scala.io.Source.scala Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of scala-library Show documentation
Show all versions of scala-library Show documentation
Standard library for the Scala Programming Language
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package io
import scala.collection.{AbstractIterator, BufferedIterator}
import java.io.{Closeable, FileInputStream, FileNotFoundException, InputStream, PrintStream, File => JFile}
import java.net.{URI, URL}
import scala.annotation.nowarn
/** This object provides convenience methods to create an iterable
* representation of a source file.
*/
object Source {
val DefaultBufSize = 2048
/** Creates a `Source` from System.in.
*/
def stdin = fromInputStream(System.in)
/** Creates a Source from an Iterable.
*
* @param iterable the Iterable
* @return the Source
*/
def fromIterable(iterable: Iterable[Char]): Source = new Source {
val iter = iterable.iterator
} withReset(() => fromIterable(iterable))
/** Creates a Source instance from a single character.
*/
def fromChar(c: Char): Source = fromIterable(Array(c))
/** creates Source from array of characters, with empty description.
*/
def fromChars(chars: Array[Char]): Source = fromIterable(chars)
/** creates Source from a String, with no description.
*/
def fromString(s: String): Source = fromIterable(s)
/** creates Source from file with given name, setting its description to
* filename.
*/
def fromFile(name: String)(implicit codec: Codec): BufferedSource =
fromFile(new JFile(name))(codec)
/** creates Source from file with given name, using given encoding, setting
* its description to filename.
*/
def fromFile(name: String, enc: String): BufferedSource =
fromFile(name)(Codec(enc))
/** creates `source` from file with given file `URI`.
*/
def fromFile(uri: URI)(implicit codec: Codec): BufferedSource =
fromFile(new JFile(uri))(codec)
/** creates Source from file with given file: URI
*/
def fromFile(uri: URI, enc: String): BufferedSource =
fromFile(uri)(Codec(enc))
/** creates Source from file, using default character encoding, setting its
* description to filename.
*/
def fromFile(file: JFile)(implicit codec: Codec): BufferedSource =
fromFile(file, Source.DefaultBufSize)(codec)
/** same as fromFile(file, enc, Source.DefaultBufSize)
*/
def fromFile(file: JFile, enc: String): BufferedSource =
fromFile(file)(Codec(enc))
def fromFile(file: JFile, enc: String, bufferSize: Int): BufferedSource =
fromFile(file, bufferSize)(Codec(enc))
/** Creates Source from `file`, using given character encoding, setting
* its description to filename. Input is buffered in a buffer of size
* `bufferSize`.
*/
def fromFile(file: JFile, bufferSize: Int)(implicit codec: Codec): BufferedSource = {
val inputStream = new FileInputStream(file)
createBufferedSource(
inputStream,
bufferSize,
() => fromFile(file, bufferSize)(codec),
() => inputStream.close()
)(codec) withDescription s"file:${file.getAbsolutePath}"
}
/** Create a `Source` from array of bytes, decoding
* the bytes according to codec.
*
* @return the created `Source` instance.
*/
def fromBytes(bytes: Array[Byte])(implicit codec: Codec): Source =
fromString(new String(bytes, codec.name))
def fromBytes(bytes: Array[Byte], enc: String): Source =
fromBytes(bytes)(Codec(enc))
/** Create a `Source` from array of bytes, assuming
* one byte per character (ISO-8859-1 encoding.)
*/
def fromRawBytes(bytes: Array[Byte]): Source =
fromString(new String(bytes, Codec.ISO8859.name))
/** creates `Source` from file with given file: URI
*/
def fromURI(uri: URI)(implicit codec: Codec): BufferedSource =
fromFile(new JFile(uri))(codec)
/** same as fromURL(new URL(s))(Codec(enc))
*/
def fromURL(s: String, enc: String): BufferedSource =
fromURL(s)(Codec(enc))
/** same as fromURL(new URL(s))
*/
def fromURL(s: String)(implicit codec: Codec): BufferedSource =
fromURL(new URL(s))(codec)
/** same as fromInputStream(url.openStream())(Codec(enc))
*/
def fromURL(url: URL, enc: String): BufferedSource =
fromURL(url)(Codec(enc))
/** same as fromInputStream(url.openStream())(codec)
*/
def fromURL(url: URL)(implicit codec: Codec): BufferedSource =
fromInputStream(url.openStream())(codec)
/** Reads data from inputStream with a buffered reader, using the encoding
* in implicit parameter codec.
*
* @param inputStream the input stream from which to read
* @param bufferSize buffer size (defaults to Source.DefaultBufSize)
* @param reset a () => Source which resets the stream (if unset, reset() will throw an Exception)
* @param close a () => Unit method which closes the stream (if unset, close() will do nothing)
* @param codec (implicit) a scala.io.Codec specifying behavior (defaults to Codec.default)
* @return the buffered source
*/
def createBufferedSource(
inputStream: InputStream,
bufferSize: Int = DefaultBufSize,
reset: () => Source = null,
close: () => Unit = null
)(implicit codec: Codec): BufferedSource = {
// workaround for default arguments being unable to refer to other parameters
val resetFn = if (reset == null) () => createBufferedSource(inputStream, bufferSize, reset, close)(codec) else reset
new BufferedSource(inputStream, bufferSize)(codec) withReset resetFn withClose close
}
def fromInputStream(is: InputStream, enc: String): BufferedSource =
fromInputStream(is)(Codec(enc))
def fromInputStream(is: InputStream)(implicit codec: Codec): BufferedSource =
createBufferedSource(is, reset = () => fromInputStream(is)(codec), close = () => is.close())(codec)
/** Reads data from a classpath resource, using either a context classloader (default) or a passed one.
*
* @param resource name of the resource to load from the classpath
* @param classLoader classloader to be used, or context classloader if not specified
* @return the buffered source
*/
def fromResource(resource: String, classLoader: ClassLoader = Thread.currentThread().getContextClassLoader())(implicit codec: Codec): BufferedSource =
Option(classLoader.getResourceAsStream(resource)) match {
case Some(in) => fromInputStream(in)
case None => throw new FileNotFoundException(s"resource '$resource' was not found in the classpath from the given classloader.")
}
}
/** An iterable representation of source data.
* It may be reset with the optional [[reset]] method.
*
* Subclasses must supply [[scala.io.Source.iter the underlying iterator]].
*
* Error handling may be customized by overriding the [[scala.io.Source.report report]] method.
*
* The [[scala.io.Source.ch current input]] and [[scala.io.Source.pos position]],
* as well as the [[scala.io.Source.next next character]] methods delegate to
* [[scala.io.Source#Positioner the positioner]].
*
* The default positioner encodes line and column numbers in the position passed to [[report]].
* This behavior can be changed by supplying a
* [[scala.io.Source.withPositioning(pos:* custom positioner]].
*
*/
abstract class Source extends Iterator[Char] with Closeable {
/** the actual iterator */
protected val iter: Iterator[Char]
// ------ public values
/** description of this source, default empty */
var descr: String = ""
var nerrors = 0
var nwarnings = 0
private def lineNum(line: Int): String = (getLines() drop (line - 1) take 1).mkString
class LineIterator extends AbstractIterator[String] with Iterator[String] {
private[this] val sb = new StringBuilder
lazy val iter: BufferedIterator[Char] = Source.this.iter.buffered
def isNewline(ch: Char): Boolean = ch == '\r' || ch == '\n'
def getc(): Boolean = iter.hasNext && {
val ch = iter.next()
if (ch == '\n') false
else if (ch == '\r') {
if (iter.hasNext && iter.head == '\n')
iter.next()
false
}
else {
sb append ch
true
}
}
def hasNext: Boolean = iter.hasNext
def next(): String = {
sb.clear()
while (getc()) { }
sb.toString
}
}
/** Returns an iterator who returns lines (NOT including newline character(s)).
* It will treat any of \r\n, \r, or \n as a line separator (longest match) - if
* you need more refined behavior you can subclass Source#LineIterator directly.
*/
def getLines(): Iterator[String] = new LineIterator()
/** Returns `'''true'''` if this source has more characters.
*/
def hasNext: Boolean = iter.hasNext
/** Returns next character.
*/
def next(): Char = positioner.next()
@nowarn("cat=deprecation")
class Positioner(encoder: Position) {
def this() = this(RelaxedPosition)
/** the last character returned by next. */
var ch: Char = _
/** position of last character returned by next */
var pos = 0
/** current line and column */
var cline = 1
var ccol = 1
/** default col increment for tabs '\t', set to 4 initially */
var tabinc = 4
def next(): Char = {
ch = iter.next()
pos = encoder.encode(cline, ccol)
ch match {
case '\n' =>
ccol = 1
cline += 1
case '\t' =>
ccol += tabinc
case _ =>
ccol += 1
}
ch
}
}
/** A Position implementation which ignores errors in
* the positions.
*/
@nowarn("cat=deprecation")
object RelaxedPosition extends Position {
def checkInput(line: Int, column: Int): Unit = ()
}
object RelaxedPositioner extends Positioner(RelaxedPosition) { }
object NoPositioner extends Positioner(Position) {
override def next(): Char = iter.next()
}
def ch: Char = positioner.ch
def pos: Int = positioner.pos
/** Reports an error message to the output stream `out`.
*
* @param pos the source position (line/column)
* @param msg the error message to report
* @param out PrintStream to use (optional: defaults to `Console.err`)
*/
def reportError(
pos: Int,
msg: String,
out: PrintStream = Console.err): Unit =
{
nerrors += 1
report(pos, msg, out)
}
private def spaces(n: Int) = List.fill(n)(' ').mkString
/**
* @param pos the source position (line/column)
* @param msg the error message to report
* @param out PrintStream to use
*/
def report(pos: Int, msg: String, out: PrintStream): Unit = {
val line = Position line pos
val col = Position column pos
out println "%s:%d:%d: %s%s%s^".format(descr, line, col, msg, lineNum(line), spaces(col - 1))
}
/**
* @param pos the source position (line/column)
* @param msg the warning message to report
* @param out PrintStream to use (optional: defaults to `Console.out`)
*/
def reportWarning(
pos: Int,
msg: String,
out: PrintStream = Console.out): Unit =
{
nwarnings += 1
report(pos, "warning! " + msg, out)
}
private[this] var resetFunction: () => Source = null
private[this] var closeFunction: () => Unit = null
private[this] var positioner: Positioner = RelaxedPositioner
def withReset(f: () => Source): this.type = {
resetFunction = f
this
}
def withClose(f: () => Unit): this.type = {
closeFunction = f
this
}
def withDescription(text: String): this.type = {
descr = text
this
}
/** Change or disable the positioner. */
def withPositioning(on: Boolean): this.type = {
positioner = if (on) RelaxedPositioner else NoPositioner
this
}
def withPositioning(pos: Positioner): this.type = {
positioner = pos
this
}
/** The close() method closes the underlying resource. */
def close(): Unit = {
if (closeFunction != null) closeFunction()
}
/** The reset() method creates a fresh copy of this Source. */
def reset(): Source =
if (resetFunction != null) resetFunction()
else throw new UnsupportedOperationException("Source's reset() method was not set.")
}