From 54970c34f06cc23dd32ca7b0855c66be0cd9cee7 Mon Sep 17 00:00:00 2001
From: Ben Kalman <kalman@users.noreply.github.com>
Date: Tue, 28 Jun 2016 10:03:00 -0700
Subject: [PATCH] Add set indexing for paths (#1922)

---
 go/types/path.go      | 20 ++++++++++++-----
 go/types/path_test.go | 52 ++++++++++++++++++++++++++-----------------
 2 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/go/types/path.go b/go/types/path.go
index 2cb9eca143..2f825eb296 100644
--- a/go/types/path.go
+++ b/go/types/path.go
@@ -180,22 +180,30 @@ func newHashIndexPart(h hash.Hash) hashIndexPart {
 }
 
 func (hip hashIndexPart) Resolve(v Value) (res Value) {
-	m, ok := v.(Map)
-	if !ok {
+	var seq orderedSequence
+	var getCurrentValue func(cur *sequenceCursor) Value
+
+	switch v := v.(type) {
+	case Set:
+		seq = v.seq
+		getCurrentValue = func(cur *sequenceCursor) Value { return cur.current().(Value) }
+	case Map:
+		seq = v.seq
+		getCurrentValue = func(cur *sequenceCursor) Value { return cur.current().(mapEntry).value }
+	default:
 		return nil
 	}
 
-	cur := newCursorAt(m.seq, orderedKeyFromHash(hip.h), false, false)
+	cur := newCursorAt(seq, orderedKeyFromHash(hip.h), false, false)
 	if !cur.valid() {
 		return nil
 	}
 
-	entry := cur.current().(mapEntry)
-	if entry.key.Hash() != hip.h {
+	if getCurrentKey(cur).h != hip.h {
 		return nil
 	}
 
-	return entry.value
+	return getCurrentValue(cur)
 }
 
 func (hip hashIndexPart) String() string {
diff --git a/go/types/path_test.go b/go/types/path_test.go
index 9eeffbd6d4..6a24946390 100644
--- a/go/types/path_test.go
+++ b/go/types/path_test.go
@@ -94,48 +94,60 @@ func TestPathHashIndex(t *testing.T) {
 	b := Bool(true)
 	br := NewRef(b)
 	i := Number(0)
-	s := String("foo")
-	l := NewList(b, i, s)
+	str := String("foo")
+	l := NewList(b, i, str)
 	lr := NewRef(l)
 	m := NewMap(
 		b, br,
 		br, i,
-		i, s,
+		i, str,
 		l, lr,
 		lr, b,
 	)
+	s := NewSet(b, br, i, str, l, lr)
 
 	hashStr := func(v Value) string {
 		return fmt.Sprintf("[#%s]", v.Hash())
 	}
 
+	resolvesTo := func(col, exp, val Value) {
+		assertPathResolvesTo(assert, exp, col, NewPath().AddHashIndex(val.Hash()))
+		assertPathStringResolvesTo(assert, exp, col, hashStr(val))
+	}
+
 	// Primitives are only addressable by their values.
-	assertPathResolvesTo(assert, nil, m, NewPath().AddHashIndex(b.Hash()))
-	assertPathStringResolvesTo(assert, nil, m, hashStr(b))
-	assertPathResolvesTo(assert, nil, m, NewPath().AddHashIndex(i.Hash()))
-	assertPathStringResolvesTo(assert, nil, m, hashStr(i))
-	assertPathResolvesTo(assert, nil, m, NewPath().AddHashIndex(s.Hash()))
-	assertPathStringResolvesTo(assert, nil, m, hashStr(s))
+	resolvesTo(m, nil, b)
+	resolvesTo(m, nil, i)
+	resolvesTo(m, nil, str)
+	resolvesTo(s, nil, b)
+	resolvesTo(s, nil, i)
+	resolvesTo(s, nil, str)
 
 	// Other values are only addressable by their hashes.
-	assertPathResolvesTo(assert, i, m, NewPath().AddHashIndex(br.Hash()))
-	assertPathStringResolvesTo(assert, i, m, hashStr(br))
-	assertPathResolvesTo(assert, lr, m, NewPath().AddHashIndex(l.Hash()))
-	assertPathStringResolvesTo(assert, lr, m, hashStr(l))
-	assertPathResolvesTo(assert, b, m, NewPath().AddHashIndex(lr.Hash()))
-	assertPathStringResolvesTo(assert, b, m, hashStr(lr))
+
+	resolvesTo(m, i, br)
+	resolvesTo(m, lr, l)
+	resolvesTo(m, b, lr)
+	resolvesTo(s, br, br)
+	resolvesTo(s, l, l)
+	resolvesTo(s, lr, lr)
 
 	// Lists cannot be addressed by hashes, obviously.
-	assertPathResolvesTo(assert, nil, l, NewPath().AddHashIndex(i.Hash()))
-	assertPathStringResolvesTo(assert, nil, l, hashStr(i))
+	resolvesTo(l, nil, i)
 }
 
-func TestPathHashIndexOfSingletonMap(t *testing.T) {
+func TestPathHashIndexOfSingletonCollection(t *testing.T) {
 	// This test is to make sure we don't accidentally return |b| if it's the only element.
 	assert := assert.New(t)
+
+	resolvesToNil := func(col, val Value) {
+		assertPathResolvesTo(assert, nil, col, NewPath().AddHashIndex(val.Hash()))
+		assertPathStringResolvesTo(assert, nil, col, fmt.Sprintf("[#%s]", val.Hash()))
+	}
+
 	b := Bool(true)
-	m := NewMap(b, b)
-	assertPathResolvesTo(assert, nil, m, NewPath().AddHashIndex(b.Hash()))
+	resolvesToNil(NewMap(b, b), b)
+	resolvesToNil(NewSet(b), b)
 }
 
 func TestPathMulti(t *testing.T) {