The ‘phpcpd’ command is a copy and paste detector for PHP code. It helps to identify duplicated code in PHP files or directories. This tool is useful for maintaining clean and efficient code, as duplicated code can lead to code redundancy and increase the chances of introducing bugs.

Use case 1: Analyze duplicated code for a specific file or directory

Code:

phpcpd path/to/file_or_directory

Motivation: By running ‘phpcpd’ with the path to a file or directory, you can analyze the code and identify any duplicate blocks or lines within that file or directory. This allows you to refactor or eliminate duplicated code, improving code quality.

Explanation: ‘path/to/file_or_directory’ should be replaced with the actual file or directory you want to analyze for duplicated code.

Example output:

Found 2 clones with 10 duplicated lines in 1 files:

 - path/to/file.php:5-14, 20-29

This output indicates that 2 clone sets (block of duplicated code) were found, consisting of a total of 10 duplicated lines. The clone sets were found in the file ‘path/to/file.php’ at lines 5-14 and 20-29.

Use case 2: Analyze using fuzzy matching for variable names

Code:

phpcpd --fuzzy path/to/file_or_directory

Motivation: Sometimes, code blocks may contain almost identical code but have differences in variable names. By using fuzzy matching with the “–fuzzy” flag, ‘phpcpd’ will consider code blocks with similar variable names as potential duplicates, providing a more comprehensive analysis.

Explanation: ‘–fuzzy’ is a flag used to enable fuzzy matching for variable names when analyzing for duplicated code.

Example output:

Found 2 clones with 8 duplicated lines in 1 files:

 - path/to/file.php:5-12

In this example, ‘phpcpd’ detected 2 clone sets with 8 duplicated lines. The duplicated code was found in the file ‘path/to/file.php’ at lines 5-12, considering fuzzy matching for variable names.

Use case 3: Specify a minimum number of identical lines

Code:

phpcpd --min-lines 10 path/to/file_or_directory

Motivation: By setting a minimum threshold for the number of identical lines using the “–min-lines” flag, ‘phpcpd’ will only report clone sets that have at least the specified number of identical lines. This allows you to focus on potential code duplication that is significant enough to warrant attention.

Explanation: ‘–min-lines’ is used to specify the minimum number of identical lines required for a clone set to be reported.

Example output:

Found 1 clone with 10 duplicated lines in 1 files:

 - path/to/file.php:5-14

In this case, ‘phpcpd’ identified 1 clone set with 10 duplicated lines in the file ‘path/to/file.php’ at lines 5-14. Since the minimum threshold is set to 10, it only reported clone sets that meet this requirement.

Use case 4: Specify a minimum number of identical tokens

Code:

phpcpd --min-tokens 80 path/to/file_or_directory

Motivation: Token-based comparison provides a more accurate analysis of code duplication. By using the “–min-tokens” flag to set a minimum number of identical tokens, ‘phpcpd’ will only report clone sets that have at least the specified number of identical tokens. This allows you to focus on potential code duplication that is significant at the token level.

Explanation: ‘–min-tokens’ is used to specify the minimum number of identical tokens required for a clone set to be reported.

Example output:

Found 1 clone with 80 duplicated tokens in 1 files:

 - path/to/file.php:5-25

Here, ‘phpcpd’ found 1 clone set with 80 duplicated tokens in the file ‘path/to/file.php’ at lines 5-25. The minimum threshold of 80 tokens ensured that only clone sets meeting this criteria were reported.

Use case 5: Exclude a directory from analysis

Code:

phpcpd --exclude path/to/excluded_directory path/to/file_or_directory

Motivation: In some cases, you may want to exclude specific directories from the analysis, such as test directories or third-party libraries. By using the “–exclude” flag, ‘phpcpd’ will not analyze any files within the specified excluded directory, allowing you to focus on code duplication within the relevant codebase.

Explanation: ‘–exclude’ is used to specify the path to the directory that should be excluded from the analysis. The path should be relative to the source directory.

Example output:

Found 1 clone with 10 duplicated lines in 1 files:

 - path/to/file.php:10-19

In this example, ‘phpcpd’ identified 1 clone set with 10 duplicated lines in the file ‘path/to/file.php’ at lines 10-19. The analysis excluded any files within the ‘path/to/excluded_directory’, allowing you to focus on code duplication within the other parts of the codebase.

Use case 6: Output the results to a PHP-CPD XML file

Code:

phpcpd --log-pmd path/to/log_file path/to/file_or_directory

Motivation: By outputting the results to a PHP-CPD XML file using the “–log-pmd” flag, you can generate a report that can be used to track code duplication trends over time, integrate with other tools, or share the analysis results with team members.

Explanation: ‘–log-pmd’ is used to specify the path to the PHP-CPD XML file where the analysis results will be logged.

Example output: (XML file - path/to/log_file.xml)

<phpcpd>
    <duplication lines="10" tokens="75">
        <file path="path/to/file.php" />
    </duplication>
</phpcpd>

In this case, ‘phpcpd’ identified 1 clone set with 10 duplicated lines and 75 duplicated tokens in the file ‘path/to/file.php’. The analysis result is logged in the specified PHP-CPD XML file, which can be used for further analysis or reporting purposes.

Conclusion:

Using the ‘phpcpd’ command provides an efficient way to identify duplicated code in PHP files or directories. By using the various options and flags available, you can fine-tune the analysis to meet your specific requirements. This helps in maintaining code quality, reducing code redundancy, and improving overall code maintainability.