forked from grafana/jfr-parser
/
reader.go
154 lines (133 loc) · 2.81 KB
/
reader.go
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package parser
import (
"encoding/binary"
"errors"
"fmt"
"io"
reader2 "github.com/GuanceCloud/jfr-parser/reader"
)
type Reader interface {
Boolean() (bool, error)
Byte() (int8, error)
Short() (int16, error)
Char() (uint16, error)
Int() (int32, error)
Long() (int64, error)
Float() (float32, error)
Double() (float64, error)
String(pool *CPool) (string, error)
reader2.VarReader
// TODO: Support arrays
}
type InputReader interface {
io.Reader
io.ByteReader
}
type reader struct {
InputReader
varR reader2.VarReader
}
func NewReader(r InputReader, compressed bool) Reader {
var varR reader2.VarReader
if compressed {
varR = reader2.NewCompressed(r)
} else {
varR = reader2.NewUncompressed(r)
}
return reader{
InputReader: r,
varR: varR,
}
}
func (r reader) Boolean() (bool, error) {
var n int8
err := binary.Read(r, binary.BigEndian, &n)
if n == 0 {
return false, err
}
return true, err
}
func (r reader) Byte() (int8, error) {
var n int8
err := binary.Read(r, binary.BigEndian, &n)
return n, err
}
func (r reader) Short() (int16, error) {
return reader2.Short(r)
}
func (r reader) Char() (uint16, error) {
var n uint16
err := binary.Read(r, binary.BigEndian, &n)
return n, err
}
func (r reader) Int() (int32, error) {
return reader2.Int(r)
}
func (r reader) Long() (int64, error) {
return reader2.Long(r)
}
func (r reader) Float() (float32, error) {
var n float32
err := binary.Read(r, binary.BigEndian, &n)
return n, err
}
func (r reader) Double() (float64, error) {
var n float64
err := binary.Read(r, binary.BigEndian, &n)
return n, err
}
// TODO: Should we differentiate between null and empty?
func (r reader) String(pool *CPool) (string, error) {
enc, err := r.Byte()
if err != nil {
return "", err
}
switch enc {
case 0:
return "", nil
case 1:
return "", nil
case 2: // constant pool reference
idx, err := r.VarLong()
if err != nil {
fmt.Printf("get constant refrence idx fail: %s\n", err)
return "", err
}
if pool == nil {
return "", errors.New("the string constant pool is nil")
}
v, ok := pool.Pool[int(idx)]
if !ok {
return "", fmt.Errorf("string not found in the pool")
}
str, ok := v.(*String)
if !ok {
return "", fmt.Errorf("not type of parser.String")
}
return string(*str), nil
case 3, 4, 5:
return r.utf8()
default:
// TODO
return "", fmt.Errorf("Unsupported string type :%d", enc)
}
}
func (r reader) VarShort() (int16, error) {
return r.varR.VarShort()
}
func (r reader) VarInt() (int32, error) {
return r.varR.VarInt()
}
func (r reader) VarLong() (int64, error) {
return r.varR.VarLong()
}
func (r reader) utf8() (string, error) {
n, err := r.varR.VarInt()
if err != nil {
return "", nil
}
// TODO: make sure n is reasonable
b := make([]byte, n)
_, err = io.ReadFull(r, b)
return string(b), err
}