Flatten OR/AND operators in EXPLAIN AST output

Add collectBooleanOperands helper function to flatten chained OR and AND
expressions into a flat list, matching ClickHouse's EXPLAIN AST format.

Previously, "a OR b OR c" would produce nested output like:
  Function or
    ExpressionList (2)
      Function or (2)
        a
        b
      c

Now it produces the expected flat format:
  Function or
    ExpressionList (3)
      a
      b
      c

This change applies the flattening in three places:
- explainBinaryExpr (main expression handling)
- explainAliasedExpr (aliased expressions)
- explainWithElement (WITH clause elements)

This fixes 419 explain tests.

Author: claude

internal/explain/expressions.go

@@ -264,6 +264,18 @@ func explainBinaryExpr(sb *strings.Builder, n *ast.BinaryExpr, indent string, de
 		return
 	}
 
+	// For OR and AND operators, flatten chained expressions
+	opLower := strings.ToLower(n.Op)
+	if opLower == "or" || opLower == "and" {
+		operands := collectBooleanOperands(n, opLower)
+		fmt.Fprintf(sb, "%sFunction %s (children %d)\n", indent, fnName, 1)
+		fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, len(operands))
+		for _, op := range operands {
+			Node(sb, op, depth+2)
+		}
+		return
+	}
+
 	fmt.Fprintf(sb, "%sFunction %s (children %d)\n", indent, fnName, 1)
 	fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, 2)
 	Node(sb, n.Left, depth+2)
@@ -291,6 +303,27 @@ func collectConcatOperands(n *ast.BinaryExpr) []ast.Expression {
 	return operands
 }
 
+// collectBooleanOperands flattens chained OR/AND operations into a list of operands
+func collectBooleanOperands(n *ast.BinaryExpr, op string) []ast.Expression {
+	var operands []ast.Expression
+
+	// Recursively collect from left side if it's also the same operator
+	if left, ok := n.Left.(*ast.BinaryExpr); ok && strings.ToLower(left.Op) == op {
+		operands = append(operands, collectBooleanOperands(left, op)...)
+	} else {
+		operands = append(operands, n.Left)
+	}
+
+	// Recursively collect from right side if it's also the same operator
+	if right, ok := n.Right.(*ast.BinaryExpr); ok && strings.ToLower(right.Op) == op {
+		operands = append(operands, collectBooleanOperands(right, op)...)
+	} else {
+		operands = append(operands, n.Right)
+	}
+
+	return operands
+}
+
 func explainUnaryExpr(sb *strings.Builder, n *ast.UnaryExpr, indent string, depth int) {
 	// Handle negate of literal numbers - output as negative literal instead of function
 	if n.Op == "-" {
@@ -410,6 +443,14 @@ func explainAliasedExpr(sb *strings.Builder, n *ast.AliasedExpr, depth int) {
 			for _, op := range operands {
 				Node(sb, op, depth+2)
 			}
+		} else if opLower := strings.ToLower(e.Op); opLower == "or" || opLower == "and" {
+			// For OR and AND operators, flatten chained expressions
+			operands := collectBooleanOperands(e, opLower)
+			fmt.Fprintf(sb, "%sFunction %s (alias %s) (children %d)\n", indent, fnName, escapeAlias(n.Alias), 1)
+			fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, len(operands))
+			for _, op := range operands {
+				Node(sb, op, depth+2)
+			}
 		} else {
 			fmt.Fprintf(sb, "%sFunction %s (alias %s) (children %d)\n", indent, fnName, escapeAlias(n.Alias), 1)
 			fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, 2)
@@ -585,6 +626,18 @@ func explainWithElement(sb *strings.Builder, n *ast.WithElement, indent string,
 			for _, op := range operands {
 				Node(sb, op, depth+2)
 			}
+		} else if opLower := strings.ToLower(e.Op); opLower == "or" || opLower == "and" {
+			// For OR and AND operators, flatten chained expressions
+			operands := collectBooleanOperands(e, opLower)
+			if n.Name != "" {
+				fmt.Fprintf(sb, "%sFunction %s (alias %s) (children %d)\n", indent, fnName, n.Name, 1)
+			} else {
+				fmt.Fprintf(sb, "%sFunction %s (children %d)\n", indent, fnName, 1)
+			}
+			fmt.Fprintf(sb, "%s ExpressionList (children %d)\n", indent, len(operands))
+			for _, op := range operands {
+				Node(sb, op, depth+2)
+			}
 		} else {
 			if n.Name != "" {
 				fmt.Fprintf(sb, "%sFunction %s (alias %s) (children %d)\n", indent, fnName, n.Name, 1)

parser/testdata/00091_prewhere_two_conditions/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt11":true,"stmt12":true,"stmt5":true,"stmt6":true,"stmt7":true}}
+{}

parser/testdata/00093_prewhere_array_join/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt2": true
-  }
-}
+{}

parser/testdata/00110_external_sort/metadata.json

@@ -1,7 +1 @@
-{
-  "explain_todo": {
-    "stmt6": true,
-    "stmt7": true,
-    "stmt8": true
-  }
-}
+{}

parser/testdata/00167_read_bytes_from_fs/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt4":true}}
+{}

parser/testdata/00170_s3_cache/metadata.json

@@ -1,12 +1 @@
-{
-  "explain_todo": {
-    "stmt28": true,
-    "stmt42": true,
-    "stmt43": true,
-    "stmt44": true,
-    "stmt45": true,
-    "stmt46": true,
-    "stmt47": true,
-    "stmt48": true
-  }
-}
+{}

parser/testdata/00172_early_constant_folding/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt3":true,"stmt4":true}}
+{}

parser/testdata/00229_prewhere_column_missing/metadata.json

@@ -1,6 +1 @@
-{
-  "explain_todo": {
-    "stmt20": true,
-    "stmt21": true
-  }
-}
+{}

parser/testdata/00234_disjunctive_equality_chains_optimization/metadata.json

@@ -1 +1 @@
-{"explain_todo":{"stmt3":true}}
+{}

parser/testdata/00239_type_conversion_in_in/metadata.json

@@ -1,7 +1 @@
-{
-  "explain_todo": {
-    "stmt1": true,
-    "stmt2": true,
-    "stmt3": true
-  }
-}
+{}