Add support for Kotlin multiline (and single line) literals (#90)

selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/guts/Literals.kt

@@ -99,29 +99,49 @@ internal object LiteralLong : LiteralFormat<Long>() {
 }
 
 private const val TRIPLE_QUOTE = "\"\"\""
+private const val KOTLIN_DOLLAR = "\${'\$'}"
+private const val KOTLIN_DOLLARQUOTE = "\${'\"'}"
 
 internal object LiteralString : LiteralFormat<String>() {
   override fun encode(value: String, language: Language): String =
       if (value.indexOf('\n') == -1)
           when (language) {
+            Language.SCALA, // scala only does $ substitution for s" and f" strings
             Language.JAVA_PRE15,
-            Language.JAVA -> singleLineJavaToSource(value)
+            Language.JAVA -> encodeSingleJava(value)
             Language.GROOVY,
-            Language.SCALA,
-            Language.KOTLIN -> singleLineJavaToSource(value)
+            Language.KOTLIN -> encodeSingleJavaWithDollars(value)
           }
       else
           when (language) {
-            Language.GROOVY,
             Language.SCALA,
-            Language.JAVA_PRE15 -> singleLineJavaToSource(value)
-            Language.JAVA -> multiLineJavaToSource(value)
-            Language.KOTLIN -> multiLineJavaToSource(value)
+            Language.JAVA_PRE15 -> encodeSingleJava(value)
+            Language.JAVA -> encodeMultiJava(value)
+            Language.GROOVY,
+            Language.KOTLIN -> encodeMultiKotlin(value)
           }
   override fun parse(str: String, language: Language): String =
-      if (str.startsWith(TRIPLE_QUOTE)) multiLineJavaFromSource(str)
-      else singleLineJavaFromSource(str)
-  fun singleLineJavaToSource(value: String): String {
+      if (!str.startsWith(TRIPLE_QUOTE))
+          when (language) {
+            Language.SCALA,
+            Language.JAVA_PRE15,
+            Language.JAVA -> parseSingleJava(str)
+            Language.GROOVY,
+            Language.KOTLIN -> parseSingleJavaWithDollars(str)
+          }
+      else
+          when (language) {
+            Language.SCALA ->
+                throw UnsupportedOperationException(
+                    "Selfie doesn't support triple-quoted strings in Scala")
+            Language.JAVA_PRE15,
+            Language.JAVA -> parseMultiJava(str)
+            Language.GROOVY,
+            Language.KOTLIN -> parseMultiKotlin(str)
+          }
+  fun encodeSingleJava(value: String): String = encodeSingleJavaish(value, false)
+  fun encodeSingleJavaWithDollars(value: String) = encodeSingleJavaish(value, true)
+  private fun encodeSingleJavaish(value: String, escapeDollars: Boolean): String {
     val source = StringBuilder()
     source.append("\"")
     for (char in value) {
@@ -132,6 +152,7 @@ internal object LiteralString : LiteralFormat<String>() {
         '\t' -> source.append("\\t")
         '\"' -> source.append("\\\"")
         '\\' -> source.append("\\\\")
+        '$' -> if (escapeDollars) source.append(KOTLIN_DOLLAR) else source.append('$')
         else ->
             if (isControlChar(char)) {
               source.append("\\u")
@@ -147,7 +168,40 @@ internal object LiteralString : LiteralFormat<String>() {
   private fun isControlChar(c: Char): Boolean {
     return c in '\u0000'..'\u001F' || c == '\u007F'
   }
-  fun multiLineJavaToSource(arg: String): String {
+  fun parseSingleJava(sourceWithQuotes: String) = parseSingleJavaish(sourceWithQuotes, false)
+  fun parseSingleJavaWithDollars(sourceWithQuotes: String) =
+      parseSingleJavaish(sourceWithQuotes, true)
+  private fun parseSingleJavaish(sourceWithQuotes: String, removeDollars: Boolean): String {
+    check(sourceWithQuotes.startsWith('"'))
+    check(sourceWithQuotes.endsWith('"'))
+    val source = sourceWithQuotes.substring(1, sourceWithQuotes.length - 1)
+    val toUnescape = if (removeDollars) inlineDollars(source) else source
+    return unescapeJava(toUnescape)
+  }
+  fun encodeMultiKotlin(arg: String): String {
+    val escapeDollars = arg.replace("$", KOTLIN_DOLLAR)
+    val escapeTripleQuotes =
+        escapeDollars.replace(
+            TRIPLE_QUOTE, "$KOTLIN_DOLLARQUOTE$KOTLIN_DOLLARQUOTE$KOTLIN_DOLLARQUOTE")
+    val protectWhitespace =
+        escapeTripleQuotes.lines().joinToString("\n") { line ->
+          val protectTrailingWhitespace =
+              if (line.endsWith(" ")) {
+                line.dropLast(1) + "\${' '}"
+              } else if (line.endsWith("\t")) {
+                line.dropLast(1) + "\${'\\t'}"
+              } else line
+          val protectLeadingWhitespace =
+              if (protectTrailingWhitespace.startsWith(" ")) {
+                "\${' '}" + protectTrailingWhitespace.drop(1)
+              } else if (protectTrailingWhitespace.startsWith("\t")) {
+                "\${'\\t'}" + protectTrailingWhitespace.drop(1)
+              } else protectTrailingWhitespace
+          protectLeadingWhitespace
+        }
+    return "$TRIPLE_QUOTE$protectWhitespace$TRIPLE_QUOTE"
+  }
+  fun encodeMultiJava(arg: String): String {
     val escapeBackslashes = arg.replace("\\", "\\\\")
     val escapeTripleQuotes = escapeBackslashes.replace(TRIPLE_QUOTE, "\\\"\\\"\\\"")
     val protectWhitespace =
@@ -168,10 +222,29 @@ internal object LiteralString : LiteralFormat<String>() {
         }
     return "$TRIPLE_QUOTE\n$protectWhitespace$TRIPLE_QUOTE"
   }
-  fun singleLineJavaFromSource(sourceWithQuotes: String): String {
-    check(sourceWithQuotes.startsWith('"'))
-    check(sourceWithQuotes.endsWith('"'))
-    return unescapeJava(sourceWithQuotes.substring(1, sourceWithQuotes.length - 1))
+  private val charLiteralRegex = """\$\{'(\\?.)'\}""".toRegex()
+  private fun inlineDollars(source: String): String {
+    if (source.indexOf('$') == -1) {
+      return source
+    }
+    return charLiteralRegex.replace(source) { matchResult ->
+      val charLiteral = matchResult.groupValues[1]
+      when {
+        charLiteral.length == 1 -> charLiteral
+        charLiteral.length == 2 && charLiteral[0] == '\\' ->
+            when (charLiteral[1]) {
+              't' -> "\t"
+              'b' -> "\b"
+              'n' -> "\n"
+              'r' -> "\r"
+              '\'' -> "'"
+              '\\' -> "\\"
+              '$' -> "$"
+              else -> charLiteral
+            }
+        else -> throw IllegalArgumentException("Unknown character literal $charLiteral")
+      }
+    }
   }
   private fun unescapeJava(source: String): String {
     val firstEscape = source.indexOf('\\')
@@ -209,7 +282,7 @@ internal object LiteralString : LiteralFormat<String>() {
     }
     return value.toString()
   }
-  fun multiLineJavaFromSource(sourceWithQuotes: String): String {
+  fun parseMultiJava(sourceWithQuotes: String): String {
     check(sourceWithQuotes.startsWith("$TRIPLE_QUOTE\n"))
     check(sourceWithQuotes.endsWith(TRIPLE_QUOTE))
     val source =
@@ -233,6 +306,14 @@ internal object LiteralString : LiteralFormat<String>() {
       }
     }
   }
+  fun parseMultiKotlin(sourceWithQuotes: String): String {
+    check(sourceWithQuotes.startsWith(TRIPLE_QUOTE))
+    check(sourceWithQuotes.endsWith(TRIPLE_QUOTE))
+    val source =
+        sourceWithQuotes.substring(
+            TRIPLE_QUOTE.length, sourceWithQuotes.length - TRIPLE_QUOTE.length)
+    return inlineDollars(source)
+  }
 }
 
 internal object LiteralBoolean : LiteralFormat<Boolean>() {

selfie-lib/src/commonMain/kotlin/com/diffplug/selfie/guts/WriteTracker.kt

@@ -87,10 +87,17 @@ class InlineWriteTracker : WriteTracker<CallLocation, LiteralValue<*>>() {
     if (literalValue.expected != null) {
       // if expected == null, it's a `toBe_TODO()`, so there's nothing to check
       val content = SourceFile(layout.fs.name(file), layout.fs.fileRead(file))
-      val parsedValue = content.parseToBe(call.location.line).parseLiteral(literalValue.format)
+      val parsedValue =
+          try {
+            content.parseToBe(call.location.line).parseLiteral(literalValue.format)
+          } catch (e: Exception) {
+            throw AssertionError(
+                "Error while parsing the literal at ${call.location.ideLink(layout)}. Please report this error at https://github.com/diffplug/selfie",
+                e)
+          }
       if (parsedValue != literalValue.expected) {
         throw layout.fs.assertFailed(
-            "There is likely a bug in Selfie's literal parsing.",
+            "Selfie cannot modify the literal at ${call.location.ideLink(layout)} because Selfie has a parsing bug. Please report this error at https://github.com/diffplug/selfie",
             literalValue.expected,
             parsedValue)
       }

selfie-lib/src/commonTest/kotlin/com/diffplug/selfie/guts/KotlinMultilineString.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2024 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.selfie.guts
+
+import io.kotest.matchers.shouldBe
+import kotlin.test.Test
+
+class KotlinMultilineString {
+  @Test
+  fun newlines() {
+    """first
+""" shouldBe "first\n"
+    """
+second""" shouldBe "\nsecond"
+  }
+
+  @Test
+  fun indentation() {
+    """
+""" shouldBe "\n"
+    """
+  """ shouldBe "\n  "
+  }
+}

selfie-lib/src/commonTest/kotlin/com/diffplug/selfie/guts/LiteralStringTest.kt

@@ -20,48 +20,83 @@ import kotlin.test.Test
 
 class LiteralStringTest {
   @Test
-  fun singleLineJavaToSource() {
-    singleLineJavaToSource("1", "'1'")
-    singleLineJavaToSource("\\", "'\\\\'")
-    singleLineJavaToSource("1\n\tABC", "'1\\n\\tABC'")
+  fun encodeSingleJava() {
+    encodeSingleJava("1", "'1'")
+    encodeSingleJava("\\", "'\\\\'")
+    encodeSingleJava("1\n\tABC", "'1\\n\\tABC'")
   }
-  private fun singleLineJavaToSource(value: String, expected: String) {
-    val actual = LiteralString.singleLineJavaToSource(value)
+  private fun encodeSingleJava(value: String, expected: String) {
+    val actual = LiteralString.encodeSingleJava(value)
     actual shouldBe expected.replace("'", "\"")
   }
 
   @Test
-  fun multiLineJavaToSource() {
-    multiLineJavaToSource("1", "'''\n1'''")
-    multiLineJavaToSource("\\", "'''\n\\\\'''")
-    multiLineJavaToSource("  leading\ntrailing  ", "'''\n" + "\\s leading\n" + "trailing \\s'''")
+  fun encodeSingleJavaWithDollars() {
+    encodeSingleJavaWithDollars("1", "`1`")
+    encodeSingleJavaWithDollars("\\", "`\\\\`")
+    encodeSingleJavaWithDollars("$", "`s{'s'}`".replace('s', '$'))
+    encodeSingleJavaWithDollars("1\n\tABC", "`1\\n\\tABC`")
   }
-  private fun multiLineJavaToSource(value: String, expected: String) {
-    val actual = LiteralString.multiLineJavaToSource(value)
+  private fun encodeSingleJavaWithDollars(value: String, expected: String) {
+    val actual = LiteralString.encodeSingleJavaWithDollars(value)
+    actual shouldBe expected.replace("`", "\"")
+  }
+
+  @Test
+  fun encodeMultiJava() {
+    encodeMultiJava("1", "'''\n1'''")
+    encodeMultiJava("\\", "'''\n\\\\'''")
+    encodeMultiJava("  leading\ntrailing  ", "'''\n" + "\\s leading\n" + "trailing \\s'''")
+  }
+  private fun encodeMultiJava(value: String, expected: String) {
+    val actual = LiteralString.encodeMultiJava(value)
     actual shouldBe expected.replace("'", "\"")
   }
+  private val KOTLIN_DOLLAR = "s{'s'}".replace('s', '$')
+
+  @Test
+  fun encodeMultiKotlin() {
+    encodeMultiKotlin("1", "```1```")
+    encodeMultiKotlin("$", "```$KOTLIN_DOLLAR```")
+  }
+  private fun encodeMultiKotlin(value: String, expected: String) {
+    val actual = LiteralString.encodeMultiKotlin(value)
+    actual shouldBe expected.replace("`", "\"")
+  }
+
+  @Test
+  fun parseSingleJava() {
+    parseSingleJava("1", "1")
+    parseSingleJava("\\\\", "\\")
+    parseSingleJava("1\\n\\tABC", "1\n\tABC")
+  }
+  private fun parseSingleJava(value: String, expected: String) {
+    val actual = LiteralString.parseSingleJava("\"${value.replace("'", "\"")}\"")
+    actual shouldBe expected
+  }
 
   @Test
-  fun singleLineJavaFromSource() {
-    singleLineJavaFromSource("1", "1")
-    singleLineJavaFromSource("\\\\", "\\")
-    singleLineJavaFromSource("1\\n\\tABC", "1\n\tABC")
+  fun parseMultiJava() {
+    parseMultiJava("\n123\nabc", "123\nabc")
+    parseMultiJava("\n  123\n  abc", "123\nabc")
+    parseMultiJava("\n  123  \n  abc\t", "123\nabc")
+    parseMultiJava("\n  123  \n  abc\t", "123\nabc")
+    parseMultiJava("\n  123  \\s\n  abc\t\\s", "123   \nabc\t ")
   }
-  private fun singleLineJavaFromSource(value: String, expected: String) {
-    val actual = LiteralString.singleLineJavaFromSource("\"${value.replace("'", "\"")}\"")
+  private fun parseMultiJava(value: String, expected: String) {
+    val actual = LiteralString.parseMultiJava("\"\"\"${value.replace("'", "\"")}\"\"\"")
     actual shouldBe expected
   }
 
   @Test
-  fun multiLineJavaFromSource() {
-    multiLineJavaFromSource("\n123\nabc", "123\nabc")
-    multiLineJavaFromSource("\n  123\n  abc", "123\nabc")
-    multiLineJavaFromSource("\n  123  \n  abc\t", "123\nabc")
-    multiLineJavaFromSource("\n  123  \n  abc\t", "123\nabc")
-    multiLineJavaFromSource("\n  123  \\s\n  abc\t\\s", "123   \nabc\t ")
+  fun parseSingleJavaWithDollars() {
+    parseSingleJavaWithDollars("1", "1")
+    parseSingleJavaWithDollars("\\\\", "\\")
+    parseSingleJavaWithDollars("s{'s'}".replace('s', '$'), "$")
+    parseSingleJavaWithDollars("1\\n\\tABC", "1\n\tABC")
   }
-  private fun multiLineJavaFromSource(value: String, expected: String) {
-    val actual = LiteralString.multiLineJavaFromSource("\"\"\"${value.replace("'", "\"")}\"\"\"")
+  private fun parseSingleJavaWithDollars(value: String, expected: String) {
+    val actual = LiteralString.parseSingleJavaWithDollars("\"${value}\"")
     actual shouldBe expected
   }
 }

selfie-runner-junit5/src/test/kotlin/com/diffplug/selfie/junit5/StringLiteralsKotlinTest.kt

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2024 DiffPlug
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.diffplug.selfie.junit5
+
+import kotlin.test.Test
+import org.junit.jupiter.api.MethodOrderer
+import org.junit.jupiter.api.Order
+import org.junit.jupiter.api.TestMethodOrder
+import org.junitpioneer.jupiter.DisableIfTestFails
+
+@TestMethodOrder(MethodOrderer.OrderAnnotation::class)
+@DisableIfTestFails
+class StringLiteralsKotlinTest : Harness("undertest-junit5") {
+  @Test @Order(1)
+  fun readFailsBecauseTodo() {
+    gradleReadSSFail()
+  }
+
+  @Test @Order(2)
+  fun writeSucceeds() {
+    gradleWriteSS()
+  }
+
+  @Test @Order(3)
+  fun nowReadSucceeds() {
+    gradleReadSS()
+  }
+
+  @Test @Order(4)
+  fun cleanup() {
+    ut_mirror().restoreFromGit()
+  }
+}

undertest-junit5/src/test/java/undertest/junit5/UT_StringLiteralsJavaTest.java

@@ -26,6 +26,12 @@ public void newlines() {
         expectSelfie("\n\n\n").toBe_TODO();
     }
 
+    @Test
+    public void escapableCharacters() {
+        expectSelfie(" ' \" $ ").toBe_TODO();
+        expectSelfie(" ' \" $ \n \"\"\"\"\"\"\"\"\"\t").toBe_TODO();
+    }
+
     @Test
     public void allOfIt() {
         expectSelfie("  a\n" +