Leveraging Static Code Analysis in PHP: Improving Productivity and Reducing Bugs
As a web developer using PHP, writing code can be a complex and time-consuming process. While PHP is a versatile language, it can be riddled with syntax errors, bugs, and overcomplicated expressions that can cause significant delays.
Performing static code analysis is a powerful tool for detecting errors, increasing productivity, and improving the overall quality of the code. In this article, we will explore static code analysis in PHP and how leveraging the PHP type system can help streamline the process.
Methods of Performing Static Code Analysis in PHP
Lint Mode
Lint mode is the most fundamental form of static code analysis in PHP. It is a built-in command-line tool that checks for syntax errors, unused variable assignments, and adherence to coding standards.
In essence, it is a linter that performs small diagnostic tests on the code before execution. While lint mode is a simple form of static code analysis, it can quickly catch syntax errors and improve code quality.
PHPMD or
PHP Depend Project
PHP Mess Detector (
PHPMD) is a detector tool that searches for code smells, potential bugs, and overcomplicated expressions. It is an open-source command-line tool that analyzes PHP code and creates a report of potential issues.
Additionally, PHP Depend is a PHP static analyzer that computes software metrics such as Design Size, Cyclomatic Complexity, and Lack of Cohesion in Methods (LCOM). Unlike lint mode,
PHPMD and PHP Depend provide developers with a more in-depth analysis of the code and can identify potential bugs, performance issues, and adherence to coding standards.
Pfff Tool
Pfff Tool is a collection of tools that analyze PHP code using static code analysis. It is designed to help developers navigate, search, and refactor code.
Using the indexing capabilities of Pfff, developers can easily visualize the structure of a project and refactor it as needed. Unlike
PHPMD and PHP Depend,
Pfff Tool provides built-in visualization and navigation features that allow developers to interactively explore the codebase.
HHVM
HipHop Virtual Machine (
HHVM) is a high-performance virtual machine and a PHP runtime. It is optimized for server side workloads running PHP web applications.
The
HHVM project provides extensive performance statistics and allows developers to profile code execution. Additionally, by utilizing its FastCGI server and proxygen, it provides a high-performance server to minimize system overhead.
Leveraging the PHP Type System for Static Code Analysis
In recent years, there has been a significant push toward utilizing the PHP type system for static code analysis. The PHP type system allows developers to declare function inputs and outputs using PHPDoc comments and function declarations.
This additional information helps static analysis tools detect bugs and improve code quality. Lets explore some examples of leveraging the PHP type system for static code analysis.
Declaring Types in Code
Declaring types in code is a powerful tool for improving code quality. By declaring the type of function inputs and outputs, static analysis tools can detect when the code is misused or whether it violates any constraints.
For example, consider a function that expects a string input parameter:
`function myFunction(string $value) { //… }`
When a static analyzer detects that myFunction is incorrectly called on an integer input value, an error will be flagged.
This ensures that the function is used correctly and that any potential mistakes are caught early.
Benefits of Type Declaration
There are a number of benefits to declaring types in code. Firstly, it enables developers to detect and reduce bugs early in the development lifecycle.
This results in significantly less time spent debugging and frees developers up to work on other areas of the project. Additionally, with enforced types, developers can enjoy improved productivity as code editors and development tools can provide auto-completion and suggestions.
Lastly, enforcing types makes refactoring code much more manageable, as there is less chance of introducing breaking changes.
Examples of Type Declaration in Code
As alluded to above, there are two primary ways of declaring types in PHP code the PHPDoc comment and the function declaration. For example, the following code snippet uses a PHPDoc comment to declare the type of the function input parameter:
`/**`
`* @param string $value`
`* @return integer`
`*/`
`function myFunction($value) { //…
}`
Alternatively, function declaration can be used to declare the types of input and output parameters explicitly. Here’s an example where function declarations are used to enforce typing:
`function add(int $a, int $b) : int`
`{`
` return $a + $b;`
`}`
Conclusion
Static code analysis is a powerful tool for developers using PHP to write web applications. By leveraging the tools and methods highlighted in this article, developers can significantly reduce debugging time and improve the overall quality of the code they write.
Additionally, by utilizing the PHP type system, developers can improve productivity, utilize auto-completion, and refactor code with greater ease.
Using Lint Mode for Static Code Analysis
As a PHP developer, you may encounter situations where the code you’ve written doesn’t work as expected. You may see no output or, worse, error messages.
It can be challenging to diagnose the root cause of the issue. Lint mode is a powerful tool for detecting syntax errors and validating code prior to execution.
In this section, we will explore
PHP Lint,
High-level and Low-level Static Analyzers, and
Runtime Analyzers.
PHP Lint
PHP Lint is a built-in PHP command-line tool that checks for syntax errors in the PHP source code. It validates whether the PHP source code conforms to the PHP syntax.
The errors identified by
PHP Lint are known as syntax errors. This tool only checks the syntax of the code, without executing it.
PHP Lint is utilized in the terminal or shell to scan PHP source code files for syntax errors. It typically takes a file that contains PHP source code as input and produces syntax errors as output, if any.
This output can assist developers in identifying errors in their code. For example, consider the following PHP code:
`
`$x = 3;`
`$y = “Hello`
`?>`
Here, we’ve deliberately included a syntax error – a missing semicolon (;) at the end of line 2.
When we run
PHP Lint on this file using the command:
`php -l myfile.php`
The tool throws a syntax error message:
`Parse error: syntax error, unexpected ‘?>’ in myfile.php, line 3`
High-level and Low-level Static Analyzers
High-level and low-level static analyzers are additional tools available to PHP developers for static code analysis. These tools perform a deep analysis of the code and identify bugs, security vulnerabilities, and performance issues.
Low-level static analyzers, including php-sat, PHPStan, PHP-CS-Fixer, and phan, inspect the source code at the token level (individual words, symbols, and operators). The tools can spot syntax errors, unreachable code or variables, unused code, and potential runtime errors.
php-sat is a static analysis tool that allows developers to identify unreachable code, missing semicolons, and low-quality code. PHPStan is another static analysis tool that checks code compliance with the strict PHP 7 type system.
It can be installed with Composer and is known for its rigor and ease of use. PHP-CS-Fixer performs code quality checks, identifies coding standards violations, and can automatically fix many of these issues.
Finally, phan is a PHP static analyzer built with the Phan language tooling framework that identifies subtle application-level bugs. High-level static analyzers typically aim to identify suboptimal code, security vulnerabilities, code smells, and development anti-patterns.
PHP Parser is one such tool that can be used as a framework for building custom static analyzers. This tool traverses PHP code and builds up a representation of the code’s structures, including class, namespace, function, and method declarations.
Similarly, phantm is a PHP type-checking tool that checks for encoding errors in code.
Runtime Analyzers
Runtime analyzers run PHP code and monitor its performance by profiling the running code. With this information, developers can optimize their code for performance and fix runtime issues.
These analyze running code and focus on identifying performance bottlenecks or flaws which cannot be identified during static analysis. Xdebug is one of the most popular runtime analysis tools available in the PHP community.
It can perform function-level tracing and profiling data collection to help pinpoint performance issues. phpweaver is another PHP concurrency profiler that can help developers find performance issues related to parallel code execution.
Finally, xhprof is a lightweight, low-overhead sampling profile that can be used to collect and analyze code performance. Performing Static Code Analysis with
PHPMD or
PHP Depend Project
In addition to Lint mode,
PHPMD and PHP Depend are a pair of open-source static code analysis tools that can be used for PHP code validation, cleaning, and bug prevention. While
PHPMD detects general quality issues in computer code, PHP Depend performs analyzes on the code structure and dependencies.
PHPMD
PHPMD stands for PHP Mess Detector. It is a user-friendly, easy-to-configure, and open-source static analysis tool that can search for potential bugs, suboptimal code, and general issues in PHP source code.
The tool comes with pre-defined rules that can be applied to the source code to detect issues and provide developers with a comprehensive report.
PHPMD offers developers a range of metrics including lines of code, cyclomatic complexity, number of classes, and lines of comments. This helps developers see how their code performs and identify areas for improvement before their code goes live.
PHP Depend Project
PHP Depend is a spin-off of
PHPMD. It is an equivalent static code analyzer that performs a more sophisticated analysis of code structure than
PHPMD.
PHP Depend scans the code and its dependencies and creates a rich representation of the codebase with dependencies and annotations. This representation is then used to run custom code rules and detect issues with the code.
PHP Depend can identify overcomplicated dependencies, thresholds for coding conventions, and adjust to accommodate specifications for new software features. The tool comes with command-line interfaces for easy and fast integration with continuous integration servers.
Command Line Usage of
PHPMD
PHPMD is typically run via the command line interface (CLI). Simply download and extract the
PHPMD release and install it accordingly.
To scan a single file or an entire directory of files, you call
PHPMD from the command line with the appropriate arguments. Here’s an example:
`$ bin/phpmd /path/to/myfile.php text codesize,unusedcode,naming`
This command analyzes the PHP file named myfile.php, outputting detected code issues to the command line, as specified in the selected rules.
Conclusion
Lint mode, high-level and low-level static analyzers, and runtime analyzers, along with
PHPMD and the PHP Depend project, are powerful tools that PHP developers can use to detect bugs early in the development phase. These tools can help debug code, identify potential performance issues, improve the quality of the code, and ultimately save time and money.
Whether by employing command-line interfaces, APIs, or the PHP type system tools, there is a variety of PHP tools and resources to assist in writing high-quality, efficient PHP code. Utilizing the
Pfff Tool for Static Code Analysis
Static code analysis is an important technique for identifying potential issues and improving the quality of software code.
Pfff is a set of APIs and tools that provide an effective way of indexing, transforming, and analyzing code. In this section, we will explore how to compile and install Pfff and the different commands available, including scheck, stag, sgrep, spatch, codemap, pfff_db, codegraph, and codequery.to Pfff
Pfff is a set of APIs and tools for indexing, transforming, and analyzing source code.
It consists of a collection of more than 20 command-line tools designed to perform various code analysis functions. Pfff also includes a library of code processing APIs that developers can use to build custom tools for their projects.
One of the key features of Pfff is its ability to index codebases quickly. It can index code in a variety of programming languages, including PHP, JavaScript, and C++.
Pfff is not just a toolbox, it is also a high-performance code indexer that enables code queries, providing easy access to certain aspects of the code.
Compiling and Installing Pfff
To install Pfff, first, you need to download and install its dependencies. These include phparser and commons.
After that, download the Pfff source code and unpack it in a top-level directory. The next step is to configure and compile Pfff.
The Makefile builds all the tools and dependencies with recursive make commands. Once you have installed Pfff, you’ll need to index your codebase.
This is accomplished by running the following command from the command line:
`$ pfff -lang php -mindex -space .`
This command instructs Pfff to index all PHP files under the current directory, excluding vendor source files.
Pfff Commands
Pfff provides a wide range of command-line tools for analyzing code. Some of the most useful commands are:
– scheck: scheck is a static checker for PHP code.
It checks for various coding errors and performance issues within the code. – stag: stag is an indexing command that can be used to create a symbol database for large source codebases.
The symbol database is searchable for navigation and other tasks. – sgrep: sgrep is a search and replace tool that is useful for finding code snippets within a source codebase.
– spatch: spatch is a tool for modifying code by applying a predefined set of rules. – codemap: codemap is an interactive tool that creates a map of the codebase.
This map can be used for both software navigation and documentation. – pfff_db: pfff_db is a tool for creating a database from the Pfff indexed files.
The Pfff database is used by other commands to obtain information about the codebase. – codegraph: codegraph generates a code flow graph.
It assists developers in understanding the code’s behavior. – codequery: codequery is a query engine that helps developers search the codebase for specific patterns.
Employing
HHVM for Static Code Analysis
HHVM is an open-source virtual machine designed to execute PHP 7 code. It is known for its excellent performance, thanks to its Just-In-Time compilation.
Additionally, it provides developers with a high degree of development flexibility and improved productivity. In this section, we will take a closer look at
HHVM and explore how to configure, start, and utilize it for static code analysis.
Overview of
HHVM
HHVM is an open-source virtual machine for PHP 7 code execution. It is known for its Just-in-time (JIT) compilation and excellent performance.
Additionally, it is designed to be highly flexible, providing developers with a range of features for building and optimizing web applications.
HHVM can be used for a wide range of purposes, including static code analysis. Its compatibility with most PHP extensions and projects makes
HHVM a powerful tool for PHP developers.
Configuring
HHVM
To use
HHVM for static code analysis, you must first install and configure it to run in server mode. Proxygen and FastCGI are two of the server modes used to run
HHVM.
Proxygen is a lightweight and fast HTTP server that works well with
HHVM. It is widely used by Facebook, which developed
HHVM, and can perform well on high-traffic web applications.
The FastCGI server mode is another option of the
HHVM PHP runtime. It is robust, maintains transport control, performs better than Apache, and is commonly used for web applications serving static content.
Once installed,
HHVM can be configured by changing the relevant settings in its .ini file. You can set up the document root by uncommenting and customizing the `hhvm.server.document_root` line in the configuration file.
Starting
HHVM at Boot
When using
HHVM for a web application, it is recommended to run it as