Lizard
Lizard is an extensible Cyclomatic Complexity Analyzer for many programming languages including C/C++ (doesn’t require all the header files or Java imports). It also does copy-paste detection (code clone detection/code duplicate detection) and many other forms of static code analysis.
A list of supported languages:
C# (C Sharp)
C/C++ (works with C++14)
Erlang
Fortran
GDScript
Golang
Java
JavaScript (With ES6 and JSX)
Kotlin
Lua
Objective-C
Perl
PHP
PL/SQL
Python
R
Ruby
Rust
Scala
Solidity
Structured Text (St)
Swift
TTCN-3
TypeScript (With TSX)
VueJS
Zig
By default lizard will search for any source code that it knows and mix all the results together. This might not be what you want. You can use the “-l” option to select language(s).
It counts
the nloc (lines of code without comments),
CCN (cyclomatic complexity number),
token count of functions.
parameter count of functions.
You can set limits for CCN (-C) and the number of parameters (-a). Functions that exceed these limits will generate warnings. The exit code of lizard will be non-zero if there are warnings.
This tool actually calculates how complex the code ‘looks’ rather than how complex the code really ‘is’. People will need this tool because it’s often very hard to get all the included folders and files right when they are complicated. But we don’t really need that kind of accuracy for cyclomatic complexity.
It requires python3.8 or above (early versions are not verified).
JavaScript and TypeScript defaults
Each default parameter or destructuring initializer adds 1 to CCN, because the initializer runs only when the supplied value is undefined. For example, function f(a = 1, b = a + 1) { return a + b; } has CCN 3: the base complexity of 1 plus two defaults. Defaults in object and array destructuring also count, including nested defaults and destructuring inside a function body. Explicit decisions within an initializer, such as a ternary expression or && / ||, contribute separately.
This also applies to JSX and TSX. Existing CCN scores can increase for functions that use defaults, which may cause them to exceed a configured CCN threshold.
Installation
lizard.py can be used as a standalone Python script, most functionalities are there. You can always use it without any installation. To acquire all the functionalities of lizard, you will need a proper install.
python lizard.py
If you want a proper install:
[sudo] pip install lizard
Or if you’ve got the source:
[sudo] python setup.py install --prefix=/path/to/installation/directory/
Usage
lizard [options] [PATH or FILE] [PATH] ...
Run for the code under current folder (recursively):
lizard
Exclude anything in the tests folder:
lizard mySource/ -x"./tests/*"
Use .gitignore file:
lizard mySource/
If there is a .gitignore file in the given path, lizard will automatically use it as an additional filter to exclude files that match the gitignore patterns. This is useful when you want to analyze only the tracked files in your git repository. To analyze all discovered source files regardless of .gitignore, use –no-gitignore:
lizard --no-gitignore mySource/
Command-line reference
See the command-line reference for all options, sample reports, and threshold examples.
Using lizard as Python module
You can also use lizard as a Python module in your code:
>>> import lizard
>>> i = lizard.analyze_file("../cpputest/tests/AllTests.cpp")
>>> print(i.__dict__)
{'nloc': 9, 'function_list': [<lizard.FunctionInfo object at 0x10bf7af10>], 'filename': '../cpputest/tests/AllTests.cpp'}
>>> print(i.function_list[0].__dict__)
{'cyclomatic_complexity': 1, 'token_count': 22, 'name': 'main', 'parameter_count': 2, 'nloc': 3, 'long_name': 'main( int ac , const char ** av )', 'start_line': 30}You can also use source code string instead of file. But you need to provide a file name (to identify the language).
>>> i = lizard.analyze_file.analyze_source_code("AllTests.cpp", "int foo(){}")Extensions and warning controls
See extensions and warning controls for duplicate detection, word counts, Cognitive Complexity, generated code, whitelists, and forgiveness comments.
Limitations
Lizard requires syntactically correct code. Upon processing input with incorrect or unknown syntax:
Lizard guarantees to terminate eventually (i.e., no forever loops, hangs) without hard failures (e.g., exit, crash, exceptions).
There is a chance of a combination of the following soft failures:
omission
misinterpretation
improper analysis / tally
success (the code under consideration is not relevant, e.g., global macros in C)
This approach makes the Lizard implementation simpler and more focused with partial parsers for various languages. Developers of Lizard attempt to minimize the possibility of soft failures. Hard failures are bugs in Lizard code, while soft failures are trade-offs or potential bugs.
In addition to asserting the correct code, Lizard may choose not to deal with some advanced or complicated language features:
C/C++ digraphs and trigraphs are not recognized.
C/C++ preprocessing or macro expansion is not performed. For example, using macro instead of parentheses (or partial statements in macros) can confuse Lizard’s bracket stacks.
Some C++ complicated templates may cause confusion with matching angle brackets and processing less-than < or more-than > operators inside of template arguments.
Literature Referring to Lizard
Lizard is often used in software-related research. If you used it to support your work, you may contact the lizard author to add your work in the following list.
Software Quality in the ATLAS experiment at CERN, which refers to Lizard as one of the tools, has been published in the Journal of Physics: http://iopscience.iop.org/article/10.1088/1742-6596/898/7/072011
S Martin-Haugh et al 2017 J. Phys.: Conf. Ser. 898 072011
Lizard is also used as a plugin for fastlane to help check code complexity and submit xml report to sonar.
How To Contribute
Contributions are welcome. Project-specific development rules are in AGENTS.md. Adding a language reader uses .agents/skills/lizard-language-support/.
AI lifecycle guidance is installed under .agents/skills/ and .claude/skills/.
1 maintainer
Metadata
1 maintainer
Release files for lizard 1.24.2
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Total release size: 255.6 kB
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