Added base for autoprops

.gitignore

@@ -1,4 +1,5 @@
 .vs
+.idea
 bin
 obj
 src/artifacts

src/Draco.Compiler/Internal/Symbols/Syntax/SyntaxAutoPropertySymbol.cs

@@ -0,0 +1,38 @@
+using System;
+using Draco.Compiler.Api.Semantics;
+using Draco.Compiler.Api.Syntax;
+using Draco.Compiler.Internal.Binding;
+using Draco.Compiler.Internal.Documentation;
+using Draco.Compiler.Internal.Documentation.Extractors;
+using Draco.Compiler.Internal.Symbols.Source;
+
+namespace Draco.Compiler.Internal.Symbols.Syntax;
+
+/// <summary>
+/// The base for auto-properties defined based on some syntax.
+/// </summary>
+internal abstract class SyntaxAutoPropertySymbol : PropertySymbol, ISourceSymbol
+{
+    public override Symbol ContainingSymbol { get; }
+    public override VariableDeclarationSyntax DeclaringSyntax { get; }
+
+    public override string Name => this.DeclaringSyntax.Name.Text;
+
+    public override Visibility Visibility =>
+        GetVisibilityFromTokenKind(this.DeclaringSyntax.VisibilityModifier?.Kind);
+
+    internal override string RawDocumentation => this.DeclaringSyntax.Documentation;
+
+    protected SyntaxAutoPropertySymbol(Symbol containingSymbol, VariableDeclarationSyntax syntax)
+    {
+        if (syntax.FieldModifier is not null) throw new ArgumentException("a property must not have the field modifier", nameof(syntax));
+
+        this.ContainingSymbol = containingSymbol;
+        this.DeclaringSyntax = syntax;
+    }
+
+    public abstract void Bind(IBinderProvider binderProvider);
+
+    private SymbolDocumentation BuildDocumentation() =>
+        MarkdownDocumentationExtractor.Extract(this);
+}