index: add ClaimsAttrValue

ClaimsAttrValue can be used in clients of pkg index, such
as in search on values returned by Index.AppendClaims to
query permanode attributes.

Related: issue #777

Change-Id: I5a8fa2a970d88f9ddbcc3de350215a196e124b64

pkg/index/corpus.go

@@ -1008,41 +1008,7 @@ func (c *Corpus) PermanodeAttrValue(permaNode blob.Ref,
 		}
 		return ""
 	}
-	if at.IsZero() {
-		at = time.Now()
-	}
-	var v []string
-	for _, cl := range pm.Claims {
-		if cl.Attr != attr || cl.Date.After(at) {
-			continue
-		}
-		if signerFilter.Valid() && signerFilter != cl.Signer {
-			continue
-		}
-		switch cl.Type {
-		case string(schema.DelAttributeClaim):
-			if cl.Value == "" {
-				v = v[:0]
-			} else {
-				i := 0
-				for _, w := range v {
-					if w != cl.Value {
-						v[i] = w
-						i++
-					}
-				}
-				v = v[:i]
-			}
-		case string(schema.SetAttributeClaim):
-			v = append(v[:0], cl.Value)
-		case string(schema.AddAttributeClaim):
-			v = append(v, cl.Value)
-		}
-	}
-	if len(v) != 0 {
-		return v[0]
-	}
-	return ""
+	return claimPtrsAttrValue(pm.Claims, attr, at, signerFilter)
 }
 
 // AppendPermanodeAttrValues appends to dst all the values for the attribute

pkg/index/util.go

@@ -18,6 +18,11 @@ package index
 
 import (
 	"net/url"
+	"time"
+
+	"camlistore.org/pkg/blob"
+	"camlistore.org/pkg/schema"
+	"camlistore.org/pkg/types/camtypes"
 )
 
 var urle = url.QueryEscape
@@ -42,3 +47,71 @@ func (s *dupSkipper) Dup(v string) bool {
 	s.m[v] = true
 	return false
 }
+
+// ClaimsAttrValue returns the value of attr from claims,
+// or the empty string if not found.
+// Claims should be sorted by claim.Date.
+func ClaimsAttrValue(claims []camtypes.Claim, attr string, at time.Time, signerFilter blob.Ref) string {
+	return claimsIntfAttrValue(claimSlice(claims), attr, at, signerFilter)
+}
+
+// claimPtrsAttrValue returns the value of attr from claims,
+// or the empty string if not found.
+// Claims should be sorted by claim.Date.
+func claimPtrsAttrValue(claims []*camtypes.Claim, attr string, at time.Time, signerFilter blob.Ref) string {
+	return claimsIntfAttrValue(claimPtrSlice(claims), attr, at, signerFilter)
+}
+
+type claimsIntf interface {
+	Len() int
+	Claim(i int) *camtypes.Claim
+}
+
+type claimSlice []camtypes.Claim
+
+func (s claimSlice) Len() int                    { return len(s) }
+func (s claimSlice) Claim(i int) *camtypes.Claim { return &s[i] }
+
+type claimPtrSlice []*camtypes.Claim
+
+func (s claimPtrSlice) Len() int                    { return len(s) }
+func (s claimPtrSlice) Claim(i int) *camtypes.Claim { return s[i] }
+
+func claimsIntfAttrValue(claims claimsIntf, attr string, at time.Time, signerFilter blob.Ref) string {
+	if at.IsZero() {
+		at = time.Now()
+	}
+	var v []string
+	for i := 0; i < claims.Len(); i++ {
+		cl := claims.Claim(i)
+		if cl.Attr != attr || cl.Date.After(at) {
+			continue
+		}
+		if signerFilter.Valid() && signerFilter != cl.Signer {
+			continue
+		}
+		switch cl.Type {
+		case string(schema.DelAttributeClaim):
+			if cl.Value == "" {
+				v = v[:0]
+			} else {
+				i := 0
+				for _, w := range v {
+					if w != cl.Value {
+						v[i] = w
+						i++
+					}
+				}
+				v = v[:i]
+			}
+		case string(schema.SetAttributeClaim):
+			v = append(v[:0], cl.Value)
+		case string(schema.AddAttributeClaim):
+			v = append(v, cl.Value)
+		}
+	}
+	if len(v) != 0 {
+		return v[0]
+	}
+	return ""
+}

pkg/index/util_test.go

@@ -0,0 +1,87 @@
+/*
+Copyright 2016 The Camlistore AUTHORS
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package index
+
+import (
+	"testing"
+	"time"
+
+	"camlistore.org/pkg/blob"
+	"camlistore.org/pkg/types/camtypes"
+)
+
+func TestClaimsAttrValue(t *testing.T) {
+	tm := time.Unix(99, 0)
+	claim := func(verb, attr, val string) camtypes.Claim {
+		tm = tm.Add(time.Second)
+		return camtypes.Claim{
+			Type:  verb + "-attribute",
+			Attr:  attr,
+			Value: val,
+			Date:  tm,
+		}
+	}
+
+	claims := []camtypes.Claim{
+		claim("set", "foo", "foov"), // time 100
+
+		claim("add", "tag", "a"), // time 101
+		claim("add", "tag", "b"), // time 102
+		claim("del", "tag", ""),
+		claim("add", "tag", "c"),
+		claim("add", "tag", "d"),
+		claim("add", "tag", "e"),
+		claim("del", "tag", "d"),
+
+		claim("add", "DelAll", "a"),
+		claim("add", "DelAll", "b"),
+		claim("add", "DelAll", "c"),
+		claim("del", "DelAll", ""),
+
+		claim("add", "DelOne", "a"),
+		claim("add", "DelOne", "b"),
+		claim("add", "DelOne", "c"),
+		claim("add", "DelOne", "d"),
+		claim("del", "DelOne", "d"),
+		claim("del", "DelOne", "a"),
+
+		claim("add", "SetAfterAdd", "a"),
+		claim("add", "SetAfterAdd", "b"),
+		claim("set", "SetAfterAdd", "setv"),
+	}
+
+	tests := []struct {
+		attr string
+		want string
+		t    time.Time
+	}{
+		{attr: "foo", want: "foov"},
+		{attr: "tag", want: "c"},
+		{attr: "tag", want: "a", t: time.Unix(102, 0)},
+		{attr: "DelAll", want: ""},
+		{attr: "DelOne", want: "b"},
+		{attr: "SetAfterAdd", want: "setv"},
+	}
+
+	for i, tt := range tests {
+		got := ClaimsAttrValue(claims, tt.attr, tt.t, blob.Ref{})
+		if got != tt.want {
+			t.Errorf("%d. attr %q = %v; want %v",
+				i, tt.attr, got, tt.want)
+		}
+	}
+}