Optimization: Dispatch Translator by virtual functions instead of switch statements

Orm/Xtensive.Orm.Firebird/Sql.Drivers.Firebird/v2_5/Translator.cs

@@ -231,34 +231,14 @@ public override void Translate(IOutput output, SqlDatePart datePart)
       }
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlSelect node, SelectSection section)
-    {
-      switch (section) {
-        case SelectSection.Limit:
-          _ = context.Output.Append("FIRST");
-          break;
-        case SelectSection.Offset:
-          _ = context.Output.Append("SKIP");
-          break;
-        default:
-          base.Translate(context, node, section);
-          break;
-      }
-    }
+    public override void SelectLimit(SqlCompilerContext context, SqlSelect node) =>
+      context.Output.AppendSpacePrefixed("FIRST ");
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlUpdate node, UpdateSection section)
-    {
-      switch (section) {
-        case UpdateSection.Limit:
-          _ = context.Output.Append("ROWS");
-          break;
-        default:
-          base.Translate(context, node, section);
-          break;
-      }
-    }
+    public override void SelectOffset(SqlCompilerContext context, SqlSelect node) =>
+      context.Output.AppendSpacePrefixed("SKIP ");
+
+    public override void UpdateLimit(SqlCompilerContext context) =>
+      context.Output.AppendSpaceIfNecessary().Append("ROWS").AppendSpaceIfNecessary();
 
     /// <inheritdoc />
     public override void Translate(SqlCompilerContext context, SqlDelete node, DeleteSection section)
@@ -380,4 +360,4 @@ public Translator(SqlDriver driver)
       DoubleFormatString = $"{base.DoubleFormatString}e0";
     }
   }
-}
+}

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Compiler.cs

@@ -258,15 +258,15 @@ public override void Visit(SqlPlaceholder node)
     protected override void VisitSelectLimitOffset(SqlSelect node)
     {
       if (node.Limit is not null) {
-        AppendTranslated(node, SelectSection.Limit);
+        translator.SelectLimit(context, node);
         node.Limit.AcceptVisitor(this);
       }
       if (node.Offset is not null) {
         if (node.Limit is null) {
-          AppendTranslated(node, SelectSection.Limit);
+          translator.SelectLimit(context, node);
           _ = context.Output.Append(" 18446744073709551615 "); // magic number from http://dev.mysql.com/doc/refman/5.0/en/select.html
         }
-        AppendTranslated(node, SelectSection.Offset);
+        translator.SelectOffset(context, node);
         node.Offset.AcceptVisitor(this);
       }
     }

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Translator.cs

@@ -63,34 +63,26 @@ protected override void TranslateChar(IOutput output, char ch)
       }
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlSelect node, SelectSection section)
+    public override void SelectHintsEntry(SqlCompilerContext context, SqlSelect node) { }
+
+    public override void SelectHintsExit(SqlCompilerContext context, SqlSelect node)
     {
-      switch (section) {
-        case SelectSection.HintsEntry:
-          break;
-        case SelectSection.HintsExit:
-          if (node.Hints.Count == 0) {
-            break;
+      if (node.Hints.Count != 0) {
+        var hints = new List<string>(node.Hints.Count);
+        foreach (var hint in node.Hints) {
+          if (hint is SqlNativeHint sqlNativeHint) {
+            hints.Add(QuoteIdentifier(sqlNativeHint.HintText));
           }
-          var hints = new List<string>(node.Hints.Count);
-          foreach (var hint in node.Hints) {
-            if (hint is SqlNativeHint sqlNativeHint) {
-              hints.Add(QuoteIdentifier(sqlNativeHint.HintText));
-            }
-          }
-          if (hints.Count > 0) {
-            _ = context.Output.Append("USE INDEX (")
-              .Append(string.Join(", ", hints))
-              .Append(")");
-          }
-          break;
-        default:
-          base.Translate(context, node, section);
-          break;
+        }
+        if (hints.Count > 0) {
+          _ = context.Output.Append("USE INDEX (")
+            .Append(string.Join(", ", hints))
+            .Append(")");
+        }
       }
     }
 
+
     /// <inheritdoc/>
     public override void Translate(IOutput output, SqlFunctionType type)
     {
@@ -356,16 +348,8 @@ public override void Translate(SqlCompilerContext context, SqlAlterTable node, A
       }
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlInsert node, InsertSection section)
-    {
-      if (section == InsertSection.DefaultValues) {
-        _ = context.Output.Append("() VALUES ()");
-      }
-      else {
-        base.Translate(context, node, section);
-      }
-    }
+    public override void InsertDefaultValues(SqlCompilerContext context) =>
+      context.Output.AppendSpaceIfNecessary().AppendOpeningPunctuation("() VALUES ()");
 
     /// <inheritdoc/>
     public override void Translate(SqlCompilerContext context, SqlBreak node)

Orm/Xtensive.Orm.Oracle/Sql.Drivers.Oracle/v09/Translator.cs

@@ -70,24 +70,14 @@ public override void TranslateString(IOutput output, string str)
       base.TranslateString(output, str);
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlSelect node, SelectSection section)
-    {
-      switch (section) {
-        case SelectSection.HintsEntry:
-          _ = context.Output.Append("/*+");
-          break;
-        case SelectSection.HintsExit:
-          _ = context.Output.Append("*/");
-          break;
-        case SelectSection.Limit:
-        case SelectSection.Offset:
-          throw new NotSupportedException();
-        default:
-          base.Translate(context, node, section);
-          break;
-      }
-    }
+    public override void SelectLimit(SqlCompilerContext context, SqlSelect node) => throw new NotSupportedException();
+    public override void SelectOffset(SqlCompilerContext context, SqlSelect node) => throw new NotSupportedException();
+
+    public override void SelectHintsEntry(SqlCompilerContext context, SqlSelect node) =>
+      context.Output.AppendSpacePrefixed("/*+ ");
+
+    public override void SelectHintsExit(SqlCompilerContext context, SqlSelect node) =>
+      context.Output.AppendSpacePrefixed("*/ ");
 
     /// <inheritdoc/>
     public override string Translate(SqlJoinMethod method)

Orm/Xtensive.Orm.Oracle/Sql.Drivers.Oracle/v11/Translator.cs

@@ -13,13 +13,8 @@ namespace Xtensive.Sql.Drivers.Oracle.v11
 {
   internal class Translator : v10.Translator
   {
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlOrder node, NodeSection section)
-    {
-      if (section == NodeSection.Exit) {
-        _ = context.Output.Append(node.Ascending ? "ASC NULLS FIRST" : "DESC NULLS LAST");
-      }
-    }
+    public override void OrderExit(SqlCompilerContext context, SqlOrder node) =>
+      context.Output.Append(node.Ascending ? "ASC NULLS FIRST" : "DESC NULLS LAST");
 
     /// <inheritdoc/>
     public override string Translate(SqlValueType type)

Orm/Xtensive.Orm.PostgreSql/Sql.Drivers.PostgreSql/v8_0/Translator.cs

@@ -453,23 +453,11 @@ public override void Translate(SqlCompilerContext context, SqlDeclareCursor node
       }
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlFetch node, FetchSection section)
-    {
-      switch (section) {
-        case FetchSection.Entry:
-          _ = context.Output.Append("FETCH ").Append(node.Option.ToString().ToUpper());
-          return;
-        case FetchSection.Targets:
-          var output = context.Output;
-          _ = output.Append("FROM ");
-          TranslateIdentifier(output, node.Cursor.Name);
-          return;
-        case FetchSection.Exit:
-          break;
-      }
-      base.Translate(context, node, section);
-    }
+    public override void FetchEntry(SqlCompilerContext context, SqlFetch node) =>
+      context.Output.Append("FETCH ").Append(node.Option.ToString().ToUpper());
+
+    public override void FetchTarget(SqlCompilerContext context, SqlFetch node) =>
+      TranslateIdentifier(context.Output.AppendSpaceIfNecessary().Append("FROM "), node.Cursor.Name);
 
     /// <inheritdoc/>
     public override void Translate(SqlCompilerContext context, SqlOpenCursor node)
@@ -962,4 +950,4 @@ public Translator(SqlDriver driver)
       DoubleFormatString = base.DoubleFormatString + "'::float8'";
     }
   }
-}
+}

Orm/Xtensive.Orm.PostgreSql/Sql.Drivers.PostgreSql/v8_3/Translator.cs

@@ -44,13 +44,8 @@ public override void Translate(SqlCompilerContext context, SqlCreateIndex node,
       }
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlOrder node, NodeSection section)
-    {
-      if (section == NodeSection.Exit) {
-        _ = context.Output.Append(node.Ascending ? "ASC NULLS FIRST" : "DESC NULLS LAST");
-      }
-    }
+    public override void OrderExit(SqlCompilerContext context, SqlOrder node) =>
+      context.Output.Append(node.Ascending ? "ASC NULLS FIRST" : "DESC NULLS LAST");
 
     internal protected string GetFulltextVector(SqlCompilerContext context, FullTextIndex index)
     {

Orm/Xtensive.Orm.SqlServer/Sql.Drivers.SqlServer/v09/Compiler.cs

@@ -83,7 +83,7 @@ protected override void VisitUpdateLimit(SqlUpdate node)
           throw new NotSupportedException(Strings.ExStorageDoesNotSupportLimitationOfRowCountToUpdate);
         }
 
-        AppendTranslated(node, UpdateSection.Limit);
+        translator.UpdateLimit(context);
         _ = context.Output.AppendOpeningPunctuation("(");
         node.Limit.AcceptVisitor(this);
         _ = context.Output.Append(")");

Orm/Xtensive.Orm.SqlServer/Sql.Drivers.SqlServer/v09/Translator.cs

@@ -318,45 +318,32 @@ public override string Translate(SqlJoinMethod method)
       };
     }
 
-    /// <inheritdoc/>
-    public override void Translate(SqlCompilerContext context, SqlSelect node, SelectSection section)
+    public override void SelectLimit(SqlCompilerContext context, SqlSelect node) =>
+      context.Output.AppendSpacePrefixed("TOP ");
+
+    public override void SelectOffset(SqlCompilerContext context, SqlSelect node) => throw new NotSupportedException();
+
+    public override void SelectExit(SqlCompilerContext context, SqlSelect node)
     {
       var output = context.Output;
-      switch (section) {
-        case SelectSection.Entry:
-          base.Translate(context, node, section);
-          break;
-        case SelectSection.Limit:
-          _ = output.Append("TOP");
-          break;
-        case SelectSection.Offset:
-          throw new NotSupportedException();
-        case SelectSection.Exit:
-          var hasHints = false;
-          foreach (var hint in node.Hints) {
-            switch (hint) {
-              case SqlForceJoinOrderHint:
-                AppendHint(output, "FORCE ORDER", ref hasHints);
-                break;
-              case SqlFastFirstRowsHint sqlFastFirstRowsHint:
-                AppendHint(output, "FAST ", ref hasHints);
-                _ = output.Append(sqlFastFirstRowsHint.Amount);
-                break;
-              case SqlNativeHint sqlNativeHint:
-                AppendHint(output, sqlNativeHint.HintText, ref hasHints);
-                break;
-            }
-          }
-          if (hasHints) {
-            _ = output.Append(")");
-          }
-          break;
-        default:
-          base.Translate(context, node, section);
-          break;
+      var hasHints = false;
+      foreach (var hint in node.Hints) {
+        switch (hint) {
+          case SqlForceJoinOrderHint:
+            AppendHint(output, "FORCE ORDER", ref hasHints);
+            break;
+          case SqlFastFirstRowsHint sqlFastFirstRowsHint:
+            AppendHint(output, "FAST ", ref hasHints);
+            _ = output.Append(sqlFastFirstRowsHint.Amount);
+            break;
+          case SqlNativeHint sqlNativeHint:
+            AppendHint(output, sqlNativeHint.HintText, ref hasHints);
+            break;
+        }
+      }
+      if (hasHints) {
+        _ = output.Append(")");
       }
-
-    /// <inheritdoc/>
 
       static void AppendHint(IOutput output, string hint, ref bool hasHints)
       {
@@ -371,17 +358,8 @@ static void AppendHint(IOutput output, string hint, ref bool hasHints)
       }
     }
 
-    public override void Translate(SqlCompilerContext context, SqlUpdate node, UpdateSection section)
-    {
-      switch (section) {
-        case UpdateSection.Limit:
-          _ = context.Output.Append("TOP");
-          break;
-        default:
-          base.Translate(context, node, section);
-          break;
-      }
-    }
+    public override void UpdateLimit(SqlCompilerContext context) =>
+      context.Output.AppendSpaceIfNecessary().Append("TOP").AppendSpaceIfNecessary();
 
     /// <inheritdoc/>
     public override void Translate(SqlCompilerContext context, SqlDelete node, DeleteSection section)

Orm/Xtensive.Orm.SqlServer/Sql.Drivers.SqlServer/v11/Compiler.cs

@@ -26,7 +26,7 @@ protected override void VisitSelectLimitOffset(SqlSelect node)
         return; // Nothing to process.
       }
 
-      AppendTranslated(node, SelectSection.Offset);
+      translator.SelectOffset(context, node);
 
       if (node.HasOffset) {
         node.Offset.AcceptVisitor(this);
@@ -35,14 +35,12 @@ protected override void VisitSelectLimitOffset(SqlSelect node)
         _ = context.Output.Append("0");
       }
 
-      AppendSpaceIfNecessary();
-      translator.Translate(context, node, SelectSection.OffsetEnd);
+      translator.SelectOffsetEnd(context, node);
 
       if (node.HasLimit) {
-        AppendTranslated(node, SelectSection.Limit);
+        translator.SelectLimit(context, node);
         node.Limit.AcceptVisitor(this);
-        AppendSpaceIfNecessary();
-        translator.Translate(context, node, SelectSection.LimitEnd);
+        translator.SelectLimitEnd(context, node);
       }
     }