mirror of
https://github.com/mudler/luet.git
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ba0d625b5f
This refactors DefaultPackage into types.Package and gets rid of the interface. This is a preceeding for a follow up where accessors will be removed from the code. It also does several cleanup, so we get rid also of some unneeded dependencies.
136 lines
3.2 KiB
Go
136 lines
3.2 KiB
Go
// Copyright © 2021-2022 Ettore Di Giacinto <mudler@mocaccino.org>
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with this program; if not, see <http://www.gnu.org/licenses/>.
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package solver
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"strings"
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"github.com/crillab/gophersat/bf"
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"github.com/crillab/gophersat/explain"
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types "github.com/mudler/luet/pkg/api/core/types"
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"github.com/pkg/errors"
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)
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type Explainer struct{}
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func decodeDimacs(vars map[string]string, dimacs string) (string, error) {
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res := ""
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sc := bufio.NewScanner(bytes.NewBufferString(dimacs))
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lines := strings.Split(dimacs, "\n")
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linenum := 1
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SCAN:
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for sc.Scan() {
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line := sc.Text()
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fields := strings.Fields(line)
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if len(fields) == 0 {
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continue
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}
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switch fields[0] {
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case "p":
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continue SCAN
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default:
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for i := 0; i < len(fields)-1; i++ {
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v := fields[i]
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negative := false
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if strings.HasPrefix(fields[i], "-") {
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v = strings.TrimLeft(fields[i], "-")
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negative = true
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}
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variable := vars[v]
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if negative {
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res += fmt.Sprintf("!(%s)", variable)
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} else {
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res += variable
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}
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if i != len(fields)-2 {
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res += fmt.Sprintf(" or ")
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}
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}
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if linenum != len(lines)-1 {
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res += fmt.Sprintf(" and \n")
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}
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}
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linenum++
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}
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if err := sc.Err(); err != nil {
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return res, fmt.Errorf("could not parse problem: %v", err)
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}
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return res, nil
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}
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func parseVars(r io.Reader) (map[string]string, error) {
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sc := bufio.NewScanner(r)
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res := map[string]string{}
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for sc.Scan() {
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line := sc.Text()
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fields := strings.Fields(line)
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if len(fields) == 0 {
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continue
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}
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switch fields[0] {
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case "c":
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data := strings.Split(fields[1], "=")
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res[data[1]] = data[0]
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default:
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continue
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}
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}
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if err := sc.Err(); err != nil {
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return nil, fmt.Errorf("could not parse problem: %v", err)
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}
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return res, nil
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}
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// Solve tries to find the MUS (minimum unsat) formula from the original problem.
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// it returns an error with the decoded dimacs
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func (*Explainer) Solve(f bf.Formula, s types.PackageSolver) (types.PackagesAssertions, error) {
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buf := bytes.NewBufferString("")
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if err := bf.Dimacs(f, buf); err != nil {
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return nil, errors.Wrap(err, "cannot extract dimacs from formula")
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}
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copy := *buf
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pb, err := explain.ParseCNF(©)
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if err != nil {
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return nil, errors.Wrap(err, "could not parse problem")
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}
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pb2, err := pb.MUS()
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if err != nil {
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return nil, errors.Wrap(err, "could not extract subset")
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}
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variables, err := parseVars(buf)
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if err != nil {
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return nil, errors.Wrap(err, "could not parse variables")
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}
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res, err := decodeDimacs(variables, pb2.CNF())
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if err != nil {
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return nil, errors.Wrap(err, "could not parse dimacs")
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}
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return nil, fmt.Errorf("could not satisfy the constraints: \n%s", res)
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}
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