public class Diff extends Object
change
objects which form an
edit script. The objects compared are traditionally lines
of text from two files. Comparison options such as "ignore
whitespace" are implemented by modifying the equals
and hashcode
methods for the objects compared.
The basic algorithm is described in: "An O(ND) Difference Algorithm and its Variations", Eugene Myers, Algorithmica Vol. 1 No. 2, 1986, p 251.
This class outputs different results from GNU diff 1.15 on some inputs. Our results are actually better (smaller change list, smaller total size of changes), but it would be nice to know why. Perhaps there is a memory overwrite bug in GNU diff 1.15.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 1, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Modifier and Type | Class and Description |
---|---|
static class |
Diff.change
The result of comparison is an "edit script": a chain of change objects.
|
(package private) class |
Diff.file_data
Data on one input file being compared.
|
(package private) static class |
Diff.ForwardScript |
(package private) static class |
Diff.ReverseScript
Scan the tables of which lines are inserted and deleted,
producing an edit script in reverse order.
|
static interface |
Diff.ScriptBuilder |
Modifier and Type | Field and Description |
---|---|
private int[] |
bdiag |
private int |
bdiagoff |
private int |
cost |
private int |
equiv_max
1 more than the maximum equivalence value used for this or its
sibling file.
|
private int[] |
fdiag |
private int |
fdiagoff |
private Diff.file_data[] |
filevec |
static Diff.ScriptBuilder |
forwardScript
Standard ScriptBuilders.
|
boolean |
heuristic
When set to true, the comparison uses a heuristic to speed it up.
|
private boolean |
inhibit |
boolean |
no_discards
When set to true, the algorithm returns a guarranteed minimal
set of changes.
|
static Diff.ScriptBuilder |
reverseScript
Standard ScriptBuilders.
|
private static int |
SNAKE_LIMIT
Snakes bigger than this are considered "big".
|
private int[] |
xvec |
private int[] |
yvec |
Constructor and Description |
---|
Diff(Object[] a,
Object[] b)
Prepare to find differences between two arrays.
|
Modifier and Type | Method and Description |
---|---|
private void |
compareseq(int xoff,
int xlim,
int yoff,
int ylim)
Compare in detail contiguous subsequences of the two files
which are known, as a whole, to match each other.
|
private int |
diag(int xoff,
int xlim,
int yoff,
int ylim)
Find the midpoint of the shortest edit script for a specified
portion of the two files.
|
Diff.change |
diff_2(boolean reverse) |
Diff.change |
diff(Diff.ScriptBuilder bld)
Get the results of comparison as an edit script.
|
private void |
discard_confusing_lines()
Discard lines from one file that have no matches in the other file.
|
private void |
shift_boundaries()
Adjust inserts/deletes of blank lines to join changes
as much as possible.
|
private int equiv_max
public boolean heuristic
public boolean no_discards
private int[] xvec
private int[] yvec
private int[] fdiag
private int[] bdiag
private int fdiagoff
private int bdiagoff
private final Diff.file_data[] filevec
private int cost
private static final int SNAKE_LIMIT
private boolean inhibit
public static final Diff.ScriptBuilder forwardScript
public static final Diff.ScriptBuilder reverseScript
public Diff(Object[] a, Object[] b)
equals
. The original Object arrays
are no longer needed for computing the differences. They will
be needed again later to print the results of the comparison as
an edit script, if desired.private int diag(int xoff, int xlim, int yoff, int ylim)
private void compareseq(int xoff, int xlim, int yoff, int ylim)
private void discard_confusing_lines()
private void shift_boundaries()
public final Diff.change diff_2(boolean reverse)
public Diff.change diff(Diff.ScriptBuilder bld)
bld
- an object to build the script from change flagsWebARTS Library Licensed Under the GNU - General Public License. Other Libraries licensed under their respective Open Source Licenses