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/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 {
@@ -565,7 +572,13 @@ func injectPass(name string, params *types.Tuple, injectSig outputSignature, cal
  a = disambiguate(a, ig.nameInInjector)
  }
  ig.paramNames = append(ig.paramNames, a)
- ig.p("%s %s", ig.paramNames[i], types.TypeString(pi.Type(), ig.g.qualifyPkg))
+ 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 {
@@ -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)