tools/src/cnf/decompose.go

// Copyright 2023 The Dawn & Tint Authors
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package cnf

import (
	"dawn.googlesource.com/dawn/tools/src/container"
)

// / Decomposed holds a decomposed expression
// / See Decompose()
type Decomposed struct {
	Ands   []Ands  // The decomposed Ands
	Ors    []Ors   // The decomposed Ors
	Unarys []Unary // The decomposed Unarys
}

// Decompose returns the unique Ands, Ors and Unarys that make up the expression.
// If e has two or more OR expressions AND'd together, then Decomposed.Ands will
// hold the deduplicated AND expressions, otherwise Decomposed.Ands will be
// empty.
// If e has two or more Unary expressions OR'd together, then Decomposed.ORs
// will hold the deduplicated OR expressions, otherwise Decomposed.ORs will be
// empty.
// Decomposed.Unarys will hold all the deduplicated Unary expressions.
func Decompose(e Expr) Decomposed {
	ors := container.NewMap[Key, Ors]()
	unarys := container.NewMap[Key, Unary]()
	for _, o := range e {
		for _, u := range o {
			unarys.Add(u.Key(), u)
		}
		if len(o) > 1 {
			ors.Add(o.Key(), o)
		}
	}
	d := Decomposed{}
	if len(e) > 1 {
		d.Ands = []Ands{e}
	}
	if len(ors) > 0 {
		d.Ors = ors.Values()
	}
	if len(unarys) > 0 {
		d.Unarys = unarys.Values()
	}
	return d
}