/
main.go
126 lines (114 loc) · 2.92 KB
/
main.go
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// Copyright (c) 2017 David R. Jenni. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Fixplurals removes redundant parameter and result types
// from function signatures.
//
// For example, the following function signature:
// func fun(a string, b string) (c string, d string)
// becomes:
// func fun(a, b string) (c, d string)
// after applying fixplurals.
//
// Usage:
//
// % fixplurals [-dry] packages
//
// Flags:
//
// -dry: changes are printed to stdout instead of rewriting the source files
//
package main
import (
"bytes"
"flag"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"go/types"
"io/ioutil"
"log"
"github.com/kisielk/gotool"
"golang.org/x/tools/go/loader"
)
func main() {
log.SetFlags(0)
log.SetPrefix("fixplurals: ")
dryRun := flag.Bool("dry", false, "dry run: print changes to stdout")
flag.Parse()
importPaths := gotool.ImportPaths(flag.Args())
if len(importPaths) == 0 {
return
}
conf := loader.Config{ParserMode: parser.ParseComments}
for _, importPath := range importPaths {
conf.ImportWithTests(importPath)
}
prog, err := conf.Load()
if err != nil {
log.Fatal(err)
}
for _, pkg := range prog.InitialPackages() {
for _, file := range pkg.Files {
filename := conf.Fset.File(file.Pos()).Name()
ast.Inspect(file, func(node ast.Node) bool {
if f, ok := node.(*ast.FuncDecl); ok {
var before []byte
if *dryRun {
if before, err = printNode(f.Type, prog.Fset); err != nil {
log.Fatal(err)
}
}
ch1 := fixPlurals(pkg.Info, f.Type.Params)
ch2 := fixPlurals(pkg.Info, f.Type.Results)
if ch1 || ch2 {
if *dryRun {
after, err := printNode(f.Type, prog.Fset)
if err != nil {
log.Fatal(err)
}
fmt.Printf("--- %s\nbefore: %s\nafter: %s\n\n", filename, string(before), string(after))
} else {
src, err := printNode(file, prog.Fset)
if err != nil {
log.Fatal(err)
}
if err := ioutil.WriteFile(filename, src, 0644); err != nil {
log.Fatal(err)
}
}
}
}
return true
})
}
}
}
func printNode(n ast.Node, fset *token.FileSet) ([]byte, error) {
var buf bytes.Buffer
if err := format.Node(&buf, fset, n); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func fixPlurals(info types.Info, fields *ast.FieldList) (changed bool) {
if fields == nil || fields.List == nil {
return
}
var prev *ast.Field
for i := len(fields.List) - 1; i >= 0; i-- {
field := fields.List[i]
if i != len(fields.List)-1 && len(field.Names) > 0 && types.Identical(info.Types[prev.Type].Type, info.Types[field.Type].Type) {
prev.Names = append(field.Names, prev.Names...)
copy(fields.List[i:], fields.List[i+1:])
fields.List[len(fields.List)-1] = nil
fields.List = fields.List[:len(fields.List)-1]
changed = true
} else {
prev = field
}
}
return changed
}