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exp/template: simplify method and function calls by using the value's Method

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rather than the type's, so a method's invocation works the same as a function's.

R=golang-dev, rsc, r
CC=golang-dev
https://golang.org/cl/4704049
This commit is contained in:
Rob Pike 2011-07-14 11:00:23 +10:00
parent 689a2ec8c3
commit 19e207d24d
1 changed files with 18 additions and 20 deletions
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38
src/pkg/exp/template/exec.go
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@ -337,7 +337,7 @@ func (s *state) evalVariableNode(dot reflect.Value, v *variableNode, args []node
func (s *state) evalFieldChain(dot, receiver reflect.Value, ident []string, args []node, final reflect.Value) reflect.Value {
n := len(ident)
for i := 0; i < n-1; i++ {
receiver = s.evalField(dot, ident[i], args[:1], zero, receiver)
receiver = s.evalField(dot, ident[i], nil, zero, receiver)
}
// Now if it's a method, it gets the arguments.
return s.evalField(dot, ident[n-1], args, final, receiver)
@ -348,7 +348,7 @@ func (s *state) evalFunction(dot reflect.Value, name string, args []node, final
if !ok {
s.errorf("%q is not a defined function", name)
}
return s.evalCall(dot, zero, function, name, args, final)
return s.evalCall(dot, function, name, args, final)
}
// Is this an exported - upper case - name?
@ -372,8 +372,8 @@ func (s *state) evalField(dot reflect.Value, fieldName string, args []node, fina
if ptr.CanAddr() {
ptr = ptr.Addr()
}
if method, ok := methodByName(ptr.Type(), fieldName); ok {
return s.evalCall(dot, ptr, method.Func, fieldName, args, final)
if method, ok := methodByName(ptr, fieldName); ok {
return s.evalCall(dot, method, fieldName, args, final)
}
// It's not a method; is it a field of a struct?
receiver, isNil := indirect(receiver)
@ -396,25 +396,28 @@ func (s *state) evalField(dot reflect.Value, fieldName string, args []node, fina
}
// TODO: delete when reflect's own MethodByName is released.
func methodByName(typ reflect.Type, name string) (reflect.Method, bool) {
func methodByName(receiver reflect.Value, name string) (reflect.Value, bool) {
typ := receiver.Type()
for i := 0; i < typ.NumMethod(); i++ {
if typ.Method(i).Name == name {
return typ.Method(i), true
return receiver.Method(i), true // This value includes the receiver.
}
}
return reflect.Method{}, false
return zero, false
}
var (
osErrorType = reflect.TypeOf(new(os.Error)).Elem()
)
func (s *state) evalCall(dot, receiver, fun reflect.Value, name string, args []node, final reflect.Value) reflect.Value {
typ := fun.Type()
isMethod := receiver.IsValid()
if !isMethod && len(args) > 0 { // Args will be nil if it's a niladic call in an argument list
args = args[1:] // first arg is name of function; not used in call.
// evalCall executes a function or method call. If it's a method, fun already has the receiver bound, so
// it looks just like a function call. The arg list, if non-nil, includes (in the manner of the shell), arg[0]
// as the function itself.
func (s *state) evalCall(dot, fun reflect.Value, name string, args []node, final reflect.Value) reflect.Value {
if args != nil {
args = args[1:] // Zeroth arg is function name/node; not passed to function.
}
typ := fun.Type()
numIn := len(args)
if final.IsValid() {
numIn++
@ -433,17 +436,12 @@ func (s *state) evalCall(dot, receiver, fun reflect.Value, name string, args []n
}
// Build the arg list.
argv := make([]reflect.Value, numIn)
// First arg is the receiver.
// Args must be evaluated. Fixed args first.
i := 0
if isMethod {
argv[0] = receiver
i++
}
// Others must be evaluated. Fixed args first.
for ; i < numFixed; i++ {
argv[i] = s.evalArg(dot, typ.In(i), args[i])
}
// And now the ... args.
// Now the ... args.
if typ.IsVariadic() {
argType := typ.In(typ.NumIn() - 1).Elem() // Argument is a slice.
for ; i < len(args); i++ {
@ -452,7 +450,7 @@ func (s *state) evalCall(dot, receiver, fun reflect.Value, name string, args []n
}
// Add final value if necessary.
if final.IsValid() {
argv[len(args)] = final
argv[i] = final
}
result := fun.Call(argv)
// If we have an os.Error that is not nil, stop execution and return that error to the caller.