Preserve outer bracket spacing for array literals with whitespace

Track whether there's whitespace after the opening [ bracket in array
literals and use this to format arrays with outer spaces when appropriate.
This matches ClickHouse's EXPLAIN AST behavior for multi-line arrays.

Author: claude

ast/ast.go

@@ -1261,14 +1261,15 @@ func (t *TableIdentifier) expressionNode()     {}
 
 // Literal represents a literal value.
 type Literal struct {
-	Position      token.Position `json:"-"`
-	Type          LiteralType    `json:"type"`
-	Value         interface{}    `json:"value"`
-	Source        string         `json:"source,omitempty"`        // Original source text (for preserving 0.0 vs 0)
-	Negative      bool           `json:"negative,omitempty"`      // True if literal was explicitly negative (for -0)
-	Parenthesized bool           `json:"parenthesized,omitempty"` // True if wrapped in explicit parentheses
-	SpacedCommas  bool           `json:"spaced_commas,omitempty"` // True if array/tuple had spaces after commas
-	IsBigInt      bool           `json:"is_big_int,omitempty"`    // True if this is a large integer stored as string
+	Position       token.Position `json:"-"`
+	Type           LiteralType    `json:"type"`
+	Value          interface{}    `json:"value"`
+	Source         string         `json:"source,omitempty"`          // Original source text (for preserving 0.0 vs 0)
+	Negative       bool           `json:"negative,omitempty"`        // True if literal was explicitly negative (for -0)
+	Parenthesized  bool           `json:"parenthesized,omitempty"`   // True if wrapped in explicit parentheses
+	SpacedCommas   bool           `json:"spaced_commas,omitempty"`   // True if array/tuple had spaces after commas
+	SpacedBrackets bool           `json:"spaced_brackets,omitempty"` // True if array had whitespace after [ and before ]
+	IsBigInt       bool           `json:"is_big_int,omitempty"`      // True if this is a large integer stored as string
 }
 
 func (l *Literal) Pos() token.Position { return l.Position }

internal/explain/format.go

@@ -558,6 +558,10 @@ func formatArrayAsStringFromLiteral(lit *ast.Literal) string {
 	if lit.SpacedCommas {
 		separator = ", "
 	}
+	// Use outer spaces when source had whitespace after [ (e.g., for multi-line arrays)
+	if lit.SpacedBrackets {
+		return "[ " + strings.Join(parts, separator) + " ]"
+	}
 	return "[" + strings.Join(parts, separator) + "]"
 }
 

parser/expression.go

@@ -1224,8 +1224,13 @@ func (p *Parser) parseArrayLiteral() ast.Expression {
 		Position: p.current.Pos,
 		Type:     ast.LiteralArray,
 	}
+	bracketPos := p.current.Pos.Offset
 	p.nextToken() // skip [
 
+	// Check if there's whitespace/newline after the opening bracket
+	// A bracket is 1 byte, so if offset difference > 1, there's whitespace
+	spacedBrackets := p.current.Pos.Offset > bracketPos+1
+
 	var elements []ast.Expression
 	spacedCommas := false
 
@@ -1257,6 +1262,7 @@ func (p *Parser) parseArrayLiteral() ast.Expression {
 	}
 	lit.Value = elements
 	lit.SpacedCommas = spacedCommas
+	lit.SpacedBrackets = spacedBrackets
 
 	p.expect(token.RBRACKET)
 	return lit

parser/testdata/03254_timeseries_instant_value_aggregate_functions/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt9": true
-  }
-}
+{}