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// Copyright [2019] LinkedIn Corp. Licensed under the Apache License, Version
// 2.0 (the "License"); you may not use this file except in compliance with the
// License. You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
package goavro
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"math"
"strconv"
)
const (
doubleEncodedLength = 8 // double requires 8 bytes
floatEncodedLength = 4 // float requires 4 bytes
)
////////////////////////////////////////
// Binary Decode
////////////////////////////////////////
func doubleNativeFromBinary(buf []byte) (interface{}, []byte, error) {
if len(buf) < doubleEncodedLength {
return nil, nil, fmt.Errorf("cannot decode binary double: %s", io.ErrShortBuffer)
}
return math.Float64frombits(binary.LittleEndian.Uint64(buf[:doubleEncodedLength])), buf[doubleEncodedLength:], nil
}
func floatNativeFromBinary(buf []byte) (interface{}, []byte, error) {
if len(buf) < floatEncodedLength {
return nil, nil, fmt.Errorf("cannot decode binary float: %s", io.ErrShortBuffer)
}
return math.Float32frombits(binary.LittleEndian.Uint32(buf[:floatEncodedLength])), buf[floatEncodedLength:], nil
}
////////////////////////////////////////
// Binary Encode
////////////////////////////////////////
func doubleBinaryFromNative(buf []byte, datum interface{}) ([]byte, error) {
var value float64
switch v := datum.(type) {
case float64:
value = v
case float32:
value = float64(v)
case int:
if value = float64(v); int(value) != v {
return nil, fmt.Errorf("cannot encode binary double: provided Go int would lose precision: %d", v)
}
case int64:
if value = float64(v); int64(value) != v {
return nil, fmt.Errorf("cannot encode binary double: provided Go int64 would lose precision: %d", v)
}
case int32:
if value = float64(v); int32(value) != v {
return nil, fmt.Errorf("cannot encode binary double: provided Go int32 would lose precision: %d", v)
}
default:
return nil, fmt.Errorf("cannot encode binary double: expected: Go numeric; received: %T", datum)
}
buf = append(buf, 0, 0, 0, 0, 0, 0, 0, 0)
binary.LittleEndian.PutUint64(buf[len(buf)-doubleEncodedLength:], math.Float64bits(value))
return buf, nil
}
func floatBinaryFromNative(buf []byte, datum interface{}) ([]byte, error) {
var value float32
switch v := datum.(type) {
case float32:
value = v
case float64:
// Assume runtime can cast special floats correctly, and if there is a
// loss of precision from float64 and float32, that should be expected
// or at least understood by the client.
value = float32(v)
case int:
if value = float32(v); int(value) != v {
return nil, fmt.Errorf("cannot encode binary float: provided Go int would lose precision: %d", v)
}
case int64:
if value = float32(v); int64(value) != v {
return nil, fmt.Errorf("cannot encode binary float: provided Go int64 would lose precision: %d", v)
}
case int32:
if value = float32(v); int32(value) != v {
return nil, fmt.Errorf("cannot encode binary float: provided Go int32 would lose precision: %d", v)
}
default:
return nil, fmt.Errorf("cannot encode binary float: expected: Go numeric; received: %T", datum)
}
// return floatingBinaryEncoder(buf, uint64(math.Float32bits(value)), floatEncodedLength)
buf = append(buf, 0, 0, 0, 0)
binary.LittleEndian.PutUint32(buf[len(buf)-floatEncodedLength:], uint32(math.Float32bits(value)))
return buf, nil
}
////////////////////////////////////////
// Text Decode
////////////////////////////////////////
func doubleNativeFromTextual(buf []byte) (interface{}, []byte, error) {
return floatingTextDecoder(buf, 64)
}
func floatNativeFromTextual(buf []byte) (interface{}, []byte, error) {
return floatingTextDecoder(buf, 32)
}
func floatingTextDecoder(buf []byte, bitSize int) (interface{}, []byte, error) {
buflen := len(buf)
if buflen >= 4 {
if bytes.Equal(buf[:4], []byte("null")) {
return math.NaN(), buf[4:], nil
}
if buflen >= 5 {
if bytes.Equal(buf[:5], []byte("1e999")) {
return math.Inf(1), buf[5:], nil
}
if buflen >= 6 {
if bytes.Equal(buf[:6], []byte("-1e999")) {
return math.Inf(-1), buf[6:], nil
}
}
}
}
index, err := numberLength(buf, true) // NOTE: floatAllowed = true
if err != nil {
return nil, nil, err
}
datum, err := strconv.ParseFloat(string(buf[:index]), bitSize)
if err != nil {
return nil, nil, err
}
if bitSize == 32 {
return float32(datum), buf[index:], nil
}
return datum, buf[index:], nil
}
func numberLength(buf []byte, floatAllowed bool) (int, error) {
// ALGORITHM: increment index as long as bytes are valid for number state engine.
var index, buflen, count int
var b byte
// STATE 0: begin, optional: -
if buflen = len(buf); index == buflen {
return 0, io.ErrShortBuffer
}
if buf[index] == '-' {
if index++; index == buflen {
return 0, io.ErrShortBuffer
}
}
// STATE 1: if 0, goto 2; otherwise if 1-9, goto 3; otherwise bail
if b = buf[index]; b == '0' {
if index++; index == buflen {
return index, nil // valid number
}
} else if b >= '1' && b <= '9' {
if index++; index == buflen {
return index, nil // valid number
}
// STATE 3: absorb zero or more digits
for {
if b = buf[index]; b < '0' || b > '9' {
break
}
if index++; index == buflen {
return index, nil // valid number
}
}
} else {
return 0, fmt.Errorf("unexpected byte: %q", b)
}
if floatAllowed {
// STATE 2: if ., goto 4; otherwise goto 5
if buf[index] == '.' {
if index++; index == buflen {
return 0, io.ErrShortBuffer
}
// STATE 4: absorb one or more digits
for {
if b = buf[index]; b < '0' || b > '9' {
break
}
count++
if index++; index == buflen {
return index, nil // valid number
}
}
if count == 0 {
// did not get at least one digit
return 0, fmt.Errorf("unexpected byte: %q", b)
}
}
// STATE 5: if e|e, goto 6; otherwise goto 7
if b = buf[index]; b == 'e' || b == 'E' {
if index++; index == buflen {
return 0, io.ErrShortBuffer
}
// STATE 6: if -|+, goto 8; otherwise goto 8
if b = buf[index]; b == '+' || b == '-' {
if index++; index == buflen {
return 0, io.ErrShortBuffer
}
}
// STATE 8: absorb one or more digits
count = 0
for {
if b = buf[index]; b < '0' || b > '9' {
break
}
count++
if index++; index == buflen {
return index, nil // valid number
}
}
if count == 0 {
// did not get at least one digit
return 0, fmt.Errorf("unexpected byte: %q", b)
}
}
}
// STATE 7: end
return index, nil
}
////////////////////////////////////////
// Text Encode
////////////////////////////////////////
func floatTextualFromNative(buf []byte, datum interface{}) ([]byte, error) {
return floatingTextEncoder(buf, datum, 32)
}
func doubleTextualFromNative(buf []byte, datum interface{}) ([]byte, error) {
return floatingTextEncoder(buf, datum, 64)
}
func floatingTextEncoder(buf []byte, datum interface{}, bitSize int) ([]byte, error) {
var isFloat bool
var someFloat64 float64
var someInt64 int64
switch v := datum.(type) {
case float32:
isFloat = true
someFloat64 = float64(v)
case float64:
isFloat = true
someFloat64 = v
case int:
if someInt64 = int64(v); int(someInt64) != v {
if bitSize == 64 {
return nil, fmt.Errorf("cannot encode textual double: provided Go int would lose precision: %d", v)
}
return nil, fmt.Errorf("cannot encode textual float: provided Go int would lose precision: %d", v)
}
case int64:
someInt64 = v
case int32:
if someInt64 = int64(v); int32(someInt64) != v {
if bitSize == 64 {
return nil, fmt.Errorf("cannot encode textual double: provided Go int32 would lose precision: %d", v)
}
return nil, fmt.Errorf("cannot encode textual float: provided Go int32 would lose precision: %d", v)
}
default:
if bitSize == 64 {
return nil, fmt.Errorf("cannot encode textual double: expected: Go numeric; received: %T", datum)
}
return nil, fmt.Errorf("cannot encode textual float: expected: Go numeric; received: %T", datum)
}
if isFloat {
if math.IsNaN(someFloat64) {
return append(buf, "null"...), nil
}
if math.IsInf(someFloat64, 1) {
return append(buf, "1e999"...), nil
}
if math.IsInf(someFloat64, -1) {
return append(buf, "-1e999"...), nil
}
return strconv.AppendFloat(buf, someFloat64, 'g', -1, bitSize), nil
}
return strconv.AppendInt(buf, someInt64, 10), nil
}
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