com.alkacon.diff.rangedifferencer
Class RangeDifferencer

java.lang.Object
  com.alkacon.diff.rangedifferencer.RangeDifferencer

public final class RangeDifferencer
extends java.lang.Object

A RangeDifferencer finds the differences between two or three IRangeComparators.

To use the differencer, clients provide an IRangeComparator that breaks their input data into a sequence of comparable entities. The differencer returns the differences among these sequences as an array of RangeDifference objects (findDifferences methods). Every RangeDifference represents a single kind of difference and the corresponding ranges of the underlying comparable entities in the left, right, and optionally ancestor sides.

Alternatively, the findRanges methods not only return objects for the differing ranges but for non-differing ranges too.

The algorithm used is an objectified version of one described in: A File Comparison Program, by Webb Miller and Eugene W. Myers, Software Practice and Experience, Vol. 15, Nov. 1985. Please note: This class has been modified by Alkacon from the original Eclipse source! The dependencies to org.eclipse.jface.util.Assert and org.eclipse.core.runtime.IProgressMonitor have been removed. The progress monitor is not used anyway, and the assert method has been inlined. The source code has been reformatted and checkstyle / findbugs warnings where removed (AK).

See Also:

I_RangeComparator, RangeDifference

Method Summary

static boolean	assertIsTrue(boolean expression) Asserts that the given boolean is true.
static RangeDifference[]	findDifferences(I_RangeComparator left, I_RangeComparator right) Finds the differences between two IRangeComparators.
static RangeDifference[]	findDifferences(I_RangeComparator ancestor, I_RangeComparator left, I_RangeComparator right) Finds the differences among three IRangeComparators.
static RangeDifference[]	findRanges(I_RangeComparator left, I_RangeComparator right) Finds the differences among two IRangeComparators.
static RangeDifference[]	findRanges(I_RangeComparator ancestor, I_RangeComparator left, I_RangeComparator right) Finds the differences among three IRangeComparators.

Methods inherited from class java.lang.Object

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

Method Detail

assertIsTrue

public static boolean assertIsTrue(boolean expression)

Asserts that the given boolean is true. If this is not the case, some kind of unchecked exception is thrown.

Parameters:

expression - the outcome of the check

Returns:

true if the check passes (does not return if the check fails)

findDifferences

public static RangeDifference[] findDifferences(I_RangeComparator left,
                                                I_RangeComparator right)

Finds the differences between two IRangeComparators. The differences are returned as an array of RangeDifferences. If no differences are detected an empty array is returned.

Parameters:

left - the left range comparator

right - the right range comparator

Returns:

an array of range differences, or an empty array if no differences were found

Since:

2.0

findDifferences

public static RangeDifference[] findDifferences(I_RangeComparator ancestor,
                                                I_RangeComparator left,
                                                I_RangeComparator right)

Finds the differences among three IRangeComparators. The differences are returned as a list of RangeDifferences. If no differences are detected an empty list is returned. If the ancestor range comparator is null, a two-way comparison is performed.

Parameters:

ancestor - the ancestor range comparator or null

left - the left range comparator

right - the right range comparator

Returns:

an array of range differences, or an empty array if no differences were found

Since:

2.0

findRanges

public static RangeDifference[] findRanges(I_RangeComparator left,
                                           I_RangeComparator right)

Finds the differences among two IRangeComparators. In contrast to findDifferences, the result contains RangeDifference elements for non-differing ranges too.

Parameters:

left - the left range comparator

right - the right range comparator

Returns:

an array of range differences

Since:

2.0

findRanges

public static RangeDifference[] findRanges(I_RangeComparator ancestor,
                                           I_RangeComparator left,
                                           I_RangeComparator right)

Finds the differences among three IRangeComparators. In contrast to findDifferences, the result contains RangeDifference elements for non-differing ranges too. If the ancestor range comparator is null, a two-way comparison is performed.

Parameters:

ancestor - the ancestor range comparator or null

left - the left range comparator

right - the right range comparator

Returns:

an array of range differences

Since:

2.0