internal/persistent: use generics

Now that we're on 1.18+, make internal/persistent.Map generic.

Change-Id: I3403241fe22e28f969d7feb09a752b52f0d2ee4d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/524759
gopls-CI: kokoro <noreply+kokoro@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>

gopls/internal/lsp/cache/check.go

@@ -849,7 +849,7 @@ func (s *snapshot) getPackageHandles(ctx context.Context, ids []PackageID) (map[
 				unfinishedSuccs: int32(len(m.DepsByPkgPath)),
 			}
 			if entry, hit := b.s.packages.Get(m.ID); hit {
-				n.ph = entry.(*packageHandle)
+				n.ph = entry
 			}
 			if n.unfinishedSuccs == 0 {
 				leaves = append(leaves, n)
@@ -1118,12 +1118,11 @@ func (b *packageHandleBuilder) buildPackageHandle(ctx context.Context, n *handle
 	}
 
 	// Check the packages map again in case another goroutine got there first.
-	if alt, ok := b.s.packages.Get(n.m.ID); ok && alt.(*packageHandle).validated {
-		altPH := alt.(*packageHandle)
-		if altPH.m != n.m {
+	if alt, ok := b.s.packages.Get(n.m.ID); ok && alt.validated {
+		if alt.m != n.m {
 			bug.Reportf("existing package handle does not match for %s", n.m.ID)
 		}
-		n.ph = altPH
+		n.ph = alt
 	} else {
 		b.s.packages.Set(n.m.ID, n.ph, nil)
 	}

gopls/internal/lsp/cache/load.go

@@ -217,8 +217,7 @@ func (s *snapshot) load(ctx context.Context, allowNetwork bool, scopes ...loadSc
 	s.mu.Lock()
 
 	// Assert the invariant s.packages.Get(id).m == s.meta.metadata[id].
-	s.packages.Range(func(k, v interface{}) {
-		id, ph := k.(PackageID), v.(*packageHandle)
+	s.packages.Range(func(id PackageID, ph *packageHandle) {
 		if s.meta.metadata[id] != ph.m {
 			panic("inconsistent metadata")
 		}

gopls/internal/lsp/cache/maps.go

@@ -10,21 +10,14 @@ import (
 	"golang.org/x/tools/internal/persistent"
 )
 
-// TODO(euroelessar): Use generics once support for go1.17 is dropped.
-
 type filesMap struct {
-	impl       *persistent.Map
+	impl       *persistent.Map[span.URI, source.FileHandle]
 	overlayMap map[span.URI]*Overlay // the subset that are overlays
 }
 
-// uriLessInterface is the < relation for "any" values containing span.URIs.
-func uriLessInterface(a, b interface{}) bool {
-	return a.(span.URI) < b.(span.URI)
-}
-
 func newFilesMap() filesMap {
 	return filesMap{
-		impl:       persistent.NewMap(uriLessInterface),
+		impl:       new(persistent.Map[span.URI, source.FileHandle]),
 		overlayMap: make(map[span.URI]*Overlay),
 	}
 }
@@ -53,9 +46,7 @@ func (m filesMap) Get(key span.URI) (source.FileHandle, bool) {
 }
 
 func (m filesMap) Range(do func(key span.URI, value source.FileHandle)) {
-	m.impl.Range(func(key, value interface{}) {
-		do(key.(span.URI), value.(source.FileHandle))
-	})
+	m.impl.Range(do)
 }
 
 func (m filesMap) Set(key span.URI, value source.FileHandle) {
@@ -86,19 +77,13 @@ func (m filesMap) overlays() []*Overlay {
 	return overlays
 }
 
-func packageIDLessInterface(x, y interface{}) bool {
-	return x.(PackageID) < y.(PackageID)
-}
-
 type knownDirsSet struct {
-	impl *persistent.Map
+	impl *persistent.Map[span.URI, struct{}]
 }
 
 func newKnownDirsSet() knownDirsSet {
 	return knownDirsSet{
-		impl: persistent.NewMap(func(a, b interface{}) bool {
-			return a.(span.URI) < b.(span.URI)
-		}),
+		impl: new(persistent.Map[span.URI, struct{}]),
 	}
 }
 
@@ -118,8 +103,8 @@ func (s knownDirsSet) Contains(key span.URI) bool {
 }
 
 func (s knownDirsSet) Range(do func(key span.URI)) {
-	s.impl.Range(func(key, value interface{}) {
-		do(key.(span.URI))
+	s.impl.Range(func(key span.URI, value struct{}) {
+		do(key)
 	})
 }
 
@@ -128,7 +113,7 @@ func (s knownDirsSet) SetAll(other knownDirsSet) {
 }
 
 func (s knownDirsSet) Insert(key span.URI) {
-	s.impl.Set(key, nil, nil)
+	s.impl.Set(key, struct{}{}, nil)
 }
 
 func (s knownDirsSet) Remove(key span.URI) {

gopls/internal/lsp/cache/mod.go

@@ -52,7 +52,7 @@ func (s *snapshot) ParseMod(ctx context.Context, fh source.FileHandle) (*source.
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}
@@ -130,7 +130,7 @@ func (s *snapshot) ParseWork(ctx context.Context, fh source.FileHandle) (*source
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}
@@ -240,7 +240,7 @@ func (s *snapshot) ModWhy(ctx context.Context, fh source.FileHandle) (map[string
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}

gopls/internal/lsp/cache/mod_tidy.go

@@ -85,7 +85,7 @@ func (s *snapshot) ModTidy(ctx context.Context, pm *source.ParsedModule) (*sourc
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}

gopls/internal/lsp/cache/mod_vuln.go

@@ -55,7 +55,7 @@ func (s *snapshot) ModVuln(ctx context.Context, modURI span.URI) (*govulncheck.R
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}

gopls/internal/lsp/cache/session.go

@@ -20,6 +20,7 @@ import (
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/gocommand"
 	"golang.org/x/tools/internal/imports"
+	"golang.org/x/tools/internal/memoize"
 	"golang.org/x/tools/internal/persistent"
 	"golang.org/x/tools/internal/xcontext"
 )
@@ -169,18 +170,18 @@ func (s *Session) createView(ctx context.Context, name string, folder span.URI,
 		backgroundCtx:        backgroundCtx,
 		cancel:               cancel,
 		store:                s.cache.store,
-		packages:             persistent.NewMap(packageIDLessInterface),
+		packages:             new(persistent.Map[PackageID, *packageHandle]),
 		meta:                 new(metadataGraph),
 		files:                newFilesMap(),
-		activePackages:       persistent.NewMap(packageIDLessInterface),
-		symbolizeHandles:     persistent.NewMap(uriLessInterface),
+		activePackages:       new(persistent.Map[PackageID, *Package]),
+		symbolizeHandles:     new(persistent.Map[span.URI, *memoize.Promise]),
 		workspacePackages:    make(map[PackageID]PackagePath),
 		unloadableFiles:      make(map[span.URI]struct{}),
-		parseModHandles:      persistent.NewMap(uriLessInterface),
-		parseWorkHandles:     persistent.NewMap(uriLessInterface),
-		modTidyHandles:       persistent.NewMap(uriLessInterface),
-		modVulnHandles:       persistent.NewMap(uriLessInterface),
-		modWhyHandles:        persistent.NewMap(uriLessInterface),
+		parseModHandles:      new(persistent.Map[span.URI, *memoize.Promise]),
+		parseWorkHandles:     new(persistent.Map[span.URI, *memoize.Promise]),
+		modTidyHandles:       new(persistent.Map[span.URI, *memoize.Promise]),
+		modVulnHandles:       new(persistent.Map[span.URI, *memoize.Promise]),
+		modWhyHandles:        new(persistent.Map[span.URI, *memoize.Promise]),
 		knownSubdirs:         newKnownDirsSet(),
 		workspaceModFiles:    wsModFiles,
 		workspaceModFilesErr: wsModFilesErr,

gopls/internal/lsp/cache/snapshot.go

@@ -101,7 +101,7 @@ type snapshot struct {
 
 	// symbolizeHandles maps each file URI to a handle for the future
 	// result of computing the symbols declared in that file.
-	symbolizeHandles *persistent.Map // from span.URI to *memoize.Promise[symbolizeResult]
+	symbolizeHandles *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[symbolizeResult]
 
 	// packages maps a packageKey to a *packageHandle.
 	// It may be invalidated when a file's content changes.
@@ -110,13 +110,13 @@ type snapshot struct {
 	//  - packages.Get(id).meta == meta.metadata[id] for all ids
 	//  - if a package is in packages, then all of its dependencies should also
 	//    be in packages, unless there is a missing import
-	packages *persistent.Map // from packageID to *packageHandle
+	packages *persistent.Map[PackageID, *packageHandle]
 
 	// activePackages maps a package ID to a memoized active package, or nil if
 	// the package is known not to be open.
 	//
 	// IDs not contained in the map are not known to be open or not open.
-	activePackages *persistent.Map // from packageID to *Package
+	activePackages *persistent.Map[PackageID, *Package]
 
 	// workspacePackages contains the workspace's packages, which are loaded
 	// when the view is created. It contains no intermediate test variants.
@@ -137,18 +137,18 @@ type snapshot struct {
 
 	// parseModHandles keeps track of any parseModHandles for the snapshot.
 	// The handles need not refer to only the view's go.mod file.
-	parseModHandles *persistent.Map // from span.URI to *memoize.Promise[parseModResult]
+	parseModHandles *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[parseModResult]
 
 	// parseWorkHandles keeps track of any parseWorkHandles for the snapshot.
 	// The handles need not refer to only the view's go.work file.
-	parseWorkHandles *persistent.Map // from span.URI to *memoize.Promise[parseWorkResult]
+	parseWorkHandles *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[parseWorkResult]
 
 	// Preserve go.mod-related handles to avoid garbage-collecting the results
 	// of various calls to the go command. The handles need not refer to only
 	// the view's go.mod file.
-	modTidyHandles *persistent.Map // from span.URI to *memoize.Promise[modTidyResult]
-	modWhyHandles  *persistent.Map // from span.URI to *memoize.Promise[modWhyResult]
-	modVulnHandles *persistent.Map // from span.URI to *memoize.Promise[modVulnResult]
+	modTidyHandles *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[modTidyResult]
+	modWhyHandles  *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[modWhyResult]
+	modVulnHandles *persistent.Map[span.URI, *memoize.Promise] // *memoize.Promise[modVulnResult]
 
 	// knownSubdirs is the set of subdirectory URIs in the workspace,
 	// used to create glob patterns for file watching.
@@ -871,7 +871,7 @@ func (s *snapshot) getActivePackage(id PackageID) *Package {
 	defer s.mu.Unlock()
 
 	if value, ok := s.activePackages.Get(id); ok {
-		return value.(*Package) // possibly nil, if we have already checked this id.
+		return value
 	}
 	return nil
 }
@@ -895,7 +895,7 @@ func (s *snapshot) setActivePackage(id PackageID, pkg *Package) {
 
 func (s *snapshot) resetActivePackagesLocked() {
 	s.activePackages.Destroy()
-	s.activePackages = persistent.NewMap(packageIDLessInterface)
+	s.activePackages = new(persistent.Map[PackageID, *Package])
 }
 
 const fileExtensions = "go,mod,sum,work"
@@ -2189,7 +2189,7 @@ func (s *snapshot) clone(ctx, bgCtx context.Context, changes map[span.URI]*fileC
 			result.packages.Delete(id)
 		} else {
 			if entry, hit := result.packages.Get(id); hit {
-				ph := entry.(*packageHandle).clone(false)
+				ph := entry.clone(false)
 				result.packages.Set(id, ph, nil)
 			}
 		}
@@ -2291,12 +2291,11 @@ func (s *snapshot) clone(ctx, bgCtx context.Context, changes map[span.URI]*fileC
 // changed that happens not to be present in the map, but that's OK: the goal
 // of this function is to guarantee that IF the nearest mod file is present in
 // the map, it is invalidated.
-func deleteMostRelevantModFile(m *persistent.Map, changed span.URI) {
+func deleteMostRelevantModFile(m *persistent.Map[span.URI, *memoize.Promise], changed span.URI) {
 	var mostRelevant span.URI
 	changedFile := changed.Filename()
 
-	m.Range(func(key, value interface{}) {
-		modURI := key.(span.URI)
+	m.Range(func(modURI span.URI, _ *memoize.Promise) {
 		if len(modURI) > len(mostRelevant) {
 			if source.InDir(filepath.Dir(modURI.Filename()), changedFile) {
 				mostRelevant = modURI

gopls/internal/lsp/cache/symbols.go

@@ -15,7 +15,6 @@ import (
 	"golang.org/x/tools/gopls/internal/lsp/protocol"
 	"golang.org/x/tools/gopls/internal/lsp/source"
 	"golang.org/x/tools/gopls/internal/span"
-	"golang.org/x/tools/internal/memoize"
 )
 
 // symbolize returns the result of symbolizing the file identified by uri, using a cache.
@@ -51,7 +50,7 @@ func (s *snapshot) symbolize(ctx context.Context, uri span.URI) ([]source.Symbol
 	}
 
 	// Await result.
-	v, err := s.awaitPromise(ctx, entry.(*memoize.Promise))
+	v, err := s.awaitPromise(ctx, entry)
 	if err != nil {
 		return nil, err
 	}

internal/constraints/constraint.go

@@ -0,0 +1,52 @@
+// 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.
+
+// Package constraints defines a set of useful constraints to be used
+// with type parameters.
+package constraints
+
+// Copied from x/exp/constraints.
+
+// Signed is a constraint that permits any signed integer type.
+// If future releases of Go add new predeclared signed integer types,
+// this constraint will be modified to include them.
+type Signed interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64
+}
+
+// Unsigned is a constraint that permits any unsigned integer type.
+// If future releases of Go add new predeclared unsigned integer types,
+// this constraint will be modified to include them.
+type Unsigned interface {
+	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+// Integer is a constraint that permits any integer type.
+// If future releases of Go add new predeclared integer types,
+// this constraint will be modified to include them.
+type Integer interface {
+	Signed | Unsigned
+}
+
+// Float is a constraint that permits any floating-point type.
+// If future releases of Go add new predeclared floating-point types,
+// this constraint will be modified to include them.
+type Float interface {
+	~float32 | ~float64
+}
+
+// Complex is a constraint that permits any complex numeric type.
+// If future releases of Go add new predeclared complex numeric types,
+// this constraint will be modified to include them.
+type Complex interface {
+	~complex64 | ~complex128
+}
+
+// Ordered is a constraint that permits any ordered type: any type
+// that supports the operators < <= >= >.
+// If future releases of Go add new ordered types,
+// this constraint will be modified to include them.
+type Ordered interface {
+	Integer | Float | ~string
+}