support expressions in window frame -- draft

src/Interpreters/ExpressionAnalyzer.cpp

@@ -14,17 +14,18 @@
 #include <DataTypes/DataTypesNumber.h>
 #include <Columns/IColumn.h>
 
-#include <Interpreters/ExpressionAnalyzer.h>
-#include <Interpreters/ExpressionActions.h>
 #include <Interpreters/ArrayJoinAction.h>
+#include <Interpreters/Context.h>
+#include <Interpreters/DictionaryReader.h>
+#include <Interpreters/evaluateConstantExpression.h>
+#include <Interpreters/ExpressionActions.h>
+#include <Interpreters/ExpressionAnalyzer.h>
 #include <Interpreters/ExternalDictionariesLoader.h>
+#include <Interpreters/HashJoin.h>
+#include <Interpreters/JoinSwitcher.h>
+#include <Interpreters/MergeJoin.h>
 #include <Interpreters/Set.h>
 #include <Interpreters/TableJoin.h>
-#include <Interpreters/JoinSwitcher.h>
-#include <Interpreters/HashJoin.h>
-#include <Interpreters/MergeJoin.h>
-#include <Interpreters/DictionaryReader.h>
-#include <Interpreters/Context.h>
 
 #include <Processors/QueryPlan/ExpressionStep.h>
 
@@ -474,7 +475,8 @@ bool ExpressionAnalyzer::makeAggregateDescriptions(ActionsDAGPtr & actions)
     return !aggregates().empty();
 }
 
-void makeWindowDescriptionFromAST(const WindowDescriptions & existing_descriptions,
+void makeWindowDescriptionFromAST(const Context & context,
+    const WindowDescriptions & existing_descriptions,
     WindowDescription & desc, const IAST * ast)
 {
     const auto & definition = ast->as<const ASTWindowDefinition &>();
@@ -580,6 +582,22 @@ void makeWindowDescriptionFromAST(const WindowDescriptions & existing_descriptio
     }
 
     desc.frame = definition.frame;
+
+    if (definition.frame.end_type == WindowFrame::BoundaryType::Offset)
+    {
+        auto [value, _] = evaluateConstantExpression(
+            definition.frame_end_offset,
+            const_pointer_cast<Context>(context.shared_from_this()));
+        desc.frame.end_offset = value;
+    }
+
+    if (definition.frame.begin_type == WindowFrame::BoundaryType::Offset)
+    {
+        auto [value, _] = evaluateConstantExpression(
+            definition.frame_begin_offset,
+            const_pointer_cast<Context>(context.shared_from_this()));
+        desc.frame.begin_offset = value;
+    }
 }
 
 void ExpressionAnalyzer::makeWindowDescriptions(ActionsDAGPtr actions)
@@ -605,7 +623,8 @@ void ExpressionAnalyzer::makeWindowDescriptions(ActionsDAGPtr actions)
             const auto & elem = ptr->as<const ASTWindowListElement &>();
             WindowDescription desc;
             desc.window_name = elem.name;
-            makeWindowDescriptionFromAST(window_descriptions, desc, elem.definition.get());
+            makeWindowDescriptionFromAST(*getContext(), window_descriptions,
+                desc, elem.definition.get());
 
             auto [it, inserted] = window_descriptions.insert(
                 {desc.window_name, desc});
@@ -690,7 +709,8 @@ void ExpressionAnalyzer::makeWindowDescriptions(ActionsDAGPtr actions)
                 const ASTWindowDefinition &>();
             WindowDescription desc;
             desc.window_name = definition.getDefaultWindowName();
-            makeWindowDescriptionFromAST(window_descriptions, desc, &definition);
+            makeWindowDescriptionFromAST(*getContext(), window_descriptions,
+                desc, &definition);
 
             auto [it, inserted] = window_descriptions.insert(
                 {desc.window_name, desc});

src/Parsers/ASTWindowDefinition.cpp

@@ -28,6 +28,18 @@ ASTPtr ASTWindowDefinition::clone() const
 
     result->frame = frame;
 
+    if (frame_begin_offset)
+    {
+        result->frame_begin_offset = frame_begin_offset->clone();
+        result->children.push_back(result->frame_begin_offset);
+    }
+
+    if (frame_end_offset)
+    {
+        result->frame_end_offset = frame_end_offset->clone();
+        result->children.push_back(result->frame_end_offset);
+    }
+
     return result;
 }
 
@@ -93,8 +105,7 @@ void ASTWindowDefinition::formatImpl(const FormatSettings & settings,
         }
         else
         {
-            settings.ostr << applyVisitor(FieldVisitorToString(),
+            frame_begin_offset->formatImpl(settings, state, format_frame);
-                frame.begin_offset);
             settings.ostr << " "
                 << (!frame.begin_preceding ? "FOLLOWING" : "PRECEDING");
         }
@@ -109,8 +120,7 @@ void ASTWindowDefinition::formatImpl(const FormatSettings & settings,
         }
         else
         {
-            settings.ostr << applyVisitor(FieldVisitorToString(),
+            frame_end_offset->formatImpl(settings, state, format_frame);
-                frame.end_offset);
             settings.ostr << " "
                 << (!frame.end_preceding ? "FOLLOWING" : "PRECEDING");
         }

src/Parsers/ASTWindowDefinition.h

@@ -16,8 +16,12 @@ struct ASTWindowDefinition : public IAST
 
     ASTPtr order_by;
 
+    // Be careful: offsets can contain constant expressions such as INTERVAL 1 DAY,
+    // that are evaluated later by ExpressionAnalyzer. The WindowFrame struct
+    // can be incomplete after parsing.
     WindowFrame frame;
-
+    ASTPtr frame_begin_offset;
+    ASTPtr frame_end_offset;
 
     ASTPtr clone() const override;
 

src/Parsers/ExpressionElementParsers.cpp

@@ -569,16 +569,14 @@ static bool tryParseFrameDefinition(ASTWindowDefinition * node, IParser::Pos & p
     }
     else
     {
-        ParserLiteral parser_literal;
+        ParserExpression parser_expression;
-        ASTPtr ast_literal;
         if (keyword_unbounded.ignore(pos, expected))
         {
             node->frame.begin_type = WindowFrame::BoundaryType::Unbounded;
         }
-        else if (parser_literal.parse(pos, ast_literal, expected))
+        else if (parser_expression.parse(pos, node->frame_begin_offset, expected))
         {
-            const Field & value = ast_literal->as<ASTLiteral &>().value;
+            // We will evaluate the expression for offset expression later.
-            node->frame.begin_offset = value;
             node->frame.begin_type = WindowFrame::BoundaryType::Offset;
         }
         else
@@ -618,16 +616,14 @@ static bool tryParseFrameDefinition(ASTWindowDefinition * node, IParser::Pos & p
         }
         else
         {
-            ParserLiteral parser_literal;
+            ParserExpression parser_expression;
-            ASTPtr ast_literal;
             if (keyword_unbounded.ignore(pos, expected))
             {
                 node->frame.end_type = WindowFrame::BoundaryType::Unbounded;
             }
-            else if (parser_literal.parse(pos, ast_literal, expected))
+            else if (parser_expression.parse(pos, node->frame_end_offset, expected))
             {
-                const Field & value = ast_literal->as<ASTLiteral &>().value;
+                // We will evaluate the expression for offset expression later.
-                node->frame.end_offset = value;
                 node->frame.end_type = WindowFrame::BoundaryType::Offset;
             }
             else