go/types: Steps towards removing ast.Object from exported API.

- introduced type Method for methods
- renamed StructField -> Field
- removed ObjList
- methods are not sorted anymore in interfaces (for now)

R=adonovan
CC=golang-dev
https://golang.org/cl/7023043

src/pkg/go/types/api.go

@@ -5,6 +5,8 @@
 // Package types declares the data structures for representing
 // Go types and implements typechecking of package files.
 //
+// WARNING: THE TYPES API IS SUBJECT TO SIGNIFICANT CHANGE.
+//
 package types
 
 import (

src/pkg/go/types/errors.go

@@ -197,7 +197,7 @@ func typeString(typ Type) string {
 	return buf.String()
 }
 
-func writeParams(buf *bytes.Buffer, params ObjList, isVariadic bool) {
+func writeParams(buf *bytes.Buffer, params []*ast.Object, isVariadic bool) {
 	buf.WriteByte('(')
 	for i, par := range params {
 		if i > 0 {
@@ -287,7 +287,7 @@ func writeType(buf *bytes.Buffer, typ Type) {
 				buf.WriteString("; ")
 			}
 			buf.WriteString(m.Name)
-			writeSignature(buf, m.Type.(*Signature))
+			writeSignature(buf, m.Type)
 		}
 		buf.WriteByte('}')
 

src/pkg/go/types/expr.go

@@ -22,7 +22,7 @@ import (
 // - clients need access to builtins type information
 // - API tests are missing (e.g., identifiers should be handled as expressions in callbacks)
 
-func (check *checker) collectParams(list *ast.FieldList, variadicOk bool) (params ObjList, isVariadic bool) {
+func (check *checker) collectParams(list *ast.FieldList, variadicOk bool) (params []*ast.Object, isVariadic bool) {
 	if list == nil {
 		return
 	}
@@ -70,7 +70,7 @@ func (check *checker) collectParams(list *ast.FieldList, variadicOk bool) (param
 	return
 }
 
-func (check *checker) collectMethods(list *ast.FieldList) (methods ObjList) {
+func (check *checker) collectMethods(list *ast.FieldList) (methods []*Method) {
 	if list == nil {
 		return
 	}
@@ -81,14 +81,13 @@ func (check *checker) collectMethods(list *ast.FieldList) (methods ObjList) {
 		if len(f.Names) > 0 {
 			// methods (the parser ensures that there's only one
 			// and we don't care if a constructed AST has more)
-			if _, ok := typ.(*Signature); !ok {
+			sig, ok := typ.(*Signature)
+			if !ok {
 				check.invalidAST(f.Type.Pos(), "%s is not a method signature", typ)
 				continue
 			}
 			for _, name := range f.Names {
-				obj := name.Obj
-				obj.Type = typ
-				methods = append(methods, obj)
+				methods = append(methods, &Method{name.Name, sig})
 			}
 		} else {
 			// embedded interface
@@ -101,14 +100,20 @@ func (check *checker) collectMethods(list *ast.FieldList) (methods ObjList) {
 			}
 		}
 	}
-	// check for double declarations
-	methods.Sort()
-	prev := ""
-	for _, obj := range methods {
-		if obj.Name == prev {
-			check.errorf(list.Pos(), "multiple methods named %s", prev)
+	// Check for double declarations.
+	// The parser inserts methods into an interface-local scope, so local
+	// double declarations are reported by the parser already. We need to
+	// check again for conflicts due to embedded interfaces. This will lead
+	// to a 2nd error message if the double declaration was reported before
+	// by the parser.
+	// TODO(gri) clean this up a bit
+	seen := make(map[string]bool)
+	for _, m := range methods {
+		if seen[m.Name] {
+			check.errorf(list.Pos(), "multiple methods named %s", m.Name)
 			return // keep multiple entries, lookup will only return the first entry
 		}
+		seen[m.Name] = true
 	}
 	return
 }
@@ -125,7 +130,7 @@ func (check *checker) tag(t *ast.BasicLit) string {
 	return ""
 }
 
-func (check *checker) collectFields(list *ast.FieldList, cycleOk bool) (fields []*StructField) {
+func (check *checker) collectFields(list *ast.FieldList, cycleOk bool) (fields []*Field) {
 	if list == nil {
 		return
 	}
@@ -135,15 +140,15 @@ func (check *checker) collectFields(list *ast.FieldList, cycleOk bool) (fields [
 		if len(f.Names) > 0 {
 			// named fields
 			for _, name := range f.Names {
-				fields = append(fields, &StructField{name.Name, typ, tag, false})
+				fields = append(fields, &Field{name.Name, typ, tag, false})
 			}
 		} else {
 			// anonymous field
 			switch t := deref(typ).(type) {
 			case *Basic:
-				fields = append(fields, &StructField{t.Name, typ, tag, true})
+				fields = append(fields, &Field{t.Name, typ, tag, true})
 			case *NamedType:
-				fields = append(fields, &StructField{t.Obj.Name, typ, tag, true})
+				fields = append(fields, &Field{t.Obj.Name, typ, tag, true})
 			default:
 				if typ != Typ[Invalid] {
 					check.invalidAST(f.Type.Pos(), "anonymous field type %s must be named", typ)
@@ -921,7 +926,7 @@ func (check *checker) rawExpr(x *operand, e ast.Expr, hint Type, iota int, cycle
 			arg.Type = x.typ
 			x.mode = value
 			x.typ = &Signature{
-				Params:     append(ObjList{arg}, sig.Params...),
+				Params:     append([]*ast.Object{arg}, sig.Params...),
 				Results:    sig.Results,
 				IsVariadic: sig.IsVariadic,
 			}

src/pkg/go/types/gcimporter.go

@@ -383,8 +383,8 @@ func (p *gcParser) parseName() (name string) {
 
 // Field = Name Type [ string_lit ] .
 //
-func (p *gcParser) parseField() *StructField {
-	var f StructField
+func (p *gcParser) parseField() *Field {
+	var f Field
 	f.Name = p.parseName()
 	f.Type = p.parseType()
 	if p.tok == scanner.String {
@@ -406,7 +406,7 @@ func (p *gcParser) parseField() *StructField {
 // FieldList  = Field { ";" Field } .
 //
 func (p *gcParser) parseStructType() Type {
-	var fields []*StructField
+	var fields []*Field
 
 	parseField := func() {
 		fields = append(fields, p.parseField())
@@ -510,12 +510,12 @@ func (p *gcParser) parseSignature() *Signature {
 // visible in the export data.
 //
 func (p *gcParser) parseInterfaceType() Type {
-	var methods ObjList
+	var methods []*Method
 
 	parseMethod := func() {
-		obj := ast.NewObj(ast.Fun, p.parseName())
-		obj.Type = p.parseSignature()
-		methods = append(methods, obj)
+		name := p.parseName()
+		typ := p.parseSignature()
+		methods = append(methods, &Method{name, typ})
 	}
 
 	p.expectKeyword("interface")
@@ -529,7 +529,6 @@ func (p *gcParser) parseInterfaceType() Type {
 	}
 	p.expect('}')
 
-	methods.Sort()
 	return &Interface{Methods: methods}
 }
 

src/pkg/go/types/operand.go

@@ -301,10 +301,10 @@ func lookupFieldBreadthFirst(list []embeddedType, name string) (res lookupResult
 
 			case *Interface:
 				// look for a matching method
-				for _, obj := range typ.Methods {
-					if obj.Name == name {
-						assert(obj.Type != nil)
-						if !potentialMatch(e.multiples, value, obj.Type.(Type)) {
+				for _, m := range typ.Methods {
+					if m.Name == name {
+						assert(m.Type != nil)
+						if !potentialMatch(e.multiples, value, m.Type) {
 							return // name collision
 						}
 					}
@@ -380,9 +380,9 @@ func lookupField(typ Type, name string) (operandMode, Type) {
 		}
 
 	case *Interface:
-		for _, obj := range typ.Methods {
-			if obj.Name == name {
-				return value, obj.Type.(Type)
+		for _, m := range typ.Methods {
+			if m.Name == name {
+				return value, m.Type
 			}
 		}
 	}

src/pkg/go/types/predicates.go

@@ -165,7 +165,7 @@ func isIdentical(x, y Type) bool {
 		// the same names and identical function types. Lower-case method names from
 		// different packages are always different. The order of the methods is irrelevant.
 		if y, ok := y.(*Interface); ok {
-			return identicalTypes(x.Methods, y.Methods) // methods are sorted
+			return identicalMethods(x.Methods, y.Methods) // methods are sorted
 		}
 
 	case *Map:
@@ -194,17 +194,36 @@ func isIdentical(x, y Type) bool {
 
 // identicalTypes returns true if both lists a and b have the
 // same length and corresponding objects have identical types.
-func identicalTypes(a, b ObjList) bool {
-	if len(a) == len(b) {
-		for i, x := range a {
-			y := b[i]
-			if !isIdentical(x.Type.(Type), y.Type.(Type)) {
-				return false
-			}
-		}
-		return true
+func identicalTypes(a, b []*ast.Object) bool {
+	if len(a) != len(b) {
+		return false
 	}
-	return false
+	for i, x := range a {
+		y := b[i]
+		if !isIdentical(x.Type.(Type), y.Type.(Type)) {
+			return false
+		}
+	}
+	return true
+}
+
+// identicalMethods returns true if both lists a and b have the
+// same length and corresponding methods have identical types.
+// TODO(gri) make this more efficient
+func identicalMethods(a, b []*Method) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	m := make(map[string]*Method)
+	for _, x := range a {
+		m[x.Name] = x
+	}
+	for _, y := range b {
+		if x := m[y.Name]; x == nil || !isIdentical(x.Type, y.Type) {
+			return false
+		}
+	}
+	return true
 }
 
 // underlying returns the underlying type of typ.
@@ -257,14 +276,14 @@ func defaultType(typ Type) Type {
 // it returns the first missing method required by T and whether it
 // is missing or simply has the wrong type.
 //
-func missingMethod(typ Type, T *Interface) (method *ast.Object, wrongType bool) {
+func missingMethod(typ Type, T *Interface) (method *Method, wrongType bool) {
 	// TODO(gri): distinguish pointer and non-pointer receivers
 	// an interface type implements T if it has no methods with conflicting signatures
 	// Note: This is stronger than the current spec. Should the spec require this?
 	if ityp, _ := underlying(typ).(*Interface); ityp != nil {
 		for _, m := range T.Methods {
 			mode, sig := lookupField(ityp, m.Name) // TODO(gri) no need to go via lookupField
-			if mode != invalid && !isIdentical(sig, m.Type.(Type)) {
+			if mode != invalid && !isIdentical(sig, m.Type) {
 				return m, true
 			}
 		}
@@ -277,7 +296,7 @@ func missingMethod(typ Type, T *Interface) (method *ast.Object, wrongType bool)
 		if mode == invalid {
 			return m, false
 		}
-		if !isIdentical(sig, m.Type.(Type)) {
+		if !isIdentical(sig, m.Type) {
 			return m, true
 		}
 	}

src/pkg/go/types/testdata/decls0.src

@@ -127,7 +127,7 @@ type (
 	I2 interface {
 		m1()
 	}
-	I3 interface {
+	I3 interface { /* ERROR "multiple methods named m1" */
 		m1()
 		m1 /* ERROR "redeclared" */ ()
 	}

src/pkg/go/types/types.go

@@ -4,13 +4,9 @@
 
 package types
 
-import (
-	"go/ast"
-	"sort"
-)
+import "go/ast"
 
 // All types implement the Type interface.
-// TODO(gri) Eventually determine what common Type functionality should be exported.
 type Type interface {
 	aType()
 }
@@ -95,7 +91,8 @@ type Slice struct {
 	Elt Type
 }
 
-type StructField struct {
+// A Field represents a field of a struct.
+type Field struct {
 	Name        string // unqualified type name for anonymous fields
 	Type        Type
 	Tag         string
@@ -105,7 +102,7 @@ type StructField struct {
 // A Struct represents a struct type struct{...}.
 type Struct struct {
 	implementsType
-	Fields []*StructField
+	Fields []*Field
 }
 
 func (typ *Struct) fieldIndex(name string) int {
@@ -126,16 +123,16 @@ type Pointer struct {
 // A Result represents a (multi-value) function call result.
 type Result struct {
 	implementsType
-	Values ObjList // Signature.Results of the function called
+	Values []*ast.Object // Signature.Results of the function called
 }
 
 // A Signature represents a user-defined function type func(...) (...).
 type Signature struct {
 	implementsType
-	Recv       *ast.Object // nil if not a method
-	Params     ObjList     // (incoming) parameters from left to right; or nil
-	Results    ObjList     // (outgoing) results from left to right; or nil
-	IsVariadic bool        // true if the last parameter's type is of the form ...T
+	Recv       *ast.Object   // nil if not a method
+	Params     []*ast.Object // (incoming) parameters from left to right; or nil
+	Results    []*ast.Object // (outgoing) results from left to right; or nil
+	IsVariadic bool          // true if the last parameter's type is of the form ...T
 }
 
 // builtinId is an id of a builtin function.
@@ -180,10 +177,16 @@ type builtin struct {
 	isStatement bool // true if the built-in is valid as an expression statement
 }
 
+// A Method represents a method of an interface.
+type Method struct {
+	Name string
+	Type *Signature
+}
+
 // An Interface represents an interface type interface{...}.
 type Interface struct {
 	implementsType
-	Methods ObjList // interface methods sorted by name; or nil
+	Methods []*Method // TODO(gri) consider keeping them in sorted order
 }
 
 // A Map represents a map type map[Key]Elt.
@@ -206,17 +209,6 @@ type NamedType struct {
 	Underlying Type        // nil if not fully declared yet; never a *NamedType
 }
 
-// An ObjList represents an ordered (in some fashion) list of objects.
-type ObjList []*ast.Object
-
-// ObjList implements sort.Interface.
-func (list ObjList) Len() int           { return len(list) }
-func (list ObjList) Less(i, j int) bool { return list[i].Name < list[j].Name }
-func (list ObjList) Swap(i, j int)      { list[i], list[j] = list[j], list[i] }
-
-// Sort sorts an object list by object name.
-func (list ObjList) Sort() { sort.Sort(list) }
-
 // All concrete types embed implementsType which
 // ensures that all types implement the Type interface.
 type implementsType struct{}

src/pkg/go/types/types_test.go

@@ -88,10 +88,7 @@ var testTypes = []testEntry{
 	// interfaces
 	dup("interface{}"),
 	dup("interface{m()}"),
-	{`interface{
-		m(int) float32
-		String() string
-	}`, `interface{String() string; m(int) float32}`}, // methods are sorted
+	dup(`interface{m(int) float32; String() string}`),
 	// TODO(gri) add test for interface w/ anonymous field
 
 	// maps

src/pkg/go/types/universe.go

@@ -118,10 +118,9 @@ func init() {
 	{
 		res := ast.NewObj(ast.Var, "")
 		res.Type = Typ[String]
-		err := ast.NewObj(ast.Fun, "Error")
-		err.Type = &Signature{Results: ObjList{res}}
+		err := &Method{"Error", &Signature{Results: []*ast.Object{res}}}
 		obj := def(ast.Typ, "error")
-		obj.Type = &NamedType{Underlying: &Interface{Methods: ObjList{err}}, Obj: obj}
+		obj.Type = &NamedType{Underlying: &Interface{Methods: []*Method{err}}, Obj: obj}
 	}
 
 	// predeclared constants