Add inferred runtime identifiers

src/Microsoft.DotNet.Build.Tasks.Packaging/src/Microsoft.DotNet.Build.Tasks.Packaging.csproj

@@ -48,6 +48,10 @@
     <BeforePack>$(BeforePack);AddRuntimeJson</BeforePack>
   </PropertyGroup>
 
+  <ItemGroup>
+    <InternalsVisibleTo Include="Microsoft.DotNet.Build.Tasks.Packaging.Tests" />
+  </ItemGroup>
+
   <ItemGroup>
     <!-- nuget pack needs an actual empty file to use for placeholders for empty directories
          so we must provide one.

src/Microsoft.DotNet.Build.Tasks.Packaging/src/RID.cs

@@ -0,0 +1,204 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics;
+using System.Text;
+
+namespace Microsoft.DotNet.Build.Tasks.Packaging
+{
+    internal class RID
+    {
+        internal const char VersionDelimiter = '.';
+        internal const char ArchitectureDelimiter = '-';
+        internal const char QualifierDelimiter = '-';
+
+        public string BaseRID { get; set; }
+        public bool OmitVersionDelimiter { get; set; }
+        public RuntimeVersion Version { get; set; }
+        public string Architecture { get; set; }
+        public string Qualifier { get; set; }
+
+        public override string ToString()
+        {
+            StringBuilder builder = new StringBuilder(BaseRID);
+
+            if (HasVersion)
+            {
+                if (!OmitVersionDelimiter)
+                {
+                    builder.Append(VersionDelimiter);
+                }
+                builder.Append(Version);
+            }
+
+            if (HasArchitecture)
+            {
+                builder.Append(ArchitectureDelimiter);
+                builder.Append(Architecture);
+            }
+
+            if (HasQualifier)
+            {
+                builder.Append(QualifierDelimiter);
+                builder.Append(Qualifier);
+            }
+
+            return builder.ToString();
+        }
+
+
+        enum RIDPart : int
+        {
+            Base = 0,
+            Version,
+            Architcture,
+            Qualifier,
+            Max = Qualifier
+        }
+
+        public static RID Parse(string runtimeIdentifier)
+        {
+            string[] parts = new string[(int)RIDPart.Max + 1];
+            bool omitVersionDelimiter = true;
+            RIDPart parseState = RIDPart.Base;
+
+            int partStart = 0, partLength = 0;
+
+            // qualifier is indistinguishable from arch so we cannot distinguish it for parsing purposes
+            Debug.Assert(ArchitectureDelimiter == QualifierDelimiter);
+
+            for (int i = 0; i < runtimeIdentifier.Length; i++)
+            {
+                char current = runtimeIdentifier[i];
+                partLength = i - partStart;
+
+                switch (parseState)
+                {
+                    case RIDPart.Base:
+                        // treat any number as the start of the version
+                        if (current == VersionDelimiter || (current >= '0' && current <= '9'))
+                        {
+                            SetPart();
+                            partStart = i;
+                            if (current == VersionDelimiter)
+                            {
+                                omitVersionDelimiter = false;
+                                partStart = i + 1;
+                            }
+                            parseState = RIDPart.Version;
+                        }
+                        // version might be omitted
+                        else if (current == ArchitectureDelimiter)
+                        {
+                            // ensure there's no version later in the string
+                            if (-1 != runtimeIdentifier.IndexOf(VersionDelimiter, i))
+                            {
+                                break;
+                            }
+                            SetPart();
+                            partStart = i + 1;  // skip delimiter
+                            parseState = RIDPart.Architcture;
+                        }
+                        break;
+                    case RIDPart.Version:
+                        if (current == ArchitectureDelimiter)
+                        {
+                            SetPart();
+                            partStart = i + 1;  // skip delimiter
+                            parseState = RIDPart.Architcture;
+                        }
+                        break;
+                    case RIDPart.Architcture:
+                        if (current == QualifierDelimiter)
+                        {
+                            SetPart();
+                            partStart = i + 1;  // skip delimiter
+                            parseState = RIDPart.Qualifier;
+                        }
+                        break;
+                    default:
+                        break;
+                }
+            }
+
+            partLength = runtimeIdentifier.Length - partStart;
+            if (partLength > 0)
+            {
+                SetPart();
+            }
+
+            string GetPart(RIDPart part)
+            {
+                return parts[(int)part];
+            }
+
+            void SetPart()
+            {
+                if (partLength == 0)
+                {
+                    throw new ArgumentException($"unexpected delimiter at position {partStart} in {runtimeIdentifier}");
+                }
+
+                parts[(int)parseState] = runtimeIdentifier.Substring(partStart, partLength);
+            }
+
+            string version = GetPart(RIDPart.Version);
+
+            if (version == null)
+            {
+                omitVersionDelimiter = false;
+            }
+
+            return new RID()
+            {
+                BaseRID = GetPart(RIDPart.Base),
+                OmitVersionDelimiter = omitVersionDelimiter,
+                Version = version == null ? null : new RuntimeVersion(version),
+                Architecture = GetPart(RIDPart.Architcture),
+                Qualifier = GetPart(RIDPart.Qualifier)
+            };
+        }
+
+
+        public bool HasVersion => Version != null;
+
+        public bool HasArchitecture => Architecture != null;
+
+        public bool HasQualifier => Qualifier != null;
+
+        public override bool Equals(object obj)
+        {
+            return Equals(obj as RID);
+        }
+
+        public bool Equals(RID obj)
+        {
+            return object.ReferenceEquals(obj, this) ||
+                (!(obj is null) &&
+                BaseRID == obj.BaseRID &&
+                OmitVersionDelimiter == obj.OmitVersionDelimiter &&
+                Version == obj.Version &&
+                Architecture == obj.Architecture &&
+                Qualifier == obj.Qualifier);
+
+        }
+
+        public override int GetHashCode()
+        {
+#if NETFRAMEWORK
+            return BaseRID.GetHashCode();
+#else
+            HashCode hashCode = new HashCode();
+            hashCode.Add(BaseRID);
+            hashCode.Add(VersionDelimiter);
+            hashCode.Add(Version);
+            hashCode.Add(ArchitectureDelimiter);
+            hashCode.Add(Architecture);
+            hashCode.Add(QualifierDelimiter);
+            hashCode.Add(Qualifier);
+            return hashCode.ToHashCode();
+#endif
+        }
+    }
+}