generator.go

package tower

import (
	"path/filepath"
	"strings"

	"github.com/consensys/bavard"

	"github.com/consensys/gurvy/internal/generators/tower/templates/fp12"
	"github.com/consensys/gurvy/internal/generators/tower/templates/fp2"
	"github.com/consensys/gurvy/internal/generators/tower/templates/fp6"
)

// Data data used to generate the templates
type Data struct {
	Fpackage        string
	Fp2NonResidue   string
	Fp6NonResidue   string
	EmbeddingDegree int

	// data needed in the template, always set to constants
	Fp2Name  string
	Fp6Name  string
	Fp12Name string

	// these members are computed as needed
	TwoInv []uint64 // fp.Element, used only when Fp2NonResidue==-1 and Fp6NonResidue==(1,1). TODO there must be a better way to do this.
}

// Generate generates pairing
func Generate(d Data, outputDir string) error {

	rootPath := filepath.Join(outputDir, d.Fpackage)

	// inverse of 2 in fp is used by some curves
	// TODO this sucks, generalize it
	if d.Fp2NonResidue == "-1" && d.Fp6NonResidue == "1,1" {
		d.InitTwoInv()
	}

	// fp2
	if d.EmbeddingDegree >= 2 {
		src := []string{
			fp2.Base,
			fp2.Inline,
			fp2.Mul,
		}
		if err := bavard.Generate(filepath.Join(rootPath, strings.ToLower(d.Fp2Name)+".go"), src, d,
			bavard.Package(d.Fpackage),
			bavard.Apache2("ConsenSys AG", 2020),
			bavard.GeneratedBy("gurvy/internal/generators"),
		); err != nil {
			return err
		}
	}

	// fp6
	if d.EmbeddingDegree >= 6 {
		src := []string{
			fp6.Base,
			fp2.Inline,
			fp6.Inline,
			fp6.Mul,
		}
		if err := bavard.Generate(filepath.Join(rootPath, strings.ToLower(d.Fp6Name)+".go"), src, d,
			bavard.Package(d.Fpackage),
			bavard.Apache2("ConsenSys AG", 2020),
			bavard.GeneratedBy("gurvy/internal/generators"),
		); err != nil {
			return err
		}
	}

	// fp12
	if d.EmbeddingDegree >= 12 {
		src := []string{
			fp12.Base,
			fp2.Inline,
			fp6.Inline,
			fp12.Inline,
			fp12.Mul,
		}
		if err := bavard.Generate(filepath.Join(rootPath, strings.ToLower(d.Fp12Name)+".go"), src, d,
			bavard.Package(d.Fpackage),
			bavard.Apache2("ConsenSys AG", 2020),
			bavard.GeneratedBy("gurvy/internal/generators"),
		); err != nil {
			return err
		}
	}

	return nil
}

// InitTwoInv set z.TwoInv to the inverse of 2 as an fp.Element
func (z *Data) InitTwoInv() *Data {
	var twoInv fpElement
	twoInv.SetUint64(2).Inverse(&twoInv)
	z.TwoInv = twoInv[:]
	return z
}

const TwoInvTemplate = `
import "github.com/consensys/gurvy/{{$.Fpackage}}/fp"

type fpElement = fp.Element
`