forked from google/wire
/
parse.go
1247 lines (1154 loc) · 38.7 KB
/
parse.go
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// 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 wire
import (
"context"
"errors"
"fmt"
"go/ast"
"go/token"
"go/types"
"os"
"reflect"
"strconv"
"strings"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/go/packages"
"golang.org/x/tools/go/types/typeutil"
)
// A providerSetSrc captures the source for a type provided by a ProviderSet.
// Exactly one of the fields will be set.
type providerSetSrc struct {
Provider *Provider
Binding *IfaceBinding
Value *Value
Import *ProviderSet
InjectorArg *InjectorArg
Field *Field
}
// description returns a string describing the source of p, including line numbers.
func (p *providerSetSrc) description(fset *token.FileSet, typ types.Type) string {
quoted := func(s string) string {
if s == "" {
return ""
}
return fmt.Sprintf("%q ", s)
}
switch {
case p.Provider != nil:
kind := "provider"
if p.Provider.IsStruct {
kind = "struct provider"
}
return fmt.Sprintf("%s %s(%s)", kind, quoted(p.Provider.Name), fset.Position(p.Provider.Pos))
case p.Binding != nil:
return fmt.Sprintf("wire.Bind (%s)", fset.Position(p.Binding.Pos))
case p.Value != nil:
return fmt.Sprintf("wire.Value (%s)", fset.Position(p.Value.Pos))
case p.Import != nil:
return fmt.Sprintf("provider set %s(%s)", quoted(p.Import.VarName), fset.Position(p.Import.Pos))
case p.InjectorArg != nil:
args := p.InjectorArg.Args
return fmt.Sprintf("argument %s to injector function %s (%s)", args.Tuple.At(p.InjectorArg.Index).Name(), args.Name, fset.Position(args.Pos))
case p.Field != nil:
return fmt.Sprintf("wire.FieldsOf (%s)", fset.Position(p.Field.Pos))
}
panic("providerSetSrc with no fields set")
}
// trace returns a slice of strings describing the (possibly recursive) source
// of p, including line numbers.
func (p *providerSetSrc) trace(fset *token.FileSet, typ types.Type) []string {
var retval []string
// Only Imports need recursion.
if p.Import != nil {
if parent := p.Import.srcMap.At(typ); parent != nil {
retval = append(retval, parent.(*providerSetSrc).trace(fset, typ)...)
}
}
retval = append(retval, p.description(fset, typ))
return retval
}
// A ProviderSet describes a set of providers. The zero value is an empty
// ProviderSet.
type ProviderSet struct {
// Pos is the position of the call to wire.NewSet or wire.Build that
// created the set.
Pos token.Pos
// PkgPath is the import path of the package that declared this set.
PkgPath string
// VarName is the variable name of the set, if it came from a package
// variable.
VarName string
Providers []*Provider
Bindings []*IfaceBinding
Values []*Value
Fields []*Field
Imports []*ProviderSet
// InjectorArgs is only filled in for wire.Build.
InjectorArgs *InjectorArgs
// providerMap maps from provided type to a *ProvidedType.
// It includes all of the imported types.
providerMap *typeutil.Map
// srcMap maps from provided type to a *providerSetSrc capturing the
// Provider, Binding, Value, or Import that provided the type.
srcMap *typeutil.Map
}
// Outputs returns a new slice containing the set of possible types the
// provider set can produce. The order is unspecified.
func (set *ProviderSet) Outputs() []types.Type {
return set.providerMap.Keys()
}
// For returns a ProvidedType for the given type, or the zero ProvidedType.
func (set *ProviderSet) For(t types.Type) ProvidedType {
pt := set.providerMap.At(t)
if pt == nil {
return ProvidedType{}
}
return *pt.(*ProvidedType)
}
// An IfaceBinding declares that a type should be used to satisfy inputs
// of the given interface type.
type IfaceBinding struct {
// Iface is the interface type, which is what can be injected.
Iface types.Type
// Provided is always a type that is assignable to Iface.
Provided types.Type
// Pos is the position where the binding was declared.
Pos token.Pos
}
// Provider records the signature of a provider. A provider is a
// single Go object, either a function or a named struct type.
type Provider struct {
// Pkg is the package that the Go object resides in.
Pkg *types.Package
// Name is the name of the Go object.
Name string
// Pos is the source position of the func keyword or type spec
// defining this provider.
Pos token.Pos
// 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
// Out is the set of types this provider produces. It will always
// contain at least one type.
Out []types.Type
// HasCleanup reports whether the provider function returns a cleanup
// function. (Always false for structs.)
HasCleanup bool
// HasErr reports whether the provider function can return an error.
// (Always false for structs.)
HasErr bool
}
// ProviderInput describes an incoming edge in the provider graph.
type ProviderInput struct {
Type types.Type
// If the provider is a struct, FieldName will be the field name to set.
FieldName string
}
// Value describes a value expression.
type Value struct {
// Pos is the source position of the expression defining this value.
Pos token.Pos
// Out is the type this value produces.
Out types.Type
// expr is the expression passed to wire.Value.
expr ast.Expr
// info is the type info for the expression.
info *types.Info
}
// InjectorArg describes a specific argument passed to an injector function.
type InjectorArg struct {
// Args is the full set of arguments.
Args *InjectorArgs
// Index is the index into Args.Tuple for this argument.
Index int
}
// InjectorArgs describes the arguments passed to an injector function.
type InjectorArgs struct {
// Name is the name of the injector function.
Name string
// Tuple represents the arguments.
Tuple *types.Tuple
// Pos is the source position of the injector function.
Pos token.Pos
}
// Field describes a specific field selected from a struct.
type Field struct {
// Parent is the struct or pointer to the struct that the field belongs to.
Parent types.Type
// Name is the field name.
Name string
// Pkg is the package that the struct resides in.
Pkg *types.Package
// Pos is the source position of the field declaration.
// defining these fields.
Pos token.Pos
// Out is the field's provided types. The first element provides the
// field type. If the field is coming from a pointer to a struct,
// there will be a second element providing a pointer to the field.
Out []types.Type
}
// Load finds all the provider sets in the packages that match the given
// patterns, as well as the provider sets' transitive dependencies. It
// may return both errors and Info. The patterns are defined by the
// underlying build system. For the go tool, this is described at
// https://golang.org/cmd/go/#hdr-Package_lists_and_patterns
//
// wd is the working directory and env is the set of environment
// variables to use when loading the packages specified by patterns. If
// env is nil or empty, it is interpreted as an empty set of variables.
// In case of duplicate environment variables, the last one in the list
// takes precedence.
func Load(ctx context.Context, wd string, env []string, tags string, patterns []string) (*Info, []error) {
pkgs, errs := load(ctx, wd, env, tags, patterns)
if len(errs) > 0 {
return nil, errs
}
if len(pkgs) == 0 {
return new(Info), nil
}
fset := pkgs[0].Fset
info := &Info{
Fset: fset,
Sets: make(map[ProviderSetID]*ProviderSet),
}
oc := newObjectCache(pkgs)
ec := new(errorCollector)
for _, pkg := range pkgs {
if isWireImport(pkg.PkgPath) {
// The marker function package confuses analysis.
continue
}
scope := pkg.Types.Scope()
for _, name := range scope.Names() {
obj := scope.Lookup(name)
if !isProviderSetType(obj.Type()) {
continue
}
item, errs := oc.get(obj)
if len(errs) > 0 {
ec.add(notePositionAll(fset.Position(obj.Pos()), errs)...)
continue
}
pset := item.(*ProviderSet)
// pset.Name may not equal name, since it could be an alias to
// another provider set.
id := ProviderSetID{ImportPath: pset.PkgPath, VarName: name}
info.Sets[id] = pset
}
for _, f := range pkg.Syntax {
for _, decl := range f.Decls {
fn, ok := decl.(*ast.FuncDecl)
if !ok {
continue
}
buildCall, err := findInjectorBuild(pkg.TypesInfo, fn)
if err != nil {
ec.add(notePosition(fset.Position(fn.Pos()), fmt.Errorf("inject %s: %v", fn.Name.Name, err)))
continue
}
if buildCall == nil {
continue
}
sig := pkg.TypesInfo.ObjectOf(fn.Name).Type().(*types.Signature)
ins, out, err := injectorFuncSignature(sig)
if err != nil {
if w, ok := err.(*wireErr); ok {
ec.add(notePosition(w.position, fmt.Errorf("inject %s: %v", fn.Name.Name, w.error)))
} else {
ec.add(notePosition(fset.Position(fn.Pos()), fmt.Errorf("inject %s: %v", fn.Name.Name, err)))
}
continue
}
injectorArgs := &InjectorArgs{
Name: fn.Name.Name,
Tuple: ins,
Pos: fn.Pos(),
}
set, errs := oc.processNewSet(pkg.TypesInfo, pkg.PkgPath, buildCall, injectorArgs, "")
if len(errs) > 0 {
ec.add(notePositionAll(fset.Position(fn.Pos()), errs)...)
continue
}
_, errs = solve(fset, out.out, ins, set)
if len(errs) > 0 {
ec.add(mapErrors(errs, func(e error) error {
if w, ok := e.(*wireErr); ok {
return notePosition(w.position, fmt.Errorf("inject %s: %v", fn.Name.Name, w.error))
}
return notePosition(fset.Position(fn.Pos()), fmt.Errorf("inject %s: %v", fn.Name.Name, e))
})...)
continue
}
info.Injectors = append(info.Injectors, &Injector{
ImportPath: pkg.PkgPath,
FuncName: fn.Name.Name,
})
}
}
}
return info, ec.errors
}
// load typechecks the packages that match the given patterns and
// includes source for all transitive dependencies. The patterns are
// defined by the underlying build system. For the go tool, this is
// described at https://golang.org/cmd/go/#hdr-Package_lists_and_patterns
//
// wd is the working directory and env is the set of environment
// variables to use when loading the packages specified by patterns. If
// env is nil or empty, it is interpreted as an empty set of variables.
// In case of duplicate environment variables, the last one in the list
// takes precedence.
func load(ctx context.Context, wd string, env []string, tags string, patterns []string) ([]*packages.Package, []error) {
cfg := &packages.Config{
Context: ctx,
Mode: packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles | packages.NeedImports | packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo,
Dir: wd,
Env: env,
BuildFlags: []string{"-tags=wireinject"},
// TODO(light): Use ParseFile to skip function bodies and comments in indirect packages.
}
if len(tags) > 0 {
cfg.BuildFlags[0] += " " + tags
}
escaped := make([]string, len(patterns))
for i := range patterns {
escaped[i] = "pattern=" + patterns[i]
}
pkgs, err := packages.Load(cfg, escaped...)
if err != nil {
return nil, []error{err}
}
var errs []error
for _, p := range pkgs {
for _, e := range p.Errors {
errs = append(errs, e)
}
}
if len(errs) > 0 {
return nil, errs
}
return pkgs, nil
}
// Info holds the result of Load.
type Info struct {
Fset *token.FileSet
// Sets contains all the provider sets in the initial packages.
Sets map[ProviderSetID]*ProviderSet
// Injectors contains all the injector functions in the initial packages.
// The order is undefined.
Injectors []*Injector
}
// A ProviderSetID identifies a named provider set.
type ProviderSetID struct {
ImportPath string
VarName string
}
// String returns the ID as ""path/to/pkg".Foo".
func (id ProviderSetID) String() string {
return strconv.Quote(id.ImportPath) + "." + id.VarName
}
// An Injector describes an injector function.
type Injector struct {
ImportPath string
FuncName string
}
// String returns the injector name as ""path/to/pkg".Foo".
func (in *Injector) String() string {
return strconv.Quote(in.ImportPath) + "." + in.FuncName
}
// objectCache is a lazily evaluated mapping of objects to Wire structures.
type objectCache struct {
fset *token.FileSet
packages map[string]*packages.Package
objects map[objRef]objCacheEntry
hasher typeutil.Hasher
}
type objRef struct {
importPath string
name string
}
type objCacheEntry struct {
val interface{} // *Provider, *ProviderSet, *IfaceBinding, or *Value
errs []error
}
func newObjectCache(pkgs []*packages.Package) *objectCache {
if len(pkgs) == 0 {
panic("object cache must have packages to draw from")
}
oc := &objectCache{
fset: pkgs[0].Fset,
packages: make(map[string]*packages.Package),
objects: make(map[objRef]objCacheEntry),
hasher: typeutil.MakeHasher(),
}
// Depth-first search of all dependencies to gather import path to
// packages.Package mapping. go/packages guarantees that for a single
// call to packages.Load and an import path X, there will exist only
// one *packages.Package value with PkgPath X.
stk := append([]*packages.Package(nil), pkgs...)
for len(stk) > 0 {
p := stk[len(stk)-1]
stk = stk[:len(stk)-1]
if oc.packages[p.PkgPath] != nil {
continue
}
oc.packages[p.PkgPath] = p
for _, imp := range p.Imports {
stk = append(stk, imp)
}
}
return oc
}
// get converts a Go object into a Wire structure. It may return a *Provider, an
// *IfaceBinding, a *ProviderSet, a *Value, or a []*Field.
func (oc *objectCache) get(obj types.Object) (val interface{}, errs []error) {
ref := objRef{
importPath: obj.Pkg().Path(),
name: obj.Name(),
}
if ent, cached := oc.objects[ref]; cached {
return ent.val, append([]error(nil), ent.errs...)
}
defer func() {
oc.objects[ref] = objCacheEntry{
val: val,
errs: append([]error(nil), errs...),
}
}()
switch obj := obj.(type) {
case *types.Var:
spec := oc.varDecl(obj)
if spec == nil || len(spec.Values) == 0 {
return nil, []error{fmt.Errorf("%v is not a provider or a provider set", obj)}
}
var i int
for i = range spec.Names {
if spec.Names[i].Name == obj.Name() {
break
}
}
pkgPath := obj.Pkg().Path()
return oc.processExpr(oc.packages[pkgPath].TypesInfo, pkgPath, spec.Values[i], obj.Name())
case *types.Func:
return processFuncProvider(oc.fset, obj)
default:
return nil, []error{fmt.Errorf("%v is not a provider or a provider set", obj)}
}
}
// varDecl finds the declaration that defines the given variable.
func (oc *objectCache) varDecl(obj *types.Var) *ast.ValueSpec {
// TODO(light): Walk files to build object -> declaration mapping, if more performant.
// Recommended by https://golang.org/s/types-tutorial
pkg := oc.packages[obj.Pkg().Path()]
pos := obj.Pos()
for _, f := range pkg.Syntax {
tokenFile := oc.fset.File(f.Pos())
if base := tokenFile.Base(); base <= int(pos) && int(pos) < base+tokenFile.Size() {
path, _ := astutil.PathEnclosingInterval(f, pos, pos)
for _, node := range path {
if spec, ok := node.(*ast.ValueSpec); ok {
return spec
}
}
}
}
return nil
}
// processExpr converts an expression into a Wire structure. It may return a
// *Provider, an *IfaceBinding, a *ProviderSet, a *Value or a []*Field.
func (oc *objectCache) processExpr(info *types.Info, pkgPath string, expr ast.Expr, varName string) (interface{}, []error) {
exprPos := oc.fset.Position(expr.Pos())
expr = astutil.Unparen(expr)
if obj := qualifiedIdentObject(info, expr); obj != nil {
item, errs := oc.get(obj)
return item, mapErrors(errs, func(err error) error {
return notePosition(exprPos, err)
})
}
if call, ok := expr.(*ast.CallExpr); ok {
fnObj := qualifiedIdentObject(info, call.Fun)
if fnObj == nil {
return nil, []error{notePosition(exprPos, errors.New("unknown pattern fnObj nil"))}
}
pkg := fnObj.Pkg()
if pkg == nil {
return nil, []error{notePosition(exprPos, fmt.Errorf("unknown pattern - pkg in fnObj is nil - %s", fnObj))}
}
if !isWireImport(pkg.Path()) {
return nil, []error{notePosition(exprPos, errors.New("unknown pattern"))}
}
switch fnObj.Name() {
case "NewSet":
pset, errs := oc.processNewSet(info, pkgPath, call, nil, varName)
return pset, notePositionAll(exprPos, errs)
case "Bind":
b, err := processBind(oc.fset, info, call)
if err != nil {
return nil, []error{notePosition(exprPos, err)}
}
return b, nil
case "Value":
v, err := processValue(oc.fset, info, call)
if err != nil {
return nil, []error{notePosition(exprPos, err)}
}
return v, nil
case "InterfaceValue":
v, err := processInterfaceValue(oc.fset, info, call)
if err != nil {
return nil, []error{notePosition(exprPos, err)}
}
return v, nil
case "Struct":
s, err := processStructProvider(oc.fset, info, call)
if err != nil {
return nil, []error{notePosition(exprPos, err)}
}
return s, nil
case "FieldsOf":
v, err := processFieldsOf(oc.fset, info, call)
if err != nil {
return nil, []error{notePosition(exprPos, err)}
}
return v, nil
default:
return nil, []error{notePosition(exprPos, errors.New("unknown pattern"))}
}
}
if tn := structArgType(info, expr); tn != nil {
p, errs := processStructLiteralProvider(oc.fset, tn)
if len(errs) > 0 {
return nil, notePositionAll(exprPos, errs)
}
return p, nil
}
return nil, []error{notePosition(exprPos, errors.New("unknown pattern"))}
}
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.
pset := &ProviderSet{
Pos: call.Pos(),
InjectorArgs: args,
PkgPath: pkgPath,
VarName: varName,
}
ec := new(errorCollector)
for _, arg := range call.Args {
item, errs := oc.processExpr(info, pkgPath, arg, "")
if len(errs) > 0 {
ec.add(errs...)
continue
}
switch item := item.(type) {
case *Provider:
pset.Providers = append(pset.Providers, item)
case *ProviderSet:
pset.Imports = append(pset.Imports, item)
case *IfaceBinding:
pset.Bindings = append(pset.Bindings, item)
case *Value:
pset.Values = append(pset.Values, item)
case []*Field:
pset.Fields = append(pset.Fields, item...)
default:
panic("unknown item type")
}
}
if len(ec.errors) > 0 {
return nil, ec.errors
}
var errs []error
pset.providerMap, pset.srcMap, errs = buildProviderMap(oc.fset, oc.hasher, pset)
if len(errs) > 0 {
return nil, errs
}
if errs := verifyAcyclic(pset.providerMap, oc.hasher); len(errs) > 0 {
return nil, errs
}
return pset, nil
}
// structArgType attempts to interpret an expression as a simple struct type.
// It assumes any parentheses have been stripped.
func structArgType(info *types.Info, expr ast.Expr) *types.TypeName {
lit, ok := expr.(*ast.CompositeLit)
if !ok {
return nil
}
tn, ok := qualifiedIdentObject(info, lit.Type).(*types.TypeName)
if !ok {
return nil
}
if _, isStruct := tn.Type().Underlying().(*types.Struct); !isStruct {
return nil
}
return tn
}
// qualifiedIdentObject finds the object for an identifier or a
// qualified identifier, or nil if the object could not be found.
func qualifiedIdentObject(info *types.Info, expr ast.Expr) types.Object {
switch expr := expr.(type) {
case *ast.Ident:
return info.ObjectOf(expr)
case *ast.SelectorExpr:
pkgName, ok := expr.X.(*ast.Ident)
if !ok {
return nil
}
if _, ok := info.ObjectOf(pkgName).(*types.PkgName); !ok {
return nil
}
return info.ObjectOf(expr.Sel)
default:
return nil
}
}
// processFuncProvider creates a provider for a function declaration.
func processFuncProvider(fset *token.FileSet, fn *types.Func) (*Provider, []error) {
sig := fn.Type().(*types.Signature)
fpos := fn.Pos()
providerSig, err := funcOutput(sig)
if err != nil {
return nil, []error{notePosition(fset.Position(fpos), fmt.Errorf("wrong signature for provider %s: %v", fn.Name(), err))}
}
params := sig.Params()
provider := &Provider{
Pkg: fn.Pkg(),
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,
}
for i := 0; i < params.Len(); i++ {
provider.Args[i] = ProviderInput{
Type: params.At(i).Type(),
}
for j := 0; j < i; j++ {
if types.Identical(provider.Args[i].Type, provider.Args[j].Type) {
return nil, []error{notePosition(fset.Position(fpos), fmt.Errorf("provider has multiple parameters of type %s", types.TypeString(provider.Args[j].Type, nil)))}
}
}
}
return provider, nil
}
func injectorFuncSignature(sig *types.Signature) (*types.Tuple, outputSignature, error) {
out, err := funcOutput(sig)
if err != nil {
return nil, outputSignature{}, err
}
return sig.Params(), out, nil
}
type outputSignature struct {
out types.Type
cleanup bool
err bool
}
// funcOutput validates an injector or provider function's return signature.
func funcOutput(sig *types.Signature) (outputSignature, error) {
results := sig.Results()
switch results.Len() {
case 0:
return outputSignature{}, errors.New("no return values")
case 1:
return outputSignature{out: results.At(0).Type()}, nil
case 2:
out := results.At(0).Type()
switch t := results.At(1).Type(); {
case types.Identical(t, errorType):
return outputSignature{out: out, err: true}, nil
case types.Identical(t, cleanupType):
return outputSignature{out: out, cleanup: true}, nil
default:
return outputSignature{}, fmt.Errorf("second return type is %s; must be error or func()", types.TypeString(t, nil))
}
case 3:
if t := results.At(1).Type(); !types.Identical(t, cleanupType) {
return outputSignature{}, fmt.Errorf("second return type is %s; must be func()", types.TypeString(t, nil))
}
if t := results.At(2).Type(); !types.Identical(t, errorType) {
return outputSignature{}, fmt.Errorf("third return type is %s; must be error", types.TypeString(t, nil))
}
return outputSignature{
out: results.At(0).Type(),
cleanup: true,
err: true,
}, nil
default:
return outputSignature{}, errors.New("too many return values")
}
}
// processStructLiteralProvider creates a provider for a named struct type.
// It produces pointer and non-pointer variants via two values in Out.
//
// This is a copy of the old processStructProvider, which is deprecated now.
// It will not support any new feature introduced after v0.2. Please use the new
// wire.Struct syntax for those.
func processStructLiteralProvider(fset *token.FileSet, typeName *types.TypeName) (*Provider, []error) {
out := typeName.Type()
st, ok := out.Underlying().(*types.Struct)
if !ok {
return nil, []error{fmt.Errorf("%v does not name a struct", typeName)}
}
pos := typeName.Pos()
fmt.Fprintf(os.Stderr,
"Warning: %v, see https://godoc.org/github.com/google/wire#Struct for more information.\n",
notePosition(fset.Position(pos),
fmt.Errorf("using struct literal to inject %s is deprecated and will be removed in the next release; use wire.Struct instead",
typeName.Type())))
provider := &Provider{
Pkg: typeName.Pkg(),
Name: typeName.Name(),
Pos: pos,
Args: make([]ProviderInput, st.NumFields()),
IsStruct: true,
Out: []types.Type{out, types.NewPointer(out)},
}
for i := 0; i < st.NumFields(); i++ {
f := st.Field(i)
provider.Args[i] = ProviderInput{
Type: f.Type(),
FieldName: f.Name(),
}
for j := 0; j < i; j++ {
if types.Identical(provider.Args[i].Type, provider.Args[j].Type) {
return nil, []error{notePosition(fset.Position(pos), fmt.Errorf("provider struct has multiple fields of type %s", types.TypeString(provider.Args[j].Type, nil)))}
}
}
}
return provider, nil
}
// processStructProvider creates a provider for a named struct type.
// It produces pointer and non-pointer variants via two values in Out.
func processStructProvider(fset *token.FileSet, info *types.Info, call *ast.CallExpr) (*Provider, error) {
// Assumes that call.Fun is wire.Struct.
if len(call.Args) < 1 {
return nil, notePosition(fset.Position(call.Pos()),
errors.New("call to Struct must specify the struct to be injected"))
}
const firstArgReqFormat = "first argument to Struct must be a pointer to a named struct; found %s"
structType := info.TypeOf(call.Args[0])
structPtr, ok := structType.(*types.Pointer)
if !ok {
return nil, notePosition(fset.Position(call.Pos()),
fmt.Errorf(firstArgReqFormat, types.TypeString(structType, nil)))
}
st, ok := structPtr.Elem().Underlying().(*types.Struct)
if !ok {
return nil, notePosition(fset.Position(call.Pos()),
fmt.Errorf(firstArgReqFormat, types.TypeString(structPtr, nil)))
}
stExpr := call.Args[0].(*ast.CallExpr)
typeName := qualifiedIdentObject(info, stExpr.Args[0]) // should be either an identifier or selector
provider := &Provider{
Pkg: typeName.Pkg(),
Name: typeName.Name(),
Pos: typeName.Pos(),
IsStruct: true,
Out: []types.Type{structPtr.Elem(), structPtr},
}
if allFields(call) {
for i := 0; i < st.NumFields(); i++ {
if isPrevented(st.Tag(i)) {
continue
}
f := st.Field(i)
provider.Args = append(provider.Args, ProviderInput{
Type: f.Type(),
FieldName: f.Name(),
})
}
} else {
provider.Args = make([]ProviderInput, len(call.Args)-1)
for i := 1; i < len(call.Args); i++ {
v, err := checkField(call.Args[i], st)
if err != nil {
return nil, notePosition(fset.Position(call.Pos()), err)
}
provider.Args[i-1] = ProviderInput{
Type: v.Type(),
FieldName: v.Name(),
}
}
}
for i := 0; i < len(provider.Args); i++ {
for j := 0; j < i; j++ {
if types.Identical(provider.Args[i].Type, provider.Args[j].Type) {
f := st.Field(j)
return nil, notePosition(fset.Position(f.Pos()), fmt.Errorf("provider struct has multiple fields of type %s", types.TypeString(provider.Args[j].Type, nil)))
}
}
}
return provider, nil
}
func allFields(call *ast.CallExpr) bool {
if len(call.Args) != 2 {
return false
}
b, ok := call.Args[1].(*ast.BasicLit)
if !ok {
return false
}
return strings.EqualFold(strconv.Quote("*"), b.Value)
}
// isPrevented checks whether field i is prevented by tag "-".
// Since this is the only tag used by wire, we can do string comparison
// without using reflect.
func isPrevented(tag string) bool {
return reflect.StructTag(tag).Get("wire") == "-"
}
// processBind creates an interface binding from a wire.Bind call.
func processBind(fset *token.FileSet, info *types.Info, call *ast.CallExpr) (*IfaceBinding, error) {
// Assumes that call.Fun is wire.Bind.
if len(call.Args) != 2 {
return nil, notePosition(fset.Position(call.Pos()),
errors.New("call to Bind takes exactly two arguments"))
}
// TODO(light): Verify that arguments are simple expressions.
ifaceArgType := info.TypeOf(call.Args[0])
ifacePtr, ok := ifaceArgType.(*types.Pointer)
if !ok {
return nil, notePosition(fset.Position(call.Pos()),
fmt.Errorf("first argument to Bind must be a pointer to an interface type; found %s", types.TypeString(ifaceArgType, nil)))
}
iface := ifacePtr.Elem()
methodSet, ok := iface.Underlying().(*types.Interface)
if !ok {
return nil, notePosition(fset.Position(call.Pos()),
fmt.Errorf("first argument to Bind must be a pointer to an interface type; found %s", types.TypeString(ifaceArgType, nil)))
}
provided := info.TypeOf(call.Args[1])
if bindShouldUsePointer(info, call) {
providedPtr, ok := provided.(*types.Pointer)
if !ok {
return nil, notePosition(fset.Position(call.Args[0].Pos()),
fmt.Errorf("second argument to Bind must be a pointer or a pointer to a pointer; found %s", types.TypeString(provided, nil)))
}
provided = providedPtr.Elem()
}
if types.Identical(iface, provided) {
return nil, notePosition(fset.Position(call.Pos()),
errors.New("cannot bind interface to itself"))
}
if !types.Implements(provided, methodSet) {
return nil, notePosition(fset.Position(call.Pos()),
fmt.Errorf("%s does not implement %s", types.TypeString(provided, nil), types.TypeString(iface, nil)))
}
return &IfaceBinding{
Pos: call.Pos(),
Iface: iface,
Provided: provided,
}, nil
}
// processValue creates a value from a wire.Value call.
func processValue(fset *token.FileSet, info *types.Info, call *ast.CallExpr) (*Value, error) {
// Assumes that call.Fun is wire.Value.
if len(call.Args) != 1 {
return nil, notePosition(fset.Position(call.Pos()), errors.New("call to Value takes exactly one argument"))
}
ok := true
ast.Inspect(call.Args[0], func(node ast.Node) bool {
switch expr := node.(type) {
case nil, *ast.ArrayType, *ast.BasicLit, *ast.BinaryExpr, *ast.ChanType, *ast.CompositeLit, *ast.FuncType, *ast.Ident, *ast.IndexExpr, *ast.InterfaceType, *ast.KeyValueExpr, *ast.MapType, *ast.ParenExpr, *ast.SelectorExpr, *ast.SliceExpr, *ast.StarExpr, *ast.StructType, *ast.TypeAssertExpr:
// Good!
case *ast.UnaryExpr:
if expr.Op == token.ARROW {
ok = false
return false
}
case *ast.CallExpr:
// Only acceptable if it's a type conversion.
if _, isFunc := info.TypeOf(expr.Fun).(*types.Signature); isFunc {
ok = false
return false
}
default:
ok = false
return false
}
return true
})
if !ok {
return nil, notePosition(fset.Position(call.Pos()), errors.New("argument to Value is too complex"))
}
// Result type can't be an interface type; use wire.InterfaceValue for that.
argType := info.TypeOf(call.Args[0])
if _, isInterfaceType := argType.Underlying().(*types.Interface); isInterfaceType {
return nil, notePosition(fset.Position(call.Pos()), fmt.Errorf("argument to Value may not be an interface value (found %s); use InterfaceValue instead", types.TypeString(argType, nil)))
}
return &Value{
Pos: call.Args[0].Pos(),
Out: info.TypeOf(call.Args[0]),
expr: call.Args[0],
info: info,
}, nil
}
// processInterfaceValue creates a value from a wire.InterfaceValue call.
func processInterfaceValue(fset *token.FileSet, info *types.Info, call *ast.CallExpr) (*Value, error) {
// Assumes that call.Fun is wire.InterfaceValue.
if len(call.Args) != 2 {
return nil, notePosition(fset.Position(call.Pos()), errors.New("call to InterfaceValue takes exactly two arguments"))
}
ifaceArgType := info.TypeOf(call.Args[0])
ifacePtr, ok := ifaceArgType.(*types.Pointer)
if !ok {
return nil, notePosition(fset.Position(call.Pos()), fmt.Errorf("first argument to InterfaceValue must be a pointer to an interface type; found %s", types.TypeString(ifaceArgType, nil)))
}
iface := ifacePtr.Elem()
methodSet, ok := iface.Underlying().(*types.Interface)
if !ok {
return nil, notePosition(fset.Position(call.Pos()), fmt.Errorf("first argument to InterfaceValue must be a pointer to an interface type; found %s", types.TypeString(ifaceArgType, nil)))
}
provided := info.TypeOf(call.Args[1])
if !types.Implements(provided, methodSet) {
return nil, notePosition(fset.Position(call.Pos()), fmt.Errorf("%s does not implement %s", types.TypeString(provided, nil), types.TypeString(iface, nil)))
}
return &Value{
Pos: call.Args[1].Pos(),
Out: iface,
expr: call.Args[1],
info: info,
}, nil