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@@ -0,0 +1,762 @@
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+// Copyright 2018 The Go Authors. All rights reserved.
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+// Use of this source code is governed by a BSD-style
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+// license that can be found in the LICENSE file.
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+
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+// Package objectpath defines a naming scheme for types.Objects
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+// (that is, named entities in Go programs) relative to their enclosing
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+// package.
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+//
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+// Type-checker objects are canonical, so they are usually identified by
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+// their address in memory (a pointer), but a pointer has meaning only
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+// within one address space. By contrast, objectpath names allow the
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+// identity of an object to be sent from one program to another,
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+// establishing a correspondence between types.Object variables that are
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+// distinct but logically equivalent.
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+//
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+// A single object may have multiple paths. In this example,
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+//
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+// type A struct{ X int }
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+// type B A
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+//
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+// the field X has two paths due to its membership of both A and B.
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+// The For(obj) function always returns one of these paths, arbitrarily
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+// but consistently.
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+package objectpath
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+
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+import (
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+ "fmt"
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+ "go/types"
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+ "sort"
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+ "strconv"
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+ "strings"
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+
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+ "golang.org/x/tools/internal/typeparams"
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+
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+ _ "unsafe" // for go:linkname
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+)
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+
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+// A Path is an opaque name that identifies a types.Object
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+// relative to its package. Conceptually, the name consists of a
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+// sequence of destructuring operations applied to the package scope
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+// to obtain the original object.
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+// The name does not include the package itself.
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+type Path string
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+
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+// Encoding
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+//
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+// An object path is a textual and (with training) human-readable encoding
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+// of a sequence of destructuring operators, starting from a types.Package.
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+// The sequences represent a path through the package/object/type graph.
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+// We classify these operators by their type:
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+//
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+// PO package->object Package.Scope.Lookup
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+// OT object->type Object.Type
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+// TT type->type Type.{Elem,Key,Params,Results,Underlying} [EKPRU]
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+// TO type->object Type.{At,Field,Method,Obj} [AFMO]
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+//
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+// All valid paths start with a package and end at an object
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+// and thus may be defined by the regular language:
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+//
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+// objectpath = PO (OT TT* TO)*
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+//
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+// The concrete encoding follows directly:
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+// - The only PO operator is Package.Scope.Lookup, which requires an identifier.
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+// - The only OT operator is Object.Type,
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+// which we encode as '.' because dot cannot appear in an identifier.
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+// - The TT operators are encoded as [EKPRUTC];
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+// one of these (TypeParam) requires an integer operand,
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+// which is encoded as a string of decimal digits.
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+// - The TO operators are encoded as [AFMO];
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+// three of these (At,Field,Method) require an integer operand,
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+// which is encoded as a string of decimal digits.
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+// These indices are stable across different representations
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+// of the same package, even source and export data.
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+// The indices used are implementation specific and may not correspond to
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+// the argument to the go/types function.
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+//
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+// In the example below,
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+//
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+// package p
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+//
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+// type T interface {
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+// f() (a string, b struct{ X int })
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+// }
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+//
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+// field X has the path "T.UM0.RA1.F0",
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+// representing the following sequence of operations:
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+//
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+// p.Lookup("T") T
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+// .Type().Underlying().Method(0). f
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+// .Type().Results().At(1) b
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+// .Type().Field(0) X
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+//
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+// The encoding is not maximally compact---every R or P is
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+// followed by an A, for example---but this simplifies the
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+// encoder and decoder.
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+const (
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+ // object->type operators
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+ opType = '.' // .Type() (Object)
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+
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+ // type->type operators
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+ opElem = 'E' // .Elem() (Pointer, Slice, Array, Chan, Map)
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+ opKey = 'K' // .Key() (Map)
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+ opParams = 'P' // .Params() (Signature)
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+ opResults = 'R' // .Results() (Signature)
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+ opUnderlying = 'U' // .Underlying() (Named)
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+ opTypeParam = 'T' // .TypeParams.At(i) (Named, Signature)
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+ opConstraint = 'C' // .Constraint() (TypeParam)
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+
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+ // type->object operators
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+ opAt = 'A' // .At(i) (Tuple)
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+ opField = 'F' // .Field(i) (Struct)
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+ opMethod = 'M' // .Method(i) (Named or Interface; not Struct: "promoted" names are ignored)
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+ opObj = 'O' // .Obj() (Named, TypeParam)
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+)
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+
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+// For returns the path to an object relative to its package,
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+// or an error if the object is not accessible from the package's Scope.
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+//
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+// The For function guarantees to return a path only for the following objects:
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+// - package-level types
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+// - exported package-level non-types
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+// - methods
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+// - parameter and result variables
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+// - struct fields
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+// These objects are sufficient to define the API of their package.
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+// The objects described by a package's export data are drawn from this set.
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+//
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+// For does not return a path for predeclared names, imported package
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+// names, local names, and unexported package-level names (except
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+// types).
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+//
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+// Example: given this definition,
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+//
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+// package p
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+//
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+// type T interface {
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+// f() (a string, b struct{ X int })
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+// }
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+//
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+// For(X) would return a path that denotes the following sequence of operations:
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+//
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+// p.Scope().Lookup("T") (TypeName T)
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+// .Type().Underlying().Method(0). (method Func f)
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+// .Type().Results().At(1) (field Var b)
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+// .Type().Field(0) (field Var X)
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+//
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+// where p is the package (*types.Package) to which X belongs.
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+func For(obj types.Object) (Path, error) {
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+ return newEncoderFor()(obj)
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+}
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+
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+// An encoder amortizes the cost of encoding the paths of multiple objects.
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+// Nonexported pending approval of proposal 58668.
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+type encoder struct {
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+ scopeNamesMemo map[*types.Scope][]string // memoization of Scope.Names()
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+ namedMethodsMemo map[*types.Named][]*types.Func // memoization of namedMethods()
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+}
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+
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+// Exposed to gopls via golang.org/x/tools/internal/typesinternal
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+// pending approval of proposal 58668.
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+//
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+//go:linkname newEncoderFor
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+func newEncoderFor() func(types.Object) (Path, error) { return new(encoder).For }
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+
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+func (enc *encoder) For(obj types.Object) (Path, error) {
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+ pkg := obj.Pkg()
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+
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+ // This table lists the cases of interest.
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+ //
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+ // Object Action
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+ // ------ ------
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+ // nil reject
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+ // builtin reject
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+ // pkgname reject
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+ // label reject
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+ // var
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+ // package-level accept
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+ // func param/result accept
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+ // local reject
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+ // struct field accept
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+ // const
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+ // package-level accept
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+ // local reject
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+ // func
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+ // package-level accept
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+ // init functions reject
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+ // concrete method accept
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+ // interface method accept
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+ // type
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+ // package-level accept
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+ // local reject
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+ //
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+ // The only accessible package-level objects are members of pkg itself.
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+ //
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+ // The cases are handled in four steps:
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+ //
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+ // 1. reject nil and builtin
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+ // 2. accept package-level objects
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+ // 3. reject obviously invalid objects
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+ // 4. search the API for the path to the param/result/field/method.
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+
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+ // 1. reference to nil or builtin?
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+ if pkg == nil {
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+ return "", fmt.Errorf("predeclared %s has no path", obj)
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+ }
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+ scope := pkg.Scope()
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+
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+ // 2. package-level object?
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+ if scope.Lookup(obj.Name()) == obj {
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+ // Only exported objects (and non-exported types) have a path.
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+ // Non-exported types may be referenced by other objects.
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+ if _, ok := obj.(*types.TypeName); !ok && !obj.Exported() {
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+ return "", fmt.Errorf("no path for non-exported %v", obj)
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+ }
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+ return Path(obj.Name()), nil
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+ }
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+
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+ // 3. Not a package-level object.
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+ // Reject obviously non-viable cases.
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+ switch obj := obj.(type) {
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+ case *types.TypeName:
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+ if _, ok := obj.Type().(*typeparams.TypeParam); !ok {
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+ // With the exception of type parameters, only package-level type names
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+ // have a path.
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+ return "", fmt.Errorf("no path for %v", obj)
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+ }
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+ case *types.Const, // Only package-level constants have a path.
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+ *types.Label, // Labels are function-local.
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+ *types.PkgName: // PkgNames are file-local.
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+ return "", fmt.Errorf("no path for %v", obj)
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+
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+ case *types.Var:
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+ // Could be:
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+ // - a field (obj.IsField())
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+ // - a func parameter or result
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+ // - a local var.
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+ // Sadly there is no way to distinguish
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+ // a param/result from a local
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+ // so we must proceed to the find.
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+
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+ case *types.Func:
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+ // A func, if not package-level, must be a method.
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+ if recv := obj.Type().(*types.Signature).Recv(); recv == nil {
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+ return "", fmt.Errorf("func is not a method: %v", obj)
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+ }
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+
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+ if path, ok := enc.concreteMethod(obj); ok {
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+ // Fast path for concrete methods that avoids looping over scope.
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+ return path, nil
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+ }
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+
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+ default:
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+ panic(obj)
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+ }
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+
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+ // 4. Search the API for the path to the var (field/param/result) or method.
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+
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+ // First inspect package-level named types.
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+ // In the presence of path aliases, these give
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+ // the best paths because non-types may
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+ // refer to types, but not the reverse.
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+ empty := make([]byte, 0, 48) // initial space
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+ names := enc.scopeNames(scope)
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+ for _, name := range names {
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+ o := scope.Lookup(name)
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+ tname, ok := o.(*types.TypeName)
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+ if !ok {
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+ continue // handle non-types in second pass
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+ }
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+
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+ path := append(empty, name...)
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+ path = append(path, opType)
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+
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+ T := o.Type()
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+
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+ if tname.IsAlias() {
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+ // type alias
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+ if r := find(obj, T, path, nil); r != nil {
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+ return Path(r), nil
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+ }
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+ } else {
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+ if named, _ := T.(*types.Named); named != nil {
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+ if r := findTypeParam(obj, typeparams.ForNamed(named), path, nil); r != nil {
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+ // generic named type
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+ return Path(r), nil
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+ }
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+ }
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+ // defined (named) type
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+ if r := find(obj, T.Underlying(), append(path, opUnderlying), nil); r != nil {
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+ return Path(r), nil
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+ }
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+ }
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+ }
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+
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+ // Then inspect everything else:
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+ // non-types, and declared methods of defined types.
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+ for _, name := range names {
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+ o := scope.Lookup(name)
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+ path := append(empty, name...)
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+ if _, ok := o.(*types.TypeName); !ok {
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+ if o.Exported() {
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+ // exported non-type (const, var, func)
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+ if r := find(obj, o.Type(), append(path, opType), nil); r != nil {
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+ return Path(r), nil
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+ }
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+ }
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+ continue
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+ }
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+
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+ // Inspect declared methods of defined types.
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+ if T, ok := o.Type().(*types.Named); ok {
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+ path = append(path, opType)
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+ // Note that method index here is always with respect
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+ // to canonical ordering of methods, regardless of how
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+ // they appear in the underlying type.
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+ for i, m := range enc.namedMethods(T) {
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+ path2 := appendOpArg(path, opMethod, i)
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+ if m == obj {
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+ return Path(path2), nil // found declared method
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+ }
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+ if r := find(obj, m.Type(), append(path2, opType), nil); r != nil {
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+ return Path(r), nil
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+ }
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+ }
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+ }
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+ }
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+
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+ return "", fmt.Errorf("can't find path for %v in %s", obj, pkg.Path())
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+}
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+
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+func appendOpArg(path []byte, op byte, arg int) []byte {
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+ path = append(path, op)
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+ path = strconv.AppendInt(path, int64(arg), 10)
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+ return path
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+}
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+
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+// concreteMethod returns the path for meth, which must have a non-nil receiver.
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+// The second return value indicates success and may be false if the method is
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+// an interface method or if it is an instantiated method.
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+//
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+// This function is just an optimization that avoids the general scope walking
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+// approach. You are expected to fall back to the general approach if this
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+// function fails.
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+func (enc *encoder) concreteMethod(meth *types.Func) (Path, bool) {
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+ // Concrete methods can only be declared on package-scoped named types. For
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+ // that reason we can skip the expensive walk over the package scope: the
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+ // path will always be package -> named type -> method. We can trivially get
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+ // the type name from the receiver, and only have to look over the type's
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+ // methods to find the method index.
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+ //
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+ // Methods on generic types require special consideration, however. Consider
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+ // the following package:
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+ //
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+ // L1: type S[T any] struct{}
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|
|
+ // L2: func (recv S[A]) Foo() { recv.Bar() }
|
|
|
|
+ // L3: func (recv S[B]) Bar() { }
|
|
|
|
+ // L4: type Alias = S[int]
|
|
|
|
+ // L5: func _[T any]() { var s S[int]; s.Foo() }
|
|
|
|
+ //
|
|
|
|
+ // The receivers of methods on generic types are instantiations. L2 and L3
|
|
|
|
+ // instantiate S with the type-parameters A and B, which are scoped to the
|
|
|
|
+ // respective methods. L4 and L5 each instantiate S with int. Each of these
|
|
|
|
+ // instantiations has its own method set, full of methods (and thus objects)
|
|
|
|
+ // with receivers whose types are the respective instantiations. In other
|
|
|
|
+ // words, we have
|
|
|
|
+ //
|
|
|
|
+ // S[A].Foo, S[A].Bar
|
|
|
|
+ // S[B].Foo, S[B].Bar
|
|
|
|
+ // S[int].Foo, S[int].Bar
|
|
|
|
+ //
|
|
|
|
+ // We may thus be trying to produce object paths for any of these objects.
|
|
|
|
+ //
|
|
|
|
+ // S[A].Foo and S[B].Bar are the origin methods, and their paths are S.Foo
|
|
|
|
+ // and S.Bar, which are the paths that this function naturally produces.
|
|
|
|
+ //
|
|
|
|
+ // S[A].Bar, S[B].Foo, and both methods on S[int] are instantiations that
|
|
|
|
+ // don't correspond to the origin methods. For S[int], this is significant.
|
|
|
|
+ // The most precise object path for S[int].Foo, for example, is Alias.Foo,
|
|
|
|
+ // not S.Foo. Our function, however, would produce S.Foo, which would
|
|
|
|
+ // resolve to a different object.
|
|
|
|
+ //
|
|
|
|
+ // For S[A].Bar and S[B].Foo it could be argued that S.Bar and S.Foo are
|
|
|
|
+ // still the correct paths, since only the origin methods have meaningful
|
|
|
|
+ // paths. But this is likely only true for trivial cases and has edge cases.
|
|
|
|
+ // Since this function is only an optimization, we err on the side of giving
|
|
|
|
+ // up, deferring to the slower but definitely correct algorithm. Most users
|
|
|
|
+ // of objectpath will only be giving us origin methods, anyway, as referring
|
|
|
|
+ // to instantiated methods is usually not useful.
|
|
|
|
+
|
|
|
|
+ if typeparams.OriginMethod(meth) != meth {
|
|
|
|
+ return "", false
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ recvT := meth.Type().(*types.Signature).Recv().Type()
|
|
|
|
+ if ptr, ok := recvT.(*types.Pointer); ok {
|
|
|
|
+ recvT = ptr.Elem()
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ named, ok := recvT.(*types.Named)
|
|
|
|
+ if !ok {
|
|
|
|
+ return "", false
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ if types.IsInterface(named) {
|
|
|
|
+ // Named interfaces don't have to be package-scoped
|
|
|
|
+ //
|
|
|
|
+ // TODO(dominikh): opt: if scope.Lookup(name) == named, then we can apply this optimization to interface
|
|
|
|
+ // methods, too, I think.
|
|
|
|
+ return "", false
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ // Preallocate space for the name, opType, opMethod, and some digits.
|
|
|
|
+ name := named.Obj().Name()
|
|
|
|
+ path := make([]byte, 0, len(name)+8)
|
|
|
|
+ path = append(path, name...)
|
|
|
|
+ path = append(path, opType)
|
|
|
|
+ for i, m := range enc.namedMethods(named) {
|
|
|
|
+ if m == meth {
|
|
|
|
+ path = appendOpArg(path, opMethod, i)
|
|
|
|
+ return Path(path), true
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ panic(fmt.Sprintf("couldn't find method %s on type %s", meth, named))
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+// find finds obj within type T, returning the path to it, or nil if not found.
|
|
|
|
+//
|
|
|
|
+// The seen map is used to short circuit cycles through type parameters. If
|
|
|
|
+// nil, it will be allocated as necessary.
|
|
|
|
+func find(obj types.Object, T types.Type, path []byte, seen map[*types.TypeName]bool) []byte {
|
|
|
|
+ switch T := T.(type) {
|
|
|
|
+ case *types.Basic, *types.Named:
|
|
|
|
+ // Named types belonging to pkg were handled already,
|
|
|
|
+ // so T must belong to another package. No path.
|
|
|
|
+ return nil
|
|
|
|
+ case *types.Pointer:
|
|
|
|
+ return find(obj, T.Elem(), append(path, opElem), seen)
|
|
|
|
+ case *types.Slice:
|
|
|
|
+ return find(obj, T.Elem(), append(path, opElem), seen)
|
|
|
|
+ case *types.Array:
|
|
|
|
+ return find(obj, T.Elem(), append(path, opElem), seen)
|
|
|
|
+ case *types.Chan:
|
|
|
|
+ return find(obj, T.Elem(), append(path, opElem), seen)
|
|
|
|
+ case *types.Map:
|
|
|
|
+ if r := find(obj, T.Key(), append(path, opKey), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ return find(obj, T.Elem(), append(path, opElem), seen)
|
|
|
|
+ case *types.Signature:
|
|
|
|
+ if r := findTypeParam(obj, typeparams.ForSignature(T), path, seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ if r := find(obj, T.Params(), append(path, opParams), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ return find(obj, T.Results(), append(path, opResults), seen)
|
|
|
|
+ case *types.Struct:
|
|
|
|
+ for i := 0; i < T.NumFields(); i++ {
|
|
|
|
+ fld := T.Field(i)
|
|
|
|
+ path2 := appendOpArg(path, opField, i)
|
|
|
|
+ if fld == obj {
|
|
|
|
+ return path2 // found field var
|
|
|
|
+ }
|
|
|
|
+ if r := find(obj, fld.Type(), append(path2, opType), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+ return nil
|
|
|
|
+ case *types.Tuple:
|
|
|
|
+ for i := 0; i < T.Len(); i++ {
|
|
|
|
+ v := T.At(i)
|
|
|
|
+ path2 := appendOpArg(path, opAt, i)
|
|
|
|
+ if v == obj {
|
|
|
|
+ return path2 // found param/result var
|
|
|
|
+ }
|
|
|
|
+ if r := find(obj, v.Type(), append(path2, opType), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+ return nil
|
|
|
|
+ case *types.Interface:
|
|
|
|
+ for i := 0; i < T.NumMethods(); i++ {
|
|
|
|
+ m := T.Method(i)
|
|
|
|
+ path2 := appendOpArg(path, opMethod, i)
|
|
|
|
+ if m == obj {
|
|
|
|
+ return path2 // found interface method
|
|
|
|
+ }
|
|
|
|
+ if r := find(obj, m.Type(), append(path2, opType), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+ return nil
|
|
|
|
+ case *typeparams.TypeParam:
|
|
|
|
+ name := T.Obj()
|
|
|
|
+ if name == obj {
|
|
|
|
+ return append(path, opObj)
|
|
|
|
+ }
|
|
|
|
+ if seen[name] {
|
|
|
|
+ return nil
|
|
|
|
+ }
|
|
|
|
+ if seen == nil {
|
|
|
|
+ seen = make(map[*types.TypeName]bool)
|
|
|
|
+ }
|
|
|
|
+ seen[name] = true
|
|
|
|
+ if r := find(obj, T.Constraint(), append(path, opConstraint), seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ return nil
|
|
|
|
+ }
|
|
|
|
+ panic(T)
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+func findTypeParam(obj types.Object, list *typeparams.TypeParamList, path []byte, seen map[*types.TypeName]bool) []byte {
|
|
|
|
+ for i := 0; i < list.Len(); i++ {
|
|
|
|
+ tparam := list.At(i)
|
|
|
|
+ path2 := appendOpArg(path, opTypeParam, i)
|
|
|
|
+ if r := find(obj, tparam, path2, seen); r != nil {
|
|
|
|
+ return r
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+ return nil
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+// Object returns the object denoted by path p within the package pkg.
|
|
|
|
+func Object(pkg *types.Package, p Path) (types.Object, error) {
|
|
|
|
+ if p == "" {
|
|
|
|
+ return nil, fmt.Errorf("empty path")
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ pathstr := string(p)
|
|
|
|
+ var pkgobj, suffix string
|
|
|
|
+ if dot := strings.IndexByte(pathstr, opType); dot < 0 {
|
|
|
|
+ pkgobj = pathstr
|
|
|
|
+ } else {
|
|
|
|
+ pkgobj = pathstr[:dot]
|
|
|
|
+ suffix = pathstr[dot:] // suffix starts with "."
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ obj := pkg.Scope().Lookup(pkgobj)
|
|
|
|
+ if obj == nil {
|
|
|
|
+ return nil, fmt.Errorf("package %s does not contain %q", pkg.Path(), pkgobj)
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ // abstraction of *types.{Pointer,Slice,Array,Chan,Map}
|
|
|
|
+ type hasElem interface {
|
|
|
|
+ Elem() types.Type
|
|
|
|
+ }
|
|
|
|
+ // abstraction of *types.{Named,Signature}
|
|
|
|
+ type hasTypeParams interface {
|
|
|
|
+ TypeParams() *typeparams.TypeParamList
|
|
|
|
+ }
|
|
|
|
+ // abstraction of *types.{Named,TypeParam}
|
|
|
|
+ type hasObj interface {
|
|
|
|
+ Obj() *types.TypeName
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ // The loop state is the pair (t, obj),
|
|
|
|
+ // exactly one of which is non-nil, initially obj.
|
|
|
|
+ // All suffixes start with '.' (the only object->type operation),
|
|
|
|
+ // followed by optional type->type operations,
|
|
|
|
+ // then a type->object operation.
|
|
|
|
+ // The cycle then repeats.
|
|
|
|
+ var t types.Type
|
|
|
|
+ for suffix != "" {
|
|
|
|
+ code := suffix[0]
|
|
|
|
+ suffix = suffix[1:]
|
|
|
|
+
|
|
|
|
+ // Codes [AFM] have an integer operand.
|
|
|
|
+ var index int
|
|
|
|
+ switch code {
|
|
|
|
+ case opAt, opField, opMethod, opTypeParam:
|
|
|
|
+ rest := strings.TrimLeft(suffix, "0123456789")
|
|
|
|
+ numerals := suffix[:len(suffix)-len(rest)]
|
|
|
|
+ suffix = rest
|
|
|
|
+ i, err := strconv.Atoi(numerals)
|
|
|
|
+ if err != nil {
|
|
|
|
+ return nil, fmt.Errorf("invalid path: bad numeric operand %q for code %q", numerals, code)
|
|
|
|
+ }
|
|
|
|
+ index = int(i)
|
|
|
|
+ case opObj:
|
|
|
|
+ // no operand
|
|
|
|
+ default:
|
|
|
|
+ // The suffix must end with a type->object operation.
|
|
|
|
+ if suffix == "" {
|
|
|
|
+ return nil, fmt.Errorf("invalid path: ends with %q, want [AFMO]", code)
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ if code == opType {
|
|
|
|
+ if t != nil {
|
|
|
|
+ return nil, fmt.Errorf("invalid path: unexpected %q in type context", opType)
|
|
|
|
+ }
|
|
|
|
+ t = obj.Type()
|
|
|
|
+ obj = nil
|
|
|
|
+ continue
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ if t == nil {
|
|
|
|
+ return nil, fmt.Errorf("invalid path: code %q in object context", code)
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ // Inv: t != nil, obj == nil
|
|
|
|
+
|
|
|
|
+ switch code {
|
|
|
|
+ case opElem:
|
|
|
|
+ hasElem, ok := t.(hasElem) // Pointer, Slice, Array, Chan, Map
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want pointer, slice, array, chan or map)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = hasElem.Elem()
|
|
|
|
+
|
|
|
|
+ case opKey:
|
|
|
|
+ mapType, ok := t.(*types.Map)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want map)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = mapType.Key()
|
|
|
|
+
|
|
|
|
+ case opParams:
|
|
|
|
+ sig, ok := t.(*types.Signature)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = sig.Params()
|
|
|
|
+
|
|
|
|
+ case opResults:
|
|
|
|
+ sig, ok := t.(*types.Signature)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = sig.Results()
|
|
|
|
+
|
|
|
|
+ case opUnderlying:
|
|
|
|
+ named, ok := t.(*types.Named)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = named.Underlying()
|
|
|
|
+
|
|
|
|
+ case opTypeParam:
|
|
|
|
+ hasTypeParams, ok := t.(hasTypeParams) // Named, Signature
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or signature)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ tparams := hasTypeParams.TypeParams()
|
|
|
|
+ if n := tparams.Len(); index >= n {
|
|
|
|
+ return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
|
|
|
|
+ }
|
|
|
|
+ t = tparams.At(index)
|
|
|
|
+
|
|
|
|
+ case opConstraint:
|
|
|
|
+ tparam, ok := t.(*typeparams.TypeParam)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want type parameter)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = tparam.Constraint()
|
|
|
|
+
|
|
|
|
+ case opAt:
|
|
|
|
+ tuple, ok := t.(*types.Tuple)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want tuple)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ if n := tuple.Len(); index >= n {
|
|
|
|
+ return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
|
|
|
|
+ }
|
|
|
|
+ obj = tuple.At(index)
|
|
|
|
+ t = nil
|
|
|
|
+
|
|
|
|
+ case opField:
|
|
|
|
+ structType, ok := t.(*types.Struct)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want struct)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ if n := structType.NumFields(); index >= n {
|
|
|
|
+ return nil, fmt.Errorf("field index %d out of range [0-%d)", index, n)
|
|
|
|
+ }
|
|
|
|
+ obj = structType.Field(index)
|
|
|
|
+ t = nil
|
|
|
|
+
|
|
|
|
+ case opMethod:
|
|
|
|
+ switch t := t.(type) {
|
|
|
|
+ case *types.Interface:
|
|
|
|
+ if index >= t.NumMethods() {
|
|
|
|
+ return nil, fmt.Errorf("method index %d out of range [0-%d)", index, t.NumMethods())
|
|
|
|
+ }
|
|
|
|
+ obj = t.Method(index) // Id-ordered
|
|
|
|
+
|
|
|
|
+ case *types.Named:
|
|
|
|
+ methods := namedMethods(t) // (unmemoized)
|
|
|
|
+ if index >= len(methods) {
|
|
|
|
+ return nil, fmt.Errorf("method index %d out of range [0-%d)", index, len(methods))
|
|
|
|
+ }
|
|
|
|
+ obj = methods[index] // Id-ordered
|
|
|
|
+
|
|
|
|
+ default:
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want interface or named)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ t = nil
|
|
|
|
+
|
|
|
|
+ case opObj:
|
|
|
|
+ hasObj, ok := t.(hasObj)
|
|
|
|
+ if !ok {
|
|
|
|
+ return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or type param)", code, t, t)
|
|
|
|
+ }
|
|
|
|
+ obj = hasObj.Obj()
|
|
|
|
+ t = nil
|
|
|
|
+
|
|
|
|
+ default:
|
|
|
|
+ return nil, fmt.Errorf("invalid path: unknown code %q", code)
|
|
|
|
+ }
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ if obj.Pkg() != pkg {
|
|
|
|
+ return nil, fmt.Errorf("path denotes %s, which belongs to a different package", obj)
|
|
|
|
+ }
|
|
|
|
+
|
|
|
|
+ return obj, nil // success
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+// namedMethods returns the methods of a Named type in ascending Id order.
|
|
|
|
+func namedMethods(named *types.Named) []*types.Func {
|
|
|
|
+ methods := make([]*types.Func, named.NumMethods())
|
|
|
|
+ for i := range methods {
|
|
|
|
+ methods[i] = named.Method(i)
|
|
|
|
+ }
|
|
|
|
+ sort.Slice(methods, func(i, j int) bool {
|
|
|
|
+ return methods[i].Id() < methods[j].Id()
|
|
|
|
+ })
|
|
|
|
+ return methods
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+// scopeNames is a memoization of scope.Names. Callers must not modify the result.
|
|
|
|
+func (enc *encoder) scopeNames(scope *types.Scope) []string {
|
|
|
|
+ m := enc.scopeNamesMemo
|
|
|
|
+ if m == nil {
|
|
|
|
+ m = make(map[*types.Scope][]string)
|
|
|
|
+ enc.scopeNamesMemo = m
|
|
|
|
+ }
|
|
|
|
+ names, ok := m[scope]
|
|
|
|
+ if !ok {
|
|
|
|
+ names = scope.Names() // allocates and sorts
|
|
|
|
+ m[scope] = names
|
|
|
|
+ }
|
|
|
|
+ return names
|
|
|
|
+}
|
|
|
|
+
|
|
|
|
+// namedMethods is a memoization of the namedMethods function. Callers must not modify the result.
|
|
|
|
+func (enc *encoder) namedMethods(named *types.Named) []*types.Func {
|
|
|
|
+ m := enc.namedMethodsMemo
|
|
|
|
+ if m == nil {
|
|
|
|
+ m = make(map[*types.Named][]*types.Func)
|
|
|
|
+ enc.namedMethodsMemo = m
|
|
|
|
+ }
|
|
|
|
+ methods, ok := m[named]
|
|
|
|
+ if !ok {
|
|
|
|
+ methods = namedMethods(named) // allocates and sorts
|
|
|
|
+ m[named] = methods
|
|
|
|
+ }
|
|
|
|
+ return methods
|
|
|
|
+
|
|
|
|
+}
|