1 files changed, 93 insertions, 0 deletions
diff --git a/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs b/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs
new file mode 100644
index 00000000..68b5001e
--- /dev/null
+++ b/src/SMAPI.ModBuildConfig.Analyzer/AnalyzerUtilities.cs
@@ -0,0 +1,93 @@
+using System.Collections.Generic;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace StardewModdingAPI.ModBuildConfig.Analyzer
+{
+    /// <summary>Provides generic utilities for SMAPI's Roslyn analyzers.</summary>
+    internal static class AnalyzerUtilities
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Get the metadata for an explicit cast or 'x as y' expression.</summary>
+        /// <param name="node">The member access expression.</param>
+        /// <param name="semanticModel">provides methods for asking semantic questions about syntax nodes.</param>
+        /// <param name="fromExpression">The expression whose value is being converted.</param>
+        /// <param name="fromType">The type being converted from.</param>
+        /// <param name="toType">The type being converted to.</param>
+        /// <returns>Returns true if the node is a matched expression, else false.</returns>
+        public static bool TryGetCastOrAsInfo(SyntaxNode node, SemanticModel semanticModel, out ExpressionSyntax fromExpression, out TypeInfo fromType, out TypeInfo toType)
+        {
+            // (type)x
+            if (node is CastExpressionSyntax cast)
+            {
+                fromExpression = cast.Expression;
+                fromType = semanticModel.GetTypeInfo(fromExpression);
+                toType = semanticModel.GetTypeInfo(cast.Type);
+                return true;
+            }
+
+            // x as y
+            if (node is BinaryExpressionSyntax binary && binary.Kind() == SyntaxKind.AsExpression)
+            {
+                fromExpression = binary.Left;
+                fromType = semanticModel.GetTypeInfo(fromExpression);
+                toType = semanticModel.GetTypeInfo(binary.Right);
+                return true;
+            }
+
+            // invalid
+            fromExpression = null;
+            fromType = default(TypeInfo);
+            toType = default(TypeInfo);
+            return false;
+        }
+
+        /// <summary>Get the metadata for a member access expression.</summary>
+        /// <param name="node">The member access expression.</param>
+        /// <param name="semanticModel">provides methods for asking semantic questions about syntax nodes.</param>
+        /// <param name="declaringType">The object type which has the member.</param>
+        /// <param name="memberType">The type of the accessed member.</param>
+        /// <param name="memberName">The name of the accessed member.</param>
+        /// <returns>Returns true if the node is a member access expression, else false.</returns>
+        public static bool TryGetMemberInfo(SyntaxNode node, SemanticModel semanticModel, out ITypeSymbol declaringType, out TypeInfo memberType, out string memberName)
+        {
+            // simple access
+            if (node is MemberAccessExpressionSyntax memberAccess)
+            {
+                declaringType = semanticModel.GetTypeInfo(memberAccess.Expression).Type;
+                memberType = semanticModel.GetTypeInfo(node);
+                memberName = memberAccess.Name.Identifier.Text;
+                return true;
+            }
+
+            // conditional access
+            if (node is ConditionalAccessExpressionSyntax conditionalAccess && conditionalAccess.WhenNotNull is MemberBindingExpressionSyntax conditionalBinding)
+            {
+                declaringType = semanticModel.GetTypeInfo(conditionalAccess.Expression).Type;
+                memberType = semanticModel.GetTypeInfo(node);
+                memberName = conditionalBinding.Name.Identifier.Text;
+                return true;
+            }
+
+            // invalid
+            declaringType = null;
+            memberType = default(TypeInfo);
+            memberName = null;
+            return false;
+        }
+
+        /// <summary>Get the class types in a type's inheritance chain, including itself.</summary>
+        /// <param name="type">The initial type.</param>
+        public static IEnumerable<ITypeSymbol> GetConcreteTypes(ITypeSymbol type)
+        {
+            while (type != null)
+            {
+                yield return type;
+                type = type.BaseType;
+            }
+        }
+    }
+}