Editing Diff (section)

=== Algorithmic derivatives ===
Utilities that compare source files by their syntactic structure have been built mostly as research tools for some programming languages;<ref>{{cite journal|last1=Horwitz|first1=Susan|title=Identifying the semantic and textual differences between two versions of a program|journal=ACM SIGPLAN Notices|date=June 1990|volume=25|issue=6|pages=234–245|doi=10.1145/93548.93574|url=http://www.cs.wisc.edu/wpis/papers/sigplan90.ps|citeseerx=10.1.1.49.3377|access-date=2017-11-01|archive-date=2010-06-12|archive-url=https://web.archive.org/web/20100612103752/http://www.cs.wisc.edu/wpis/papers/sigplan90.ps|url-status=live}}</ref><ref>{{cite journal|last1=Yang|first1=Wuu|title=Identifying syntactic differences between two programs|journal=Software: Practice and Experience|date=July 1991|volume=21|issue=7|pages=739–755|doi=10.1002/spe.4380210706|citeseerx=10.1.1.13.9377|s2cid=10853673}}</ref><ref>Grass. Cdiff: A syntax directed Diff for C++ programs. Proceedings USENIX C++ Conf., pp. 181-193, 1992</ref> some are available as commercial tools.<ref>Compare++, http://www.coodesoft.com/ {{Webarchive|url=https://web.archive.org/web/20111129033738/http://www.coodesoft.com/ |date=2011-11-29 }}</ref><ref>SmartDifferencer, http://www.semanticdesigns.com/Products/SmartDifferencer {{Webarchive|url=https://web.archive.org/web/20091014160445/http://www.semanticdesigns.com/Products/SmartDifferencer/ |date=2009-10-14 }}</ref> In addition, free tools that perform syntax-aware diff include:
* C++: zograscope, AST-based.<ref>{{cite web |title=xaizek/zograscope |url=https://github.com/xaizek/zograscope |website=GitHub |date=26 May 2020 |access-date=27 June 2020 |archive-date=21 December 2020 |archive-url=https://web.archive.org/web/20201221105419/https://github.com/xaizek/zograscope |url-status=live }}</ref>
* HTML: Daisydiff,<ref>''DaisyDiff'', https://code.google.com/p/daisydiff/ {{Webarchive|url=https://web.archive.org/web/20150319014218/http://code.google.com/p/daisydiff/ |date=2015-03-19 }}</ref> html-differ.
* XML: ''xmldiffpatch'' by Microsoft and ''xmldiffmerge'' for IBM.<ref>''xmldiffpatch'', http://msdn.microsoft.com/en-us/library/aa302294.aspx {{Webarchive|url=https://web.archive.org/web/20091027123710/http://msdn.microsoft.com/en-us/library/aa302294.aspx |date=2009-10-27 }}</ref><ref>''xmldiffmerge'', http://www.alphaworks.ibm.com/tech/xmldiffmerge {{Webarchive|url=https://web.archive.org/web/20090924034538/http://www.alphaworks.ibm.com/tech/xmldiffmerge |date=2009-09-24 }}</ref>
* [[JavaScript]]: astii (AST-based).
* Multi-language: [[Pretty Diff]] (format code and then diff)<ref>Cheney, Austin. ''Pretty Diff - Documentation''. http://prettydiff.com/documentation.php {{Webarchive|url=https://web.archive.org/web/20120731233435/http://prettydiff.com/documentation.php |date=2012-07-31 }}</ref>

'''spiff''' is a variant of ''diff'' that ignores differences in floating point calculations with roundoff errors and [[Space (punctuation)|whitespace]], both of which are generally irrelevant to source code comparison. [[Telcordia Technologies|Bellcore]] wrote the original version.<ref name="dontcallme"/><ref name="hpux"/> An [[HPUX]] port is the most current public release. spiff does not support binary files. spiff outputs to the [[standard output]] in standard diff format and accepts inputs in the [[C (programming language)|C]], [[Bourne shell]], [[Fortran]], [[Modula-2]] and [[Lisp (programming language)|Lisp]] [[programming language]]s.<ref>{{cite web|url=http://www.math.utah.edu/cgi-bin/man2html.cgi?/usr/local/man/man1/spiff.1|title=SPIFF 1|date=1988-02-02|access-date=2013-06-16|archive-date=2016-10-02|archive-url=https://web.archive.org/web/20161002135508/http://www.math.utah.edu/cgi-bin/man2html.cgi?%2Fusr%2Flocal%2Fman%2Fman1%2Fspiff.1|url-status=live}}</ref><ref>{{cite web|url=http://hpux.connect.org.uk/hppd/hpux/Text/spiff-1.0/man.html|title=Man page|location=UK|first=Daniel W|last=Nachbar|date=1988-02-02|access-date=2013-06-16|archive-date=2012-09-10|archive-url=https://web.archive.org/web/20120910004102/http://hpux.connect.org.uk/hppd/hpux/Text/spiff-1.0/man.html|url-status=live}}</ref><ref name="dontcallme">{{cite web|url=https://github.com/dontcallmedom/spiff|title=spiff|author=dontcallmedotcom|website=[[GitHub]]|access-date=2013-06-16|archive-date=2015-03-26|archive-url=https://web.archive.org/web/20150326181245/https://github.com/dontcallmedom/spiff|url-status=live}}</ref><ref>{{cite web|url=https://stackoverflow.com/a/1489107/2291035|date=2009-09-28|author=Davide|title=stackoverflow|access-date=2013-06-16|archive-date=2022-02-19|archive-url=https://web.archive.org/web/20220219233604/https://stackoverflow.com/questions/1428177/diff-tool-that-ignores-floating-point-formats-but-not-values-in-text/1489107|url-status=live}}</ref><ref name="hpux">{{cite web|url=http://hpux.connect.org.uk/hppd/hpux/Text/spiff-1.0/|title=HP-UX Porting and Archiving|location=UK|first=Daniel W|last=Nachbar|date=1999-12-01|access-date=2013-06-13|archive-date=2012-09-05|archive-url=https://web.archive.org/web/20120905154135/http://hpux.connect.org.uk/hppd/hpux/Text/spiff-1.0/|url-status=live}}</ref>

LibXDiff is an LGPL [[Library (computing)|library]] that provides an interface to many algorithms from 1998. An improved Myers algorithm with [[Rabin fingerprint]] was originally implemented (as of the final release of 2008),<ref>{{cite web |last1=Libenzi |first1=Davide |title=LibXDiff |url=http://freshmeat.sourceforge.net/projects/xdiff-lib |website=SourceForge FreshMeat |language=en |access-date=2020-06-28 |archive-date=2020-07-01 |archive-url=https://web.archive.org/web/20200701070301/http://freshmeat.sourceforge.net/projects/xdiff-lib |url-status=live }}</ref> but [[git]] and [[libgit2]]'s fork has since expanded the repository with many of its own. One algorithm called "histogram" is generally regarded as much better than the original Myers algorithm, both in speed and quality.<ref>{{cite journal |last1=Nugroho |first1=Yusuf Sulistyo |last2=Hata |first2=Hideaki |last3=Matsumoto |first3=Kenichi |title=How different are different diff algorithms in Git?: Use --histogram for code changes |website=Empirical Software Engineering |pages=790–823 |language=en |doi=10.1007/s10664-019-09772-z |date=January 2020|s2cid=59608676 |doi-access=free |arxiv=1902.02467 }}</ref><ref>{{cite web |title=algorithm - What's the difference between 'git diff --patience' and 'git diff --histogram'? |url=https://stackoverflow.com/a/32367597/ |website=Stack Overflow |quote=This does indeed show that histogram diff slightly beats Myers, while patience is much slower than the others. |access-date=2020-06-28 |archive-date=2022-02-19 |archive-url=https://web.archive.org/web/20220219233605/https://stackoverflow.com/questions/32365271/whats-the-difference-between-git-diff-patience-and-git-diff-histogram/32367597 |url-status=live }}</ref> This is the modern version of ''LibXDiff'' used by Vim.<ref name="brabandt2018"/>