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[dev.typeparams] cmd/compile/internal/types2: better names for things (cleanup)

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- use the symbol 𝓤 (as in 𝓤niverse) instead of ⊤ to denote the set
  of all types (for better readabilty, ⊤ is hard to distinguish from
  T in some fonts)

- use isAll instead of isTop to test for the set of all types

- use allTermlist instead of topTermlist to denote the termlist
  representing all types

Change-Id: Idcb0b3398782b38653338e65173c0dbb935e430a
Reviewed-on: https://go-review.googlesource.com/c/go/+/339891
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
This commit is contained in:
Robert Griesemer 2021-08-04 15:18:37 -07:00
parent 110343e4a2
commit 5aac85ad5e
8 changed files with 100 additions and 101 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/compile/internal/types2/instantiate.go
View File

@ -174,7 +174,7 @@ func (check *Checker) satisfies(pos syntax.Pos, targ Type, tpar *TypeParam, smap
// if iface is comparable, targ must be comparable
// TODO(gri) the error messages needs to be better, here
if iface.IsComparable() && !Comparable(targ) {
if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsTop() {
if tpar := asTypeParam(targ); tpar != nil && tpar.iface().typeSet().IsAll() {
check.softErrorf(pos, "%s has no constraints", targ)
return false
}

2
src/cmd/compile/internal/types2/interface.go
View File

@ -92,7 +92,7 @@ func (t *Interface) NumMethods() int { return t.typeSet().NumMethods() }
func (t *Interface) Method(i int) *Func { return t.typeSet().Method(i) }
// Empty reports whether t is the empty interface.
func (t *Interface) Empty() bool { return t.typeSet().IsTop() }
func (t *Interface) Empty() bool { return t.typeSet().IsAll() }
// IsComparable reports whether each type in interface t's type set is comparable.
func (t *Interface) IsComparable() bool { return t.typeSet().IsComparable() }

22
src/cmd/compile/internal/types2/termlist.go
View File

@ -13,9 +13,9 @@ import "bytes"
// normal form.
type termlist []*term
// topTermlist represents the set of all types.
// allTermlist represents the set of all types.
// It is in normal form.
var topTermlist = termlist{new(term)}
var allTermlist = termlist{new(term)}
// String prints the termlist exactly (without normalization).
func (xl termlist) String() string {
@ -45,9 +45,9 @@ func (xl termlist) isEmpty() bool {
return true
}
// isTop reports whether the termlist xl represents the set of all types.
func (xl termlist) isTop() bool {
// If there's a ⊤ (top) term, the entire list is ⊤ (top).
// isAll reports whether the termlist xl represents the set of all types.
func (xl termlist) isAll() bool {
// If there's a 𝓤 term, the entire list is 𝓤.
// If the termlist is in normal form, this requires at most
// one iteration.
for _, x := range xl {
@ -74,14 +74,14 @@ func (xl termlist) norm() termlist {
continue
}
if u1, u2 := xi.union(xj); u2 == nil {
// If we encounter a ⊤ (top) term, the entire
// list is ⊤ (top). Exit early.
// If we encounter a 𝓤 term, the entire list is 𝓤.
// Exit early.
// (Note that this is not just an optimization;
// if we continue, we may end up with a ⊤ term
// if we continue, we may end up with a 𝓤 term
// and other terms and the result would not be
// in normal form.)
if u1.typ == nil {
return topTermlist
return allTermlist
}
xi = u1
used[j] = true // xj is now unioned into xi - ignore it in future iterations
@ -92,11 +92,11 @@ func (xl termlist) norm() termlist {
return rl
}
// If the type set represented by xl is specified by a single (non-⊤) term,
// If the type set represented by xl is specified by a single (non-𝓤) term,
// structuralType returns that type. Otherwise it returns nil.
func (xl termlist) structuralType() Type {
if nl := xl.norm(); len(nl) == 1 {
return nl[0].typ // if nl.isTop() then typ is nil, which is ok
return nl[0].typ // if nl.isAll() then typ is nil, which is ok
}
return nil
}

78
src/cmd/compile/internal/types2/termlist_test.go
View File

@ -21,20 +21,20 @@ func maketl(s string) termlist {
}
func TestTermlistTop(t *testing.T) {
if !topTermlist.isTop() {
t.Errorf("topTermlist is not top")
if !allTermlist.isAll() {
t.Errorf("allTermlist is not the set of all types")
}
}
func TestTermlistString(t *testing.T) {
for _, want := range []string{
"∅",
"⊤",
"𝓤",
"int",
"~int",
"∅ ∪ ∅",
"⊤ ∪ ⊤",
"∅ ∪ ⊤ ∪ int",
"𝓤 ∪ 𝓤",
"∅ ∪ 𝓤 ∪ int",
} {
if got := maketl(want).String(); got != want {
t.Errorf("(%v).String() == %v", want, got)
@ -46,9 +46,9 @@ func TestTermlistIsEmpty(t *testing.T) {
for test, want := range map[string]bool{
"∅": true,
"∅ ∪ ∅": true,
"∅ ∪ ∅ ∪ ⊤": false,
"⊤": false,
"⊤ ∪ int": false,
"∅ ∪ ∅ ∪ 𝓤": false,
"𝓤": false,
"𝓤 ∪ int": false,
} {
xl := maketl(test)
got := xl.isEmpty()
@ -58,19 +58,19 @@ func TestTermlistIsEmpty(t *testing.T) {
}
}
func TestTermlistIsTop(t *testing.T) {
func TestTermlistIsAll(t *testing.T) {
for test, want := range map[string]bool{
"∅": false,
"∅ ∪ ∅": false,
"int ∪ ~string": false,
"∅ ∪ ∅ ∪ ⊤": true,
"⊤": true,
"⊤ ∪ int": true,
"∅ ∪ ∅ ∪ 𝓤": true,
"𝓤": true,
"𝓤 ∪ int": true,
} {
xl := maketl(test)
got := xl.isTop()
got := xl.isAll()
if got != want {
t.Errorf("(%v).isTop() == %v; want %v", test, got, want)
t.Errorf("(%v).isAll() == %v; want %v", test, got, want)
}
}
}
@ -82,10 +82,10 @@ func TestTermlistNorm(t *testing.T) {
{"∅", "∅"},
{"∅ ∪ ∅", "∅"},
{"∅ ∪ int", "int"},
{"⊤ ∪ int", "⊤"},
{"𝓤 ∪ int", "𝓤"},
{"~int ∪ int", "~int"},
{"int ∪ ~string ∪ int", "int ∪ ~string"},
{"~int ∪ string ∪ ⊤ ∪ ~string ∪ int", "⊤"},
{"~int ∪ string ∪ 𝓤 ∪ ~string ∪ int", "𝓤"},
} {
xl := maketl(test.xl)
got := maketl(test.xl).norm()
@ -106,7 +106,7 @@ func TestTermlistStructuralType(t *testing.T) {
for test, want := range map[string]string{
"∅": "nil",
"⊤": "nil",
"𝓤": "nil",
"int": "int",
"~int": "int",
"~int ∪ string": "nil",
@ -128,15 +128,15 @@ func TestTermlistUnion(t *testing.T) {
}{
{"∅", "∅", "∅"},
{"∅", "⊤", "⊤"},
{"∅", "𝓤", "𝓤"},
{"∅", "int", "int"},
{"⊤", "~int", "⊤"},
{"𝓤", "~int", "𝓤"},
{"int", "~int", "~int"},
{"int", "string", "int ∪ string"},
{"int ∪ string", "~string", "int ∪ ~string"},
{"~int ∪ string", "~string ∪ int", "~int ∪ ~string"},
{"~int ∪ string ∪ ∅", "~string ∪ int", "~int ∪ ~string"},
{"~int ∪ string ∪ ⊤", "~string ∪ int", "⊤"},
{"~int ∪ string ∪ 𝓤", "~string ∪ int", "𝓤"},
} {
xl := maketl(test.xl)
yl := maketl(test.yl)
@ -153,15 +153,15 @@ func TestTermlistIntersect(t *testing.T) {
}{
{"∅", "∅", "∅"},
{"∅", "⊤", "∅"},
{"∅", "𝓤", "∅"},
{"∅", "int", "∅"},
{"⊤", "~int", "~int"},
{"𝓤", "~int", "~int"},
{"int", "~int", "int"},
{"int", "string", "∅"},
{"int ∪ string", "~string", "string"},
{"~int ∪ string", "~string ∪ int", "int ∪ string"},
{"~int ∪ string ∪ ∅", "~string ∪ int", "int ∪ string"},
{"~int ∪ string ∪ ⊤", "~string ∪ int", "int ∪ ~string"},
{"~int ∪ string ∪ 𝓤", "~string ∪ int", "int ∪ ~string"},
} {
xl := maketl(test.xl)
yl := maketl(test.yl)
@ -178,10 +178,10 @@ func TestTermlistEqual(t *testing.T) {
want bool
}{
{"∅", "∅", true},
{"∅", "⊤", false},
{"⊤", "⊤", true},
{"⊤ ∪ int", "⊤", true},
{"⊤ ∪ int", "string ∪ ⊤", true},
{"∅", "𝓤", false},
{"𝓤", "𝓤", true},
{"𝓤 ∪ int", "𝓤", true},
{"𝓤 ∪ int", "string ∪ 𝓤", true},
{"int ∪ ~string", "string ∪ int", false},
{"int ∪ ~string ∪ ∅", "string ∪ int ∪ ~string", true},
} {
@ -200,14 +200,14 @@ func TestTermlistIncludes(t *testing.T) {
want bool
}{
{"∅", "int", false},
{"⊤", "int", true},
{"𝓤", "int", true},
{"~int", "int", true},
{"int", "string", false},
{"~int", "string", false},
{"int ∪ string", "string", true},
{"~int ∪ string", "int", true},
{"~int ∪ string ∪ ∅", "string", true},
{"~string ∪ ∅ ∪ ⊤", "int", true},
{"~string ∪ ∅ ∪ 𝓤", "int", true},
} {
xl := maketl(test.xl)
yl := testTerm(test.typ).typ
@ -224,12 +224,12 @@ func TestTermlistSupersetOf(t *testing.T) {
want bool
}{
{"∅", "∅", true},
{"∅", "⊤", false},
{"∅", "𝓤", false},
{"∅", "int", false},
{"⊤", "∅", true},
{"⊤", "⊤", true},
{"⊤", "int", true},
{"⊤", "~int", true},
{"𝓤", "∅", true},
{"𝓤", "𝓤", true},
{"𝓤", "int", true},
{"𝓤", "~int", true},
{"~int", "int", true},
{"~int", "~int", true},
{"int", "~int", false},
@ -239,7 +239,7 @@ func TestTermlistSupersetOf(t *testing.T) {
{"int ∪ string", "~string", false},
{"~int ∪ string", "int", true},
{"~int ∪ string ∪ ∅", "string", true},
{"~string ∪ ∅ ∪ ⊤", "int", true},
{"~string ∪ ∅ ∪ 𝓤", "int", true},
} {
xl := maketl(test.xl)
y := testTerm(test.typ)
@ -256,16 +256,16 @@ func TestTermlistSubsetOf(t *testing.T) {
want bool
}{
{"∅", "∅", true},
{"∅", "⊤", true},
{"⊤", "∅", false},
{"⊤", "⊤", true},
{"∅", "𝓤", true},
{"𝓤", "∅", false},
{"𝓤", "𝓤", true},
{"int", "int ∪ string", true},
{"~int", "int ∪ string", false},
{"~int", "string ∪ string ∪ int ∪ ~int", true},
{"int ∪ string", "string", false},
{"int ∪ string", "string ∪ int", true},
{"int ∪ ~string", "string ∪ int", false},
{"int ∪ ~string", "string ∪ int ∪ ⊤", true},
{"int ∪ ~string", "string ∪ int ∪ 𝓤", true},
{"int ∪ ~string", "string ∪ int ∪ ∅ ∪ string", false},
} {
xl := maketl(test.xl)

22
src/cmd/compile/internal/types2/typeset.go
View File

@ -25,17 +25,19 @@ type TypeSet struct {
// IsEmpty reports whether type set s is the empty set.
func (s *TypeSet) IsEmpty() bool { return s.terms.isEmpty() }
// IsTop reports whether type set s is the set of all types (corresponding to the empty interface).
func (s *TypeSet) IsTop() bool { return !s.comparable && len(s.methods) == 0 && s.terms.isTop() }
// IsAll reports whether type set s is the set of all types (corresponding to the empty interface).
func (s *TypeSet) IsAll() bool {
return !s.comparable && len(s.methods) == 0 && s.terms.isAll()
}
// TODO(gri) IsMethodSet is not a great name for this predicate. Find a better one.
// IsMethodSet reports whether the type set s is described by a single set of methods.
func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isTop() }
func (s *TypeSet) IsMethodSet() bool { return !s.comparable && s.terms.isAll() }
// IsComparable reports whether each type in the set is comparable.
func (s *TypeSet) IsComparable() bool {
if s.terms.isTop() {
if s.terms.isAll() {
return s.comparable
}
return s.is(func(t *term) bool {
@ -67,8 +69,8 @@ func (s *TypeSet) String() string {
switch {
case s.IsEmpty():
return "∅"
case s.IsTop():
return "⊤"
case s.IsAll():
return "𝓤"
}
hasMethods := len(s.methods) > 0
@ -103,7 +105,7 @@ func (s *TypeSet) String() string {
// ----------------------------------------------------------------------------
// Implementation
func (s *TypeSet) hasTerms() bool { return !s.terms.isTop() }
func (s *TypeSet) hasTerms() bool { return !s.terms.isAll() }
func (s *TypeSet) structuralType() Type { return s.terms.structuralType() }
func (s *TypeSet) includes(t Type) bool { return s.terms.includes(t) }
func (s1 *TypeSet) subsetOf(s2 *TypeSet) bool { return s1.terms.subsetOf(s2.terms) }
@ -156,7 +158,7 @@ func (s *TypeSet) underIs(f func(Type) bool) bool {
}
// topTypeSet may be used as type set for the empty interface.
var topTypeSet = TypeSet{terms: topTermlist}
var topTypeSet = TypeSet{terms: allTermlist}
// computeInterfaceTypeSet may be called with check == nil.
func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *TypeSet {
@ -195,7 +197,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T
// have valid interfaces. Mark the interface as complete to avoid
// infinite recursion if the validType check occurs later for some
// reason.
ityp.tset = &TypeSet{terms: topTermlist} // TODO(gri) is this sufficient?
ityp.tset = &TypeSet{terms: allTermlist} // TODO(gri) is this sufficient?
// Methods of embedded interfaces are collected unchanged; i.e., the identity
// of a method I.m's Func Object of an interface I is the same as that of
@ -256,7 +258,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *T
}
// collect embedded elements
var allTerms = topTermlist
var allTerms = allTermlist
for i, typ := range ityp.embeddeds {
// The embedding position is nil for imported interfaces
// and also for interface copies after substitution (but

31
src/cmd/compile/internal/types2/typeterm.go
View File

@ -4,13 +4,10 @@
package types2
// TODO(gri) use a different symbol instead of ⊤ for the set of all types
// (⊤ is hard to distinguish from T in some fonts)
// A term describes elementary type sets:
//
// ∅: (*term)(nil) == ∅ // set of no types (empty set)
// ⊤: &term{} == ⊤ // set of all types
// 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
//
@ -24,7 +21,7 @@ func (x *term) String() string {
case x == nil:
return "∅"
case x.typ == nil:
return "⊤"
return "𝓤"
case x.tilde:
return "~" + x.typ.String()
default:
@ -41,7 +38,7 @@ func (x *term) equal(y *term) bool {
case x.typ == nil || y.typ == nil:
return x.typ == y.typ
}
// ∅ ⊂ x, y ⊂ ⊤
// ∅ ⊂ x, y ⊂ 𝓤
return x.tilde == y.tilde && Identical(x.typ, y.typ)
}
@ -57,11 +54,11 @@ func (x *term) union(y *term) (_, _ *term) {
case y == nil:
return x, nil // x ∪ ∅ == x
case x.typ == nil:
return x, nil // ⊤ ∪ y == ⊤
return x, nil // 𝓤 ∪ y == 𝓤
case y.typ == nil:
return y, nil // x ∪ ⊤ == ⊤
return y, nil // x ∪ 𝓤 == 𝓤
}
// ∅ ⊂ x, y ⊂ ⊤
// ∅ ⊂ x, y ⊂ 𝓤
if x.disjoint(y) {
return x, y // x ∪ y == (x, y) if x ∩ y == ∅
@ -85,11 +82,11 @@ func (x *term) intersect(y *term) *term {
case x == nil || y == nil:
return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
case x.typ == nil:
return y // ⊤ ∩ y == y
return y // 𝓤 ∩ y == y
case y.typ == nil:
return x // x ∩ ⊤ == x
return x // x ∩ 𝓤 == x
}
// ∅ ⊂ x, y ⊂ ⊤
// ∅ ⊂ x, y ⊂ 𝓤
if x.disjoint(y) {
return nil // x ∩ y == ∅ if x ∩ y == ∅
@ -113,9 +110,9 @@ func (x *term) includes(t Type) bool {
case x == nil:
return false // t ∈ ∅ == false
case x.typ == nil:
return true // t ∈ ⊤ == true
return true // t ∈ 𝓤 == true
}
// ∅ ⊂ x ⊂ ⊤
// ∅ ⊂ x ⊂ 𝓤
u := t
if x.tilde {
@ -133,11 +130,11 @@ func (x *term) subsetOf(y *term) bool {
case y == nil:
return false // x ⊆ ∅ == false since x != ∅
case y.typ == nil:
return true // x ⊆ ⊤ == true
return true // x ⊆ 𝓤 == true
case x.typ == nil:
return false // ⊤ ⊆ y == false since y != ⊤
return false // 𝓤 ⊆ y == false since y != 𝓤
}
// ∅ ⊂ x, y ⊂ ⊤
// ∅ ⊂ x, y ⊂ 𝓤
if x.disjoint(y) {
return false // x ⊆ y == false if x ∩ y == ∅

42
src/cmd/compile/internal/types2/typeterm_test.go
View File

@ -11,7 +11,7 @@ import (
var testTerms = map[string]*term{
"∅": nil,
"⊤": {},
"𝓤": {},
"int": {false, Typ[Int]},
"~int": {true, Typ[Int]},
"string": {false, Typ[String]},
@ -46,14 +46,14 @@ func testTerm(name string) *term {
func TestTermEqual(t *testing.T) {
for _, test := range []string{
"∅ ∅ T",
"⊤ ⊤ T",
"𝓤 𝓤 T",
"int int T",
"~int ~int T",
"∅ ⊤ F",
"∅ 𝓤 F",
"∅ int F",
"∅ ~int F",
"⊤ int F",
"⊤ ~int F",
"𝓤 int F",
"𝓤 ~int F",
"int ~int F",
} {
args := split(test, 3)
@ -74,12 +74,12 @@ func TestTermEqual(t *testing.T) {
func TestTermUnion(t *testing.T) {
for _, test := range []string{
"∅ ∅ ∅ ∅",
"∅ ⊤ ⊤ ∅",
"∅ 𝓤 𝓤 ∅",
"∅ int int ∅",
"∅ ~int ~int ∅",
"⊤ ⊤ ⊤ ∅",
"⊤ int ⊤ ∅",
"⊤ ~int ⊤ ∅",
"𝓤 𝓤 𝓤 ∅",
"𝓤 int 𝓤 ∅",
"𝓤 ~int 𝓤 ∅",
"int int int ∅",
"int ~int ~int ∅",
"int string int string",
@ -87,11 +87,11 @@ func TestTermUnion(t *testing.T) {
"~int ~string ~int ~string",
// union is symmetric, but the result order isn't - repeat symmetric cases explictly
"⊤ ∅ ⊤ ∅",
"𝓤 ∅ 𝓤 ∅",
"int ∅ int ∅",
"~int ∅ ~int ∅",
"int ⊤ ⊤ ∅",
"~int ⊤ ⊤ ∅",
"int 𝓤 𝓤 ∅",
"~int 𝓤 𝓤 ∅",
"~int int ~int ∅",
"string int string int",
"~string int ~string int",
@ -111,12 +111,12 @@ func TestTermUnion(t *testing.T) {
func TestTermIntersection(t *testing.T) {
for _, test := range []string{
"∅ ∅ ∅",
"∅ ⊤ ∅",
"∅ 𝓤 ∅",
"∅ int ∅",
"∅ ~int ∅",
"⊤ ⊤ ⊤",
"⊤ int int",
"⊤ ~int ~int",
"𝓤 𝓤 𝓤",
"𝓤 int int",
"𝓤 ~int ~int",
"int int int",
"int ~int int",
"int string ∅",
@ -141,7 +141,7 @@ func TestTermIntersection(t *testing.T) {
func TestTermIncludes(t *testing.T) {
for _, test := range []string{
"∅ int F",
"⊤ int T",
"𝓤 int T",
"int int T",
"~int int T",
"string int F",
@ -160,14 +160,14 @@ func TestTermIncludes(t *testing.T) {
func TestTermSubsetOf(t *testing.T) {
for _, test := range []string{
"∅ ∅ T",
"⊤ ⊤ T",
"𝓤 𝓤 T",
"int int T",
"~int ~int T",
"∅ ⊤ T",
"∅ 𝓤 T",
"∅ int T",
"∅ ~int T",
"⊤ int F",
"⊤ ~int F",
"𝓤 int F",
"𝓤 ~int F",
"int ~int T",
} {
args := split(test, 3)

2
src/cmd/compile/internal/types2/universe.go
View File

@ -99,7 +99,7 @@ func defPredeclaredTypes() {
{
obj := NewTypeName(nopos, nil, "comparable", nil)
obj.setColor(black)
ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, topTermlist}}
ityp := &Interface{obj, nil, nil, nil, true, &TypeSet{true, nil, allTermlist}}
NewNamed(obj, ityp, nil)
def(obj)
}