Sedan — Sequential Edit DistANce

Structural diff for Java Maps — compute the minimum add/update/delete/move operations to transform one Map into another.

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What it does

Sedan computes a Levenshtein-like edit distance between two Map<String, Object> instances. It returns a list of typed SedanOperation instances — add, update, delete, or move — representing the minimum changes needed to transform the source map into the target. The result can be applied back to the source map to reproduce the target exactly.

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Requirements

• Java 26+ (for sedan-core; sedan-spring-boot-autoconfigure targets Java 21)
• Maven 3.9+ (for building from source)

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Modules

Module	Artifact	Purpose
sedan-core	sedan-core	Core diff/patch algorithm — no external runtime dependencies
sedan-jackson	sedan-jackson	Jackson serialization for SedanOperation
sedan-spring-boot-autoconfigure	sedan-spring-boot-autoconfigure	Spring Boot auto-configuration
sedan-spring-boot-starter	sedan-spring-boot-starter	Starter POM — include this to pull in core + autoconfigure

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Quick Start

Maven — core only

<dependency>
    <groupId>com.parisesoftware.sedan</groupId>
    <artifactId>sedan-core</artifactId>
    <version>1.0.0-SNAPSHOT</version>
</dependency>

Maven — Spring Boot starter

<dependency>
    <groupId>com.parisesoftware.sedan</groupId>
    <artifactId>sedan-spring-boot-starter</artifactId>
    <version>1.0.0-SNAPSHOT</version>
</dependency>

A SedanDriver bean is automatically registered in your application context. Override it by declaring your own @Bean.

Maven — Jackson serialization

<dependency>
    <groupId>com.parisesoftware.sedan</groupId>
    <artifactId>sedan-jackson</artifactId>
    <version>1.0.0-SNAPSHOT</version>
</dependency>

Register SedanModule with your ObjectMapper:

ObjectMapper mapper = new ObjectMapper().registerModule(new SedanModule());

Building from source

git clone https://github.com/AParise1217/Sedan.git
cd Sedan
mvn package

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Usage Examples

Example 1 — Basic diff

import com.parisesoftware.sedan.SedanDriver;
import com.parisesoftware.sedan.operation.SedanOperation;
import java.util.List;
import java.util.Map;

SedanDriver driver = new SedanDriver();

Map<String, Object> source = Map.of("name", "Alice", "role", "user");
Map<String, Object> target = Map.of("name", "Alice", "role", "admin", "city", "NYC");

List<SedanOperation> ops = driver.difference(source, target);
// ops: [UpdateSedanOperation[name=role, value=admin], AdditionSedanOperation[name=city, value=NYC]]

Example 2 — DiffResult views

import com.parisesoftware.sedan.DiffResult;

DiffResult diff = driver.diff(source, target);

diff.additions();  // [AdditionSedanOperation[name=city, value=NYC]]
diff.updates();    // [UpdateSedanOperation[name=role, value=admin]]
diff.deletions();  // []
diff.moves();      // []
diff.areEqual();   // false
diff.isEmpty();    // false

Example 3 — Apply operations (patch source to target)

Map<String, Object> patched = driver.apply(source, diff.operations());
// patched.equals(target) == true

Example 4 — MOVE detection

When a key is renamed but its value is unchanged, Sedan emits a MoveSedanOperation instead of a delete + add pair:

Map<String, Object> before = Map.of("hero", "Thor");
Map<String, Object> after  = Map.of("champion", "Thor");

List<SedanOperation> ops = driver.difference(before, after);
// ops: [MoveSedanOperation[sourceName=hero, targetName=champion, value=Thor]]

Map<String, Object> patched = driver.apply(before, ops);
// patched: {champion=Thor}

Example 5 — Jackson serialization

ObjectMapper mapper = new ObjectMapper().registerModule(new SedanModule());

String json = mapper.writeValueAsString(new AdditionSedanOperation("city", "NYC"));
// {"type":"ADD","name":"city","value":"NYC"}

SedanOperation op = mapper.readValue(json, SedanOperation.class);
// AdditionSedanOperation[name=city, value=NYC]

Example 6 — Custom data type adapter

import com.parisesoftware.sedan.data.SedanDataAdapter;
import com.parisesoftware.sedan.data.SedanDataFactory;
import com.parisesoftware.sedan.data.SedanDataSource;

SedanDataFactory.getRegistry().registerAdapter(new SedanDataAdapter<MyRecord>() {
    @Override public boolean supports(Class<?> type) { return MyRecord.class.isAssignableFrom(type); }
    @Override public SedanDataSource adapt(MyRecord source) { return new MyRecordDataSource(source); }
});

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API Reference

SedanDriver

Method	Returns	Description
difference(Map source, Map target)	List<SedanOperation>	Compute minimum edit operations
diff(Map source, Map target)	DiffResult	Same as difference but returns a rich result wrapper
apply(Map source, List<SedanOperation> ops)	Map<String, Object>	Apply operations to source, returning a new unmodifiable map

DiffResult

Method	Returns	Description
operations()	List<SedanOperation>	All operations (immutable)
additions()	List<AdditionSedanOperation>	Filter to ADD operations only
updates()	List<UpdateSedanOperation>	Filter to UPDATE operations only
deletions()	List<DeletionSedanOperation>	Filter to DELETE operations only
moves()	List<MoveSedanOperation>	Filter to MOVE operations only
isEmpty()	boolean	True when no operations were produced
areEqual()	boolean	True when source and target are equal

SedanOperation sealed hierarchy

Type	type()	name()	value()
AdditionSedanOperation	ADD	key being added	new value
UpdateSedanOperation	UPDATE	key being changed	new value
DeletionSedanOperation	DELETE	key being removed	always null
MoveSedanOperation	MOVE	source key (sourceName())	value moved; targetName() for destination key

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Extending Sedan

Sedan's data layer is open for extension via the SedanDataAdapter<T> interface. To support a new input type — such as a domain object, a JSON node, or a YAML map — implement the two required methods and register the adapter with the factory.

public class MyRecordAdapter implements SedanDataAdapter<MyRecord> {

    @Override
    public boolean supports(Class<?> type) {
        return MyRecord.class.isAssignableFrom(type);
    }

    @Override
    public SedanDataSource adapt(MyRecord source) {
        return new MyRecordDataSource(source);
    }
}

// Register once at startup
SedanDataFactory.getRegistry().registerAdapter(new MyRecordAdapter());

The registry walks its adapter list in registration order and delegates to the first adapter whose supports() returns true.

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Development

# Compile all modules
mvn compile

# Run all tests
mvn test

# Run a single test class (in sedan-core)
mvn test -pl sedan-core -Dtest=SedanDriverTest

# Full build with coverage report
mvn verify
# Coverage report at: sedan-core/target/site/jacoco/index.html

# Generate Javadoc
mvn javadoc:javadoc
# Javadoc at: sedan-core/target/site/apidocs/index.html

# Build and install all modules to local Maven repo
mvn install

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License

MIT License — see LICENSE for details.