Provide visit extension functions for java.nio.file.Path #KT-52910
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Abduqodiri Qurbonzoda
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/*
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* Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
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* Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
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*/
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package kotlin.io.path
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import java.io.IOException
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import java.nio.file.FileVisitResult
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import java.nio.file.FileVisitor
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import java.nio.file.Path
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import java.nio.file.SimpleFileVisitor
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import java.nio.file.attribute.BasicFileAttributes
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/**
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* The builder to provide implementation of the file visitor that [fileVisitor] builds.
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*/
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@ExperimentalPathApi
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@SinceKotlin("1.7")
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public sealed interface FileVisitorBuilder {
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/**
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* Overrides the corresponding function of the built file visitor with the provided [function].
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*
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* By default, [FileVisitor.preVisitDirectory] of the built file visitor returns [FileVisitResult.CONTINUE].
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*/
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public fun onPreVisitDirectory(function: (directory: Path, attributes: BasicFileAttributes) -> FileVisitResult): Unit
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/**
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* Overrides the corresponding function of the built file visitor with the provided [function].
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*
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* By default, [FileVisitor.visitFile] of the built file visitor returns [FileVisitResult.CONTINUE].
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*/
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public fun onVisitFile(function: (file: Path, attributes: BasicFileAttributes) -> FileVisitResult): Unit
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/**
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* Overrides the corresponding function of the built file visitor with the provided [function].
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*
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* By default, [FileVisitor.visitFileFailed] of the built file visitor re-throws the I/O exception
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* that prevented the file from being visited.
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*/
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public fun onVisitFileFailed(function: (file: Path, exception: IOException) -> FileVisitResult): Unit
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/**
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* Overrides the corresponding function of the built file visitor with the provided [function].
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*
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* By default, if the directory iteration completes without an I/O exception,
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* [FileVisitor.postVisitDirectory] of the built file visitor returns [FileVisitResult.CONTINUE];
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* otherwise it re-throws the I/O exception that caused the iteration of the directory to terminate prematurely.
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*/
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public fun onPostVisitDirectory(function: (directory: Path, exception: IOException?) -> FileVisitResult): Unit
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}
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@ExperimentalPathApi
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internal class FileVisitorBuilderImpl : FileVisitorBuilder {
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private var onPreVisitDirectory: ((Path, BasicFileAttributes) -> FileVisitResult)? = null
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private var onVisitFile: ((Path, BasicFileAttributes) -> FileVisitResult)? = null
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private var onVisitFileFailed: ((Path, IOException) -> FileVisitResult)? = null
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private var onPostVisitDirectory: ((Path, IOException?) -> FileVisitResult)? = null
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private var isBuilt: Boolean = false
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override fun onPreVisitDirectory(function: (directory: Path, attributes: BasicFileAttributes) -> FileVisitResult): Unit {
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checkIsNotBuilt()
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checkNotDefined(onPreVisitDirectory, "onPreVisitDirectory")
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onPreVisitDirectory = function
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}
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override fun onVisitFile(function: (file: Path, attributes: BasicFileAttributes) -> FileVisitResult): Unit {
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checkIsNotBuilt()
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checkNotDefined(onVisitFile, "onVisitFile")
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onVisitFile = function
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}
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override fun onVisitFileFailed(function: (file: Path, exception: IOException) -> FileVisitResult): Unit {
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checkIsNotBuilt()
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checkNotDefined(onVisitFileFailed, "onVisitFileFailed")
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onVisitFileFailed = function
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}
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override fun onPostVisitDirectory(function: (directory: Path, exception: IOException?) -> FileVisitResult): Unit {
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checkIsNotBuilt()
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checkNotDefined(onPostVisitDirectory, "onPostVisitDirectory")
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onPostVisitDirectory = function
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}
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fun build(): FileVisitor<Path> {
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checkIsNotBuilt()
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isBuilt = true
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return FileVisitorImpl(onPreVisitDirectory, onVisitFile, onVisitFileFailed, onPostVisitDirectory)
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}
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private fun checkIsNotBuilt() {
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if (isBuilt) throw IllegalStateException("This builder was already built")
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}
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private fun checkNotDefined(function: Any?, name: String) {
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if (function != null) throw IllegalStateException("$name was already defined")
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}
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}
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private class FileVisitorImpl(
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private val onPreVisitDirectory: ((Path, BasicFileAttributes) -> FileVisitResult)?,
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private val onVisitFile: ((Path, BasicFileAttributes) -> FileVisitResult)?,
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private val onVisitFileFailed: ((Path, IOException) -> FileVisitResult)?,
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private val onPostVisitDirectory: ((Path, IOException?) -> FileVisitResult)?,
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) : SimpleFileVisitor<Path>() {
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override fun preVisitDirectory(dir: Path, attrs: BasicFileAttributes): FileVisitResult =
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this.onPreVisitDirectory?.invoke(dir, attrs) ?: super.preVisitDirectory(dir, attrs)
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override fun visitFile(file: Path, attrs: BasicFileAttributes): FileVisitResult =
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this.onVisitFile?.invoke(file, attrs) ?: super.visitFile(file, attrs)
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override fun visitFileFailed(file: Path, exc: IOException): FileVisitResult =
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this.onVisitFileFailed?.invoke(file, exc) ?: super.visitFileFailed(file, exc)
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override fun postVisitDirectory(dir: Path, exc: IOException?): FileVisitResult =
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this.onPostVisitDirectory?.invoke(dir, exc) ?: super.postVisitDirectory(dir, exc)
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}
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@@ -15,6 +15,8 @@ import java.nio.file.*
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import java.nio.file.FileAlreadyExistsException
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import java.nio.file.NoSuchFileException
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import java.nio.file.attribute.*
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import kotlin.contracts.InvocationKind
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import kotlin.contracts.contract
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import kotlin.jvm.Throws
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/**
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@@ -1015,3 +1017,115 @@ public inline fun URI.toPath(): Path =
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@ExperimentalPathApi
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@SinceKotlin("1.7")
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public fun Path.walk(vararg options: PathWalkOption): Sequence<Path> = PathTreeWalk(this, options)
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/**
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* Visits this directory and all its content with the specified [visitor].
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*
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* The traversal is in depth-first order and starts at this directory. The specified [visitor] is invoked on each file encountered.
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*
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* @param visitor the [FileVisitor] that receives callbacks.
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* @param maxDepth the maximum depth to traverse. By default, there is no limit.
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* @param followLinks specifies whether to follow symbolic links, `false` by default.
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*
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* @see Files.walkFileTree
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*/
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@ExperimentalPathApi
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@SinceKotlin("1.7")
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public fun Path.visitFileTree(visitor: FileVisitor<Path>, maxDepth: Int = Int.MAX_VALUE, followLinks: Boolean = false): Unit {
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val options = if (followLinks) setOf(FileVisitOption.FOLLOW_LINKS) else setOf()
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Files.walkFileTree(this, options, maxDepth, visitor)
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}
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/**
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* Visits this directory and all its content with the [FileVisitor] defined in [builderAction].
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*
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* This function works the same as [Path.visitFileTree]. It is introduced to streamline
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* the cases when a [FileVisitor] is created only to be immediately used for a file tree traversal.
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* The trailing lambda [builderAction] is passed to [fileVisitor] to get the file visitor.
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*
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* Example:
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*
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* ``` kotlin
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* projectDirectory.visitFileTree {
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* onPreVisitDirectory { directory, _ ->
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* if (directory.name == "build") {
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* directory.toFile().deleteRecursively()
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* FileVisitResult.SKIP_SUBTREE
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* } else {
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* FileVisitResult.CONTINUE
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* }
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* }
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*
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* onVisitFile { file, _ ->
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* if (file.extension == "class") {
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* file.deleteExisting()
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* }
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* FileVisitResult.CONTINUE
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* }
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* }
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* ```
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*
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* @param maxDepth the maximum depth to traverse. By default, there is no limit.
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* @param followLinks specifies whether to follow symbolic links, `false` by default.
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* @param builderAction the function that defines [FileVisitor].
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*
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* @see Path.visitFileTree
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* @see fileVisitor
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*/
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@ExperimentalPathApi
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@SinceKotlin("1.7")
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public fun Path.visitFileTree(
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maxDepth: Int = Int.MAX_VALUE,
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followLinks: Boolean = false,
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builderAction: FileVisitorBuilder.() -> Unit
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): Unit {
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contract { callsInPlace(builderAction, InvocationKind.EXACTLY_ONCE) }
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visitFileTree(fileVisitor(builderAction), maxDepth, followLinks)
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}
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/**
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* Builds a [FileVisitor] whose implementation is defined in [builderAction].
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*
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* By default, the returned file visitor visits all files and re-throws I/O errors, that is:
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* * [FileVisitor.preVisitDirectory] returns [FileVisitResult.CONTINUE].
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* * [FileVisitor.visitFile] returns [FileVisitResult.CONTINUE].
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* * [FileVisitor.visitFileFailed] re-throws the I/O exception that prevented the file from being visited.
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* * [FileVisitor.postVisitDirectory] returns [FileVisitResult.CONTINUE] if the directory iteration completes without an I/O exception;
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* otherwise it re-throws the I/O exception that caused the iteration of the directory to terminate prematurely.
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*
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* To override a function provide its implementation to the corresponding
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* function of the [FileVisitorBuilder] that was passed as a receiver to [builderAction].
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* Note that each function can be overridden only once.
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* Repeated override of a function throws [IllegalStateException].
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*
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* The builder is valid only inside [builderAction] function.
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* Using it outside the function throws [IllegalStateException].
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*
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* Example:
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*
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* ``` kotlin
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* val cleanVisitor = fileVisitor {
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* onPreVisitDirectory { directory, _ ->
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* if (directory.name == "build") {
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* directory.toFile().deleteRecursively()
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* FileVisitResult.SKIP_SUBTREE
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* } else {
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* FileVisitResult.CONTINUE
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* }
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* }
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*
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* onVisitFile { file, _ ->
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* if (file.extension == "class") {
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* file.deleteExisting()
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* }
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* FileVisitResult.CONTINUE
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* }
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* }
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* ```
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*/
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@ExperimentalPathApi
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@SinceKotlin("1.7")
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public fun fileVisitor(builderAction: FileVisitorBuilder.() -> Unit): FileVisitor<Path> {
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contract { callsInPlace(builderAction, InvocationKind.EXACTLY_ONCE) }
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return FileVisitorBuilderImpl().apply(builderAction).build()
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}
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