[dev.go2go] cmd/compile/internal/syntax: add more parser tests

Updated existing tests to more closely match the go/types
tests; added *B.go2 versions for some tests, using [] for
type parameters.

Change-Id: Ie7cfd9f5515f541d9422a2b2ab8a5d3e02d0499a
Reviewed-on: https://go-review.googlesource.com/c/go/+/246261
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/syntax/testdata/go2/chansB.go2

@@ -0,0 +1,62 @@
+package chans
+
+import "runtime"
+
+// Ranger returns a Sender and a Receiver. The Receiver provides a
+// Next method to retrieve values. The Sender provides a Send method
+// to send values and a Close method to stop sending values. The Next
+// method indicates when the Sender has been closed, and the Send
+// method indicates when the Receiver has been freed.
+//
+// This is a convenient way to exit a goroutine sending values when
+// the receiver stops reading them.
+func Ranger[type T]() (*Sender[T], *Receiver[T]) {
+	c := make(chan T)
+	d := make(chan bool)
+	s := &Sender[T]{values: c, done: d}
+	r := &Receiver[T]{values: c, done: d}
+	runtime.SetFinalizer(r, r.finalize)
+	return s, r
+}
+
+// A sender is used to send values to a Receiver.
+type Sender[type T] struct {
+	values chan<- T
+	done <-chan bool
+}
+
+// Send sends a value to the receiver. It returns whether any more
+// values may be sent; if it returns false the value was not sent.
+func (s *Sender[T]) Send(v T) bool {
+	select {
+	case s.values <- v:
+		return true
+	case <-s.done:
+		return false
+	}
+}
+
+// Close tells the receiver that no more values will arrive.
+// After Close is called, the Sender may no longer be used.
+func (s *Sender[T]) Close() {
+	close(s.values)
+}
+
+// A Receiver receives values from a Sender.
+type Receiver[type T] struct {
+	values <-chan T
+	done chan<- bool
+}
+
+// Next returns the next value from the channel. The bool result
+// indicates whether the value is valid, or whether the Sender has
+// been closed and no more values will be received.
+func (r *Receiver[T]) Next() (T, bool) {
+	v, ok := <-r.values
+	return v, ok
+}
+
+// finalize is a finalizer for the receiver.
+func (r *Receiver[T]) finalize() {
+	close(r.done)
+}

src/cmd/compile/internal/syntax/testdata/go2/linalg.go2

@@ -7,12 +7,12 @@ package linalg
 import "math"
 
 // Numeric is type bound that matches any numeric type.
-// It would likely be in a contracts package in the standard library.
+// It would likely be in a constraints package in the standard library.
 type Numeric interface {
-	type int, int8, int16, int32, int64
-	type uint, uint8, uint16, uint32, uint64, uintptr
-	type float32, float64
-	type complex64, complex128
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64,
+		complex64, complex128
 }
 
 func DotProduct(type T Numeric)(s1, s2 []T) T {
@@ -42,9 +42,9 @@ func AbsDifference(type T NumericAbs)(a, b T) T {
 
 // OrderedNumeric is a type bound that matches numeric types that support the < operator.
 type OrderedNumeric interface {
-	type int, int8, int16, int32, int64
-	type uint, uint8, uint16, uint32, uint64, uintptr
-	type float32, float64
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64
 }
 
 // Complex is a type bound that matches the two complex types, which do not have a < operator.
@@ -71,7 +71,7 @@ func (a ComplexAbs(T)) Abs() ComplexAbs(T) {
 	r := float64(real(a))
 	i := float64(imag(a))
 	d := math.Sqrt(r * r + i * i)
-	return T(complex(d, 0))
+	return (ComplexAbs(T))(complex(d, 0))
 }
 
 func OrderedAbsDifference(type T OrderedNumeric)(a, b T) T {

src/cmd/compile/internal/syntax/testdata/go2/linalgB.go2

@@ -0,0 +1,83 @@
+// Copyright 2019 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 linalg
+
+import "math"
+
+// Numeric is type bound that matches any numeric type.
+// It would likely be in a constraints package in the standard library.
+type Numeric interface {
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64,
+		complex64, complex128
+}
+
+func DotProduct[type T Numeric](s1, s2 []T) T {
+	if len(s1) != len(s2) {
+		panic("DotProduct: slices of unequal length")
+	}
+	var r T
+	for i := range s1 {
+		r += s1[i] * s2[i]
+	}
+	return r
+}
+
+// NumericAbs matches numeric types with an Abs method.
+type NumericAbs[type T] interface {
+	Numeric
+
+	Abs() T
+}
+
+// AbsDifference computes the absolute value of the difference of
+// a and b, where the absolute value is determined by the Abs method.
+func AbsDifference[type T NumericAbs](a, b T) T {
+	d := a - b
+	return d.Abs()
+}
+
+// OrderedNumeric is a type bound that matches numeric types that support the < operator.
+type OrderedNumeric interface {
+	type int, int8, int16, int32, int64,
+		uint, uint8, uint16, uint32, uint64, uintptr,
+		float32, float64
+}
+
+// Complex is a type bound that matches the two complex types, which do not have a < operator.
+type Complex interface {
+	type complex64, complex128
+}
+
+// OrderedAbs is a helper type that defines an Abs method for
+// ordered numeric types.
+type OrderedAbs[type T OrderedNumeric] T
+
+func (a OrderedAbs[T]) Abs() OrderedAbs[T] {
+	if a < 0 {
+		return -a
+	}
+	return a
+}
+
+// ComplexAbs is a helper type that defines an Abs method for
+// complex types.
+type ComplexAbs[type T Complex] T
+
+func (a ComplexAbs[T]) Abs() ComplexAbs[T] {
+	r := float64(real(a))
+	i := float64(imag(a))
+	d := math.Sqrt(r * r + i * i)
+	return ComplexAbs[T](complex(d, 0))
+}
+
+func OrderedAbsDifference[type T OrderedNumeric](a, b T) T {
+	return T(AbsDifference(OrderedAbs[T](a), OrderedAbs[T](b)))
+}
+
+func ComplexAbsDifference[type T Complex](a, b T) T {
+	return T(AbsDifference(ComplexAbs[T](a), ComplexAbs[T](b)))
+}

src/cmd/compile/internal/syntax/testdata/go2/map.go2

@@ -5,8 +5,7 @@
 // Package orderedmap provides an ordered map, implemented as a binary tree.
 package orderedmap
 
-// TODO(gri) fix imports for tests
-import "chans" // ERROR could not import
+import "chans"
 
 // Map is an ordered map.
 type Map(type K, V) struct {
@@ -92,10 +91,7 @@ func (m *Map(K, V)) InOrder() *Iterator(K, V) {
 		f(m.root)
 		sender.Close()
 	}()
-	// TODO(gri) The design draft doesn't require that we repeat
-	// the type parameters here. Fix the implementation.
 	return &Iterator(K, V){receiver}
-	// return &Iterator{receiver}
 }
 
 // Iterator is used to iterate over the map.

src/cmd/compile/internal/syntax/testdata/go2/mapB.go2

@@ -0,0 +1,113 @@
+// Copyright 2019 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 orderedmap provides an ordered map, implemented as a binary tree.
+package orderedmap
+
+// TODO(gri) fix imports for tests
+import "chans" // ERROR could not import
+
+// Map is an ordered map.
+type Map[type K, V] struct {
+	root    *node[K, V]
+	compare func(K, K) int
+}
+
+// node is the type of a node in the binary tree.
+type node[type K, V] struct {
+	key         K
+	val         V
+	left, right *node[K, V]
+}
+
+// New returns a new map.
+func New[type K, V](compare func(K, K) int) *Map[K, V] {
+        return &Map[K, V]{compare: compare}
+}
+
+// find looks up key in the map, and returns either a pointer
+// to the node holding key, or a pointer to the location where
+// such a node would go.
+func (m *Map[K, V]) find(key K) **node[K, V] {
+	pn := &m.root
+	for *pn != nil {
+		switch cmp := m.compare(key, (*pn).key); {
+		case cmp < 0:
+			pn = &(*pn).left
+		case cmp > 0:
+			pn = &(*pn).right
+		default:
+			return pn
+		}
+	}
+	return pn
+}
+
+// Insert inserts a new key/value into the map.
+// If the key is already present, the value is replaced.
+// Returns true if this is a new key, false if already present.
+func (m *Map[K, V]) Insert(key K, val V) bool {
+	pn := m.find(key)
+	if *pn != nil {
+		(*pn).val = val
+		return false
+	}
+        *pn = &node[K, V]{key: key, val: val}
+	return true
+}
+
+// Find returns the value associated with a key, or zero if not present.
+// The found result reports whether the key was found.
+func (m *Map[K, V]) Find(key K) (V, bool) {
+	pn := m.find(key)
+	if *pn == nil {
+		var zero V // see the discussion of zero values, above
+		return zero, false
+	}
+	return (*pn).val, true
+}
+
+// keyValue is a pair of key and value used when iterating.
+type keyValue[type K, V] struct {
+	key K
+	val V
+}
+
+// InOrder returns an iterator that does an in-order traversal of the map.
+func (m *Map[K, V]) InOrder() *Iterator[K, V] {
+	sender, receiver := chans.Ranger[keyValue[K, V]]()
+	var f func(*node[K, V]) bool
+	f = func(n *node[K, V]) bool {
+		if n == nil {
+			return true
+		}
+		// Stop sending values if sender.Send returns false,
+		// meaning that nothing is listening at the receiver end.
+		return f(n.left) &&
+                        sender.Send(keyValue[K, V]{n.key, n.val}) &&
+			f(n.right)
+	}
+	go func() {
+		f(m.root)
+		sender.Close()
+	}()
+	return &Iterator[K, V]{receiver}
+}
+
+// Iterator is used to iterate over the map.
+type Iterator[type K, V] struct {
+	r *chans.Receiver[keyValue[K, V]]
+}
+
+// Next returns the next key and value pair, and a boolean indicating
+// whether they are valid or whether we have reached the end.
+func (it *Iterator[K, V]) Next() (K, V, bool) {
+	keyval, ok := it.r.Next()
+	if !ok {
+		var zerok K
+		var zerov V
+		return zerok, zerov, false
+	}
+	return keyval.key, keyval.val, true
+}

src/cmd/compile/internal/syntax/testdata/go2/slicesB.go2

@@ -0,0 +1,68 @@
+// Copyright 2019 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 slices implements various slice algorithms.
+package slices
+
+// Map turns a []T1 to a []T2 using a mapping function.
+func Map[type T1, T2](s []T1, f func(T1) T2) []T2 {
+	r := make([]T2, len(s))
+	for i, v := range s {
+		r[i] = f(v)
+	}
+	return r
+}
+
+// Reduce reduces a []T1 to a single value using a reduction function.
+func Reduce[type T1, T2](s []T1, initializer T2, f func(T2, T1) T2) T2 {
+	r := initializer
+	for _, v := range s {
+		r = f(r, v)
+	}
+	return r
+}
+
+// Filter filters values from a slice using a filter function.
+func Filter[type T](s []T, f func(T) bool) []T {
+	var r []T
+	for _, v := range s {
+		if f(v) {
+			r = append(r, v)
+		}
+	}
+	return r
+}
+
+// Example uses
+
+func limiter(x int) byte {
+	switch {
+	case x < 0:
+		return 0
+	default:
+		return byte(x)
+	case x > 255:
+		return 255
+	}
+}
+
+var input = []int{-4, 68954, 7, 44, 0, -555, 6945}
+var limited1 = Map[int, byte](input, limiter)
+var limited2 = Map(input, limiter) // using type inference
+
+func reducer(x float64, y int) float64 {
+	return x + float64(y)
+}
+
+var reduced1 = Reduce[int, float64](input, 0, reducer)
+var reduced2 = Reduce(input, 1i /* ERROR overflows */, reducer) // using type inference
+var reduced3 = Reduce(input, 1, reducer) // using type inference
+
+func filter(x int) bool {
+	return x&1 != 0
+}
+
+var filtered1 = Filter[int](input, filter)
+var filtered2 = Filter(input, filter) // using type inference
+