Add pattern and options properties to common Regex

And add a test that accesses them and checks they work as expected.

libraries/stdlib/common/src/kotlin/TextH.kt

@@ -43,6 +43,9 @@ expect class Regex {
     constructor(pattern: String, option: RegexOption)
     constructor(pattern: String, options: Set<RegexOption>)
 
+    val pattern: String
+    val options: Set<RegexOption>
+
     fun matchEntire(input: CharSequence): MatchResult?
     infix fun matches(input: CharSequence): Boolean
     fun containsMatchIn(input: CharSequence): Boolean

libraries/stdlib/test/text/RegexTest.kt

@@ -7,6 +7,17 @@ import kotlin.test.*
 
 class RegexTest {
 
+    @Test fun properties() {
+        val pattern = "\\s+$"
+        val regex1 = Regex(pattern, RegexOption.IGNORE_CASE)
+        assertEquals(pattern, regex1.pattern)
+        assertEquals(setOf(RegexOption.IGNORE_CASE), regex1.options)
+
+        val options2 = setOf(RegexOption.MULTILINE, RegexOption.IGNORE_CASE)
+        val regex2 = Regex(pattern, options2)
+        assertEquals(options2, regex2.options)
+    }
+
     @Test fun matchResult() {
         val p = "\\d+".toRegex()
         val input = "123 456 789"