/
BufferReader.scala
96 lines (78 loc) · 2.07 KB
/
BufferReader.scala
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/* NSC -- new Scala compiler
* Copyright 2005-2010 LAMP/EPFL
* @author Martin Odersky
*/
package com.typesafe.tools.mima.core
import java.lang.Float.intBitsToFloat
import java.lang.Double.longBitsToDouble
/**
* This class reads files byte per byte. Only used by ClassFileParser
*
* @author Philippe Altherr
* @version 1.0, 23/03/2004
*/
class BufferReader(val buf: Array[Byte]) {
/** the current input pointer
*/
var bp: Int = 0
/** return byte at offset 'pos'
*/
@throws(classOf[IndexOutOfBoundsException])
def byteAt(pos: Int): Byte = buf(pos)
/** read a byte
*/
@throws(classOf[IndexOutOfBoundsException])
def nextByte: Byte = {
val b = buf(bp)
bp += 1
b
}
/** read some bytes
*/
def nextBytes(len: Int): Array[Byte] = {
bp += len
buf.slice(bp - len, bp)
}
/** read a character
*/
def nextChar: Char =
(((nextByte & 0xff) << 8) + (nextByte & 0xff)).toChar
/** read an integer
*/
def nextInt: Int =
((nextByte & 0xff) << 24) + ((nextByte & 0xff) << 16) +
((nextByte & 0xff) << 8) + (nextByte & 0xff)
/** extract a character at position bp from buf
*/
def getChar(mybp: Int): Char =
(((buf(mybp) & 0xff) << 8) + (buf(mybp+1) & 0xff)).toChar
/** extract an integer at position bp from buf
*/
def getInt(mybp: Int): Int =
((buf(mybp ) & 0xff) << 24) + ((buf(mybp+1) & 0xff) << 16) +
((buf(mybp+2) & 0xff) << 8) + (buf(mybp+3) & 0xff)
/** extract a long integer at position bp from buf
*/
def getLong(mybp: Int): Long =
(getInt(mybp).toLong << 32) + (getInt(mybp + 4) & 0xffffffffL)
/** extract a float at position bp from buf
*/
def getFloat(mybp: Int): Float = intBitsToFloat(getInt(mybp))
/** extract a double at position bp from buf
*/
def getDouble(mybp: Int): Double = longBitsToDouble(getLong(mybp))
/** skip next 'n' bytes
*/
def skip(n: Int): Unit = { bp += n }
/** Do read operattion `op` at position `n`
*/
def at[T](n: Int)(op: => T): T = {
val oldbp = bp
bp = n
try {
op
} finally {
bp = oldbp
}
}
}