feat: add IndexOf and LastIndexOf for stream

2026-02-04 12:52:28 +08:00 · 2024-11-11 10:52:29 +08:00
parent de877e5278
commit f3579fc142
7 changed files with 263 additions and 62 deletions
--- a/cryptor/rsa_private_example.pem
+++ b/cryptor/rsa_private_example.pem
@@ -1,51 +1,51 @@
 -----BEGIN rsa private key-----
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 -----END rsa private key-----
--- a/cryptor/rsa_public_example.pem
+++ b/cryptor/rsa_public_example.pem
@@ -1,14 +1,14 @@
 -----BEGIN rsa public key-----
-MIICIjANBgkqhkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAm1rBCE+U+7M46S21q0yo
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 -----END rsa public key-----
--- a/docs/api/packages/stream.md
+++ b/docs/api/packages/stream.md
@@ -1,6 +1,6 @@
 # Stream

-Stream 流，该包仅验证简单 stream 实现，功能有限。
+Stream流，该包仅验证简单stream实现，功能有限。

 <div STYLE="page-break-after: always;"></div>

@@ -48,6 +48,8 @@ import (
 -   [NoneMatch](#NoneMatch)
 -   [Count](#Count)
 -   [ToSlice](#ToSlice)
+-   [IndexOf](#IndexOf)
+-   [LastIndexOf](#LastIndexOf)

 <div STYLE="page-break-after: always;"></div>

@@ -938,3 +940,69 @@ func main() {
    // [1 2 3]
 }
 ```
+
+### <span id="IndexOf">IndexOf</span>
+
+<p>返回在stream中找到值的第一个匹配项的索引，如果找不到值，则返回-1。</p>
+
+<b>函数签名:</b>
+
+```go
+func (s Stream[T]) IndexOf(target T, equal func(a, b T) bool) int
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/stream"
+)
+
+func main() {
+    s := stream.FromSlice([]int{1, 2, 3, 2})
+
+    result1 := s.IndexOf(0, func(a, b int) bool { return a == b })
+    result2 := s.IndexOf(2, func(a, b int) bool { return a == b })
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // -1
+    // 1
+}
+```
+
+### <span id="LastIndexOf">LastIndexOf</span>
+
+<p>返回在stream中找到值的最后一个匹配项的索引，如果找不到值，则返回-1。</p>
+
+<b>函数签名:</b>
+
+```go
+func (s Stream[T]) LastIndexOf(target T, equal func(a, b T) bool) int
+```
+
+<b>示例:<span style="float:right;display:inline-block;">[运行](todo)</span></b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/stream"
+)
+
+func main() {
+    s := stream.FromSlice([]int{1, 2, 3, 2})
+
+    result1 := s.LastIndexOf(0, func(a, b int) bool { return a == b })
+    result2 := s.LastIndexOf(2, func(a, b int) bool { return a == b })
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // -1
+    // 3
+}
+```
--- a/docs/en/api/packages/stream.md
+++ b/docs/en/api/packages/stream.md
@@ -939,3 +939,69 @@ func main() {
    // [1 2 3]
 }
 ```
+
+### <span id="IndexOf">IndexOf</span>
+
+<p>Returns the index of the first occurrence of the specified element in this stream, or -1 if this stream does not contain the element.</p>
+
+<b>Signature:</b>
+
+```go
+func (s Stream[T]) IndexOf(target T, equal func(a, b T) bool) int
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/stream"
+)
+
+func main() {
+    s := stream.FromSlice([]int{1, 2, 3, 2})
+
+    result1 := s.IndexOf(0, func(a, b int) bool { return a == b })
+    result2 := s.IndexOf(2, func(a, b int) bool { return a == b })
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // -1
+    // 1
+}
+```
+
+### <span id="LastIndexOf">LastIndexOf</span>
+
+<p>Returns the index of the last occurrence of the specified element in this stream, or -1 if this stream does not contain the element.</p>
+
+<b>Signature:</b>
+
+```go
+func (s Stream[T]) LastIndexOf(target T, equal func(a, b T) bool) int
+```
+
+<b>Example:<span style="float:right;display:inline-block;">[Run](todo)</span></b>
+
+```go
+import (
+    "fmt"
+    "github.com/duke-git/lancet/v2/stream"
+)
+
+func main() {
+    s := stream.FromSlice([]int{1, 2, 3, 2})
+
+    result1 := s.LastIndexOf(0, func(a, b int) bool { return a == b })
+    result2 := s.LastIndexOf(2, func(a, b int) bool { return a == b })
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+
+    // Output:
+    // -1
+    // 3
+}
+```
--- a/stream/stream.go
+++ b/stream/stream.go
@@ -393,6 +393,26 @@ func (s Stream[T]) Min(less func(a, b T) bool) (T, bool) {
 	return min, true
 }

+// IndexOf returns the index of the first occurrence of the specified element in this stream, or -1 if this stream does not contain the element.
+func (s Stream[T]) IndexOf(target T, equal func(a, b T) bool) int {
+	for i, v := range s.source {
+		if equal(v, target) {
+			return i
+		}
+	}
+	return -1
+}
+
+// LastIndexOf returns the index of the last occurrence of the specified element in this stream, or -1 if this stream does not contain the element.
+func (s Stream[T]) LastIndexOf(target T, equal func(a, b T) bool) int {
+	for i := len(s.source) - 1; i >= 0; i-- {
+		if equal(s.source[i], target) {
+			return i
+		}
+	}
+	return -1
+}
+
 // ToSlice return the elements in the stream.
 // Play: https://go.dev/play/p/jI6_iZZuVFE
 func (s Stream[T]) ToSlice() []T {
--- a/stream/stream_example_test.go
+++ b/stream/stream_example_test.go
@@ -384,3 +384,31 @@ func ExampleStream_Count() {
 	// 3
 	// 0
 }
+
+func ExampleStream_IndexOf() {
+	s := FromSlice([]int{1, 2, 3, 2})
+
+	result1 := s.IndexOf(0, func(a, b int) bool { return a == b })
+	result2 := s.IndexOf(2, func(a, b int) bool { return a == b })
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// -1
+	// 1
+}
+
+func ExampleStream_LastIndexOf() {
+	s := FromSlice([]int{1, 2, 3, 2})
+
+	result1 := s.LastIndexOf(0, func(a, b int) bool { return a == b })
+	result2 := s.LastIndexOf(2, func(a, b int) bool { return a == b })
+
+	fmt.Println(result1)
+	fmt.Println(result2)
+
+	// Output:
+	// -1
+	// 3
+}
--- a/stream/stream_test.go
+++ b/stream/stream_test.go
@@ -381,3 +381,22 @@ func TestStream_Min(t *testing.T) {
 	assert.Equal(1, max)
 	assert.Equal(true, ok)
 }
+
+func TestStream_IndexOf(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_IndexOf")
+
+	s := FromSlice([]int{4, 2, 1, 3, 4})
+
+	assert.Equal(-1, s.IndexOf(0, func(a, b int) bool { return a == b }))
+	assert.Equal(0, s.IndexOf(4, func(a, b int) bool { return a == b }))
+	assert.Equal(3, s.IndexOf(3, func(a, b int) bool { return a == b }))
+}
+
+func TestStream_LastIndexOf(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_LastIndexOf")
+
+	s := FromSlice([]int{4, 2, 1, 3, 2})
+
+	assert.Equal(-1, s.LastIndexOf(0, func(a, b int) bool { return a == b }))
+	assert.Equal(4, s.LastIndexOf(2, func(a, b int) bool { return a == b }))
+}