Add cdp support for xpath scrapers (#625)

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/mailru/easyjson/helpers.go

@@ -0,0 +1,88 @@
+// Package easyjson contains marshaler/unmarshaler interfaces and helper functions.
+package easyjson
+
+import (
+	"io"
+	"io/ioutil"
+	"net/http"
+	"strconv"
+
+	"github.com/mailru/easyjson/jlexer"
+	"github.com/mailru/easyjson/jwriter"
+)
+
+// Marshaler is an easyjson-compatible marshaler interface.
+type Marshaler interface {
+	MarshalEasyJSON(w *jwriter.Writer)
+}
+
+// Marshaler is an easyjson-compatible unmarshaler interface.
+type Unmarshaler interface {
+	UnmarshalEasyJSON(w *jlexer.Lexer)
+}
+
+// Optional defines an undefined-test method for a type to integrate with 'omitempty' logic.
+type Optional interface {
+	IsDefined() bool
+}
+
+// UnknownsUnmarshaler provides a method to unmarshal unknown struct fileds and save them as you want
+type UnknownsUnmarshaler interface {
+	UnmarshalUnknown(in *jlexer.Lexer, key string)
+}
+
+// UnknownsMarshaler provides a method to write additional struct fields
+type UnknownsMarshaler interface {
+	MarshalUnknowns(w *jwriter.Writer, first bool)
+}
+
+// Marshal returns data as a single byte slice. Method is suboptimal as the data is likely to be copied
+// from a chain of smaller chunks.
+func Marshal(v Marshaler) ([]byte, error) {
+	w := jwriter.Writer{}
+	v.MarshalEasyJSON(&w)
+	return w.BuildBytes()
+}
+
+// MarshalToWriter marshals the data to an io.Writer.
+func MarshalToWriter(v Marshaler, w io.Writer) (written int, err error) {
+	jw := jwriter.Writer{}
+	v.MarshalEasyJSON(&jw)
+	return jw.DumpTo(w)
+}
+
+// MarshalToHTTPResponseWriter sets Content-Length and Content-Type headers for the
+// http.ResponseWriter, and send the data to the writer. started will be equal to
+// false if an error occurred before any http.ResponseWriter methods were actually
+// invoked (in this case a 500 reply is possible).
+func MarshalToHTTPResponseWriter(v Marshaler, w http.ResponseWriter) (started bool, written int, err error) {
+	jw := jwriter.Writer{}
+	v.MarshalEasyJSON(&jw)
+	if jw.Error != nil {
+		return false, 0, jw.Error
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Content-Length", strconv.Itoa(jw.Size()))
+
+	started = true
+	written, err = jw.DumpTo(w)
+	return
+}
+
+// Unmarshal decodes the JSON in data into the object.
+func Unmarshal(data []byte, v Unmarshaler) error {
+	l := jlexer.Lexer{Data: data}
+	v.UnmarshalEasyJSON(&l)
+	return l.Error()
+}
+
+// UnmarshalFromReader reads all the data in the reader and decodes as JSON into the object.
+func UnmarshalFromReader(r io.Reader, v Unmarshaler) error {
+	data, err := ioutil.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	l := jlexer.Lexer{Data: data}
+	v.UnmarshalEasyJSON(&l)
+	return l.Error()
+}