Added special handling for types and members starting with underscores and numbers

Author: PawelGerr

src/Thinktecture.Runtime.Extensions.SourceGenerator/CodeAnalysis/AdHocUnions/AdHocUnionCodeGenerator.cs

@@ -224,7 +224,7 @@ private void GenerateToString()
          var memberType = _state.MemberTypes[i];
 
          _sb.Append(@"
-            ").Append(i + 1).Append(" => this._").Append(memberType.BackingFieldName);
+            ").Append(i + 1).Append(" => this.").Append(memberType.BackingFieldName);
 
          if (memberType.SpecialType != SpecialType.System_String)
          {
@@ -266,7 +266,7 @@ public override int GetHashCode()
          _sb.Append(@"
             ").Append(i + 1).Append(" => ");
 
-         _sb.Append("global::System.HashCode.Combine(").AppendTypeFullyQualified(_state).Append("._typeHashCode, this._").Append(memberType.BackingFieldName);
+         _sb.Append("global::System.HashCode.Combine(").AppendTypeFullyQualified(_state).Append("._typeHashCode, this.").Append(memberType.BackingFieldName);
 
          if (memberType.IsReferenceType)
             _sb.Append("?");
@@ -348,9 +348,9 @@ public bool Equals(").AppendTypeFullyQualifiedNullAnnotated(_state).Append(@" ot
             ").Append(i + 1).Append(" => ");
 
          if (memberType.IsReferenceType)
-            _sb.Append("this._").Append(memberType.BackingFieldName).Append(" is null ? other._").Append(memberType.BackingFieldName).Append(" is null : ");
+            _sb.Append("this.").Append(memberType.BackingFieldName).Append(" is null ? other.").Append(memberType.BackingFieldName).Append(" is null : ");
 
-         _sb.Append("this._").Append(memberType.BackingFieldName).Append(".Equals(other._").Append(memberType.BackingFieldName);
+         _sb.Append("this.").Append(memberType.BackingFieldName).Append(".Equals(other.").Append(memberType.BackingFieldName);
 
          if (memberType.SpecialType == SpecialType.System_String)
             _sb.Append(", global::System.StringComparison.").Append(Enum.GetName(typeof(StringComparison), _state.Settings.DefaultStringComparison));
@@ -500,7 +500,7 @@ private void GenerateIndexBasedActionSwitchBody(bool withState, bool isPartially
          if (withState)
             _sb.Append("state, ");
 
-         _sb.Append("this._").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && memberType.NullableAnnotation != NullableAnnotation.Annotated ? "!" : null).Append(@");
+         _sb.Append("this.").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && memberType.NullableAnnotation != NullableAnnotation.Annotated ? "!" : null).Append(@");
                return;");
       }
 
@@ -661,7 +661,7 @@ private void GenerateIndexBasedFuncSwitchBody(bool withState, bool isPartially)
          if (withState)
             _sb.Append("state, ");
 
-         _sb.Append("this._").Append(memberType.BackingFieldName).Append(memberType is { IsReferenceType: true, Setting.IsNullableReferenceType: false } ? "!" : null).Append(");");
+         _sb.Append("this.").Append(memberType.BackingFieldName).Append(memberType is { IsReferenceType: true, Setting.IsNullableReferenceType: false } ? "!" : null).Append(");");
       }
 
       _sb.Append(@"
@@ -844,7 +844,7 @@ private void GenerateConstructors()
 
          _sb.Append(@")
       {
-         this._").Append(memberType.BackingFieldName).Append(" = ").AppendEscaped(argName).Append(@";
+         this.").Append(memberType.BackingFieldName).Append(" = ").AppendEscaped(argName).Append(@";
          this._valueIndex = ");
 
          if (hasDuplicates)
@@ -896,7 +896,7 @@ private void GenerateMemberTypeFieldsAndProps()
             continue;
 
          _sb.Append(@"
-      private readonly ").AppendTypeFullyQualifiedNullAnnotated(memberType).Append(" _").Append(memberType.BackingFieldName).Append(";");
+      private readonly ").AppendTypeFullyQualifiedNullAnnotated(memberType).Append(" ").Append(memberType.BackingFieldName).Append(";");
       }
 
       for (var i = 0; i < _state.MemberTypes.Count; i++)
@@ -920,7 +920,7 @@ private void GenerateMemberTypeFieldsAndProps()
       /// </summary>
       /// <exception cref=""global::System.InvalidOperationException"">If the current value is not of type ").AppendTypeForXmlComment(memberType).Append(@".</exception>
       public ").AppendTypeFullyQualified(memberType).Append(" As").Append(memberType.Name).Append(" => Is").Append(memberType.Name)
-            .Append(" ? this._").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && memberType.NullableAnnotation != NullableAnnotation.Annotated ? "!" : null)
+            .Append(" ? this.").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && memberType.NullableAnnotation != NullableAnnotation.Annotated ? "!" : null)
             .Append(" : throw new global::System.InvalidOperationException($\"'{nameof(").AppendTypeFullyQualified(_state).Append(")}' is not of type '").AppendTypeMinimallyQualified(memberType).Append("'.\");");
       }
    }
@@ -956,7 +956,7 @@ private void GenerateRawValueGetter()
          var memberType = _state.MemberTypes[i];
 
          _sb.Append(@"
-         ").Append(i + 1).Append(" => this._").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && !hasNullableTypes ? "!" : null).Append(",");
+         ").Append(i + 1).Append(" => this.").Append(memberType.BackingFieldName).Append(memberType.IsReferenceType && !hasNullableTypes ? "!" : null).Append(",");
       }
 
       _sb.Append(@"

src/Thinktecture.Runtime.Extensions.SourceGenerator/CodeAnalysis/AdHocUnions/AdHocUnionMemberTypeState.cs

@@ -25,7 +25,10 @@ public AdHocUnionMemberTypeState(
    {
       Name = name;
       ArgumentName = Name.MakeArgumentName();
-      BackingFieldName = typeDuplicateCounter == 0 ? ArgumentName : defaultName.MakeArgumentName();
+
+      var backingFieldName = (typeDuplicateCounter == 0 ? Name : defaultName).MakeBackingFieldName();
+      BackingFieldName = backingFieldName == Name ? $"_{backingFieldName}" : backingFieldName;
+
       TypeDuplicateCounter = typeDuplicateCounter;
       TypeFullyQualified = typeState.TypeFullyQualified;
       TypeMinimallyQualified = typeState.TypeMinimallyQualified;

src/Thinktecture.Runtime.Extensions.SourceGenerator/Extensions/ContainingTypesExtensions.cs

@@ -23,9 +23,9 @@ public static string MakeFullyQualifiedArgumentName(
 
       var firstChar = sb[sbLength];
 
-      sb[sbLength] = firstChar == '_'
-                        ? Char.ToLowerInvariant(sb[sbLength + 1])
-                        : Char.ToLowerInvariant(firstChar);
+      sb[sbLength] = firstChar != '_' || (sb.Length > sbLength && Char.IsDigit(sb[sbLength + 1]))
+                        ? Char.ToLowerInvariant(firstChar)
+                        : Char.ToLowerInvariant(sb[sbLength + 1]);
 
       var argName = sb.ToString(sbLength, sb.Length - sbLength);
       sb.Length = sbLength;

src/Thinktecture.Runtime.Extensions.SourceGenerator/Extensions/StringExtensions.cs

@@ -7,9 +7,52 @@ public static string MakeArgumentName(this string name)
       return name.Length switch
       {
          1 => name.ToLowerInvariant(),
-         _ => name.StartsWith("_", StringComparison.Ordinal)
-                 ? $"{Char.ToLowerInvariant(name[1])}{name.Substring(2)}"
-                 : $"{Char.ToLowerInvariant(name[0])}{name.Substring(1)}"
+         _ => ToCamelCase(name, false)
       };
    }
+
+   public static string MakeBackingFieldName(this string name)
+   {
+      return name.Length switch
+      {
+         1 => name[0] == '_' ? name : $"_{Char.ToLowerInvariant(name[0])}",
+         _ => ToCamelCase(name, true)
+      };
+   }
+
+   private static string ToCamelCase(
+      string name,
+      bool leadingUnderscore)
+   {
+      var startsWithUnderscore = name[0] == '_';
+
+      for (var i = 0; i < name.Length; i++)
+      {
+         var charValue = name[i];
+
+         if (Char.IsDigit(charValue))
+            return name;
+
+         if (Char.IsLower(charValue))
+            break;
+
+         if (!Char.IsLetter(charValue))
+            continue;
+
+         if (i == 0)
+            return $"{(leadingUnderscore ? "_" : String.Empty)}{Char.ToLowerInvariant(charValue)}{name.Substring(1)}";
+
+         var prefix = leadingUnderscore && !startsWithUnderscore ? "_" : String.Empty;
+
+         if (i == name.Length - 1)
+            return $"{prefix}{name.Substring(startsWithUnderscore ? 1 : 0, i)}{Char.ToLowerInvariant(charValue)}";
+
+         return $"{prefix}{name.Substring(startsWithUnderscore ? 1 : 0, i)}{Char.ToLowerInvariant(charValue)}{name.Substring(i)}";
+      }
+
+      if (leadingUnderscore)
+         return !startsWithUnderscore ? $"_{name}" : name;
+
+      return startsWithUnderscore && name.Length > 1 ? name.Substring(1) : name;
+   }
 }