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// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: Copyright (c) 2025 Drew Devault <https://drewdevault.com>
package bare
import (
"encoding/binary"
"fmt"
"io"
"math"
"unicode/utf8"
)
type byteReader interface {
io.Reader
io.ByteReader
}
// A Reader for BARE primitive types.
type Reader struct {
base byteReader
scratch [8]byte
}
type simpleByteReader struct {
io.Reader
scratch [1]byte
}
func (r simpleByteReader) ReadByte() (byte, error) {
// using reference type here saves us allocations
_, err := r.Read(r.scratch[:])
return r.scratch[0], err
}
// Returns a new BARE primitive reader wrapping the given io.Reader.
func NewReader(base io.Reader) *Reader {
br, ok := base.(byteReader)
if !ok {
br = simpleByteReader{Reader: base}
}
return &Reader{base: br}
}
func (r *Reader) ReadUint() (uint64, error) {
x, err := binary.ReadUvarint(r.base)
if err != nil {
return x, err
}
return x, nil
}
func (r *Reader) ReadU8() (uint8, error) {
return r.base.ReadByte()
}
func (r *Reader) ReadU16() (uint16, error) {
var i uint16
if _, err := io.ReadAtLeast(r.base, r.scratch[:2], 2); err != nil {
return i, err
}
return binary.LittleEndian.Uint16(r.scratch[:]), nil
}
func (r *Reader) ReadU32() (uint32, error) {
var i uint32
if _, err := io.ReadAtLeast(r.base, r.scratch[:4], 4); err != nil {
return i, err
}
return binary.LittleEndian.Uint32(r.scratch[:]), nil
}
func (r *Reader) ReadU64() (uint64, error) {
var i uint64
if _, err := io.ReadAtLeast(r.base, r.scratch[:8], 8); err != nil {
return i, err
}
return binary.LittleEndian.Uint64(r.scratch[:]), nil
}
func (r *Reader) ReadInt() (int64, error) {
return binary.ReadVarint(r.base)
}
func (r *Reader) ReadI8() (int8, error) {
b, err := r.base.ReadByte()
return int8(b), err
}
func (r *Reader) ReadI16() (int16, error) {
var i int16
if _, err := io.ReadAtLeast(r.base, r.scratch[:2], 2); err != nil {
return i, err
}
return int16(binary.LittleEndian.Uint16(r.scratch[:])), nil
}
func (r *Reader) ReadI32() (int32, error) {
var i int32
if _, err := io.ReadAtLeast(r.base, r.scratch[:4], 4); err != nil {
return i, err
}
return int32(binary.LittleEndian.Uint32(r.scratch[:])), nil
}
func (r *Reader) ReadI64() (int64, error) {
var i int64
if _, err := io.ReadAtLeast(r.base, r.scratch[:], 8); err != nil {
return i, err
}
return int64(binary.LittleEndian.Uint64(r.scratch[:])), nil
}
func (r *Reader) ReadF32() (float32, error) {
u, err := r.ReadU32()
f := math.Float32frombits(u)
if math.IsNaN(float64(f)) {
return 0.0, fmt.Errorf("NaN is not permitted in BARE floats")
}
return f, err
}
func (r *Reader) ReadF64() (float64, error) {
u, err := r.ReadU64()
f := math.Float64frombits(u)
if math.IsNaN(f) {
return 0.0, fmt.Errorf("NaN is not permitted in BARE floats")
}
return f, err
}
func (r *Reader) ReadBool() (bool, error) {
b, err := r.ReadU8()
if err != nil {
return false, err
}
if b > 1 {
return false, fmt.Errorf("Invalid bool value: %#x", b)
}
return b == 1, nil
}
func (r *Reader) ReadString() (string, error) {
buf, err := r.ReadData()
if err != nil {
return "", err
}
if !utf8.Valid(buf) {
return "", ErrInvalidStr
}
return string(buf), nil
}
// Reads a fixed amount of arbitrary data, defined by the length of the slice.
func (r *Reader) ReadDataFixed(dest []byte) error {
var amt int = 0
for amt < len(dest) {
n, err := r.base.Read(dest[amt:])
if err != nil {
return err
}
amt += n
}
return nil
}
// Reads arbitrary data whose length is read from the message.
func (r *Reader) ReadData() ([]byte, error) {
l, err := r.ReadUint()
if err != nil {
return nil, err
}
if l >= maxUnmarshalBytes {
return nil, ErrLimitExceeded
}
buf := make([]byte, l)
var amt uint64 = 0
for amt < l {
n, err := r.base.Read(buf[amt:])
if err != nil {
return nil, err
}
amt += uint64(n)
}
return buf, nil
}
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