Package org.eclipse.jgit.diff
Class SequenceComparator<S extends Sequence>
java.lang.Object
org.eclipse.jgit.diff.SequenceComparator<S>
- Type Parameters:
S
- type of sequence the comparator supports.
- Direct Known Subclasses:
HashedSequenceComparator
,RawTextComparator
,SubsequenceComparator
Equivalence function for a
Sequence
compared by
difference algorithm.
Difference algorithms can use a comparator to compare portions of two sequences and discover the minimal edits required to transform from one sequence to the other sequence.
Indexes within a sequence are zero-based.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionabstract boolean
Compare two items to determine if they are equivalent.abstract int
Get a hash value for an item in a sequence.reduceCommonStartEnd
(S a, S b, Edit e) Modify the edit to remove common leading and trailing items.
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Constructor Details
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SequenceComparator
public SequenceComparator()
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Method Details
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equals
Compare two items to determine if they are equivalent. It is permissible to compare sequencea
with itself (by passinga
again in positionb
).- Parameters:
a
- the first sequence.ai
- item ofai
to compare.b
- the second sequence.bi
- item ofbi
to compare.- Returns:
- true if the two items are identical according to this function's equivalence rule.
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hash
Get a hash value for an item in a sequence. If two items are equal according to this comparator'sequals(Sequence, int, Sequence, int)
method, then this hash method must produce the same integer result for both items. It is not required for two items to have different hash values if they are unequal according to theequals()
method.- Parameters:
seq
- the sequence.ptr
- the item to obtain the hash for.- Returns:
- hash the hash value.
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reduceCommonStartEnd
Modify the edit to remove common leading and trailing items. The supplied edite
is reduced in size by moving the beginning A and B points so the edit does not cover any items that are in common between the two sequences. The ending A and B points are also shifted to remove common items from the end of the region.- Parameters:
a
- the first sequence.b
- the second sequence.e
- the edit to start with and update.- Returns:
e
if it was updated in-place, otherwise a new edit containing the reduced region.
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