KT-8708 Function to strip leading whitespace (stripMargin, trimMargin, stripIndent?)
This commit is contained in:
Sergey Mashkov
@@ -1,5 +1,6 @@
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package kotlin
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import java.lang
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import java.util.NoSuchElementException
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import kotlin.platform.platformName
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import kotlin.text.MatchResult
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@@ -791,6 +792,85 @@ public fun String.contains(seq: CharSequence, ignoreCase: Boolean = false): Bool
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public fun String.contains(char: Char, ignoreCase: Boolean = false): Boolean =
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indexOf(char, ignoreCase = ignoreCase) >= 0
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private fun getIndentFunction(indent: String) = when {
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indent.isEmpty() -> { line: String -> line }
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else -> { line: String -> "$indent$line" }
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}
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private inline fun List<String>.reindent(length: Int, indentAddFunction: (String) -> String, indentCutFunction: (String) -> String) = lastIndex.let { lastLineIndex ->
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withIndex()
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.dropWhile { it.index == 0 && it.value.isBlank() }
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.takeWhile { it.index != lastLineIndex || it.value.isNotBlank() }
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.map { indentCutFunction(it.value) }
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.map(indentAddFunction)
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.joinTo(StringBuilder(length), "\n")
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.toString()
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}
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/**
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* Trims leading whitespace characters followed by [marginPrefix] from every line of a source string and removes
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* first and last lines if they are blank (notice difference blank vs empty).
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* Do not preserves original line endings
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*
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* Example
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* ```kotlin
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* assertEquals("ABC\n123\n456", """ABC
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* |123
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* |456""".trimMargin())
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* ```
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*
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* @param marginPrefix characters to be used as a margin delimiter. Default is `|` (pipe character)
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* @return the trimmed String
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* @see kotlin.isWhitespace
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* @since M13
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*/
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public fun String.trimMargin(marginPrefix: String = "|", newIndent: String = ""): String {
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require(marginPrefix.isNotBlank()) { "marginPrefix should be non blank string but it is '$marginPrefix'" }
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return lines().reindent(length(), getIndentFunction(newIndent)) { line ->
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val firstNonWhitespaceIndex = line.indexOfFirst { !it.isWhitespace() }
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when {
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firstNonWhitespaceIndex == -1 -> line
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line.startsWith(marginPrefix, firstNonWhitespaceIndex) -> line.substring(firstNonWhitespaceIndex + marginPrefix.length())
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else -> line
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}
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}
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}
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/**
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* Detects a common minimal indent of all the input lines, removes it from every line and also removes first and last
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* lines if they are blank (notice difference blank vs empty).
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* Note that blank lines do not affect detected indent level.
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* Please keep in mind that if there are non-blank lines with no leading whitespace characters (no indent at all) then the
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* common indent is 0 so this function may do nothing so it is recommended to keep first line empty (will be dropped).
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*
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* Do not preserves original line endings
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*
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* Example
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* ```kotlin
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* assertEquals("ABC\n123\n456", """
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* ABC
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* 123
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* 456""".trimMargin())
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* ```
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*
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* @return deindented String
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* @see kotlin.isBlank
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* @since M13
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*/
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public fun String.trimIndent(newIndent: String = ""): String {
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val lines = lines()
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val minCommonIndent = lines
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.filter { it.isNotBlank() }
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.map { it.indentWidth() }
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.min() ?: 0
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return lines.reindent(length(), getIndentFunction(newIndent)) { line -> line.drop(minCommonIndent) }
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}
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private fun String.indentWidth(): Int = indexOfFirst { !it.isWhitespace() }.let { if (it == -1) length() else it }
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// rangesDelimitedBy
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@@ -1,6 +1,9 @@
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package test.text
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import kotlin.test.*
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import kotlin.test.assertEquals
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import kotlin.test.assertFalse
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import kotlin.test.assertTrue
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import kotlin.test.fails
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import org.junit.Test as test
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// could not be local inside isEmptyAndBlank, because non-toplevel declarations is not yet supported for JS
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@@ -555,5 +558,114 @@ class StringTest {
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assertEquals("-test", "test".replaceFirst("", "-"))
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}
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test fun trimMargin() {
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// WARNING
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// DO NOT REFORMAT AS TESTS MAY FAIL DUE TO INDENTATION CHANGE
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assertEquals("ABC\n123\n456", """ABC
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|123
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|456""".trimMargin())
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assertEquals(" ABC\n 123\n 456", """ABC
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|123
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|456""".trimMargin(newIndent = " "))
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assertEquals("ABC \n123\n456", """ABC${" "}
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|123
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|456""".trimMargin())
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assertEquals(" ABC\n123\n456", """ ABC
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>>123
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${"\t"}>>456""".trimMargin(">>"))
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assertEquals("", "".trimMargin())
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assertEquals("", """
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""".trimMargin())
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assertEquals("", """
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|""".trimMargin())
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assertEquals("", """
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""".trimMargin())
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assertEquals(" a", """
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| a
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""".trimMargin())
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assertEquals(" a", """
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| a""".trimMargin())
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assertEquals(" a", """ | a
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""".trimMargin())
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assertEquals(" a", """ | a""".trimMargin())
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assertEquals("\u0000|ABC", "${"\u0000"}|ABC".trimMargin())
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}
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test fun trimIndent() {
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// WARNING
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// DO NOT REFORMAT AS TESTS MAY FAIL DUE TO INDENTATION CHANGE
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assertEquals("123", """
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123
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""".trimIndent())
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assertEquals("123\n 456", """
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123
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456
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""".trimIndent())
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assertEquals(" 123\n456", """
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123
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456
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""".trimIndent())
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assertEquals(" 123\n 456", """
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123
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456
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""".trimIndent(newIndent = " "))
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assertEquals(" 123\n456", """
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123
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456""".trimIndent())
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assertEquals(" ", """
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${" "}
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""".trimIndent())
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val deindented = """
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,.
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,. _ oo. `88P
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]88b ,o. d88. ]88b '
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888 _ Y888o888 d88P _ _
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888 ,888 `Y88888o_ ,888 d88b d88._____
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888,888P ,oooooo. ;888888b.]88P 888' d888888888p
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888888P d88888888. J88b'YPP ]88b ,888 d888P'''888.
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8888P' ]88P `888 d88[ d88P ]88b 888' Y88b
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8888p ]88b 888 888 d88[ 888 888. `888
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,88888b 888[ 888 888. d88[ 888. Y88b Y88[
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d88PY88b `888L,d88P Y88b Y88b ]88b `888 888'
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888 Y88b Y88888P 888. 888. 888. Y88b `88P
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d88P 888 `'P' Y888. `888. `88P `Y8P '
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Y8P' ' `YP Y8P' '
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____ dXp _ _ _________
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ddXXXXXp XXP ,XX dXb Yo.XXXXXX ,oooooo.
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X'L_oXXP XX' XX[ dXb dXb YPPPPXXX'
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XYXXXXX ]XX dXb dXb dX8Xooooo dXXP
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XXb`YYXXo. YXXo_ dXP dXP YXb'''''' ,XXP'
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`XX `YYXb `YXXXXP XX[ ]XX ,XX'
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YXb YXb `'' XXXXooL `XX._____ `XXXXXXXXooooo.
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`XP ' '''''' YPXXXXXX' ''''''`''YPPP
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""".trimIndent()
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assertEquals(23, deindented.lines().size())
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val indents = deindented.lines().map { "^\\s*".toRegex().match(it)!!.value.length() }
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assertEquals(0, indents.min())
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assertEquals(42, indents.max())
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assertEquals(1, deindented.lines().count { it.isEmpty() })
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}
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}
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