feat(subtract): added Subtract function to wire

internal/wire/parse.go

@@ -546,6 +546,9 @@
 		case "NewSet":
 			pset, errs := oc.processNewSet(info, pkgPath, call, nil, varName)
 			return pset, notePositionAll(exprPos, errs)
+		case "Subtract":
+			pset, errs := oc.processSubtract(info, pkgPath, call, nil, varName)
+			return pset, notePositionAll(exprPos, errs)
 		case "Bind":
 			b, err := processBind(oc.fset, info, call)
 			if err != nil {
@@ -590,6 +593,115 @@
 	return nil, []error{notePosition(exprPos, errors.New("unknown pattern"))}
 }
 
+func (oc *objectCache) filterType(set *ProviderSet, t types.Type) []error {
+	hasType := func(outs []types.Type) bool {
+		for _, o := range outs {
+			if types.Identical(o, t) {
+				return true
+			}
+			pt, ok := o.(*types.Pointer)
+			if ok && types.Identical(pt.Elem(), t) {
+				return true
+			}
+		}
+		return false
+	}
+
+	providers := make([]*Provider, 0, len(set.Providers))
+	for _, p := range set.Providers {
+		if !hasType(p.Out) {
+			providers = append(providers, p)
+		}
+	}
+	set.Providers = providers
+
+	bindings := make([]*IfaceBinding, 0, len(set.Bindings))
+	for _, i := range set.Bindings {
+		if !types.Identical(i.Iface, t) {
+			bindings = append(bindings, i)
+		}
+	}
+	set.Bindings = bindings
+
+	values := make([]*Value, 0, len(set.Values))
+	for _, v := range set.Values {
+		if !types.Identical(v.Out, t) {
+			values = append(values, v)
+		}
+	}
+	set.Values = values
+
+	fields := make([]*Field, 0, len(set.Fields))
+	for _, f := range set.Fields {
+		if !hasType(f.Out) {
+			fields = append(fields, f)
+		}
+	}
+	set.Fields = fields
+
+	imports := make([]*ProviderSet, 0, len(set.Imports))
+	for _, p := range set.Imports {
+		clone := *p
+		if errs := oc.filterType(&clone, t); len(errs) > 0 {
+			return errs
+		}
+		imports = append(imports, &clone)
+	}
+	set.Imports = imports
+
+	var errs []error
+	set.providerMap, set.srcMap, errs = buildProviderMap(oc.fset, oc.hasher, set)
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}
+
+func (oc *objectCache) processSubtract(info *types.Info, pkgPath string, call *ast.CallExpr, args *InjectorArgs, varName string) (interface{}, []error) {
+	// Assumes that call.Fun is wire.Subtract.
+	if len(call.Args) < 2 {
+		return nil, []error{notePosition(oc.fset.Position(call.Pos()),
+			errors.New("call to Subtract must specify types to be subtracted"))}
+	}
+	firstArg, errs := oc.processExpr(info, pkgPath, call.Args[0], "")
+	if len(errs) > 0 {
+		return nil, errs
+	}
+	set, ok := firstArg.(*ProviderSet)
+	if !ok {
+		return nil, []error{notePosition(oc.fset.Position(call.Pos()),
+			fmt.Errorf("first argument to Subtract must be a Set")),
+		}
+	}
+	pset := &ProviderSet{
+		Pos:          call.Pos(),
+		InjectorArgs: args,
+		PkgPath:      pkgPath,
+		VarName:      varName,
+		// Copy the other fields.
+		Providers: set.Providers,
+		Bindings:  set.Bindings,
+		Values:    set.Values,
+		Fields:    set.Fields,
+		Imports:   set.Imports,
+	}
+	ec := new(errorCollector)
+	for _, arg := range call.Args[1:] {
+		ptr, ok := info.TypeOf(arg).(*types.Pointer)
+		if !ok {
+			ec.add(notePosition(oc.fset.Position(arg.Pos()),
+				errors.New("argument to Subtract must be a pointer"),
+			))
+			continue
+		}
+		ec.add(oc.filterType(pset, ptr.Elem())...)
+	}
+	if len(ec.errors) > 0 {
+		return nil, ec.errors
+	}
+	return pset, nil
+}
+
 func (oc *objectCache) processNewSet(info *types.Info, pkgPath string, call *ast.CallExpr, args *InjectorArgs, varName string) (*ProviderSet, []error) {
 	// Assumes that call.Fun is wire.NewSet or wire.Build.
 
@@ -1173,9 +1285,9 @@
 //
 //   - For a function provider, this is the first return value type.
 //   - For a struct provider, this is either the struct type or the pointer type
-// 	   whose element type is the struct type.
-// 	 - For a value, this is the type of the expression.
-// 	 - For an argument, this is the type of the argument.
+//     whose element type is the struct type.
+//   - For a value, this is the type of the expression.
+//   - For an argument, this is the type of the argument.
 func (pt ProvidedType) Type() types.Type {
 	return pt.t
 }

internal/wire/testdata/Subtract/foo/foo.go

@@ -0,0 +1,66 @@
+// Copyright 2018 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+type context struct{}
+
+func main() {}
+
+type FooOptions struct{}
+type Foo string
+type Bar struct{}
+type BarName string
+
+func (b *Bar) Bar() {}
+
+func provideFooOptions() *FooOptions {
+	return &FooOptions{}
+}
+
+func provideFoo(*FooOptions) Foo {
+	return Foo("foo")
+}
+
+func provideBar(Foo, BarName) *Bar {
+	return &Bar{}
+}
+
+type BarService interface {
+	Bar()
+}
+
+type FooBar struct {
+	BarService
+	Foo
+}
+
+var Set = wire.NewSet(
+	provideFooOptions,
+	provideFoo,
+	provideBar,
+)
+
+var SuperSet = wire.NewSet(Set,
+	wire.Struct(new(FooBar), "*"),
+	wire.Bind(new(BarService), new(*Bar)),
+)
+
+type FakeBarService struct{}
+
+func (f *FakeBarService) Bar() {}

internal/wire/testdata/Subtract/foo/wire.go

@@ -0,0 +1,47 @@
+// Copyright 2018 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build wireinject
+// +build wireinject
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+func inject(name BarName, opts *FooOptions) *Bar {
+	panic(wire.Build(wire.Subtract(Set, new(FooOptions))))
+}
+
+func injectBarService(name BarName, opts *FakeBarService) *FooBar {
+	panic(wire.Build(
+		wire.Subtract(SuperSet, new(BarService)),
+		wire.Bind(new(BarService), new(*FakeBarService)),
+	))
+}
+
+func injectFooBarService(name BarName, opts *FooOptions, bar *FakeBarService) *FooBar {
+	panic(wire.Build(
+		wire.Subtract(SuperSet, new(FooOptions), new(BarService)),
+		wire.Bind(new(BarService), new(*FakeBarService)),
+	))
+}
+
+func injectNone(name BarName, foo Foo, bar *FakeBarService) *FooBar {
+	panic(wire.Build(
+		wire.Subtract(SuperSet, new(Foo), new(BarService)),
+		wire.Bind(new(BarService), new(*FakeBarService)),
+	))
+}

internal/wire/testdata/Subtract/pkg

@@ -0,0 +1 @@
+example.com/foo

internal/wire/testdata/SubtractErrors/foo/foo.go

@@ -0,0 +1,46 @@
+// Copyright 2018 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+type context struct{}
+
+func main() {}
+
+type FooOptions struct{}
+type Foo string
+type Bar struct{}
+type BarName string
+
+func provideFooOptions() *FooOptions {
+	return &FooOptions{}
+}
+
+func provideFoo(*FooOptions) Foo {
+	return Foo("foo")
+}
+
+func provideBar(Foo, BarName) *Bar {
+	return &Bar{}
+}
+
+var Set = wire.NewSet(
+	provideFooOptions,
+	provideFoo,
+	provideBar,
+)

internal/wire/testdata/SubtractErrors/foo/wire.go

@@ -0,0 +1,34 @@
+// Copyright 2018 The Wire Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build wireinject
+// +build wireinject
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+func injectMissArgs(opts *FooOptions) Foo {
+	panic(wire.Build(wire.Subtract(provideFoo)))
+}
+
+func injectNonSet(opts *FooOptions) Foo {
+	panic(wire.Build(wire.Subtract(provideFoo, new(FooOptions))))
+}
+
+func injectNonPointer(name BarName, opts *FooOptions) *Bar {
+	panic(wire.Build(wire.Subtract(Set, FooOptions{})))
+}

internal/wire/testdata/SubtractErrors/pkg

@@ -0,0 +1 @@
+example.com/foo

internal/wire/testdata/SubtractErrors/want/wire_errs.txt

@@ -0,0 +1,5 @@
+example.com/foo/wire.go:x:y: call to Subtract must specify types to be subtracted
+
+example.com/foo/wire.go:x:y: first argument to Subtract must be a Set
+
+example.com/foo/wire.go:x:y: argument to Subtract must be a pointer