Support variadic provider and injector functions (#91)

Fixes #61

internal/wire/analyze.go

@@ -57,6 +57,9 @@ type call struct {
 	// This will be nil for kind == valueExpr.
 	args []int
 
+	// varargs is true if the provider function is variadic.
+	varargs bool
+
 	// fieldNames maps the arguments to struct field names.
 	// This will only be set if kind == structProvider.
 	fieldNames []string
@@ -192,6 +195,7 @@ dfs:
 				pkg:        p.Pkg,
 				name:       p.Name,
 				args:       args,
+				varargs:    p.Varargs,
 				fieldNames: p.Fields,
 				ins:        ins,
 				out:        curr.t,

internal/wire/parse.go

@@ -153,6 +153,9 @@ type Provider struct {
 	// Args is the list of data dependencies this provider has.
 	Args []ProviderInput
 
+	// Varargs is true if the provider function is variadic.
+	Varargs bool
+
 	// IsStruct is true if this provider is a named struct type.
 	// Otherwise it's a function.
 	IsStruct bool
@@ -639,6 +642,7 @@ func processFuncProvider(fset *token.FileSet, fn *types.Func) (*Provider, []erro
 		Name:       fn.Name(),
 		Pos:        fn.Pos(),
 		Args:       make([]ProviderInput, params.Len()),
+		Varargs:    sig.Variadic(),
 		Out:        []types.Type{providerSig.out},
 		HasCleanup: providerSig.cleanup,
 		HasErr:     providerSig.err,

internal/wire/testdata/Varargs/foo/foo.go

@@ -0,0 +1,31 @@
+// 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 (
+	"fmt"
+	"strings"
+)
+
+func main() {
+	fmt.Println(injectedMessage("", "Hello,", "World!"))
+}
+
+type title string
+
+// provideMessage provides a friendly user greeting.
+func provideMessage(words ...string) string {
+	return strings.Join(words, " ")
+}

internal/wire/testdata/Varargs/foo/wire.go

@@ -0,0 +1,26 @@
+// 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.
+
+//+build wireinject
+
+package main
+
+import (
+	"github.com/google/wire"
+)
+
+func injectedMessage(t title, lines ...string) string {
+	wire.Build(provideMessage)
+	return ""
+}

internal/wire/testdata/Varargs/pkg

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

internal/wire/testdata/Varargs/want/program_out.txt

@@ -0,0 +1 @@
+Hello, World!

internal/wire/testdata/Varargs/want/wire_gen.go

@@ -0,0 +1,13 @@
+// Code generated by Wire. DO NOT EDIT.
+
+//go:generate wire
+//+build !wireinject
+
+package main
+
+// Injectors from wire.go:
+
+func injectedMessage(t title, lines ...string) string {
+	string2 := provideMessage(lines...)
+	return string2
+}

internal/wire/wire.go

@@ -333,12 +333,12 @@ func (g *gen) inject(pos token.Pos, name string, sig *types.Signature, set *Prov
 	}
 
 	// Perform one pass to collect all imports, followed by the real pass.
-	injectPass(name, params, injectSig, calls, &injectorGen{
+	injectPass(name, sig, calls, &injectorGen{
 		g:       g,
 		errVar:  disambiguate("err", g.nameInFileScope),
 		discard: true,
 	})
-	injectPass(name, params, injectSig, calls, &injectorGen{
+	injectPass(name, sig, calls, &injectorGen{
 		g:       g,
 		errVar:  disambiguate("err", g.nameInFileScope),
 		discard: false,
@@ -551,7 +551,14 @@ type injectorGen struct {
 }
 
 // injectPass generates an injector given the output from analysis.
-func injectPass(name string, params *types.Tuple, injectSig outputSignature, calls []call, ig *injectorGen) {
+// The sig passed in should be verified.
+func injectPass(name string, sig *types.Signature, calls []call, ig *injectorGen) {
+	params := sig.Params()
+	injectSig, err := funcOutput(sig)
+	if err != nil {
+		// This should be checked by the caller already.
+		panic(err)
+	}
 	ig.p("func %s(", name)
 	for i := 0; i < params.Len(); i++ {
 		if i > 0 {
@@ -565,8 +572,14 @@ func injectPass(name string, params *types.Tuple, injectSig outputSignature, cal
 			a = disambiguate(a, ig.nameInInjector)
 		}
 		ig.paramNames = append(ig.paramNames, a)
+		if sig.Variadic() && i == params.Len()-1 {
+			// Keep the varargs signature instead of a slice for the last argument if the
+			// injector is variadic.
+			ig.p("%s ...%s", ig.paramNames[i], types.TypeString(pi.Type().(*types.Slice).Elem(), ig.g.qualifyPkg))
+		} else {
 			ig.p("%s %s", ig.paramNames[i], types.TypeString(pi.Type(), ig.g.qualifyPkg))
 		}
+	}
 	outTypeString := types.TypeString(injectSig.out, ig.g.qualifyPkg)
 	switch {
 	case injectSig.cleanup && injectSig.err:
@@ -639,6 +652,9 @@ func (ig *injectorGen) funcProviderCall(lname string, c *call, injectSig outputS
 			ig.p("%s", ig.localNames[a-len(ig.paramNames)])
 		}
 	}
+	if c.varargs {
+		ig.p("...")
+	}
 	ig.p(")\n")
 	if c.hasErr {
 		ig.p("\tif %s != nil {\n", ig.errVar)