1 files changed, 149 insertions, 0 deletions
diff --git a/pkg/v1/platform.go b/pkg/v1/platform.go
new file mode 100644
index 0000000..59ca402
--- /dev/null
+++ b/pkg/v1/platform.go
@@ -0,0 +1,149 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// 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 v1
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+// Platform represents the target os/arch for an image.
+type Platform struct {
+	Architecture string   `json:"architecture"`
+	OS           string   `json:"os"`
+	OSVersion    string   `json:"os.version,omitempty"`
+	OSFeatures   []string `json:"os.features,omitempty"`
+	Variant      string   `json:"variant,omitempty"`
+	Features     []string `json:"features,omitempty"`
+}
+
+func (p Platform) String() string {
+	if p.OS == "" {
+		return ""
+	}
+	var b strings.Builder
+	b.WriteString(p.OS)
+	if p.Architecture != "" {
+		b.WriteString("/")
+		b.WriteString(p.Architecture)
+	}
+	if p.Variant != "" {
+		b.WriteString("/")
+		b.WriteString(p.Variant)
+	}
+	if p.OSVersion != "" {
+		b.WriteString(":")
+		b.WriteString(p.OSVersion)
+	}
+	return b.String()
+}
+
+// ParsePlatform parses a string representing a Platform, if possible.
+func ParsePlatform(s string) (*Platform, error) {
+	var p Platform
+	parts := strings.Split(strings.TrimSpace(s), ":")
+	if len(parts) == 2 {
+		p.OSVersion = parts[1]
+	}
+	parts = strings.Split(parts[0], "/")
+	if len(parts) > 0 {
+		p.OS = parts[0]
+	}
+	if len(parts) > 1 {
+		p.Architecture = parts[1]
+	}
+	if len(parts) > 2 {
+		p.Variant = parts[2]
+	}
+	if len(parts) > 3 {
+		return nil, fmt.Errorf("too many slashes in platform spec: %s", s)
+	}
+	return &p, nil
+}
+
+// Equals returns true if the given platform is semantically equivalent to this one.
+// The order of Features and OSFeatures is not important.
+func (p Platform) Equals(o Platform) bool {
+	return p.OS == o.OS &&
+		p.Architecture == o.Architecture &&
+		p.Variant == o.Variant &&
+		p.OSVersion == o.OSVersion &&
+		stringSliceEqualIgnoreOrder(p.OSFeatures, o.OSFeatures) &&
+		stringSliceEqualIgnoreOrder(p.Features, o.Features)
+}
+
+// Satisfies returns true if this Platform "satisfies" the given spec Platform.
+//
+// Note that this is different from Equals and that Satisfies is not reflexive.
+//
+// The given spec represents "requirements" such that any missing values in the
+// spec are not compared.
+//
+// For OSFeatures and Features, Satisfies will return true if this Platform's
+// fields contain a superset of the values in the spec's fields (order ignored).
+func (p Platform) Satisfies(spec Platform) bool {
+	return satisfies(spec.OS, p.OS) &&
+		satisfies(spec.Architecture, p.Architecture) &&
+		satisfies(spec.Variant, p.Variant) &&
+		satisfies(spec.OSVersion, p.OSVersion) &&
+		satisfiesList(spec.OSFeatures, p.OSFeatures) &&
+		satisfiesList(spec.Features, p.Features)
+}
+
+func satisfies(want, have string) bool {
+	return want == "" || want == have
+}
+
+func satisfiesList(want, have []string) bool {
+	if len(want) == 0 {
+		return true
+	}
+
+	set := map[string]struct{}{}
+	for _, h := range have {
+		set[h] = struct{}{}
+	}
+
+	for _, w := range want {
+		if _, ok := set[w]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
+// stringSliceEqual compares 2 string slices and returns if their contents are identical.
+func stringSliceEqual(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i, elm := range a {
+		if elm != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// stringSliceEqualIgnoreOrder compares 2 string slices and returns if their contents are identical, ignoring order
+func stringSliceEqualIgnoreOrder(a, b []string) bool {
+	if a != nil && b != nil {
+		sort.Strings(a)
+		sort.Strings(b)
+	}
+	return stringSliceEqual(a, b)
+}