Move StringExtensions to core-util-jvm.

core-util-jvm/src/main/java/org/signal/core/util/StringExtensions.kt

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.signal.core.util
+
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
+
+/**
+ * Treats the string as a serialized list of tokens and tells you if an item is present in the list.
+ * In addition to exact matches, this handles wildcards at the end of an item.
+ *
+ * e.g. a,b,c*,d
+ */
+fun String.asListContains(item: String): Boolean {
+  val items: List<String> = this
+    .split(",")
+    .map { it.trim() }
+    .filter { it.isNotEmpty() }
+    .toList()
+
+  val exactMatches = items.filter { it.last() != '*' }
+  val prefixMatches = items.filter { it.last() == '*' }
+
+  return exactMatches.contains(item) ||
+    prefixMatches
+      .map { it.substring(0, it.length - 1) }
+      .any { item.startsWith(it) }
+}
+
+fun String?.emptyIfNull(): String {
+  return this ?: ""
+}
+
+/**
+ * Turns a multi-line string into a single-line string stripped of indentation, separated by spaces instead of newlines.
+ *
+ * e.g.
+ *
+ * a
+ *   b
+ * c
+ *
+ * turns into
+ *
+ * a b c
+ */
+fun String.toSingleLine(): String {
+  return this.trimIndent().split("\n").joinToString(separator = " ")
+}
+
+fun String?.nullIfEmpty(): String? {
+  return this?.ifEmpty {
+    null
+  }
+}
+
+fun String?.nullIfBlank(): String? {
+  return this?.ifBlank {
+    null
+  }
+}
+
+@OptIn(ExperimentalContracts::class)
+fun CharSequence?.isNotNullOrBlank(): Boolean {
+  contract {
+    returns(true) implies (this@isNotNullOrBlank != null)
+  }
+  return !this.isNullOrBlank()
+}