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# PMD Swift
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PMD Swift is a deprecated Java language module that provides basic Swift language support for PMD's Copy-Paste Detector (CPD). It enables duplicate code detection in Swift source files through tokenization and language registration within the PMD static analysis toolkit.
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## Package Information
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- **Package Name**: pmd-swift
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- **Package Type**: Maven
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- **Language**: Java
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- **Group ID**: net.sourceforge.pmd
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- **Artifact ID**: pmd-swift
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- **Version**: 6.55.0
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- **Installation**: Add Maven dependency in `pom.xml`
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```xml
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<dependency>
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    <groupId>net.sourceforge.pmd</groupId>
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    <artifactId>pmd-swift</artifactId>
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    <version>6.55.0</version>
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</dependency>
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```
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## Core Imports
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```java
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import net.sourceforge.pmd.lang.swift.SwiftLanguageModule;
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import net.sourceforge.pmd.cpd.SwiftLanguage;
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import net.sourceforge.pmd.cpd.SwiftTokenizer;
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```
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## Basic Usage
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PMD Swift integrates automatically with PMD through the Java Service Provider Interface (SPI). The module registers Swift as a supported language for copy-paste detection:
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```java
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// PMD automatically discovers Swift language support via SPI
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// No manual registration required
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// Direct usage for custom implementations
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SwiftLanguage swiftLanguage = new SwiftLanguage();
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SwiftTokenizer tokenizer = new SwiftTokenizer();
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// Language module for PMD integration
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SwiftLanguageModule languageModule = new SwiftLanguageModule();
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```
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## Architecture
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PMD Swift follows PMD's plugin architecture pattern:
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- **Language Module**: `SwiftLanguageModule` registers Swift as a supported language in PMD
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- **CPD Language**: `SwiftLanguage` provides copy-paste detection capabilities 
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- **Tokenizer**: `SwiftTokenizer` handles Swift source code parsing using ANTLR
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- **ANTLR Grammar**: `Swift.g4` defines Swift language syntax for lexical analysis
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- **Service Registration**: META-INF services enable automatic discovery by PMD
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## Capabilities
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### Swift Language Module
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Core language registration for PMD framework integration.
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```java { .api }
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/**
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 * Language Module for Swift - registers Swift language support in PMD
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 * @deprecated There is no full PMD support for Swift
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 */
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@Deprecated
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public class SwiftLanguageModule extends BaseLanguageModule {
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    /** The language name constant */
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    public static final String NAME = "Swift";
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    /** The terse name constant */
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    public static final String TERSE_NAME = "swift";
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    /**
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     * Create a new instance of Swift Language Module
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     */
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    public SwiftLanguageModule();
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}
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```
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### CPD Swift Language
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Language implementation for copy-paste detection functionality.
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```java { .api }
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/**
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 * Language implementation for Swift in CPD system
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 */
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public class SwiftLanguage extends AbstractLanguage {
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    /**
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     * Creates a new Swift Language instance with tokenizer and file extension
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     */
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    public SwiftLanguage();
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}
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```
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### Swift Tokenizer
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ANTLR-based tokenizer for Swift source code analysis.
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```java { .api }
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/**
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 * SwiftTokenizer for parsing Swift source code using ANTLR
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 */
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public class SwiftTokenizer extends AntlrTokenizer {
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    /**
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     * Get lexer for given source code
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     * @param sourceCode The source code to tokenize
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     * @return AntlrTokenManager for token processing
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     */
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    @Override
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    protected AntlrTokenManager getLexerForSource(final SourceCode sourceCode);
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}
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```
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### ANTLR Generated Components
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Generated lexer from Swift grammar definition.
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```java { .api }
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/**
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 * ANTLR-generated lexer for Swift language
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 * Generated from Swift.g4 grammar file during Maven compilation
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 * Located at: net.sourceforge.pmd.lang.swift.antlr4.SwiftLexer
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 */
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public class SwiftLexer extends org.antlr.v4.runtime.Lexer {
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    /**
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     * Create lexer with character stream input
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     * @param input Character stream from Swift source code
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     */
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    public SwiftLexer(CharStream input);
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}
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```
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## Types
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```java { .api }
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// Core PMD types used by Swift module
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import net.sourceforge.pmd.lang.BaseLanguageModule;
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import net.sourceforge.pmd.cpd.AbstractLanguage;
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import net.sourceforge.pmd.cpd.AntlrTokenizer;
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import net.sourceforge.pmd.lang.antlr.AntlrTokenManager;
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import net.sourceforge.pmd.cpd.SourceCode;
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import org.antlr.v4.runtime.CharStream;
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import net.sourceforge.pmd.lang.swift.antlr4.SwiftLexer;
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```
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## Service Provider Registration
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PMD Swift uses Java SPI for automatic discovery:
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**Language Module Service** (`META-INF/services/net.sourceforge.pmd.lang.Language`):
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```
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net.sourceforge.pmd.lang.swift.SwiftLanguageModule
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```
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**CPD Language Service** (`META-INF/services/net.sourceforge.pmd.cpd.Language`):
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```
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net.sourceforge.pmd.cpd.SwiftLanguage
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```
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## Limitations and Status
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⚠️ **Important**: This module is **deprecated** and has significant limitations:
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- **No full PMD support**: Only provides CPD (copy-paste detection) functionality
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- **No static analysis rules**: Cannot detect Swift-specific code issues or violations
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- **Limited Swift version support**: Grammar may not support latest Swift language features
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- **Maintenance status**: No active development or updates planned
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- **Functionality scope**: Restricted to duplicate code detection only
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## Dependencies
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- **pmd-core**: Core PMD functionality and base classes
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- **antlr4-runtime**: ANTLR runtime for lexer execution
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- **Swift.g4**: ANTLR grammar definition for Swift language parsing
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## Usage in PMD
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When pmd-swift is on the classpath, PMD automatically:
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1. Discovers Swift language support via SPI
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2. Registers `.swift` file extension for processing
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3. Enables CPD duplicate detection for Swift files
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4. Uses SwiftTokenizer for parsing Swift source code
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Example PMD command line usage:
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```bash
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pmd cpd --minimum-tokens 100 --language swift --files /path/to/swift/files
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```