Module ch.randelshofer.fastdoubleparser
Package ch.randelshofer.fastdoubleparser

Class ParseDigitsTaskCharSequence

  • final class ParseDigitsTaskCharSequence
extends java.lang.Object
    Parses digits.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private ParseDigitsTaskCharSequence()
      Don't let anyone instantiate this class.

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) static java.math.BigInteger parseDigitsIterative​(java.lang.CharSequence str, int from, int to)
      Parses digits in quadratic time O(N2).
      (package private) static java.math.BigInteger parseDigitsRecursive​(java.lang.CharSequence str, int from, int to, java.util.Map<java.lang.Integer,​java.math.BigInteger> powersOfTen, int recursionThreshold)
      Parses digits in O(N log N (log log N)) time.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • ParseDigitsTaskCharSequence

        private ParseDigitsTaskCharSequence()
        Don't let anyone instantiate this class.

    • Method Detail

      • parseDigitsIterative

        static java.math.BigInteger parseDigitsIterative​(java.lang.CharSequence str,
                                                 int from,
                                                 int to)
        Parses digits in quadratic time O(N2).

      • parseDigitsRecursive

        static java.math.BigInteger parseDigitsRecursive​(java.lang.CharSequence str,
                                                 int from,
                                                 int to,
                                                 java.util.Map<java.lang.Integer,​java.math.BigInteger> powersOfTen,
                                                 int recursionThreshold)
        Parses digits in O(N log N (log log N)) time.

        A conventional recursive algorithm would require O(N1.5). We achieve better performance by performing multiplications of long bit sequences in the frequency domain.