mknode.go

// +build ignore

package main

import (
	"bytes"
	"fmt"
	"go/format"
	"go/types"
	"io/ioutil"
	"log"

	"golang.org/x/tools/go/packages"
)

func main() {
	cfg := &packages.Config{
		Mode: packages.NeedSyntax | packages.NeedTypes,
	}
	pkgs, err := packages.Load(cfg, "cmd/compile/internal/ir")
	if err != nil {
		log.Fatal(err)
	}

	pkg := pkgs[0].Types
	scope := pkg.Scope()

	lookup := func(name string) *types.Named {
		return scope.Lookup(name).(*types.TypeName).Type().(*types.Named)
	}

	nodeType := lookup("Node")
	ntypeType := lookup("Ntype")
	nodesType := lookup("Nodes")
	ptrFieldType := types.NewPointer(lookup("Field"))
	slicePtrFieldType := types.NewSlice(ptrFieldType)

	var buf bytes.Buffer
	fmt.Fprintln(&buf, "// Code generated by mknode.go. DO NOT EDIT.")
	fmt.Fprintln(&buf)
	fmt.Fprintln(&buf, "package ir")
	fmt.Fprintln(&buf)
	fmt.Fprintln(&buf, `import "fmt"`)

	for _, name := range scope.Names() {
		obj, ok := scope.Lookup(name).(*types.TypeName)
		if !ok {
			continue
		}

		if !types.Implements(types.NewPointer(obj.Type()), nodeType.Underlying().(*types.Interface)) {
			continue
		}

		typ := obj.Type().(*types.Named).Underlying().(*types.Struct)

		fmt.Fprintf(&buf, "\n")
		fmt.Fprintf(&buf, "func (n *%s) String() string { return fmt.Sprint(n) }\n", name)
		fmt.Fprintf(&buf, "func (n *%s) Format(s fmt.State, verb rune) { FmtNode(n, s, verb) }\n", name)

		fmt.Fprintf(&buf, "func (n *%s) copy() Node { c := *n\n", name)
		inspectFields(typ, func(name string, is func(types.Type) bool) {
			switch {
			case is(nodesType):
				fmt.Fprintf(&buf, "c.%s = c.%s.Copy()\n", name, name)
			case is(ptrFieldType):
				fmt.Fprintf(&buf, "if c.%s != nil { c.%s = c.%s.copy() }\n", name, name, name)
			case is(slicePtrFieldType):
				fmt.Fprintf(&buf, "c.%s = copyFields(c.%s)\n", name, name)
			}
		})
		fmt.Fprintf(&buf, "return &c }\n")

		fmt.Fprintf(&buf, "func (n *%s) doChildren(do func(Node) error) error { var err error\n", name)
		inspectFields(typ, func(name string, is func(types.Type) bool) {
			switch {
			case is(nodeType), is(ntypeType):
				fmt.Fprintf(&buf, "err = maybeDo(n.%s, err, do)\n", name)
			case is(nodesType):
				fmt.Fprintf(&buf, "err = maybeDoList(n.%s, err, do)\n", name)
			case is(ptrFieldType):
				fmt.Fprintf(&buf, "err = maybeDoField(n.%s, err, do)\n", name)
			case is(slicePtrFieldType):
				fmt.Fprintf(&buf, "err = maybeDoFields(n.%s, err, do)\n", name)
			}
		})
		fmt.Fprintf(&buf, "return err }\n")

		fmt.Fprintf(&buf, "func (n *%s) editChildren(edit func(Node) Node) {\n", name)
		inspectFields(typ, func(name string, is func(types.Type) bool) {
			switch {
			case is(nodeType):
				fmt.Fprintf(&buf, "n.%s = maybeEdit(n.%s, edit)\n", name, name)
			case is(ntypeType):
				fmt.Fprintf(&buf, "n.%s = toNtype(maybeEdit(n.%s, edit))\n", name, name)
			case is(nodesType):
				fmt.Fprintf(&buf, "editList(n.%s, edit)\n", name)
			case is(ptrFieldType):
				fmt.Fprintf(&buf, "editField(n.%s, edit)\n", name)
			case is(slicePtrFieldType):
				fmt.Fprintf(&buf, "editFields(n.%s, edit)\n", name)
			}
		})
		fmt.Fprintf(&buf, "}\n")
	}

	out, err := format.Source(buf.Bytes())
	if err != nil {
		log.Fatal(err)
	}

	err = ioutil.WriteFile("gen.go", out, 0666)
	if err != nil {
		log.Fatal(err)
	}
}

func inspectFields(typ *types.Struct, f func(name string, is func(types.Type) bool)) {
	for i, n := 0, typ.NumFields(); i < n; i++ {
		v := typ.Field(i)
		if v.Embedded() {
			if typ, ok := v.Type().Underlying().(*types.Struct); ok {
				inspectFields(typ, f)
				continue
			}
		}
		f(v.Name(), func(t types.Type) bool { return types.Identical(t, v.Type()) })
	}
}