compliance package structures for license metadata

package to read, consume, and analyze license metadata and dependency
graph.

Bug: 68860345
Bug: 151177513
Bug: 151953481
Change-Id: I3ebf44e4d5195b9851fd076161049bf82ed76dd2

tools/compliance/condition.go

@@ -0,0 +1,156 @@
+// Copyright 2021 Google LLC
+//
+// 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 compliance
+
+import (
+	"fmt"
+	"strings"
+)
+
+// LicenseCondition describes an individual license condition or requirement
+// originating at a specific target node. (immutable)
+//
+// e.g. A module licensed under GPL terms would originate a `restricted` condition.
+type LicenseCondition struct {
+	name   string
+	origin *TargetNode
+}
+
+// Name returns the name of the condition. e.g. "restricted" or "notice"
+func (lc LicenseCondition) Name() string {
+	return lc.name
+}
+
+// Origin identifies the TargetNode where the condition originates.
+func (lc LicenseCondition) Origin() *TargetNode {
+	return lc.origin
+}
+
+// asString returns a string representation of a license condition:
+// origin+separator+condition.
+func (lc LicenseCondition) asString(separator string) string {
+	return lc.origin.name + separator + lc.name
+}
+
+// ConditionList implements introspection methods to arrays of LicenseCondition.
+type ConditionList []LicenseCondition
+
+
+// ConditionList orders arrays of LicenseCondition by Origin and Name.
+
+// Len returns the length of the list.
+func (l ConditionList) Len() int      { return len(l) }
+
+// Swap rearranges 2 elements in the list so each occupies the other's former position.
+func (l ConditionList) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
+
+// Less returns true when the `i`th element is lexicographically less than tht `j`th element.
+func (l ConditionList) Less(i, j int) bool {
+	if l[i].origin.name == l[j].origin.name {
+		return l[i].name < l[j].name
+	}
+	return l[i].origin.name < l[j].origin.name
+}
+
+// String returns a string representation of the set.
+func (cl ConditionList) String() string {
+	var sb strings.Builder
+	fmt.Fprintf(&sb, "[")
+	sep := ""
+	for _, lc := range cl {
+		fmt.Fprintf(&sb, "%s%s:%s", sep, lc.origin.name, lc.name)
+		sep = ", "
+	}
+	fmt.Fprintf(&sb, "]")
+	return sb.String()
+}
+
+// HasByName returns true if the list contains any condition matching `name`.
+func (cl ConditionList) HasByName(name ConditionNames) bool {
+	for _, lc := range cl {
+		if name.Contains(lc.name) {
+			return true
+		}
+	}
+	return false
+}
+
+// ByName returns the sublist of conditions that match `name`.
+func (cl ConditionList) ByName(name ConditionNames) ConditionList {
+	result := make(ConditionList, 0, cl.CountByName(name))
+	for _, lc := range cl {
+		if name.Contains(lc.name) {
+			result = append(result, lc)
+		}
+	}
+	return result
+}
+
+// CountByName returns the size of the sublist of conditions that match `name`.
+func (cl ConditionList) CountByName(name ConditionNames) int {
+	size := 0
+	for _, lc := range cl {
+		if name.Contains(lc.name) {
+			size++
+		}
+	}
+	return size
+}
+
+// HasByOrigin returns true if the list contains any condition originating at `origin`.
+func (cl ConditionList) HasByOrigin(origin *TargetNode) bool {
+	for _, lc := range cl {
+		if lc.origin.name == origin.name {
+			return true
+		}
+	}
+	return false
+}
+
+// ByOrigin returns the sublist of conditions that originate at `origin`.
+func (cl ConditionList) ByOrigin(origin *TargetNode) ConditionList {
+	result := make(ConditionList, 0, cl.CountByOrigin(origin))
+	for _, lc := range cl {
+		if lc.origin.name == origin.name {
+			result = append(result, lc)
+		}
+	}
+	return result
+}
+
+// CountByOrigin returns the size of the sublist of conditions that originate at `origin`.
+func (cl ConditionList) CountByOrigin(origin *TargetNode) int {
+	size := 0
+	for _, lc := range cl {
+		if lc.origin.name == origin.name {
+			size++
+		}
+	}
+	return size
+}
+
+// ConditionNames implements the Contains predicate for slices of condition
+// name strings.
+type ConditionNames []string
+
+// Contains returns true if the name matches one of the ConditionNames.
+func (cn ConditionNames) Contains(name string) bool {
+	for _, cname := range cn {
+		if cname == name {
+			return true
+		}
+	}
+	return false
+}