upidiff.diff
Class Diff.FileData

java.lang.Object
  |
  +--upidiff.diff.Diff.FileData

Enclosing class:

Diff

final class Diff.FileData

extends Object

Data on one input file being compared.

Field Summary

(package private) int	buffered_lines Number of elements (lines) in this file.
(package private) boolean[]	changed_flag Array, indexed by real origin-1 line number, containing true for a line that is an insertion or a deletion.
private int[]	equivs Vector, indexed by line number, containing an equivalence code for each line.
(package private) int	nondiscarded_lines Total number of nondiscarded lines.
(package private) int[]	realindexes Vector mapping virtual line numbers (not counting discarded lines) to real ones (counting those lines).
(package private) int[]	undiscarded Vector, like the previous one except that the elements for discarded lines have been squeezed out.

Constructor Summary

(package private)

Diff.FileData(Object[] data, Hashtable h)

Method Summary

(package private) void	clear() Allocate changed array for the results of comparison.
(package private) void	discard_confusing_lines(Diff.FileData f) Discard lines that have no matches in another file.
private void	discard(byte[] discards) Actually discard the lines.
private byte[]	discardable(int[] counts) Mark to be discarded each line that matches no line of another file.
(package private) int[]	equivCount() Return equiv_count[I] as the number of lines in this file that fall in equivalence class I.
private void	filterDiscards(byte[] discards) Don't really discard the provisional lines except when they occur in a run of discardables, with nonprovisionals at the beginning and end.
(package private) void	shift_boundaries(Diff.FileData f) Adjust inserts/deletes of blank lines to join changes as much as possible.

Methods inherited from class java.lang.Object

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

Field Detail

buffered_lines

final int buffered_lines

Number of elements (lines) in this file.

equivs

private final int[] equivs

Vector, indexed by line number, containing an equivalence code for each line. It is this vector that is actually compared with that of another file to generate differences.

undiscarded

final int[] undiscarded

Vector, like the previous one except that the elements for discarded lines have been squeezed out.

realindexes

final int[] realindexes

Vector mapping virtual line numbers (not counting discarded lines) to real ones (counting those lines). Both are origin-0.

nondiscarded_lines

int nondiscarded_lines

Total number of nondiscarded lines.

changed_flag

boolean[] changed_flag

Array, indexed by real origin-1 line number, containing true for a line that is an insertion or a deletion. The results of comparison are stored here.

Constructor Detail

Diff.FileData

Diff.FileData(Object[] data,
              Hashtable h)

Method Detail

clear

void clear()

Allocate changed array for the results of comparison.

equivCount

int[] equivCount()

Return equiv_count[I] as the number of lines in this file that fall in equivalence class I.

Returns:

the array of equivalence class counts.

discard_confusing_lines

void discard_confusing_lines(Diff.FileData f)

Discard lines that have no matches in another file. A line which is discarded will not be considered by the actual comparison algorithm; it will be as if that line were not in the file. The file's `realindexes' table maps virtual line numbers (which don't count the discarded lines) into real line numbers; this is how the actual comparison algorithm produces results that are comprehensible when the discarded lines are counted.

When we discard a line, we also mark it as a deletion or insertion so that it will be printed in the output.

Parameters:

f - the other file

discardable

private byte[] discardable(int[] counts)

Mark to be discarded each line that matches no line of another file. If a line matches many lines, mark it as provisionally discardable.

Parameters:

counts - The count of each equivalence number for the other file.

Returns:

0=nondiscardable, 1=discardable or 2=provisionally discardable for each line

See Also:

equivCount()

filterDiscards

private void filterDiscards(byte[] discards)

Don't really discard the provisional lines except when they occur in a run of discardables, with nonprovisionals at the beginning and end.

discard

private void discard(byte[] discards)

Actually discard the lines.

Parameters:

discards - flags lines to be discarded

shift_boundaries

void shift_boundaries(Diff.FileData f)

Adjust inserts/deletes of blank lines to join changes as much as possible. We do something when a run of changed lines include a blank line at one end and have an excluded blank line at the other. We are free to choose which blank line is included. `compareseq' always chooses the one at the beginning, but usually it is cleaner to consider the following blank line to be the "change". The only exception is if the preceding blank line would join this change to other changes.

Parameters:

f - the file being compared against