1 files changed, 281 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/go/ssa/methods.go b/vendor/golang.org/x/tools/go/ssa/methods.go
new file mode 100644
index 0000000..b956018
--- /dev/null
+++ b/vendor/golang.org/x/tools/go/ssa/methods.go
@@ -0,0 +1,281 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+// This file defines utilities for population of method sets.
+
+import (
+	"fmt"
+	"go/types"
+
+	"golang.org/x/tools/go/types/typeutil"
+	"golang.org/x/tools/internal/aliases"
+)
+
+// MethodValue returns the Function implementing method sel, building
+// wrapper methods on demand. It returns nil if sel denotes an
+// interface or generic method.
+//
+// Precondition: sel.Kind() == MethodVal.
+//
+// Thread-safe.
+//
+// Acquires prog.methodsMu.
+func (prog *Program) MethodValue(sel *types.Selection) *Function {
+	if sel.Kind() != types.MethodVal {
+		panic(fmt.Sprintf("MethodValue(%s) kind != MethodVal", sel))
+	}
+	T := sel.Recv()
+	if types.IsInterface(T) {
+		return nil // interface method or type parameter
+	}
+
+	if prog.isParameterized(T) {
+		return nil // generic method
+	}
+
+	if prog.mode&LogSource != 0 {
+		defer logStack("MethodValue %s %v", T, sel)()
+	}
+
+	var b builder
+
+	m := func() *Function {
+		prog.methodsMu.Lock()
+		defer prog.methodsMu.Unlock()
+
+		// Get or create SSA method set.
+		mset, ok := prog.methodSets.At(T).(*methodSet)
+		if !ok {
+			mset = &methodSet{mapping: make(map[string]*Function)}
+			prog.methodSets.Set(T, mset)
+		}
+
+		// Get or create SSA method.
+		id := sel.Obj().Id()
+		fn, ok := mset.mapping[id]
+		if !ok {
+			obj := sel.Obj().(*types.Func)
+			needsPromotion := len(sel.Index()) > 1
+			needsIndirection := !isPointer(recvType(obj)) && isPointer(T)
+			if needsPromotion || needsIndirection {
+				fn = createWrapper(prog, toSelection(sel))
+				fn.buildshared = b.shared()
+				b.enqueue(fn)
+			} else {
+				fn = prog.objectMethod(obj, &b)
+			}
+			if fn.Signature.Recv() == nil {
+				panic(fn)
+			}
+			mset.mapping[id] = fn
+		} else {
+			b.waitForSharedFunction(fn)
+		}
+
+		return fn
+	}()
+
+	b.iterate()
+
+	return m
+}
+
+// objectMethod returns the Function for a given method symbol.
+// The symbol may be an instance of a generic function. It need not
+// belong to an existing SSA package created by a call to
+// prog.CreatePackage.
+//
+// objectMethod panics if the function is not a method.
+//
+// Acquires prog.objectMethodsMu.
+func (prog *Program) objectMethod(obj *types.Func, b *builder) *Function {
+	sig := obj.Type().(*types.Signature)
+	if sig.Recv() == nil {
+		panic("not a method: " + obj.String())
+	}
+
+	// Belongs to a created package?
+	if fn := prog.FuncValue(obj); fn != nil {
+		return fn
+	}
+
+	// Instantiation of generic?
+	if originObj := obj.Origin(); originObj != obj {
+		origin := prog.objectMethod(originObj, b)
+		assert(origin.typeparams.Len() > 0, "origin is not generic")
+		targs := receiverTypeArgs(obj)
+		return origin.instance(targs, b)
+	}
+
+	// Consult/update cache of methods created from types.Func.
+	prog.objectMethodsMu.Lock()
+	defer prog.objectMethodsMu.Unlock()
+	fn, ok := prog.objectMethods[obj]
+	if !ok {
+		fn = createFunction(prog, obj, obj.Name(), nil, nil, "")
+		fn.Synthetic = "from type information (on demand)"
+		fn.buildshared = b.shared()
+		b.enqueue(fn)
+
+		if prog.objectMethods == nil {
+			prog.objectMethods = make(map[*types.Func]*Function)
+		}
+		prog.objectMethods[obj] = fn
+	} else {
+		b.waitForSharedFunction(fn)
+	}
+	return fn
+}
+
+// LookupMethod returns the implementation of the method of type T
+// identified by (pkg, name).  It returns nil if the method exists but
+// is an interface method or generic method, and panics if T has no such method.
+func (prog *Program) LookupMethod(T types.Type, pkg *types.Package, name string) *Function {
+	sel := prog.MethodSets.MethodSet(T).Lookup(pkg, name)
+	if sel == nil {
+		panic(fmt.Sprintf("%s has no method %s", T, types.Id(pkg, name)))
+	}
+	return prog.MethodValue(sel)
+}
+
+// methodSet contains the (concrete) methods of a concrete type (non-interface, non-parameterized).
+type methodSet struct {
+	mapping map[string]*Function // populated lazily
+}
+
+// RuntimeTypes returns a new unordered slice containing all types in
+// the program for which a runtime type is required.
+//
+// A runtime type is required for any non-parameterized, non-interface
+// type that is converted to an interface, or for any type (including
+// interface types) derivable from one through reflection.
+//
+// The methods of such types may be reachable through reflection or
+// interface calls even if they are never called directly.
+//
+// Thread-safe.
+//
+// Acquires prog.runtimeTypesMu.
+func (prog *Program) RuntimeTypes() []types.Type {
+	prog.runtimeTypesMu.Lock()
+	defer prog.runtimeTypesMu.Unlock()
+	return prog.runtimeTypes.Keys()
+}
+
+// forEachReachable calls f for type T and each type reachable from
+// its type through reflection.
+//
+// The function f must use memoization to break cycles and
+// return false when the type has already been visited.
+//
+// TODO(adonovan): publish in typeutil and share with go/callgraph/rta.
+func forEachReachable(msets *typeutil.MethodSetCache, T types.Type, f func(types.Type) bool) {
+	var visit func(T types.Type, skip bool)
+	visit = func(T types.Type, skip bool) {
+		if !skip {
+			if !f(T) {
+				return
+			}
+		}
+
+		// Recursion over signatures of each method.
+		tmset := msets.MethodSet(T)
+		for i := 0; i < tmset.Len(); i++ {
+			sig := tmset.At(i).Type().(*types.Signature)
+			// It is tempting to call visit(sig, false)
+			// but, as noted in golang.org/cl/65450043,
+			// the Signature.Recv field is ignored by
+			// types.Identical and typeutil.Map, which
+			// is confusing at best.
+			//
+			// More importantly, the true signature rtype
+			// reachable from a method using reflection
+			// has no receiver but an extra ordinary parameter.
+			// For the Read method of io.Reader we want:
+			//   func(Reader, []byte) (int, error)
+			// but here sig is:
+			//   func([]byte) (int, error)
+			// with .Recv = Reader (though it is hard to
+			// notice because it doesn't affect Signature.String
+			// or types.Identical).
+			//
+			// TODO(adonovan): construct and visit the correct
+			// non-method signature with an extra parameter
+			// (though since unnamed func types have no methods
+			// there is essentially no actual demand for this).
+			//
+			// TODO(adonovan): document whether or not it is
+			// safe to skip non-exported methods (as RTA does).
+			visit(sig.Params(), true)  // skip the Tuple
+			visit(sig.Results(), true) // skip the Tuple
+		}
+
+		switch T := T.(type) {
+		case *aliases.Alias:
+			visit(aliases.Unalias(T), skip) // emulates the pre-Alias behavior
+
+		case *types.Basic:
+			// nop
+
+		case *types.Interface:
+			// nop---handled by recursion over method set.
+
+		case *types.Pointer:
+			visit(T.Elem(), false)
+
+		case *types.Slice:
+			visit(T.Elem(), false)
+
+		case *types.Chan:
+			visit(T.Elem(), false)
+
+		case *types.Map:
+			visit(T.Key(), false)
+			visit(T.Elem(), false)
+
+		case *types.Signature:
+			if T.Recv() != nil {
+				panic(fmt.Sprintf("Signature %s has Recv %s", T, T.Recv()))
+			}
+			visit(T.Params(), true)  // skip the Tuple
+			visit(T.Results(), true) // skip the Tuple
+
+		case *types.Named:
+			// A pointer-to-named type can be derived from a named
+			// type via reflection.  It may have methods too.
+			visit(types.NewPointer(T), false)
+
+			// Consider 'type T struct{S}' where S has methods.
+			// Reflection provides no way to get from T to struct{S},
+			// only to S, so the method set of struct{S} is unwanted,
+			// so set 'skip' flag during recursion.
+			visit(T.Underlying(), true) // skip the unnamed type
+
+		case *types.Array:
+			visit(T.Elem(), false)
+
+		case *types.Struct:
+			for i, n := 0, T.NumFields(); i < n; i++ {
+				// TODO(adonovan): document whether or not
+				// it is safe to skip non-exported fields.
+				visit(T.Field(i).Type(), false)
+			}
+
+		case *types.Tuple:
+			for i, n := 0, T.Len(); i < n; i++ {
+				visit(T.At(i).Type(), false)
+			}
+
+		case *types.TypeParam, *types.Union:
+			// forEachReachable must not be called on parameterized types.
+			panic(T)
+
+		default:
+			panic(T)
+		}
+	}
+	visit(T, false)
+}