Improve handling of special characters in string resources (#4220)

Introduced a function to process and replace certain escaped symbols
like '\n', '\t', and '\uXXXX' in the strings extracted from compose
string resources.

components/resources/demo/shared/src/commonMain/composeResources/values/strings.xml

@@ -1,13 +1,12 @@
 <resources>
     <string name="app_name">Compose Resources App</string>
     <string name="hello">😊 Hello world!</string>
-    <string name="multi_line">Lorem ipsum dolor sit amet,
-        consectetur adipiscing elit.
-        Donec eget turpis ac sem ultricies consequat.</string>
-    <string name="str_template">Hello, %1$s! You have %2$d new messages.</string>
+    <string name="multi_line">Lorem ipsum dolor sit amet,\nconsectetur adipiscing elit.
+Donec eget turpis ac sem ultricies consequat.</string>
+    <string name="str_template">Hello, %1$s!\nYou have %2$d new messages.</string>
     <string-array name="str_arr">
-        <item>item 1</item>
-        <item>item 2</item>
-        <item>item 3</item>
+        <item>item \u2605</item>
+        <item>item \u2318</item>
+        <item>item \u00BD</item>
     </string-array>
 </resources>

components/resources/library/src/commonMain/kotlin/org/jetbrains/compose/resources/StringResources.kt

@@ -20,7 +20,7 @@ private val SimpleStringFormatRegex = Regex("""%(\d)\$[ds]""")
 @ExperimentalResourceApi
 @Immutable
 class StringResource
-@InternalResourceApi constructor(id: String, val key: String, items: Set<ResourceItem>): Resource(id, items)
+@InternalResourceApi constructor(id: String, val key: String, items: Set<ResourceItem>) : Resource(id, items)
 
 private sealed interface StringItem {
     data class Value(val text: String) : StringItem
@@ -53,11 +53,13 @@ private suspend fun getParsedStrings(
 private suspend fun parseStringXml(path: String, resourceReader: ResourceReader): Map<String, StringItem> {
     val nodes = resourceReader.read(path).toXmlElement().childNodes
     val strings = nodes.getElementsWithName("string").associate { element ->
-        element.getAttribute("name") to StringItem.Value(element.textContent.orEmpty())
+        val rawString = element.textContent.orEmpty()
+        element.getAttribute("name") to StringItem.Value(handleSpecialCharacters(rawString))
     }
     val arrays = nodes.getElementsWithName("string-array").associate { arrayElement ->
         val items = arrayElement.childNodes.getElementsWithName("item").map { element ->
-            element.textContent.orEmpty()
+            val rawString = element.textContent.orEmpty()
+            handleSpecialCharacters(rawString)
         }
         arrayElement.getAttribute("name") to StringItem.Array(items)
     }
@@ -203,4 +205,34 @@ private suspend fun loadStringArray(
 private fun NodeList.getElementsWithName(name: String): List<Element> =
     List(length) { item(it) }
         .filterIsInstance<Element>()
-        .filter { it.localName == name }
+        .filter { it.localName == name }
+
+//https://developer.android.com/guide/topics/resources/string-resource#escaping_quotes
+/**
+ * Replaces
+ *
+ * '\n' -> new line
+ *
+ * '\t' -> tab
+ *
+ * '\uXXXX' -> unicode symbol
+ *
+ * '\\' -> '\'
+ *
+ * @param string The input string to handle.
+ * @return The string with special characters replaced according to the logic.
+ */
+internal fun handleSpecialCharacters(string: String): String {
+    val unicodeNewLineTabRegex = Regex("""\\u[a-fA-F\d]{4}|\\n|\\t""")
+    val doubleSlashRegex = Regex("""\\\\""")
+    val doubleSlashIndexes = doubleSlashRegex.findAll(string).map { it.range.first }
+    val handledString = unicodeNewLineTabRegex.replace(string) { matchResult ->
+        if (doubleSlashIndexes.contains(matchResult.range.first - 1)) matchResult.value
+        else when (matchResult.value) {
+            "\\n" -> "\n"
+            "\\t" -> "\t"
+            else -> matchResult.value.substring(2).toInt(16).toChar().toString()
+        }
+    }.replace("""\\""", """\""")
+    return handledString
+}

components/resources/library/src/commonTest/kotlin/org/jetbrains/compose/resources/ResourceTest.kt

@@ -98,6 +98,13 @@ class ResourceTest {
         }.message.let { msg ->
             assertEquals("Resource with ID='ImageResource:test3' has more than one file: en1, en2", msg)
         }
+    }
 
+    @Test
+    fun testEscapedSymbols() {
+        assertEquals(
+            "abc \n \\n \t \\t \u1234 \ua45f \\u1234 \\ \\u355g",
+            handleSpecialCharacters("""abc \n \\n \t \\t \u1234 \ua45f \\u1234 \\ \u355g""")
+        )
     }
 }