add script for generating error constants

go.mod

@@ -0,0 +1 @@
+module scripts/errors-const/

scripts/errors-const/main.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"regexp"
+	"sort"
+	"strings"
+	"text/template"
+)
+
+type options struct {
+	jsonSource string
+	template   string
+	output     string
+}
+
+const version = "0.1.0"
+
+func main() {
+	o := &options{}
+	flag.StringVar(&o.jsonSource, "json", "", `path to the ably-common/protocol/errors.json`)
+	flag.StringVar(&o.template, "t", "", "path to the template file")
+	flag.StringVar(&o.output, "o", "", "file to write output")
+	flag.Parse()
+	if o.jsonSource == "" {
+		flag.PrintDefaults()
+		return
+	}
+	if o.template == "" {
+		fmt.Println("[error] missing -t flag")
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+	tplData, err := ioutil.ReadFile(o.template)
+	if err != nil {
+		log.Fatal(err)
+	}
+	var out io.Writer
+	if o.output != "" {
+		f, err := os.Open(o.output)
+		if err != nil {
+			log.Fatal(err)
+		}
+		defer f.Close()
+		out = f
+	} else {
+		out = os.Stdout
+	}
+	f, err := ioutil.ReadFile(o.jsonSource)
+	if err != nil {
+		log.Fatal(err)
+	}
+	re := regexp.MustCompile(`\/\*([\s\S]*?)\*\/`)
+
+	// we remove the multiline comments
+	f = re.ReplaceAll(f, []byte{})
+	m := make(map[int]string)
+	err = json.Unmarshal(f, &m)
+	if err != nil {
+		log.Fatal(err)
+	}
+	var keys []int
+	for k := range m {
+		keys = append(keys, k)
+	}
+	sort.Ints(keys)
+	tpl, err := template.New("errors").Funcs(template.FuncMap{
+		"key": func(k int) string {
+			return m[k]
+		},
+		"normalize": normalize,
+		"split": func(a, b string) []string {
+			return strings.Split(b, a)
+		},
+		"join": func(sep string, v []string) string {
+			return strings.Join(v, sep)
+		},
+		"title": func(v []string) []string {
+			for k := range v {
+				v[k] = strings.Title(v[k])
+			}
+			return v
+		},
+	}).Parse(string(tplData))
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = tpl.Execute(out, map[string]interface{}{
+		"codes":   keys,
+		"version": version,
+	})
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func normalize(v string) string {
+	idx := strings.Index(v, ")")
+	if idx != -1 {
+		v = v[:idx]
+		v = strings.Replace(v, "(", " ", -1)
+		v = strings.Replace(v, ")", " ", -1)
+	}
+	v = strings.Replace(v, "-", " ", -1)
+	return v
+}

scripts/errors-const/templates/go.tpl

@@ -0,0 +1,10 @@
+// Code generated by errors-const v{{.version}} tool DO NOT EDIT.
+
+package ably
+
+// ably error codes
+const(
+	{{- range .codes}}
+	Err{{key .|normalize|split " "|title|join ""}} = {{.}}
+	{{- end}}
+)