Use context instead of channels for cancellation. (#17)

In v1, raw channels are used. Not really a problem, but a new idiom has become popular since this library was originally authored, and this makes the muscle memory easier.

Fixes #7

README.md

@@ -12,7 +12,7 @@ Converting between slices and a queryable structure is as trivial as it should b
 original := []interface{}{"a", "b", "c"}
 subject := collection.AsEnumerable(original...)
 
-for entry := range subject.Enumerate(nil) {
+for entry := range subject.Enumerate(context.Background()) {
     fmt.Println(entry)
 }
 // Output:
@@ -28,7 +28,7 @@ subject := collection.AsEnumerable(1, 2, 3, 4, 5, 6)
 filtered := collection.Where(subject, func(num interface{}) bool{
     return num.(int) > 3
 })
-for entry := range filtered.Enumerate(nil) {
+for entry := range filtered.Enumerate(context.Background()) {
     fmt.Println(entry)
 }
 // Output:
@@ -42,7 +42,7 @@ subject := collection.AsEnumerable(1, 2, 3, 4, 5, 6)
 updated := collection.Select(subject, func(num interface{}) interface{}{
     return num.(int) + 10
 })
-for entry := range updated.Enumerate(nil) {
+for entry := range updated.Enumerate(context.Background()) {
     fmt.Println(entry)
 }
 // Output:

dictionary.go

@@ -1,6 +1,7 @@
 package collection
 
 import (
+	"context"
 	"sort"
 )
 
@@ -130,14 +131,14 @@ func (dict Dictionary) Size() int64 {
 }
 
 // Enumerate lists each word in the Dictionary alphabetically.
-func (dict Dictionary) Enumerate(cancel <-chan struct{}) Enumerator {
+func (dict Dictionary) Enumerate(ctx context.Context) Enumerator {
 	if dict.root == nil {
-		return Empty.Enumerate(cancel)
+		return Empty.Enumerate(ctx)
 	}
-	return dict.root.Enumerate(cancel)
+	return dict.root.Enumerate(ctx)
 }
 
-func (node trieNode) Enumerate(cancel <-chan struct{}) Enumerator {
+func (node trieNode) Enumerate(ctx context.Context) Enumerator {
 	var enumerateHelper func(trieNode, string)
 
 	results := make(chan interface{})
@@ -146,7 +147,7 @@ func (node trieNode) Enumerate(cancel <-chan struct{}) Enumerator {
 		if subject.IsWord {
 			select {
 			case results <- prefix:
-			case <-cancel:
+			case <-ctx.Done():
 				return
 			}
 		}

dictionary_examples_test.go

@@ -1,6 +1,7 @@
 package collection_test
 
 import (
+	"context"
 	"fmt"
 	"strings"
 
@@ -54,11 +55,11 @@ func ExampleDictionary_Enumerate() {
 		return strings.ToUpper(x.(string))
 	})
 
-	for word := range subject.Enumerate(nil) {
+	for word := range subject.Enumerate(context.Background()) {
 		fmt.Println(word)
 	}
 
-	for word := range upperCase.Enumerate(nil) {
+	for word := range upperCase.Enumerate(context.Background()) {
 		fmt.Println(word)
 	}
 

dictionary_test.go

@@ -1,6 +1,7 @@
 package collection
 
 import (
+	"context"
 	"strings"
 	"testing"
 )
@@ -38,7 +39,7 @@ func TestDictionary_Enumerate(t *testing.T) {
 			}
 
 			prev := ""
-			for result := range subject.Enumerate(nil) {
+			for result := range subject.Enumerate(context.Background()) {
 				t.Logf(result.(string))
 				if alreadySeen, ok := expected[result.(string)]; !ok {
 					t.Logf("An unadded value was returned")

doc.go

@@ -11,7 +11,7 @@
 // 		Location: "./",
 // 	}
 //
-// 	results := myDir.Enumerate(nil).Where(func(x interface{}) bool {
+// 	results := myDir.Enumerate(context.Background()).Where(func(x interface{}) bool {
 // 		return strings.HasSuffix(x.(string), ".go")
 // 	})
 //

fibonacci.go

@@ -1,11 +1,13 @@
 package collection
 
+import "context"
+
 type fibonacciGenerator struct{}
 
 // Fibonacci is an Enumerable which will dynamically generate the fibonacci sequence.
 var Fibonacci Enumerable = fibonacciGenerator{}
 
-func (gen fibonacciGenerator) Enumerate(cancel <-chan struct{}) Enumerator {
+func (gen fibonacciGenerator) Enumerate(ctx context.Context) Enumerator {
 	retval := make(chan interface{})
 
 	go func() {
@@ -16,7 +18,7 @@ func (gen fibonacciGenerator) Enumerate(cancel <-chan struct{}) Enumerator {
 			select {
 			case retval <- a:
 				a, b = b, a+b
-			case <-cancel:
+			case <-ctx.Done():
 				return
 			}
 		}

filesystem.go

@@ -1,7 +1,7 @@
 package collection
 
 import (
-	"errors"
+	"context"
 	"os"
 	"path/filepath"
 )
@@ -40,7 +40,7 @@ func (d Directory) applyOptions(loc string, info os.FileInfo) bool {
 }
 
 // Enumerate lists the items in a `Directory`
-func (d Directory) Enumerate(cancel <-chan struct{}) Enumerator {
+func (d Directory) Enumerate(ctx context.Context) Enumerator {
 	results := make(chan interface{})
 
 	go func() {
@@ -64,8 +64,8 @@ func (d Directory) Enumerate(cancel <-chan struct{}) Enumerator {
 				select {
 				case results <- currentLocation:
 					// Intentionally Left Blank
-				case <-cancel:
-					err = errors.New("directory enumeration cancelled")
+				case <-ctx.Done():
+					err = ctx.Err()
 				}
 			}
 

filesystem_test.go

@@ -1,6 +1,7 @@
 package collection
 
 import (
+	"context"
 	"fmt"
 	"math"
 	"path"
@@ -54,9 +55,7 @@ func ExampleDirectory_Enumerate() {
 		Options:  DirectoryOptionsExcludeDirectories,
 	}
 
-	done := make(chan struct{})
-
-	filesOfInterest := traverser.Enumerate(done).Select(func(subject interface{}) (result interface{}) {
+	filesOfInterest := traverser.Enumerate(context.Background()).Select(func(subject interface{}) (result interface{}) {
 		cast, ok := subject.(string)
 		if ok {
 			result = path.Base(cast)
@@ -75,7 +74,6 @@ func ExampleDirectory_Enumerate() {
 	for entry := range filesOfInterest {
 		fmt.Println(entry.(string))
 	}
-	close(done)
 
 	// Output: filesystem_test.go
 }
@@ -146,7 +144,7 @@ func TestDirectory_Enumerate(t *testing.T) {
 	for _, tc := range testCases {
 		subject.Options = tc.options
 		t.Run(fmt.Sprintf("%d", uint(tc.options)), func(t *testing.T) {
-			for entry := range subject.Enumerate(nil) {
+			for entry := range subject.Enumerate(context.Background()) {
 				cast := entry.(string)
 				if _, ok := tc.expected[cast]; !ok {
 					t.Logf("unexpected result: %q", cast)

linkedlist.go

@@ -2,6 +2,7 @@ package collection
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"strings"
@@ -98,7 +99,7 @@ func (list *LinkedList) addNodeFront(node *llNode) {
 }
 
 // Enumerate creates a new instance of Enumerable which can be executed on.
-func (list *LinkedList) Enumerate(cancel <-chan struct{}) Enumerator {
+func (list *LinkedList) Enumerate(ctx context.Context) Enumerator {
 	retval := make(chan interface{})
 
 	go func() {
@@ -111,7 +112,7 @@ func (list *LinkedList) Enumerate(cancel <-chan struct{}) Enumerator {
 			select {
 			case retval <- current.payload:
 				break
-			case <-cancel:
+			case <-ctx.Done():
 				return
 			}
 			current = current.next
@@ -356,7 +357,7 @@ func (list *LinkedList) moveToFront(node *llNode) {
 
 // ToSlice converts the contents of the LinkedList into a slice.
 func (list *LinkedList) ToSlice() []interface{} {
-	return list.Enumerate(nil).ToSlice()
+	return list.Enumerate(context.Background()).ToSlice()
 }
 
 func findLast(head *llNode) *llNode {

linkedlist_examples_test.go

@@ -1,6 +1,7 @@
 package collection_test
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/marstr/collection/v2"
@@ -27,7 +28,7 @@ func ExampleLinkedList_AddBack() {
 
 func ExampleLinkedList_Enumerate() {
 	subject := collection.NewLinkedList(2, 3, 5, 8)
-	results := subject.Enumerate(nil).Select(func(a interface{}) interface{} {
+	results := subject.Enumerate(context.Background()).Select(func(a interface{}) interface{} {
 		return -1 * a.(int)
 	})
 	for entry := range results {

linkedlist_test.go

@@ -1,6 +1,9 @@
 package collection
 
-import "testing"
+import (
+	"context"
+	"testing"
+)
 
 func TestLinkedList_findLast_empty(t *testing.T) {
 	if result := findLast(nil); result != nil {
@@ -101,7 +104,7 @@ func TestLinkedList_mergeSort_repair(t *testing.T) {
 	for _, tc := range testCases {
 		t.Run(tc.String(), func(t *testing.T) {
 			originalLength := tc.Length()
-			originalElements := tc.Enumerate(nil).ToSlice()
+			originalElements := tc.Enumerate(context.Background()).ToSlice()
 			originalContents := tc.String()
 
 			if err := tc.Sorti(); err != ErrUnexpectedType {
@@ -116,7 +119,7 @@ func TestLinkedList_mergeSort_repair(t *testing.T) {
 				t.Fail()
 			}
 
-			remaining := tc.Enumerate(nil).ToSlice()
+			remaining := tc.Enumerate(context.Background()).ToSlice()
 
 			for _, desired := range originalElements {
 				found := false

list.go

@@ -2,6 +2,7 @@ package collection
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"sync"
 )
@@ -38,7 +39,7 @@ func (l *List) AddAt(pos uint, entries ...interface{}) {
 }
 
 // Enumerate lists each element present in the collection
-func (l *List) Enumerate(cancel <-chan struct{}) Enumerator {
+func (l *List) Enumerate(ctx context.Context) Enumerator {
 	retval := make(chan interface{})
 
 	go func() {
@@ -50,7 +51,7 @@ func (l *List) Enumerate(cancel <-chan struct{}) Enumerator {
 			select {
 			case retval <- entry:
 				break
-			case <-cancel:
+			case <-ctx.Done():
 				return
 			}
 		}