/
parse.go
670 lines (601 loc) · 20 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.
// copied from github.com/google/wire/internal/wire
package pkg
import (
"context"
"errors"
"fmt"
"go/ast"
"go/token"
"go/types"
"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 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.LoadAllSyntax,
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
}
// 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
}
// 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
}
}
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")
}
}
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") == "-"
}
// checkField reports whether f is a field of st. f should be a string with the
// field name.
func checkField(f ast.Expr, st *types.Struct) (*types.Var, error) {
b, ok := f.(*ast.BasicLit)
if !ok {
return nil, fmt.Errorf("%v must be a string with the field name", f)
}
for i := 0; i < st.NumFields(); i++ {
if strings.EqualFold(strconv.Quote(st.Field(i).Name()), b.Value) {
if isPrevented(st.Tag(i)) {
return nil, fmt.Errorf("%s is prevented from injecting by wire", b.Value)
}
return st.Field(i), nil
}
}
return nil, fmt.Errorf("%s is not a field of %s", b.Value, st.String())
}
// findInjectorBuild returns the wire.Build call if fn is an injector template.
// It returns nil if the function is not an injector template.
func findInjectorBuild(info *types.Info, fn *ast.FuncDecl) (*ast.CallExpr, error) {
if fn.Body == nil {
return nil, nil
}
numStatements := 0
invalid := false
var wireBuildCall *ast.CallExpr
for _, stmt := range fn.Body.List {
switch stmt := stmt.(type) {
case *ast.ExprStmt:
numStatements++
if numStatements > 1 {
invalid = true
}
call, ok := stmt.X.(*ast.CallExpr)
if !ok {
continue
}
if qualifiedIdentObject(info, call.Fun) == types.Universe.Lookup("panic") {
if len(call.Args) != 1 {
continue
}
call, ok = call.Args[0].(*ast.CallExpr)
if !ok {
continue
}
}
buildObj := qualifiedIdentObject(info, call.Fun)
if buildObj == nil || buildObj.Pkg() == nil || !isWireImport(buildObj.Pkg().Path()) || buildObj.Name() != "Build" {
continue
}
wireBuildCall = call
case *ast.EmptyStmt:
// Do nothing.
case *ast.ReturnStmt:
// Allow the function to end in a return.
if numStatements == 0 {
return nil, nil
}
default:
invalid = true
}
}
if wireBuildCall == nil {
return nil, nil
}
if invalid {
return nil, errors.New("a call to wire.Build indicates that this function is an injector, but injectors must consist of only the wire.Build call and an optional return")
}
return wireBuildCall, nil
}
func isWireImport(path string) bool {
// TODO(light): This is depending on details of the current loader.
const vendorPart = "vendor/"
if i := strings.LastIndex(path, vendorPart); i != -1 && (i == 0 || path[i-1] == '/') {
path = path[i+len(vendorPart):]
}
return path == "github.com/google/wire"
}
func isProviderSetType(t types.Type) bool {
n, ok := t.(*types.Named)
if !ok {
return false
}
obj := n.Obj()
return obj.Pkg() != nil && isWireImport(obj.Pkg().Path()) && obj.Name() == "ProviderSet"
}
// ProvidedType represents a type provided from a source. The source
// can be a *Provider (a provider function), a *Value (wire.Value), or an
// *InjectorArgs (arguments to the injector function). The zero value has
// none of the above, and returns true for IsNil.
type ProvidedType struct {
// t is the provided concrete type.
t types.Type
p *Provider
v *Value
a *InjectorArg
f *Field
}
// IsNil reports whether pt is the zero value.
func (pt ProvidedType) IsNil() bool {
return pt.p == nil && pt.v == nil && pt.a == nil && pt.f == nil
}
// Type returns the output type.
//
// - 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.
func (pt ProvidedType) Type() types.Type {
return pt.t
}
// IsProvider reports whether pt points to a Provider.
func (pt ProvidedType) IsProvider() bool {
return pt.p != nil
}
// IsValue reports whether pt points to a Value.
func (pt ProvidedType) IsValue() bool {
return pt.v != nil
}
// IsArg reports whether pt points to an injector argument.
func (pt ProvidedType) IsArg() bool {
return pt.a != nil
}
// IsField reports whether pt points to a Fields.
func (pt ProvidedType) IsField() bool {
return pt.f != nil
}
// Provider returns pt as a Provider pointer. It panics if pt does not point
// to a Provider.
func (pt ProvidedType) Provider() *Provider {
if pt.p == nil {
panic("ProvidedType does not hold a Provider")
}
return pt.p
}
// Value returns pt as a Value pointer. It panics if pt does not point
// to a Value.
func (pt ProvidedType) Value() *Value {
if pt.v == nil {
panic("ProvidedType does not hold a Value")
}
return pt.v
}
// Arg returns pt as an *InjectorArg representing an injector argument. It
// panics if pt does not point to an arg.
func (pt ProvidedType) Arg() *InjectorArg {
if pt.a == nil {
panic("ProvidedType does not hold an Arg")
}
return pt.a
}
// Field returns pt as a Field pointer. It panics if pt does not point to a
// struct Field.
func (pt ProvidedType) Field() *Field {
if pt.f == nil {
panic("ProvidedType does not hold a Field")
}
return pt.f
}
// bindShouldUsePointer loads the wire package the user is importing from their
// injector. The call is a wire marker function call.
func bindShouldUsePointer(info *types.Info, call *ast.CallExpr) bool {
// These type assertions should not fail, otherwise panic.
fun := call.Fun.(*ast.SelectorExpr) // wire.Bind
pkgName := fun.X.(*ast.Ident) // wire
wireName := info.ObjectOf(pkgName).(*types.PkgName) // wire package
return wireName.Imported().Scope().Lookup("bindToUsePointer") != nil
}