Share entity base classes between CIL and source extraction

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CIL/Entities/Assembly.cs

@@ -40,6 +40,7 @@ public override void WriteId(TextWriter trapFile)
             trapFile.Write(FullName);
             trapFile.Write("#file:///");
             trapFile.Write(Cx.AssemblyPath.Replace("\\", "/"));
+            trapFile.Write(";assembly");
         }
 
         public override bool Equals(object? obj)
@@ -49,8 +50,6 @@ public override bool Equals(object? obj)
 
         public override int GetHashCode() => 7 * file.GetHashCode();
 
-        public override string IdSuffix => ";assembly";
-
         private string FullName => assemblyName.GetPublicKey() is null ? assemblyName.FullName + ", PublicKeyToken=null" : assemblyName.FullName;
 
         public override IEnumerable<IExtractionProduct> Contents

csharp/extractor/Semmle.Extraction.CIL/Entities/Attribute.cs

@@ -12,9 +12,9 @@ internal sealed class Attribute : UnlabelledEntity
     {
         private readonly CustomAttributeHandle handle;
         private readonly CustomAttribute attrib;
-        private readonly IEntity @object;
+        private readonly IExtractedEntity @object;
 
-        public Attribute(Context cx, IEntity @object, CustomAttributeHandle handle) : base(cx)
+        public Attribute(Context cx, IExtractedEntity @object, CustomAttributeHandle handle) : base(cx)
         {
             attrib = cx.MdReader.GetCustomAttribute(handle);
             this.handle = handle;
@@ -80,7 +80,7 @@ private static string GetStringValue(Type type, object? value)
             return value?.ToString() ?? "null";
         }
 
-        public static IEnumerable<IExtractionProduct> Populate(Context cx, IEntity @object, CustomAttributeHandleCollection attributes)
+        public static IEnumerable<IExtractionProduct> Populate(Context cx, IExtractedEntity @object, CustomAttributeHandleCollection attributes)
         {
             foreach (var attrib in attributes)
             {

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/IExtractedEntity.cs

@@ -0,0 +1,16 @@
+using System.Collections.Generic;
+
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// A CIL entity which has been extracted.
+    /// </summary>
+    public interface IExtractedEntity : IExtractionProduct, IEntity
+    {
+        /// <summary>
+        /// The contents of the entity.
+        /// </summary>
+
+        IEnumerable<IExtractionProduct> Contents { get; }
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/IExtractionProduct.cs

@@ -0,0 +1,24 @@
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// Something that is extracted from an entity.
+    /// </summary>
+    ///
+    /// <remarks>
+    /// The extraction algorithm proceeds as follows:
+    /// - Construct entity
+    /// - Call Extract()
+    /// - IExtractedEntity check if already extracted
+    /// - Enumerate Contents to produce more extraction products
+    /// - Extract these until there is nothing left to extract
+    /// </remarks>
+    public interface IExtractionProduct
+    {
+        /// <summary>
+        /// Perform further extraction/population of this item as necessary.
+        /// </summary>
+        ///
+        /// <param name="cx">The extraction context.</param>
+        void Extract(Context cx);
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/IGenericContext.cs renamed to csharp/extractor/Semmle.Extraction.CIL/Entities/Base/IGenericContext.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// An entity that needs to be populated during extraction.
+    /// This assigns a key and optionally extracts its contents.
+    /// </summary>
+    public abstract class LabelledEntity : Extraction.LabelledEntity, IExtractedEntity
+    {
+        // todo: with .NET 5 this can override the base context, and change the return type.
+        public Context Cx { get; }
+
+        protected LabelledEntity(Context cx) : base(cx.Cx)
+        {
+            this.Cx = cx;
+        }
+
+        public override Microsoft.CodeAnalysis.Location ReportingLocation => throw new NotImplementedException();
+
+        public void Extract(Context cx2)
+        {
+            cx2.Populate(this);
+        }
+
+        public override string ToString()
+        {
+            using var writer = new StringWriter();
+            WriteQuotedId(writer);
+            return writer.ToString();
+        }
+
+        public override TrapStackBehaviour TrapStackBehaviour => TrapStackBehaviour.NoLabel;
+
+        public abstract IEnumerable<IExtractionProduct> Contents { get; }
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/LabelledEntity.cs

@@ -0,0 +1,22 @@
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// A tuple that is an extraction product.
+    /// </summary>
+    internal class Tuple : IExtractionProduct
+    {
+        private readonly Extraction.Tuple tuple;
+
+        public Tuple(string name, params object[] args)
+        {
+            tuple = new Extraction.Tuple(name, args);
+        }
+
+        public void Extract(Context cx)
+        {
+            cx.Cx.Emit(tuple);
+        }
+
+        public override string ToString() => tuple.ToString();
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/Tuple.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+
+namespace Semmle.Extraction.CIL
+{
+    /// <summary>
+    /// An entity that has contents to extract. There is no need to populate
+    /// a key as it's done in the contructor.
+    /// </summary>
+    public abstract class UnlabelledEntity : Extraction.UnlabelledEntity, IExtractedEntity
+    {
+        // todo: with .NET 5 this can override the base context, and change the return type.
+        public Context Cx { get; }
+
+        protected UnlabelledEntity(Context cx) : base(cx.Cx)
+        {
+            Cx = cx;
+        }
+
+        public override Microsoft.CodeAnalysis.Location ReportingLocation => throw new NotImplementedException();
+
+        public void Extract(Context cx2)
+        {
+            cx2.Extract(this);
+        }
+
+        public override TrapStackBehaviour TrapStackBehaviour => TrapStackBehaviour.NoLabel;
+
+        public abstract IEnumerable<IExtractionProduct> Contents { get; }
+    }
+}

csharp/extractor/Semmle.Extraction.CIL/Entities/Base/UnlabelledEntity.cs

@@ -25,10 +25,9 @@ public override void WriteId(TextWriter trapFile)
             parent.WriteId(trapFile);
             trapFile.Write('.');
             trapFile.Write(Cx.ShortName(ed.Name));
+            trapFile.Write(";cil-event");
         }
 
-        public override string IdSuffix => ";cil-event";
-
         public override bool Equals(object? obj)
         {
             return obj is Event e && handle.Equals(e.handle);

csharp/extractor/Semmle.Extraction.CIL/Entities/Event.cs

@@ -8,41 +8,27 @@ namespace Semmle.Extraction.CIL.Entities
     /// <summary>
     /// An entity representing a field.
     /// </summary>
-    internal abstract class Field : IGenericContext, IMember, ICustomModifierReceiver
+    internal abstract class Field : LabelledEntity, IGenericContext, IMember, ICustomModifierReceiver
     {
-        protected Field(Context cx)
+        protected Field(Context cx) : base(cx)
         {
-            Cx = cx;
         }
 
-        public Label Label { get; set; }
-
-        public void WriteId(TextWriter trapFile)
+        public override void WriteId(TextWriter trapFile)
         {
             trapFile.WriteSubId(DeclaringType);
             trapFile.Write('.');
             trapFile.Write(Name);
+            trapFile.Write(";cil-field");
         }
 
-        public void WriteQuotedId(TextWriter trapFile)
-        {
-            trapFile.Write("@\"");
-            WriteId(trapFile);
-            trapFile.Write(idSuffix);
-            trapFile.Write('\"');
-        }
-
-        private const string idSuffix = ";cil-field";
-
         public abstract string Name { get; }
 
         public abstract Type DeclaringType { get; }
 
-        public Location ReportingLocation => throw new NotImplementedException();
-
         public abstract Type Type { get; }
 
-        public virtual IEnumerable<IExtractionProduct> Contents
+        public override IEnumerable<IExtractionProduct> Contents
         {
             get
             {
@@ -56,17 +42,8 @@ public virtual IEnumerable<IExtractionProduct> Contents
             }
         }
 
-        public void Extract(Context cx2)
-        {
-            cx2.Populate(this);
-        }
-
-        public TrapStackBehaviour TrapStackBehaviour => TrapStackBehaviour.NoLabel;
-
         public abstract IEnumerable<Type> TypeParameters { get; }
 
         public abstract IEnumerable<Type> MethodParameters { get; }
-
-        public Context Cx { get; }
     }
 }