go-ethereum/libevm/cmd/internalise/main.go
Arran Schlosberg 43878f4fab
feat: internalise command (#90)
## Why this should be merged

Replaces #86. That approach couldn't be replicated for generated JSON
marshalling, and this once also reduces the upstream delta.

## How this works

AST manipulation of a specified file, which finds specified methods and
modifies their names to be unexported.

## How this was tested

Inspection of the output (`core/types/gen_header_rlp.go` remains
unchanged).
2024-12-17 17:20:02 +01:00

117 lines
3 KiB
Go

// Copyright 2024 the libevm authors.
//
// The libevm additions to go-ethereum are free software: you can redistribute
// them and/or modify them under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The libevm additions are distributed in the hope that they will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see
// <http://www.gnu.org/licenses/>.
// The internalise command modifies Go files in place, making exported methods
// internal.
//
// Usage:
//
// internalise -file <filepath> <type>.<method> [<type>.<method> [...]]
//
// For example, with file foo.go containing declarations:
//
// func (f *Foo) Bar() { ... }
//
// func (Foo) Baz() { ... }
//
// running
//
// internalise -file foo.go Foo.Bar Foo.Baz
//
// results in
//
// func (f *Foo) bar() { ... }
//
// func (Foo) baz() { ... }
package main
import (
"flag"
"fmt"
"go/ast"
"go/format"
"go/parser"
"go/token"
"os"
"strings"
)
func main() {
file := flag.String("file", "", "File to modify")
flag.Parse()
if err := run(*file, flag.Args()...); err != nil {
fmt.Fprint(os.Stderr, err)
os.Exit(1)
}
}
func run(fileName string, args ...string) error {
methods := make(map[string]map[string]struct{})
for _, a := range args {
a = strings.TrimPrefix(strings.TrimSpace(a), "*")
parts := strings.Split(a, ".")
if len(parts) != 2 {
return fmt.Errorf("invalid method identifier %q", a)
}
typ, fn := parts[0], parts[1]
if _, ok := methods[typ]; !ok {
methods[typ] = make(map[string]struct{})
}
methods[typ][fn] = struct{}{}
}
fset := token.NewFileSet()
mode := parser.SkipObjectResolution | parser.ParseComments
parsed, err := parser.ParseFile(fset, fileName, nil, mode)
if err != nil {
return fmt.Errorf("parser.ParseFile(%q): %v", fileName, err)
}
for _, d := range parsed.Decls {
fn, ok := d.(*ast.FuncDecl)
if !ok || fn.Recv.NumFields() != 1 {
continue
}
var typ string
switch t := fn.Recv.List[0].Type.(type) {
case *ast.Ident:
typ = t.Name
case *ast.StarExpr:
typ = t.X.(*ast.Ident).Name //nolint:forcetypeassert // Invariant of valid Go method
}
name := &fn.Name.Name
if _, ok := methods[typ][*name]; !ok {
continue
}
if n := []rune(*name); n[0] >= 'A' && n[0] <= 'Z' {
n[0] += 'a' - 'A'
*name = string(n)
}
}
// Since we're not creating, the zero perm/mode is ignored.
f, err := os.OpenFile(fileName, os.O_TRUNC|os.O_WRONLY, 0) //nolint:gosec // Variable file is under our direct control in go:generate
if err != nil {
return fmt.Errorf("os.OpenFile(%q, [write-only, truncate]): %v", fileName, err)
}
if err := format.Node(f, fset, parsed); err != nil {
return fmt.Errorf("format.Node(%T): %v", parsed, err)
}
return f.Close()
}