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main.go
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main.go
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// MIT License
//
// Copyright (c) 2024 nohar
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
package main
import (
"flag"
"go/parser"
"go/token"
"html/template"
"log"
"os"
"path/filepath"
"strings"
)
var (
outFile = "zzz_errfuncs.go"
)
func init() {
log.SetOutput(os.Stderr)
log.SetFlags(0)
flag.CommandLine.SetOutput(os.Stderr)
flag.StringVar(&outFile, "out", outFile, "output `filename`")
flag.Usage = func() {
log.Printf("Usage:\n gen-errfuncs [-out <filename>] <src_file>\n\nOptions:\n")
flag.PrintDefaults()
}
flag.Parse()
}
func main() {
srcFile := flag.Arg(0)
if srcFile == "" {
flag.Usage()
log.Fatal("ERROR: missing src_file")
}
dstFile := filepath.Join(filepath.Dir(srcFile), outFile)
render(dstFile, parse(srcFile))
}
type fileSpec struct {
Package string
Errors []errSpec
}
type errSpec struct {
Name string
Radix string
}
func parse(path string) *fileSpec {
data, err := os.ReadFile(path)
if err != nil {
log.Fatal(err)
}
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, path, data, parser.ParseComments)
if err != nil {
log.Fatal(err)
}
spec := &fileSpec{
Package: file.Name.Name,
Errors: make([]errSpec, 0, 10),
}
for name := range file.Scope.Objects {
if radix, ok := strings.CutPrefix(name, "Err"); ok {
spec.Errors = append(spec.Errors, errSpec{name, radix})
}
}
return spec
}
const tplData = `//go:build !ignore_autogenerated
// +build !ignore_autogenerated
// This file was generated by gen-errfuncs. DO NOT EDIT.
package {{.Package}}
import (
"errors"
"fmt"
)
{{ range .Errors }}
func {{ .Radix }}(err error) error {
return errors.Join({{ .Name }}, err)
}
func {{ .Radix }}f(msg string, args ...any) error {
return fmt.Errorf("%w: %s", {{ .Name }}, fmt.Sprintf(msg, args...))
}
{{ end }}`
func render(path string, spec *fileSpec) {
out, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
if err != nil {
log.Fatalf("couldn't open %s: %s", path, err)
}
template.Must(template.New(path).Parse(tplData)).Execute(out, spec)
}