Merge pull request #25 from zclconf/jbardin/path-equals

implement Path.Equals and Path.HasPrefix
zclconf · Jul 8, 2019 · 19588f9 · 19588f9
2 parents 6fd39ad + 66e2eb3
commit 19588f9
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diff --git a/cty/path.go b/cty/path.go
@@ -71,6 +71,48 @@ func (p Path) GetAttr(name string) Path {
 	return ret
 }
 
+// Equals compares 2 Paths for exact equality.
+func (p Path) Equals(other Path) bool {
+	if len(p) != len(other) {
+		return false
+	}
+
+	for i := range p {
+		pv := p[i]
+		switch pv := pv.(type) {
+		case GetAttrStep:
+			ov, ok := other[i].(GetAttrStep)
+			if !ok || pv != ov {
+				return false
+			}
+		case IndexStep:
+			ov, ok := other[i].(IndexStep)
+			if !ok {
+				return false
+			}
+
+			if !pv.Key.RawEquals(ov.Key) {
+				return false
+			}
+		default:
+			// Any invalid steps default to evaluating false.
+			return false
+		}
+	}
+
+	return true
+
+}
+
+// HasPrefix determines if the path p contains the provided prefix.
+func (p Path) HasPrefix(prefix Path) bool {
+	if len(prefix) > len(p) {
+		return false
+	}
+
+	return p[:len(prefix)].Equals(prefix)
+}
+
 // GetAttrPath is a convenience method to start a new Path with a GetAttrStep.
 func GetAttrPath(name string) Path {
 	return Path{}.GetAttr(name)

diff --git a/cty/path_test.go b/cty/path_test.go
@@ -123,3 +123,135 @@ func TestPathApply(t *testing.T) {
 		})
 	}
 }
+
+func TestPathEquals(t *testing.T) {
+	tests := []struct {
+		A, B   cty.Path
+		Equal  bool
+		Prefix bool
+	}{
+		{
+			A:      nil,
+			B:      nil,
+			Equal:  true,
+			Prefix: true,
+		},
+		{
+			A:      cty.Path{},
+			B:      cty.Path{},
+			Equal:  true,
+			Prefix: true,
+		},
+		{
+			A: cty.Path{nil},
+			B: cty.Path{cty.GetAttrStep{Name: "attr"}},
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.UnknownVal(cty.String)},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("key")},
+				cty.GetAttrStep{Name: "attr"},
+			},
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.ListVal([]cty.Value{cty.UnknownVal(cty.String)})},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.ListVal([]cty.Value{cty.StringVal("known")})},
+				cty.GetAttrStep{Name: "attr"},
+			},
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.UnknownVal(cty.String)},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("known")},
+				cty.GetAttrStep{Name: "attr"},
+			},
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("known")},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("known")},
+				cty.GetAttrStep{Name: "attr"},
+			},
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("known")},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.StringVal("known")},
+			},
+			Prefix: true,
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.UnknownVal(cty.String)},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.UnknownVal(cty.String)},
+			},
+			Prefix: true,
+			Equal:  true,
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.NumberFloatVal(0)},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.NumberIntVal(0)},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			Equal:  true,
+			Prefix: true,
+		},
+		{
+			A: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.NumberIntVal(1)},
+				cty.GetAttrStep{Name: "attr"},
+			},
+			B: cty.Path{
+				cty.GetAttrStep{Name: "attr"},
+				cty.IndexStep{Key: cty.NumberIntVal(0)},
+				cty.GetAttrStep{Name: "attr"},
+			},
+		},
+	}
+
+	for i, test := range tests {
+		t.Run(fmt.Sprintf("%d-%#v", i, test.A), func(t *testing.T) {
+			if test.Equal != test.A.Equals(test.B) {
+				t.Fatalf("%#v.Equals(%#v) != %t", test.A, test.B, test.Equal)
+			}
+			if test.Prefix != test.A.HasPrefix(test.B) {
+				t.Fatalf("%#v.HasPrefix(%#v) != %t", test.A, test.B, test.Prefix)
+			}
+		})
+	}
+}