build: separate compiler and libs
This commit is contained in:
Li Jie
218
compiler/internal/typeparams/normalize.go
Normal file
218
compiler/internal/typeparams/normalize.go
Normal file
@@ -0,0 +1,218 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package typeparams
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import (
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"errors"
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"fmt"
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"go/types"
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"os"
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"strings"
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)
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//go:generate go run copytermlist.go
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const debug = false
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var ErrEmptyTypeSet = errors.New("empty type set")
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// StructuralTerms returns a slice of terms representing the normalized
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// structural type restrictions of a type parameter, if any.
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//
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// Structural type restrictions of a type parameter are created via
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// non-interface types embedded in its constraint interface (directly, or via a
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// chain of interface embeddings). For example, in the declaration
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//
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// type T[P interface{~int; m()}] int
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//
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// the structural restriction of the type parameter P is ~int.
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//
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// With interface embedding and unions, the specification of structural type
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// restrictions may be arbitrarily complex. For example, consider the
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// following:
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//
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// type A interface{ ~string|~[]byte }
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//
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// type B interface{ int|string }
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//
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// type C interface { ~string|~int }
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//
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// type T[P interface{ A|B; C }] int
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//
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// In this example, the structural type restriction of P is ~string|int: A|B
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// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int,
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// which when intersected with C (~string|~int) yields ~string|int.
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//
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// StructuralTerms computes these expansions and reductions, producing a
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// "normalized" form of the embeddings. A structural restriction is normalized
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// if it is a single union containing no interface terms, and is minimal in the
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// sense that removing any term changes the set of types satisfying the
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// constraint. It is left as a proof for the reader that, modulo sorting, there
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// is exactly one such normalized form.
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//
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// Because the minimal representation always takes this form, StructuralTerms
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// returns a slice of tilde terms corresponding to the terms of the union in
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// the normalized structural restriction. An error is returned if the
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// constraint interface is invalid, exceeds complexity bounds, or has an empty
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// type set. In the latter case, StructuralTerms returns ErrEmptyTypeSet.
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//
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// StructuralTerms makes no guarantees about the order of terms, except that it
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// is deterministic.
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func StructuralTerms(tparam *types.TypeParam) ([]*types.Term, error) {
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constraint := tparam.Constraint()
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if constraint == nil {
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return nil, fmt.Errorf("%s has nil constraint", tparam)
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}
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iface, _ := constraint.Underlying().(*types.Interface)
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if iface == nil {
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return nil, fmt.Errorf("constraint is %T, not *types.Interface", constraint.Underlying())
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}
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return InterfaceTermSet(iface)
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}
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// InterfaceTermSet computes the normalized terms for a constraint interface,
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// returning an error if the term set cannot be computed or is empty. In the
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// latter case, the error will be ErrEmptyTypeSet.
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//
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// See the documentation of StructuralTerms for more information on
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// normalization.
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func InterfaceTermSet(iface *types.Interface) ([]*types.Term, error) {
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return computeTermSet(iface)
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}
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// UnionTermSet computes the normalized terms for a union, returning an error
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// if the term set cannot be computed or is empty. In the latter case, the
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// error will be ErrEmptyTypeSet.
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//
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// See the documentation of StructuralTerms for more information on
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// normalization.
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func UnionTermSet(union *types.Union) ([]*types.Term, error) {
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return computeTermSet(union)
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}
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func computeTermSet(typ types.Type) ([]*types.Term, error) {
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tset, err := computeTermSetInternal(typ, make(map[types.Type]*termSet), 0)
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if err != nil {
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return nil, err
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}
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if tset.terms.isEmpty() {
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return nil, ErrEmptyTypeSet
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}
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if tset.terms.isAll() {
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return nil, nil
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}
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var terms []*types.Term
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for _, term := range tset.terms {
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terms = append(terms, types.NewTerm(term.tilde, term.typ))
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}
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return terms, nil
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}
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// A termSet holds the normalized set of terms for a given type.
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//
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// The name termSet is intentionally distinct from 'type set': a type set is
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// all types that implement a type (and includes method restrictions), whereas
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// a term set just represents the structural restrictions on a type.
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type termSet struct {
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complete bool
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terms termlist
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}
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func indentf(depth int, format string, args ...interface{}) {
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fmt.Fprintf(os.Stderr, strings.Repeat(".", depth)+format+"\n", args...)
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}
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func computeTermSetInternal(t types.Type, seen map[types.Type]*termSet, depth int) (res *termSet, err error) {
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if t == nil {
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panic("nil type")
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}
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if debug {
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indentf(depth, "%s", t.String())
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defer func() {
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if err != nil {
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indentf(depth, "=> %s", err)
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} else {
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indentf(depth, "=> %s", res.terms.String())
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}
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}()
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}
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const maxTermCount = 100
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if tset, ok := seen[t]; ok {
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if !tset.complete {
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return nil, fmt.Errorf("cycle detected in the declaration of %s", t)
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}
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return tset, nil
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}
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// Mark the current type as seen to avoid infinite recursion.
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tset := new(termSet)
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defer func() {
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tset.complete = true
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}()
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seen[t] = tset
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switch u := t.Underlying().(type) {
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case *types.Interface:
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// The term set of an interface is the intersection of the term sets of its
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// embedded types.
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tset.terms = allTermlist
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for i := 0; i < u.NumEmbeddeds(); i++ {
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embedded := u.EmbeddedType(i)
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if _, ok := embedded.Underlying().(*types.TypeParam); ok {
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return nil, fmt.Errorf("invalid embedded type %T", embedded)
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}
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tset2, err := computeTermSetInternal(embedded, seen, depth+1)
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if err != nil {
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return nil, err
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}
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tset.terms = tset.terms.intersect(tset2.terms)
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}
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case *types.Union:
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// The term set of a union is the union of term sets of its terms.
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tset.terms = nil
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for i := 0; i < u.Len(); i++ {
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t := u.Term(i)
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var terms termlist
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switch t.Type().Underlying().(type) {
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case *types.Interface:
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tset2, err := computeTermSetInternal(t.Type(), seen, depth+1)
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if err != nil {
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return nil, err
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}
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terms = tset2.terms
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case *types.TypeParam, *types.Union:
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// A stand-alone type parameter or union is not permitted as union
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// term.
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return nil, fmt.Errorf("invalid union term %T", t)
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default:
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if t.Type() == types.Typ[types.Invalid] {
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continue
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}
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terms = termlist{{t.Tilde(), t.Type()}}
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}
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tset.terms = tset.terms.union(terms)
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if len(tset.terms) > maxTermCount {
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return nil, fmt.Errorf("exceeded max term count %d", maxTermCount)
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}
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}
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case *types.TypeParam:
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panic("unreachable")
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default:
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// For all other types, the term set is just a single non-tilde term
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// holding the type itself.
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if u != types.Typ[types.Invalid] {
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tset.terms = termlist{{false, t}}
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}
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}
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return tset, nil
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}
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// under is a facade for the go/types internal function of the same name. It is
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// used by typeterm.go.
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func under(t types.Type) types.Type {
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return t.Underlying()
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}
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163
compiler/internal/typeparams/termlist.go
Normal file
163
compiler/internal/typeparams/termlist.go
Normal file
@@ -0,0 +1,163 @@
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// Copyright 2021 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Code generated by copytermlist.go DO NOT EDIT.
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package typeparams
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import (
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"bytes"
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"go/types"
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)
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// A termlist represents the type set represented by the union
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// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
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// A termlist is in normal form if all terms are disjoint.
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// termlist operations don't require the operands to be in
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// normal form.
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type termlist []*term
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// allTermlist represents the set of all types.
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// It is in normal form.
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var allTermlist = termlist{new(term)}
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// String prints the termlist exactly (without normalization).
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func (xl termlist) String() string {
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if len(xl) == 0 {
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return "∅"
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}
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var buf bytes.Buffer
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for i, x := range xl {
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if i > 0 {
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buf.WriteString(" | ")
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}
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buf.WriteString(x.String())
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}
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return buf.String()
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}
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// isEmpty reports whether the termlist xl represents the empty set of types.
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func (xl termlist) isEmpty() bool {
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// If there's a non-nil term, the entire list is not empty.
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// If the termlist is in normal form, this requires at most
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// one iteration.
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for _, x := range xl {
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if x != nil {
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return false
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}
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}
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return true
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}
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// isAll reports whether the termlist xl represents the set of all types.
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func (xl termlist) isAll() bool {
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// If there's a 𝓤 term, the entire list is 𝓤.
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// If the termlist is in normal form, this requires at most
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// one iteration.
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for _, x := range xl {
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if x != nil && x.typ == nil {
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return true
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}
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}
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return false
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}
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// norm returns the normal form of xl.
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func (xl termlist) norm() termlist {
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// Quadratic algorithm, but good enough for now.
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// TODO(gri) fix asymptotic performance
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used := make([]bool, len(xl))
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var rl termlist
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for i, xi := range xl {
|
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if xi == nil || used[i] {
|
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continue
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||||
}
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for j := i + 1; j < len(xl); j++ {
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xj := xl[j]
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if xj == nil || used[j] {
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continue
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}
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if u1, u2 := xi.union(xj); u2 == nil {
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// If we encounter a 𝓤 term, the entire list is 𝓤.
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// Exit early.
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// (Note that this is not just an optimization;
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// if we continue, we may end up with a 𝓤 term
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// and other terms and the result would not be
|
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// in normal form.)
|
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if u1.typ == nil {
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return allTermlist
|
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}
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xi = u1
|
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used[j] = true // xj is now unioned into xi - ignore it in future iterations
|
||||
}
|
||||
}
|
||||
rl = append(rl, xi)
|
||||
}
|
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return rl
|
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}
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|
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// union returns the union xl ∪ yl.
|
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func (xl termlist) union(yl termlist) termlist {
|
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return append(xl, yl...).norm()
|
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}
|
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|
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// intersect returns the intersection xl ∩ yl.
|
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func (xl termlist) intersect(yl termlist) termlist {
|
||||
if xl.isEmpty() || yl.isEmpty() {
|
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return nil
|
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}
|
||||
|
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// Quadratic algorithm, but good enough for now.
|
||||
// TODO(gri) fix asymptotic performance
|
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var rl termlist
|
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for _, x := range xl {
|
||||
for _, y := range yl {
|
||||
if r := x.intersect(y); r != nil {
|
||||
rl = append(rl, r)
|
||||
}
|
||||
}
|
||||
}
|
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return rl.norm()
|
||||
}
|
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|
||||
// equal reports whether xl and yl represent the same type set.
|
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func (xl termlist) equal(yl termlist) bool {
|
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// TODO(gri) this should be more efficient
|
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return xl.subsetOf(yl) && yl.subsetOf(xl)
|
||||
}
|
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|
||||
// includes reports whether t ∈ xl.
|
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func (xl termlist) includes(t types.Type) bool {
|
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for _, x := range xl {
|
||||
if x.includes(t) {
|
||||
return true
|
||||
}
|
||||
}
|
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return false
|
||||
}
|
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|
||||
// supersetOf reports whether y ⊆ xl.
|
||||
func (xl termlist) supersetOf(y *term) bool {
|
||||
for _, x := range xl {
|
||||
if y.subsetOf(x) {
|
||||
return true
|
||||
}
|
||||
}
|
||||
return false
|
||||
}
|
||||
|
||||
// subsetOf reports whether xl ⊆ yl.
|
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func (xl termlist) subsetOf(yl termlist) bool {
|
||||
if yl.isEmpty() {
|
||||
return xl.isEmpty()
|
||||
}
|
||||
|
||||
// each term x of xl must be a subset of yl
|
||||
for _, x := range xl {
|
||||
if !yl.supersetOf(x) {
|
||||
return false // x is not a subset yl
|
||||
}
|
||||
}
|
||||
return true
|
||||
}
|
||||
169
compiler/internal/typeparams/typeterm.go
Normal file
169
compiler/internal/typeparams/typeterm.go
Normal file
@@ -0,0 +1,169 @@
|
||||
// Copyright 2021 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// Code generated by copytermlist.go DO NOT EDIT.
|
||||
|
||||
package typeparams
|
||||
|
||||
import "go/types"
|
||||
|
||||
// A term describes elementary type sets:
|
||||
//
|
||||
// ∅: (*term)(nil) == ∅ // set of no types (empty set)
|
||||
// 𝓤: &term{} == 𝓤 // set of all types (𝓤niverse)
|
||||
// T: &term{false, T} == {T} // set of type T
|
||||
// ~t: &term{true, t} == {t' | under(t') == t} // set of types with underlying type t
|
||||
type term struct {
|
||||
tilde bool // valid if typ != nil
|
||||
typ types.Type
|
||||
}
|
||||
|
||||
func (x *term) String() string {
|
||||
switch {
|
||||
case x == nil:
|
||||
return "∅"
|
||||
case x.typ == nil:
|
||||
return "𝓤"
|
||||
case x.tilde:
|
||||
return "~" + x.typ.String()
|
||||
default:
|
||||
return x.typ.String()
|
||||
}
|
||||
}
|
||||
|
||||
// equal reports whether x and y represent the same type set.
|
||||
func (x *term) equal(y *term) bool {
|
||||
// easy cases
|
||||
switch {
|
||||
case x == nil || y == nil:
|
||||
return x == y
|
||||
case x.typ == nil || y.typ == nil:
|
||||
return x.typ == y.typ
|
||||
}
|
||||
// ∅ ⊂ x, y ⊂ 𝓤
|
||||
|
||||
return x.tilde == y.tilde && types.Identical(x.typ, y.typ)
|
||||
}
|
||||
|
||||
// union returns the union x ∪ y: zero, one, or two non-nil terms.
|
||||
func (x *term) union(y *term) (_, _ *term) {
|
||||
// easy cases
|
||||
switch {
|
||||
case x == nil && y == nil:
|
||||
return nil, nil // ∅ ∪ ∅ == ∅
|
||||
case x == nil:
|
||||
return y, nil // ∅ ∪ y == y
|
||||
case y == nil:
|
||||
return x, nil // x ∪ ∅ == x
|
||||
case x.typ == nil:
|
||||
return x, nil // 𝓤 ∪ y == 𝓤
|
||||
case y.typ == nil:
|
||||
return y, nil // x ∪ 𝓤 == 𝓤
|
||||
}
|
||||
// ∅ ⊂ x, y ⊂ 𝓤
|
||||
|
||||
if x.disjoint(y) {
|
||||
return x, y // x ∪ y == (x, y) if x ∩ y == ∅
|
||||
}
|
||||
// x.typ == y.typ
|
||||
|
||||
// ~t ∪ ~t == ~t
|
||||
// ~t ∪ T == ~t
|
||||
// T ∪ ~t == ~t
|
||||
// T ∪ T == T
|
||||
if x.tilde || !y.tilde {
|
||||
return x, nil
|
||||
}
|
||||
return y, nil
|
||||
}
|
||||
|
||||
// intersect returns the intersection x ∩ y.
|
||||
func (x *term) intersect(y *term) *term {
|
||||
// easy cases
|
||||
switch {
|
||||
case x == nil || y == nil:
|
||||
return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
|
||||
case x.typ == nil:
|
||||
return y // 𝓤 ∩ y == y
|
||||
case y.typ == nil:
|
||||
return x // x ∩ 𝓤 == x
|
||||
}
|
||||
// ∅ ⊂ x, y ⊂ 𝓤
|
||||
|
||||
if x.disjoint(y) {
|
||||
return nil // x ∩ y == ∅ if x ∩ y == ∅
|
||||
}
|
||||
// x.typ == y.typ
|
||||
|
||||
// ~t ∩ ~t == ~t
|
||||
// ~t ∩ T == T
|
||||
// T ∩ ~t == T
|
||||
// T ∩ T == T
|
||||
if !x.tilde || y.tilde {
|
||||
return x
|
||||
}
|
||||
return y
|
||||
}
|
||||
|
||||
// includes reports whether t ∈ x.
|
||||
func (x *term) includes(t types.Type) bool {
|
||||
// easy cases
|
||||
switch {
|
||||
case x == nil:
|
||||
return false // t ∈ ∅ == false
|
||||
case x.typ == nil:
|
||||
return true // t ∈ 𝓤 == true
|
||||
}
|
||||
// ∅ ⊂ x ⊂ 𝓤
|
||||
|
||||
u := t
|
||||
if x.tilde {
|
||||
u = under(u)
|
||||
}
|
||||
return types.Identical(x.typ, u)
|
||||
}
|
||||
|
||||
// subsetOf reports whether x ⊆ y.
|
||||
func (x *term) subsetOf(y *term) bool {
|
||||
// easy cases
|
||||
switch {
|
||||
case x == nil:
|
||||
return true // ∅ ⊆ y == true
|
||||
case y == nil:
|
||||
return false // x ⊆ ∅ == false since x != ∅
|
||||
case y.typ == nil:
|
||||
return true // x ⊆ 𝓤 == true
|
||||
case x.typ == nil:
|
||||
return false // 𝓤 ⊆ y == false since y != 𝓤
|
||||
}
|
||||
// ∅ ⊂ x, y ⊂ 𝓤
|
||||
|
||||
if x.disjoint(y) {
|
||||
return false // x ⊆ y == false if x ∩ y == ∅
|
||||
}
|
||||
// x.typ == y.typ
|
||||
|
||||
// ~t ⊆ ~t == true
|
||||
// ~t ⊆ T == false
|
||||
// T ⊆ ~t == true
|
||||
// T ⊆ T == true
|
||||
return !x.tilde || y.tilde
|
||||
}
|
||||
|
||||
// disjoint reports whether x ∩ y == ∅.
|
||||
// x.typ and y.typ must not be nil.
|
||||
func (x *term) disjoint(y *term) bool {
|
||||
if debug && (x.typ == nil || y.typ == nil) {
|
||||
panic("invalid argument(s)")
|
||||
}
|
||||
ux := x.typ
|
||||
if y.tilde {
|
||||
ux = under(ux)
|
||||
}
|
||||
uy := y.typ
|
||||
if x.tilde {
|
||||
uy = under(uy)
|
||||
}
|
||||
return !types.Identical(ux, uy)
|
||||
}
|
||||
Reference in New Issue
Block a user