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Commit cd740596 authored by Hans Boehm's avatar Hans Boehm
Browse files

Fix digitsRequired() for negative denominators 

Bug: 21789679

Also adds some tests for digitsRequired(), including one that fails
without this CL.

Change-Id: Ib007e753f90c019c37666d71c1cfd02301dcd360
parent b3f7278a

src/com/android/calculator2/BoundedRational.java

+4 −1
Original line number Diff line number Diff line
@@ -485,6 +485,7 @@ public class BoundedRational { 
    }



    private static final BigInteger BIG_FIVE = BigInteger.valueOf(5);

    private static final BigInteger BIG_MINUS_ONE = BigInteger.valueOf(-1);



    // Return the number of decimal digits to the right of the

    // decimal point required to represent the argument exactly,
@@ -514,7 +515,9 @@ public class BoundedRational { 
        // (Recall the fraction was in lowest terms to start with.)

        // Otherwise the powers of 10 we need to cancel the denominator

        // is the larger of powers_of_two and powers_of_five.

        if (!den.equals(BigInteger.ONE)) return Integer.MAX_VALUE;

        if (!den.equals(BigInteger.ONE) && !den.equals(BIG_MINUS_ONE)) {

            return Integer.MAX_VALUE;

        }

        return Math.max(powers_of_two, powers_of_five);

    }

}

tests/src/com/android/calculator2/BRTest.java

+6 −0
Original line number Diff line number Diff line
@@ -139,6 +139,12 @@ public class BRTest extends TestCase { 
        check(BR_0.signum() == 0, "signum(0)");

        check(BR_M1.signum() == -1, "signum(-1)");

        check(BR_2.signum() == 1, "signum(2)");

        check(BoundedRational.digitsRequired(BoundedRational.ZERO) == 0, "digitsRequired(0)");

        check(BoundedRational.digitsRequired(BoundedRational.HALF) == 1, "digitsRequired(1/2)");

        check(BoundedRational.digitsRequired(BoundedRational.MINUS_HALF) == 1,

                "digitsRequired(-1/2)");

        check(BoundedRational.digitsRequired(new BoundedRational(1,-2)) == 1,

                "digitsRequired(1/-2)");

        // We check values that include all interesting degree values.

        BoundedRational r = BR_M390;

        while (!r.equals(BR_390)) {