lattigo/utils/structs/matrix.go

package structs

import (
	"bufio"
	"bytes"
	"encoding/binary"
	"fmt"
	"io"

	"github.com/tuneinsight/lattigo/v4/utils/buffer"
)

// Matrix is a struct storing a vector of Vector.
type Matrix[T any] [][]T

func (m Matrix[T]) CopyNew() *Matrix[T] {

	if c, isCopiable := any(new(T)).(CopyNewer[T]); !isCopiable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), c))
	}

	mcpy := Matrix[T](make([][]T, len(m)))

	for i := range m {

		mcpy[i] = make([]T, len(m[i]))

		for j := range m[i] {
			mcpy[i][j] = *any(&m[i][j]).(CopyNewer[T]).CopyNew()
		}
	}

	return &mcpy
}

// WriteTo writes the object on an io.Writer.
// To ensure optimal efficiency and minimal allocations, the user is encouraged
// to provide a struct implementing the interface buffer.Writer, which defines
// a subset of the method of the bufio.Writer.
// If w is not compliant to the buffer.Writer interface, it will be wrapped in
// a new bufio.Writer.
// For additional information, see lattigo/utils/buffer/writer.go.
func (m *Matrix[T]) WriteTo(w io.Writer) (n int64, err error) {

	if w, isWritable := any(new(T)).(io.WriterTo); !isWritable {
		return 0, fmt.Errorf("vector component of type %T does not comply to %T", new(T), w)
	}

	switch w := w.(type) {
	case buffer.Writer:

		var inc int
		if inc, err = buffer.WriteInt(w, len(*m)); err != nil {
			return int64(inc), err
		}
		n += int64(inc)

		for _, v := range *m {
			vec := Vector[T](v)
			inc, err := vec.WriteTo(w)
			n += int64(inc)
			if err != nil {
				return n, err
			}
		}

		return n, w.Flush()

	default:
		return m.WriteTo(bufio.NewWriter(w))
	}
}

// ReadFrom reads on the object from an io.Writer.
// To ensure optimal efficiency and minimal allocations, the user is encouraged
// to provide a struct implementing the interface buffer.Reader, which defines
// a subset of the method of the bufio.Reader.
// If r is not compliant to the buffer.Reader interface, it will be wrapped in
// a new bufio.Reader.
// For additional information, see lattigo/utils/buffer/reader.go.
func (m *Matrix[T]) ReadFrom(r io.Reader) (n int64, err error) {

	if r, isReadable := any(new(T)).(io.ReaderFrom); !isReadable {
		return 0, fmt.Errorf("vector component of type %T does not comply to %T", new(T), r)
	}

	switch r := r.(type) {
	case buffer.Reader:

		var size, n int

		if n, err = buffer.ReadInt(r, &size); err != nil {
			return int64(n), fmt.Errorf("cannot read matrix size: %w", err)
		}

		if cap(*m) < size {
			*m = make([][]T, size)
		}
		*m = (*m)[:size]

		for i := range *m {
			inc, err := (*Vector[T])(&(*m)[i]).ReadFrom(r)
			n += int(inc)
			if err != nil {
				return int64(n), err
			}
		}

		return int64(n), nil

	default:
		return m.ReadFrom(bufio.NewReader(r))
	}
}

// BinarySize returns the size in bytes of the object
// when encoded using Encode.
func (m Matrix[T]) BinarySize() (size int) {

	if s, isSizable := any(new(T)).(BinarySizer); !isSizable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), s))
	}

	size += 8

	for _, v := range m {
		size += (*Vector[T])(&v).BinarySize()
	}
	return
}

// Encode encodes the object into a binary form on a preallocated slice of bytes
// and returns the number of bytes written.
func (m Matrix[T]) Encode(b []byte) (n int, err error) {

	if e, isEncodable := any(new(T)).(Encoder); !isEncodable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), e))
	}

	binary.LittleEndian.PutUint64(b[n:], uint64(len(m)))
	n += 8

	for _, v := range m {
		inc, err := (*Vector[T])(&v).Encode(b)
		n += inc
		if err != nil {
			return n, err
		}
	}

	return n, nil
}

// Decode decodes a slice of bytes generated by Encode
// on the object and returns the number of bytes read.
func (m *Matrix[T]) Decode(p []byte) (n int, err error) {

	if d, isDecodable := any(new(T)).(Decoder); !isDecodable {
		panic(fmt.Errorf("vector component of type %T does not comply to %T", new(T), d))
	}

	size := int(binary.LittleEndian.Uint64(p))
	n += 8

	if cap(*m) < size {
		*m = make([][]T, size)
	}
	*m = (*m)[:size]

	for i := range *m {
		inc, err := (*Vector[T])(&(*m)[i]).Decode(p[n:])
		n += inc
		if err != nil {
			return n, err
		}
	}

	return n, nil
}

// MarshalBinary encodes the object into a binary form on a newly allocated slice of bytes.
func (m *Matrix[T]) MarshalBinary() (p []byte, err error) {
	buf := bytes.NewBuffer([]byte{})
	_, err = m.WriteTo(buf)
	return buf.Bytes(), err
}

// UnmarshalBinary decodes a slice of bytes generated by
// MarshalBinary or WriteTo on the object.
func (m *Matrix[T]) UnmarshalBinary(p []byte) (err error) {
	_, err = m.ReadFrom(bytes.NewBuffer(p))
	return
}