/id_list.go
+++ b/report/id_list.go
@@ -3,73 +3,26 @@ package report
 import "sort"
 
 // IDList is a list of string IDs, which are always sorted and unique.
-type IDList []string
+type IDList StringSet
 
 // MakeIDList makes a new IDList.
 func MakeIDList(ids ...string) IDList {
-	if len(ids) <= 0 {
-		return IDList{}
-	}
-	sort.Strings(ids)
-	for i := 1; i < len(ids); { // shuffle down any duplicates
-		if ids[i-1] == ids[i] {
-			ids = append(ids[:i-1], ids[i:]...)
-			continue
-		}
-		i++
-	}
-	return IDList(ids)
+	return IDList(MakeStringSet(ids...))
 }
 
 // Add is the only correct way to add ids to an IDList.
 func (a IDList) Add(ids ...string) IDList {
-	for _, s := range ids {
-		i := sort.Search(len(a), func(i int) bool { return a[i] >= s })
-		if i < len(a) && a[i] == s {
-			// The list already has the element.
-			continue
-		}
-		// It a new element, insert it in order.
-		a = append(a, "")
-		copy(a[i+1:], a[i:])
-		a[i] = s
-	}
-	return a
+	return IDList(StringSet(a).Add(ids...))
 }
 
 // Copy returns a copy of the IDList.
 func (a IDList) Copy() IDList {
-	result := make(IDList, len(a))
-	copy(result, a)
-	return result
+	return IDList(StringSet(a).Copy())
 }
 
 // Merge all elements from a and b into a new list
 func (a IDList) Merge(b IDList) IDList {
-	if len(b) == 0 { // Optimise special case, to avoid allocating
-		return a // (note unit test DeepEquals breaks if we don't do this)
-	}
-	d := make(IDList, len(a)+len(b))
-	for i, j, k := 0, 0, 0; ; k++ {
-		switch {
-		case i >= len(a):
-			copy(d[k:], b[j:])
-			return d[:k+len(b)-j]
-		case j >= len(b):
-			copy(d[k:], a[i:])
-			return d[:k+len(a)-i]
-		case a[i] < b[j]:
-			d[k] = a[i]
-			i++
-		case a[i] > b[j]:
-			d[k] = b[j]
-			j++
-		default: // equal
-			d[k] = a[i]
-			i++
-			j++
-		}
-	}
+	return IDList(StringSet(a).Merge(StringSet(b)))
 }
 
 // Contains returns true if id is in the list.
diff --git a/report/topology.go b/report/topology.go
index 5faf1cc48..679337267 100644
--- a/report/topology.go
+++ b/report/topology.go
@@ -116,6 +116,7 @@ func (n Node) WithCounters(c map[string]int) Node {
 	return result
 }
 
+// WithSet returns a fresh copy of n, with set merged in at key.
 func (n Node) WithSet(key string, set StringSet) Node {
 	result := n.Copy()
 	existing := n.Sets[key]