Merge pull request #11 from JakeWharton/jw.string-builder.2023-01-23

Add `StringBuilder.appendCodePoint`

Author: cketti

src/commonImplementation/kotlin/CommonStringBuilderFunctions.kt

@@ -0,0 +1,12 @@
+package de.cketti.codepoints
+
+object CommonStringBuilderFunctions {
+    fun appendCodePoint(builder: StringBuilder, codePoint: Int) {
+        if (CodePoints.isBmpCodePoint(codePoint)) {
+            builder.append(codePoint.toChar())
+        } else {
+            builder.append(CodePoints.highSurrogate(codePoint))
+            builder.append(CodePoints.lowSurrogate(codePoint))
+        }
+    }
+}

src/commonImplementation/kotlin/StringBuilderExtensions.kt

@@ -0,0 +1,7 @@
+package de.cketti.codepoints
+
+import kotlin.text.StringBuilder
+
+actual fun StringBuilder.appendCodePoint(codePoint: Int): StringBuilder = apply {
+    CommonStringBuilderFunctions.appendCodePoint(this, codePoint)
+}

src/commonMain/kotlin/StringBuilderExtensions.kt

@@ -0,0 +1,17 @@
+@file:Suppress(
+    "EXTENSION_SHADOWED_BY_MEMBER", // Kotlin/JVM aliases StringBuilder to j.l.StringBuilder.
+    "KotlinRedundantDiagnosticSuppress", // Above suppression only needed for JVM.
+)
+
+package de.cketti.codepoints
+
+/**
+ * Appends the string representation of the [codePoint] argument to this sequence.
+ *
+ * The argument is appended to the contents of this sequence.
+ * The length of this sequence increases by [CodePoints.charCount].
+ *
+ * The overall effect is exactly as if the argument were converted to a char array by the function
+ * [CodePoints.toChars] and the characters in that array were then appended to this sequence.
+ */
+expect fun StringBuilder.appendCodePoint(codePoint: Int): StringBuilder

src/commonTest/kotlin/StringBuilderExtensionsTest.kt

@@ -0,0 +1,18 @@
+package de.cketti.codepoints
+
+import kotlin.test.assertEquals
+import kotlin.test.Test
+
+class StringBuilderExtensionsTest {
+    @Test
+    fun appendCodePoint() {
+        val actual = buildString {
+            appendCodePoint('a'.code)
+            append('b')
+            appendCodePoint("\uFFFF".codePointAt(0))
+            append('c')
+            appendCodePoint("\uD83E\uDD95".codePointAt(0))
+        }
+        assertEquals("ab\uFFFFc\uD83E\uDD95", actual)
+    }
+}

src/jvmMain/kotlin/StringBuilderExtensions.kt

@@ -0,0 +1,12 @@
+@file:Suppress(
+    "NOTHING_TO_INLINE",
+    "EXTENSION_SHADOWED_BY_MEMBER",
+)
+
+package de.cketti.codepoints
+
+import kotlin.text.StringBuilder
+
+actual inline fun StringBuilder.appendCodePoint(codePoint: Int): StringBuilder {
+    return appendCodePoint(codePoint)!!
+}