Mainly a syntax-aware diff that also provides a number of additional tools.
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README.md

zograscope, 2017 - 2018

Screenshot

  1. Description
  2. Tools
  3. Building and Installing
  4. Documentation
  5. License
  6. Credits

Name

"A zograscope is an optical device for enhancing the sense of depth perception from a flat picture." (wiki)

Description

zograscope is built around syntax-aware diff and includes a number of additional tools.

The nature of syntax-aware diff requires knowledge of structure of the code, which can be used to build other simple tools that can benefit from this information. Competing with real language front-ends in the level of accuracy is not possible, but making some things that are one step further than regular text-processing utilities seems feasible and the result might be even more practical than some of the more elaborate tools which end up requiring complicated setup process.

Status

The project is work in progress, but is useful in its current state.

Code isn't perfect and isn't extensively documented as initial version was more of an experiment, but this situation gets better.

Supported languages

Language Status
C C11 and earlier with common extensions, but without K&R syntax
C++ C++14 and earlier with common extensions
GNU Make Most of the syntax

C

The exact grammar is that of C11 with extensions implemented in popular compilers and additional extensions needed to allow processing of code with macros.

Note the following:

  • old K&R style of function declarations isn't parsed (there might be a workaround for it, but this syntax is deprecated either way)
  • preprocessor directives aren't tokenized according to language rules yet, but their contents is diffed
  • extensive use of macros in unusual places might not be parsed (this probably won't change)

Other than that code in C89, C99, C11 and GNU-versions of C language should be recognized.

C++

C++ support relies on external application called srcml and requires it to be installed in binary form (not necessary during build).

Reported standard version supported by srcml is C++14, so all previous ones should work too. Although their parser doesn't handle all language constructs equally well, it's seems to be good enough, especially for a ready to use parser that wasn't that hard to integrate.

Note the following:

  • the tuning of comparison is in progress and will be refined over time

GNU Make

It's hard to measure level of support in case of GNU Make, because there seem to be no reference for the syntax itself apart from documentation, which is not concise.

Yet parser is capable of processing quite complicated examples of Makefiles (like the one used in this project or generated by automake) which contain many features most people don't know exist. It's definitely not 100%, but 90% or even more of all existing Makefiles out there should be parsed.

Note the following:

  • the comparison might not produce best results on Makefiles as it needs some tuning, this should happen over time (Makefiles aren't changed that often)

Other

More languages should be added in the future, maybe with external parsers that are capable of preserving all information about the source code.

Tools

zs-diff

A terminal-based syntax-aware diff.

zs-find

Grep-like tool that finds elements of source code structure.

zs-gdiff

A Qt5 GUI version of syntax-aware diff.

zs-hi

Simple syntax highlighter for xterm-256color palette.

zs-stats

Counter of lines of code.

Building and Installing

# if Qt5 is available (use `qmake` if it corresponds to Qt5 on your machine)
echo 'QT5_PROG := qmake-qt5' >> config.mk
# if libgit2 is present
echo 'HAVE_LIBGIT2 := yes'   >> config.mk

make release check

This will build release version and run tests. The executables will be named release/zs-*.

There is no data, so just making them available in the $PATH will work. However, it's possible to install conventionally (/usr prefix by default):

make install

DESTDIR and PREFIX can be set to modify destination location. On invoking make uninstall same values of these values should be specified.

Dependencies

  • GNU Make
  • C++11-capable compiler (GCC 4.9 has some issues, GCC 5.3 works fine)
  • flex
  • GNU Bison
  • Boost, tested with 1.59, but older versions might work too
  • (optional, run-time, for C++) srcml
  • (optional, for gdiff tool) qt5
  • (optional, for gdiff tool) libgit2

Documentation

At the moment there is only --help option.

License

AGPLv3+

GNU Affero General Public License, version 3 or later.

Credits

dtl library is used for finding edit distance.

pmr implementation from C++17 with a small addition is employed for custom allocators.

TinyXML2 is used for parsing XML.

Catch2 is used for tests.

References

Change Distilling: Tree Differencing for Fine-Grained Source Code Change Extraction. Beat Fluri, Michael Würsch, Martin Pinzger, and Harald C. Gall. 2007.

Change Detection in Hierarchically Structured Information. Sudarshan Chawathe, Hector Garcia-molina and Jennifer Widom. 1996.

Simple fast algorithms for the editing distance between trees and related problems. Kaizhong Zhang and Dennis Shasha. 1989.