Minor reindent optimizations

libraries/stdlib/src/kotlin/text/Indent.kt

@@ -34,7 +34,7 @@ public fun String.replaceIndentByMargin(newIndent: String = "", marginPrefix: St
     require(marginPrefix.isNotBlank()) { "marginPrefix should be non blank string but it is '$marginPrefix'" }
     val lines = lines()
 
-    return lines.reindent(length() + newIndent.length() * lines.size(), getIndentFunction(newIndent)) { line ->
+    return lines.reindent(length() + newIndent.length() * lines.size(), getIndentFunction(newIndent), { line ->
         val firstNonWhitespaceIndex = line.indexOfFirst { !it.isWhitespace() }
 
         when {
@@ -42,7 +42,7 @@ public fun String.replaceIndentByMargin(newIndent: String = "", marginPrefix: St
             line.startsWith(marginPrefix, firstNonWhitespaceIndex) -> line.substring(firstNonWhitespaceIndex + marginPrefix.length())
             else -> null
         }
-    }
+    })
 }
 
 /**
@@ -80,7 +80,7 @@ public fun String.replaceIndent(newIndent: String = ""): String {
             .map { it.indentWidth() }
             .min() ?: 0
 
-    return lines.reindent(length() + newIndent.length() * lines.size(), getIndentFunction(newIndent)) { line -> line.drop(minCommonIndent) }
+    return lines.reindent(length() + newIndent.length() * lines.size(), getIndentFunction(newIndent), { line -> line.drop(minCommonIndent) })
 }
 
 /**
@@ -105,14 +105,19 @@ private fun String.indentWidth(): Int = indexOfFirst { !it.isWhitespace() }.let
 
 private fun getIndentFunction(indent: String) = when {
     indent.isEmpty() -> { line: String -> line }
-    else -> { line: String -> "$indent$line" }
+    else -> { line: String -> indent.concat(line) }
 }
 
-private inline fun List<String>.reindent(resultSizeEstimate: Int, indentAddFunction: (String) -> String, indentCutFunction: (String) -> String?) = lastIndex.let { lastLineIndex ->
-    withIndex()
-            .dropWhile { it.index == 0 && it.value.isBlank() }
-            .takeWhile { it.index != lastLineIndex || it.value.isNotBlank() }
-            .map { indentCutFunction(it.value)?.let { cutted -> indentAddFunction(cutted) } ?: it.value }
-            .joinTo(StringBuilder(resultSizeEstimate), "\n")
-            .toString()
+private inline fun List<String>.reindent(resultSizeEstimate: Int, indentAddFunction: (String) -> String, indentCutFunction: (String) -> String?): String {
+    val lastIndex = lastIndex
+    // TODO: Use mapNotNullIndexed
+    return mapIndexed { index, value ->
+            if ((index == 0 || index == lastIndex) && value.isBlank())
+                null
+            else
+                indentCutFunction(value)?.let { cutted -> indentAddFunction(cutted) } ?: value
+        }
+        .filterNotNull()
+        .joinTo(StringBuilder(resultSizeEstimate), "\n")
+        .toString()
 }

libraries/tools/kotlin-stdlib-gen/src/templates/Engine.kt

@@ -399,7 +399,7 @@ class GenericFunction(val signature: String, val keyword: String = "fun") {
         val indent: Int = body.takeWhile { it == ' ' }.length()
 
         builder.append('\n')
-        StringReader(body).forEachLine {
+        body.lineSequence().forEach {
             var count = indent
             val line = it.dropWhile { count-- > 0 && it == ' ' }.renderType()
             if (!line.isEmpty()) {