feat(reflect): add the Type iterators of Go 1.26, Method.IsExported and Method.Func

gs/reflect/type.ts

@@ -516,6 +516,21 @@ export interface Type {
   // NumMethod returns the number of methods in the type's method set
   NumMethod(): number
 
+  // Methods returns an iterator over the methods of the type's method set.
+  Methods(): iter.Seq<Method>
+
+  // Fields returns an iterator over the fields of a struct type.
+  // Panics if the type's Kind is not Struct.
+  Fields(): iter.Seq<StructField>
+
+  // Ins returns an iterator over the input types of a function type.
+  // Panics if the type's Kind is not Func.
+  Ins(): iter.Seq<Type>
+
+  // Outs returns an iterator over the output types of a function type.
+  // Panics if the type's Kind is not Func.
+  Outs(): iter.Seq<Type>
+
   // Method returns the i'th method in the type's method set.
   Method(i: number): Method
 
@@ -549,6 +564,63 @@ export interface Type {
   CanSeq2(): boolean
 }
 
+// typeMethodsSeq returns an iterator over the methods of the method set of
+// t, as Type.Methods does.
+function typeMethodsSeq(t: Type): iter.Seq<Method> {
+  return async (_yield: ((m: Method) => iter.YieldResult) | null) => {
+    for (let i = 0; i < t.NumMethod(); i++) {
+      if (!(await _yield!(t.Method(i)))) {
+        return
+      }
+    }
+  }
+}
+
+// typeFieldsSeq returns an iterator over the fields of the struct type t, as
+// Type.Fields does.
+function typeFieldsSeq(t: Type): iter.Seq<StructField> {
+  if (t.Kind() !== Struct) {
+    throw new Error('reflect: Fields of non-struct type ' + t.String())
+  }
+  return async (_yield: ((f: StructField) => iter.YieldResult) | null) => {
+    for (let i = 0; i < t.NumField(); i++) {
+      if (!(await _yield!(t.Field(i)))) {
+        return
+      }
+    }
+  }
+}
+
+// typeInsSeq returns an iterator over the input types of the function type
+// t, as Type.Ins does.
+function typeInsSeq(t: Type): iter.Seq<Type> {
+  if (t.Kind() !== Func) {
+    throw new Error('reflect: Ins of non-func type ' + t.String())
+  }
+  return async (_yield: ((in_: Type) => iter.YieldResult) | null) => {
+    for (let i = 0; i < t.NumIn(); i++) {
+      if (!(await _yield!(t.In(i)))) {
+        return
+      }
+    }
+  }
+}
+
+// typeOutsSeq returns an iterator over the output types of the function
+// type t, as Type.Outs does.
+function typeOutsSeq(t: Type): iter.Seq<Type> {
+  if (t.Kind() !== Func) {
+    throw new Error('reflect: Outs of non-func type ' + t.String())
+  }
+  return async (_yield: ((out: Type) => iter.YieldResult) | null) => {
+    for (let i = 0; i < t.NumOut(); i++) {
+      if (!(await _yield!(t.Out(i)))) {
+        return
+      }
+    }
+  }
+}
+
 // nonChanTypePanic panics for ChanDir on a type that is not a channel.
 function nonChanTypePanic(t: Type): never {
   throw new Error(`reflect: ChanDir of non-chan type ${t.String()}`)
@@ -710,6 +782,22 @@ class InvalidTypeClass implements Type {
   OverflowFloat(_x: number): boolean {
     throw new Error('reflect: OverflowFloat of invalid type')
   }
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   NumMethod(): number {
     return 0
   }
@@ -2585,6 +2673,22 @@ export class BasicType implements Type {
     )
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -2774,6 +2878,22 @@ class SliceType implements Type {
     throw new Error('reflect: call of reflect.Type.OverflowFloat on slice Type')
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -2931,6 +3051,22 @@ class ArrayType implements Type {
     throw new Error('reflect: call of reflect.Type.OverflowFloat on array Type')
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -3082,6 +3218,22 @@ class PointerType implements Type {
     )
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -3291,6 +3443,22 @@ class FunctionType implements Type {
     throw new Error('reflect: call of reflect.Type.OverflowFloat on func Type')
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -3813,6 +3981,22 @@ class MapType implements Type {
     throw new Error('reflect: call of reflect.Type.OverflowFloat on map Type')
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -4093,7 +4277,7 @@ export function visibleStructFields(t: Type): StructField[] {
 function zeroMethod(): Method {
   return new Method({
     Type: new BasicType(Invalid, '<invalid>'),
-    Func: () => undefined,
+    Func: new Value(),
   })
 }
 
@@ -4102,18 +4286,27 @@ function methodFromSignature(
   index: number,
   receiver: Type,
 ): Method {
+  const iface = receiver.Kind() === Interface
+  const type = methodTypeFromSignature(signature, receiver, !iface)
   return new Method({
     Name: signature.name,
-    Type: methodTypeFromSignature(
-      signature,
-      receiver,
-      receiver.Kind() !== Interface,
-    ),
-    Func: () => undefined,
+    Type: type,
+    Func: iface ? new Value() : methodFuncValue(signature.name, receiver, type),
     Index: index,
   })
 }
 
+// methodFuncValue returns the method name of the type receiver as a function
+// of type type, which takes the receiver as its first argument, as
+// Method.Func is.
+function methodFuncValue(name: string, receiver: Type, type: Type): Value {
+  const fn = (recv: ReflectValue, ...args: unknown[]): unknown => {
+    const bound = new Value(recv, receiver).MethodByName(name).currentValue()
+    return (bound as (...args: unknown[]) => unknown)(...args)
+  }
+  return new Value(fn, type)
+}
+
 function methodTypeFromSignature(
   signature: $.MethodSignature,
   receiver: Type,
@@ -4681,6 +4874,22 @@ class StructType implements Type {
     )
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }
@@ -5015,6 +5224,22 @@ class ChannelType implements Type {
     throw new Error('reflect: call of reflect.Type.OverflowFloat on chan Type')
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return 0
   }
@@ -5176,6 +5401,22 @@ class InterfaceType implements Type {
     )
   }
 
+  public Methods(): iter.Seq<Method> {
+    return typeMethodsSeq(this)
+  }
+
+  public Fields(): iter.Seq<StructField> {
+    return typeFieldsSeq(this)
+  }
+
+  public Ins(): iter.Seq<Type> {
+    return typeInsSeq(this)
+  }
+
+  public Outs(): iter.Seq<Type> {
+    return typeOutsSeq(this)
+  }
+
   public NumMethod(): number {
     return typeMethods(this).length
   }

gs/reflect/types.ts

@@ -159,7 +159,9 @@ export class Method {
   public Name = ''
   public PkgPath = ''
   public Type: Type | null = null
-  public Func!: ReflectFunc
+  // Func is the method as a function taking the receiver first; it is the
+  // zero Value for an interface type.
+  public Func!: Value
   public Index = 0
 
   constructor(init?: Partial<Method>) {
@@ -168,6 +170,11 @@ export class Method {
     }
   }
 
+  // IsExported reports whether the method is exported.
+  public IsExported(): boolean {
+    return this.PkgPath === ''
+  }
+
   // clone copies the method, as Go copies a Method struct value.
   public clone(): Method {
     return new Method(this)

tests/tests/reflect_value_methods_more/expected.log

@@ -5,6 +5,14 @@ clear: 0 0 2 4
 field: A int
 field: B string
 method: Sum 3
+type field: A int
+type field: B string
+type method: Sum func(main.pair) int true
+func: func(main.pair) int 3
+ptr func: func(*main.pair, int) 6
+in: string
+in: int
+out: string
 iter: k 7
 trysend: true false
 tryrecv: 3 true