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attributes.go
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attributes.go
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package document
import (
"bytes"
"encoding/json"
"fmt"
"io"
"slices"
"strings"
"go.uber.org/multierr"
)
type Attributes map[string]string
type attributeParser interface {
Parse(raw []byte) (Attributes, error)
Write(attr Attributes, w io.Writer) error
}
// Original attribute language used by runme prior to v1.3.0
//
// Only supports strings, and does not support spaces. Example:
//
// { key=value hello=world string_value=2 }
//
// Pioneered by Adam Babik
type babikMLParser struct{}
func (p *babikMLParser) Parse(raw []byte) (Attributes, error) {
return p.parseRawAttributes(p.rawAttributes(raw)), nil
}
func (*babikMLParser) parseRawAttributes(source []byte) map[string]string {
items := bytes.Split(source, []byte{' '})
if len(items) == 0 {
return nil
}
result := make(map[string]string)
for _, item := range items {
if !bytes.Contains(item, []byte{'='}) {
continue
}
kv := bytes.Split(item, []byte{'='})
result[string(kv[0])] = string(kv[1])
}
return result
}
func (*babikMLParser) rawAttributes(source []byte) []byte {
start, stop := -1, -1
for i := 0; i < len(source); i++ {
if start == -1 && source[i] == '{' && i+1 < len(source) && source[i+1] != '}' {
start = i + 1
}
if stop == -1 && source[i] == '}' {
stop = i
break
}
}
if start >= 0 && stop >= 0 {
return bytes.TrimSpace(source[start:stop])
}
return nil
}
func sortedAttrs(attr Attributes) []string {
keys := make([]string, 0, len(attr))
for k := range attr {
keys = append(keys, k)
}
if len(keys) == 0 {
return nil
}
// Sort attributes by key, however, keep the element
// with the key "name" in front.
slices.SortFunc(keys, func(a, b string) int {
if a == "name" {
return -1
}
if b == "name" {
return 1
}
return strings.Compare(a, b)
})
return keys
}
func (*babikMLParser) Write(attr Attributes, w io.Writer) error {
keys := sortedAttrs(attr)
_, _ = w.Write([]byte{'{', ' '})
i := 0
for _, k := range keys {
v := attr[k]
_, _ = w.Write([]byte(fmt.Sprintf("%s=%v", k, v)))
i++
if i < len(keys) {
_, _ = w.Write([]byte{' '})
}
}
_, _ = w.Write([]byte{' ', '}'})
return nil
}
// JSON parser
//
// Example:
//
// { key: "value", hello: "world", string_value: "2" }
type jsonParser struct{}
func (p *jsonParser) Parse(raw []byte) (Attributes, error) {
bytes := raw
parsedAttr := make(map[string]interface{})
if err := json.Unmarshal(bytes, &parsedAttr); err != nil {
return nil, err
}
attr := make(Attributes, len(parsedAttr))
for k, v := range parsedAttr {
if strVal, ok := v.(string); ok {
attr[k] = strVal
} else {
if stringified, err := json.Marshal(v); err == nil {
attr[k] = string(stringified)
}
}
}
return attr, nil
}
func (p *jsonParser) Write(attr Attributes, w io.Writer) error {
// TODO: name at front...
res, err := json.Marshal(attr)
if err != nil {
return err
}
res = bytes.TrimSpace(res)
_, _ = w.Write(res)
return nil
}
// Tries to parse attributes in sequence, until it finds a non-failing parser
type failoverAttributeParser struct {
parsers []attributeParser
writer attributeParser
}
func newFailoverAttributeParser(parsers []attributeParser, writer attributeParser) *failoverAttributeParser {
return &failoverAttributeParser{
parsers,
writer,
}
}
func (p *failoverAttributeParser) Parse(raw []byte) (attr Attributes, finalErr error) {
for _, parser := range p.parsers {
attr, err := parser.Parse(raw)
if err == nil {
return attr, nil
}
finalErr = multierr.Append(finalErr, err)
}
return
}
func (p *failoverAttributeParser) Write(attr Attributes, w io.Writer) error {
return p.writer.Write(attr, w)
}
var DefaultDocumentParser = newFailoverAttributeParser(
[]attributeParser{
&jsonParser{},
&babikMLParser{},
},
&jsonParser{},
)