Provide access to named groups of regex match result on JDK8.

#KT-12753 Fixed

libraries/stdlib/src/kotlin/internal/PlatformImplementations.kt

@@ -2,6 +2,7 @@
 package kotlin.internal
 
 import java.io.Closeable
+import java.util.regex.MatchResult
 
 internal open class PlatformImplementations {
 
@@ -16,6 +17,10 @@ internal open class PlatformImplementations {
         }
     }
 
+    public open fun getMatchResultNamedGroup(matchResult: MatchResult, name: String): MatchGroup? {
+        throw UnsupportedOperationException("Retrieving groups by name is not supported on this platform.")
+    }
+
     companion object {
         @JvmField
         @InlineExposed
@@ -52,5 +57,7 @@ internal open class PlatformImplementations {
         }
 
     }
+
+
 }
 

libraries/stdlib/src/kotlin/text/regex/MatchResult.kt

@@ -36,8 +36,17 @@ public interface MatchGroupCollection : Collection<MatchGroup?> {
      * corresponds to the entire match.
      */
     public operator fun get(index: Int): MatchGroup?
+}
 
-    // TODO: Provide get(name: String) on JVM 7+
+/**
+ * Extends [MatchGroupCollection] by introducing a way to get matched groups by name, when regex supports it.
+ */
+public interface MatchNamedGroupCollection : MatchGroupCollection {
+    /**
+     * Returns a named group with the specified [name].
+     * @return An instance of [MatchGroup] if the group with the specified [name] was matched or `null` otherwise.
+     */
+    public operator fun get(name: String): MatchGroup?
 }
 
 /**

libraries/stdlib/src/kotlin/text/regex/Regex.kt

@@ -19,6 +19,7 @@ package kotlin.text
 import java.util.*
 import java.util.regex.Matcher
 import java.util.regex.Pattern
+import kotlin.internal.DefaultPlatformImplementations
 
 private interface FlagEnum {
     public val value: Int
@@ -231,7 +232,7 @@ private class MatcherMatchResult(private val matcher: Matcher, private val input
     override val value: String
         get() = matchResult.group()
 
-    override val groups: MatchGroupCollection = object : MatchGroupCollection {
+    override val groups: MatchGroupCollection = object : MatchNamedGroupCollection {
         override val size: Int get() = matchResult.groupCount() + 1
         override fun isEmpty(): Boolean = false
         override fun contains(element: MatchGroup?): Boolean = this.any { it == element }
@@ -245,6 +246,9 @@ private class MatcherMatchResult(private val matcher: Matcher, private val input
             else
                 null
         }
+        override fun get(name: String): MatchGroup? {
+            return DefaultPlatformImplementations.INSTANCE.getMatchResultNamedGroup(matchResult, name)
+        }
     }
 
     private var groupValues_: List<String>? = null