zograscope, 2017 - 2022

Clone recursively, there are submodules:

git clone --recursive https://github.com/xaizek/zograscope.git

1. Description (Status; Supported languages; Configuration)
2. Tools
3. Building and Installing (Dependencies)
4. Documentation
5. License
6. Credits (References)

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

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)

Lua

Newly added (March 2021) with very little testing so far. However, the language is small and simple enough to not pose much difficulties.

Note the following: * non-5.3 versions might still work, albeit can produce worse results

Other

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

Configuration

Configuration is done per directory tree ("root") which is the closes parent (or current directory) that contains .zs/ directory. The .zs/ directory contains files which define how contents of the root is to be processed. Settings from multiple nested roots are not combined.

.zs/exclude file

A .gitignore-like (or .git/info/exclude-like) file that lists paths relative to the root. The purpose is to exclude uninteresting files (automatically generated, third-party or otherwise). .zs/exclude is used by tools that search for files automatically and doesn't prevent the use of the same files when they are specified explicitly.

The following kinds of entries are recognized:

• empty lines, which are ignored
• lines that start with a # (comments), which are ignored
• lines that end with / match only directories, the / is stripped and line processing continues
• lines without / are treated as shell-like globs against filename which apply at any directory level and define paths whose processing should be skipped
• lines that start with ! define exception from rules that precede them, you can't undo exclusion of files in excluded directories, for the purpose of this discussion the ! is stripped and line processing continues
• lines that start with / always match paths instead of filename and provide a way to specify files to be ignored only in the root, otherwise they are processed as specified in the next item
• other lines are treated as shell-like globs against paths relative to the root (leading / is allowed, but has no effect other than changing type of a match) which define paths whose processing should be skipped

No way to escape leading # and ! or a newline at the moment.

Globs support the following: [{char-class}], [!{char-class}], [^{char-class}], ? (doesn't match /), * (matches any (including zero) number of characters except for /) and \{char} (matches literal {char}).

Example:

# .zs/exclude

# automatically generated sources
src/c/c11-lexer.gen.cpp
src/c/c11-parser.gen.cpp
src/make/*.gen.*

# Qt-produced sources
ui_*.h
moc_*.cpp
moc_*.h

# file in root
/config.h

.zs/attributes file

Borrowing from the git project here again. This file consists of lines matching paths to attributes. Lines are trimmed before being processed.

Empty lines and comments work like in .zs/excludes file, all other lines follow this pattern:

exclude-expr [attr1=value1 [attr2=value2 [...]]]

Expressions that define exceptions (start with !) are recognized but ignored to keep syntax consistent between different files, which basically makes them another type of comments.

Each line of the file is visited in top down order and attributes from every matching entry are merged with the current state. Hierarchy of configuration values: 1. Default values (lowest priority) 2. Attributes 3. Command-line parameters (highest priority)

Supported attributes:

• lang\ Default: ""\ Those accepted by --lang command-line option: c, cxx, make, lua
• tab-size\ Default: 4\ Value should be an integer that's greater than zero

Unknown attributes are ignored.

Example:

# .zs/exclude

*.c tab-size=8
*.h tab-size=8 lang=c
tab-2.[ch] tab-size=2

# any.c has tab-size=8
# tab-2.c has tab-size=2
# tab-2.h has tab-size=2 lang=c
# any.h has tab-size=8 lang=c
# any.cpp has tab-size=4

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.

zs-tui

TUI interface with underdefined scope of functionality.

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
# if cursesw is present
echo 'HAVE_CURSESW := 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 v3+
• Boost, tested with 1.59, but older versions might work too
• (optional, run-time, for C++) srcml (v0.9.5 and v1.0.0 were tested)
• (optional, for gdiff tool) qt5
• (optional, for gdiff tool) libgit2
• (optional, for tui tool) curses with support of wide characters

For Debian-based distributions

If you are using Debian or one of its derivatives, you can install the dependencies as follows:

# install make and build tools
sudo apt install -y build-essential
# installing dependencies
sudo apt install -y libboost-filesystem-dev libboost-iostreams-dev
sudo apt install -y libboost-program-options-dev libboost-system-dev
sudo apt install -y libarchive13
sudo apt install -y bison flex
# installing srcml
wget http://131.123.42.38/lmcrs/beta/srcML-Ubuntu18.04.deb
sudo apt install ./srcML-Ubuntu18.04.deb

You can also check out the CI build script in case dependencies change in the future.

Documentation

At the moment there is only --help option.

License

Version 3 of the GNU Affero General Public License.

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.

tree-sitter is used for parsing of some languages.

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.