Method VisitPost

pkg/sql/sem/tree/normalize.go:721–756

VisitPost implements the Visitor interface.

(expr Expr)

// VisitPost implements the Visitor interface.
func (v *NormalizeVisitor) VisitPost(expr Expr) Expr {
	if v.err != nil {
		return expr
	}
	// We don't propagate errors during this step because errors might involve a
	// branch of code that isn't traversed by normal execution (for example,
	// IF(2 = 2, 1, 1 / 0)).

	// Normalize expressions that know how to normalize themselves.
	if normalizable, ok := expr.(normalizableExpr); ok {
		expr = normalizable.normalize(v)
		if v.err != nil {
			return expr
		}
	}

	// Evaluate all constant expressions.
	if v.isConst(expr) {
		value, err := expr.(TypedExpr).Eval(v.ctx)
		if err != nil {
			// Ignore any errors here (e.g. division by zero), so they can happen
			// during execution where they are correctly handled. Note that in some
			// cases we might not even get an error (if this particular expression
			// does not get evaluated when the query runs, e.g. it's inside a CASE).
			return expr
		}
		if value == DNull {
			// We don't want to return an expression that has a different type; cast
			// the NULL if necessary.
			return ReType(DNull, expr.(TypedExpr).ResolvedType())
		}
		return value
	}

	return expr
}

func (v *NormalizeVisitor) isConst(expr Expr) bool {
	return v.fastIsConstVisitor.run(expr)