// Copyright 2023 The Dawn & Tint Authors
//
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package cnf

import "dawn.googlesource.com/dawn/tools/src/transform"

// And returns a new expression that represents (lhs ∧ rhs)
func And(lhs, rhs Expr) Expr {
	return append(append(Expr{}, lhs...), rhs...)
}

// Or returns a new expression that represents (lhs ∨ rhs)
func Or(lhs, rhs Expr) Expr {
	if len(lhs) == 0 {
		return rhs
	}
	if len(rhs) == 0 {
		return lhs
	}
	out := Expr{}
	for _, aOrs := range lhs {
		for _, bOrs := range rhs {
			out = append(out, append(append(Ors{}, aOrs...), bOrs...))
		}
	}
	return out
}

// Not returns a new expression that represents (¬expr)
func Not(expr Expr) Expr {
	// Transform each of the OR expressions into AND expressions where each unary is negated.
	out := Expr{}
	for _, o := range expr {
		ands, _ := transform.Slice(o, func(u Unary) (Ors, error) {
			return Ors{Unary{Negate: !u.Negate, Var: u.Var}}, nil
		})
		out = Or(out, ands)
	}
	return out
}