Add samples for String/CharSequence filter & filterNot (#3390)

* Add samples for String/CharSequence filter & filterNot
* Link samples to stdlib generator

libraries/stdlib/common/src/generated/_Strings.kt

@@ -367,7 +367,7 @@ public inline fun String.dropWhile(predicate: (Char) -> Boolean): String {
 /**
  * Returns a char sequence containing only those characters from the original char sequence that match the given [predicate].
  * 
- * @sample samples.collections.Collections.Filtering.filter
+ * @sample samples.text.Strings.filter
  */
 public inline fun CharSequence.filter(predicate: (Char) -> Boolean): CharSequence {
     return filterTo(StringBuilder(), predicate)
@@ -376,7 +376,7 @@ public inline fun CharSequence.filter(predicate: (Char) -> Boolean): CharSequenc
 /**
  * Returns a string containing only those characters from the original string that match the given [predicate].
  * 
- * @sample samples.collections.Collections.Filtering.filter
+ * @sample samples.text.Strings.filter
  */
 public inline fun String.filter(predicate: (Char) -> Boolean): String {
     return filterTo(StringBuilder(), predicate).toString()
@@ -415,7 +415,7 @@ public inline fun <C : Appendable> CharSequence.filterIndexedTo(destination: C,
 /**
  * Returns a char sequence containing only those characters from the original char sequence that do not match the given [predicate].
  * 
- * @sample samples.collections.Collections.Filtering.filter
+ * @sample samples.text.Strings.filterNot
  */
 public inline fun CharSequence.filterNot(predicate: (Char) -> Boolean): CharSequence {
     return filterNotTo(StringBuilder(), predicate)
@@ -424,7 +424,7 @@ public inline fun CharSequence.filterNot(predicate: (Char) -> Boolean): CharSequ
 /**
  * Returns a string containing only those characters from the original string that do not match the given [predicate].
  * 
- * @sample samples.collections.Collections.Filtering.filter
+ * @sample samples.text.Strings.filterNot
  */
 public inline fun String.filterNot(predicate: (Char) -> Boolean): String {
     return filterNotTo(StringBuilder(), predicate).toString()

libraries/stdlib/samples/test/samples/text/strings.kt

@@ -79,6 +79,24 @@ class Strings {
         assertPrints(proteins.take(5).toList(), "[Isoleucine, Arginine, Glycine, Arginine, Glutamine]")
     }
 
+    @Sample
+    fun filter() {
+        val text = "a1b2c3d4e5"
+
+        val textWithOnlyDigits = text.filter { it.isDigit() }
+
+        assertPrints(textWithOnlyDigits, "12345")
+    }
+
+    @Sample
+    fun filterNot() {
+        val text = "a1b2c3d4e5"
+
+        val textWithoutDigits = text.filterNot { it.isDigit() }
+
+        assertPrints(textWithoutDigits, "abcde")
+    }
+
     @Sample
     fun zip() {
         val stringA = "abcd"

libraries/tools/kotlin-stdlib-gen/src/templates/Filtering.kt

@@ -557,6 +557,7 @@ object Filtering : TemplateGroupBase() {
         }
 
         specialFor(Strings, CharSequences) {
+            sample("samples.text.Strings.filter")
             returns("SELF")
             doc { "Returns a ${f.collection} containing only those characters from the original ${f.collection} that match the given [predicate]." }
             body { """return filterTo(StringBuilder(), predicate)${toResult(f)}""" }
@@ -686,6 +687,7 @@ object Filtering : TemplateGroupBase() {
         }
 
         specialFor(Strings, CharSequences) {
+            sample("samples.text.Strings.filterNot")
             returns("SELF")
             doc { "Returns a ${f.collection} containing only those characters from the original ${f.collection} that do not match the given [predicate]." }
             body { """return filterNotTo(StringBuilder(), predicate)${toResult(f)}""" }