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MaltParser is a system for data-driven dependency parsing, which can be used to induce a parsing model from treebank data and to parse new data using an induced model.
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package org.maltparser;

import java.util.Iterator;

import org.maltparser.core.exception.MaltChainedException;
import org.maltparser.core.flow.FlowChartInstance;
import org.maltparser.core.io.dataformat.ColumnDescription;
import org.maltparser.core.io.dataformat.DataFormatInstance;
import org.maltparser.core.io.dataformat.DataFormatSpecification;
import org.maltparser.core.options.OptionManager;
import org.maltparser.core.symbol.SymbolTable;
import org.maltparser.core.symbol.SymbolTableHandler;
import org.maltparser.core.symbol.hash.HashSymbolTableHandler;
import org.maltparser.core.syntaxgraph.DependencyGraph;
import org.maltparser.core.syntaxgraph.DependencyStructure;
import org.maltparser.core.syntaxgraph.edge.Edge;
import org.maltparser.core.syntaxgraph.node.DependencyNode;
import org.maltparser.parser.SingleMalt;

/**
 * The purpose of MaltParserService is to easily write third-party programs that uses MaltParser. 
 * 
 *  There are two ways to call the MaltParserService:
 *  1. By running experiments, which allow other programs to train a parser model or parse with a parser model. IO-handling is done by MaltParser.
 *  2. By first initialize a parser model and then call the method parse() with an array of tokens that MaltParser parses. IO-handling of the sentence is
 *  done by the third-party program.
 *  
 *  How to use MaltParserService, please see the examples provided in the directory 'examples/apiexamples/srcex'
 *  
 *  Note: This class is not thread-safe and it is not possible parser sentences concurrently with this interface. Please use 
 *  the new interface org.maltparser.concurrent.ConcurrentMaltParserService to parse sentences in a multi threaded environment
 *  
 * @author Johan Hall
 */
public class MaltParserService {
	private Engine engine;
	private FlowChartInstance flowChartInstance;
	private DataFormatInstance dataFormatInstance;
	private SingleMalt singleMalt;
	private int optionContainer;
	private boolean initialized = false;
	
	/**
	 * Creates a MaltParserService with the option container 0
	 * 
	 * @throws MaltChainedException
	 */
	public MaltParserService() throws MaltChainedException {
		this(0);
	}
	
	/**
	 * Creates a MaltParserService with the specified option container. To use different option containers allows the calling program 
	 * to load several parser models or several experiments. The option management in MaltParser uses the singleton design pattern, which means that there can only
	 * be one instance of the option manager. To be able to have several parser models or experiments at same time please use different option containers.
	 * 
	 * @param optionContainer an integer from 0 to max value of data type Integer
	 * @throws MaltChainedException
	 */
	public MaltParserService(int optionContainer) throws MaltChainedException {
		this.optionContainer = optionContainer;
		initialize();
	}
	
	/**
	 * Use this constructor only when you want a MaltParserService without an option manager. Without the option manager MaltParser cannot
	 * load or create a parser model. 
	 * 
	 * @param optionFreeInitialization true, means that MaltParserService is created without an option manager, false will do the same as MaltParserService(). 
	 * @throws MaltChainedException
	 */
	public MaltParserService(boolean optionFreeInitialization) throws MaltChainedException {
		if (optionFreeInitialization == false) {
			this.optionContainer = 0;
			initialize();
		} else {
			this.optionContainer = -1;
		}
	}
	
	/**
	 * Runs a MaltParser experiment. The experiment is controlled by a commandLine string, please see the documentation of MaltParser to see all available options.
	 * 
	 * @param commandLine a commandLine string that controls the MaltParser.
	 * @throws MaltChainedException
	 */
	public void runExperiment(String commandLine) throws MaltChainedException {
		OptionManager.instance().parseCommandLine(commandLine, optionContainer);
		engine = new Engine();
		engine.initialize(optionContainer);
		engine.process(optionContainer);
		engine.terminate(optionContainer);
	}
	
	/**
	 * Initialize a parser model that later can by used to parse sentences. MaltParser is controlled by a commandLine string, please see the documentation of MaltParser to see all available options.
	 * 
	 * @param commandLine a commandLine string that controls the MaltParser
	 * @throws MaltChainedException
	 */
	public void initializeParserModel(String commandLine) throws MaltChainedException {
		if (optionContainer == -1) {
			throw new MaltChainedException("MaltParserService has been initialized as an option free initialization and therefore no parser model can be initialized.");
		}
		OptionManager.instance().parseCommandLine(commandLine, optionContainer);
		// Creates an engine
		engine = new Engine();
		// Initialize the engine with option container and gets a flow chart instance
		flowChartInstance = engine.initialize(optionContainer);
		// Runs the preprocess chart items of the "parse" flow chart
		if (flowChartInstance.hasPreProcessChartItems()) {
			flowChartInstance.preprocess();
		}
		singleMalt = (SingleMalt)flowChartInstance.getFlowChartRegistry(org.maltparser.parser.SingleMalt.class, "singlemalt");
		singleMalt.getConfigurationDir().initDataFormat();
		dataFormatInstance = singleMalt.getConfigurationDir().getDataFormatManager().getInputDataFormatSpec().createDataFormatInstance(
				singleMalt.getSymbolTables(),
				OptionManager.instance().getOptionValueString(optionContainer, "singlemalt", "null_value")); 
		initialized = true;
	}
	

	
	/**
	 * Parses an array of tokens and returns a dependency structure. 
	 * 
	 * Note: To call this method requires that a parser model has been initialized by using the initializeParserModel(). 
	 * 
	 * @param tokens an array of tokens 
	 * @return a dependency structure
	 * @throws MaltChainedException
	 */
	public DependencyStructure parse(String[] tokens) throws MaltChainedException {
		if (!initialized) {
			throw new MaltChainedException("No parser model has been initialized. Please use the method initializeParserModel() before invoking this method.");
		}
		if (tokens == null || tokens.length == 0) {
			throw new MaltChainedException("Nothing to parse. ");
		}

		DependencyStructure outputGraph = new DependencyGraph(singleMalt.getSymbolTables());
		
		for (int i = 0; i < tokens.length; i++) {
			Iterator columns = dataFormatInstance.iterator();
			DependencyNode node = outputGraph.addDependencyNode(i+1);
			String[] items = tokens[i].split("\t");
			for (int j = 0; j < items.length; j++) {
				if (columns.hasNext()) {
					ColumnDescription column = columns.next();
					if (column.getCategory() == ColumnDescription.INPUT && node != null) {
						outputGraph.addLabel(node, column.getName(), items[j]);
					}
				}
			}
		}
		outputGraph.setDefaultRootEdgeLabel(outputGraph.getSymbolTables().getSymbolTable("DEPREL"), "ROOT");
		// Invoke parse with the output graph
		singleMalt.parse(outputGraph);
		return outputGraph;
	}
	
	/**
	 * Converts an array of tokens to a dependency structure. 
	 * 
	 * 
	 * @param tokens an array of tokens
	 * @return a dependency structure
	 * @throws MaltChainedException
	 */
	public DependencyStructure toDependencyStructure(String[] tokens) throws MaltChainedException {
		if (!initialized) {
			throw new MaltChainedException("No parser model has been initialized. Please use the method initializeParserModel() before invoking this method.");
		}
		if (tokens == null || tokens.length == 0) {
			throw new MaltChainedException("Nothing to convert. ");
		}
		DependencyStructure outputGraph = new DependencyGraph(singleMalt.getSymbolTables());
		
		for (int i = 0; i < tokens.length; i++) {
			Iterator columns = dataFormatInstance.iterator();
			DependencyNode node = outputGraph.addDependencyNode(i+1);
			String[] items = tokens[i].split("\t");
			Edge edge = null;
			for (int j = 0; j < items.length; j++) {
				if (columns.hasNext()) {
					ColumnDescription column = columns.next();
					if (column.getCategory() == ColumnDescription.INPUT && node != null) {
						outputGraph.addLabel(node, column.getName(), items[j]);
					} else if (column.getCategory() == ColumnDescription.HEAD) {
						if (column.getCategory() != ColumnDescription.IGNORE && !items[j].equals("_")) {
							edge = ((DependencyStructure)outputGraph).addDependencyEdge(Integer.parseInt(items[j]), i+1);
						}
					} else if (column.getCategory() == ColumnDescription.DEPENDENCY_EDGE_LABEL && edge != null) {
						outputGraph.addLabel(edge, column.getName(), items[j]);
					}
				}
			}
		}
		outputGraph.setDefaultRootEdgeLabel(outputGraph.getSymbolTables().getSymbolTable("DEPREL"), "ROOT");
		return outputGraph;
	}
	
	/**
	 * Reads the data format specification file
	 * 
	 * @param dataFormatFileName the path to the data format specification file
	 * @return a data format specification
	 * @throws MaltChainedException
	 */
	public DataFormatSpecification readDataFormatSpecification(String dataFormatFileName) throws MaltChainedException {
		DataFormatSpecification dataFormat = new DataFormatSpecification();
		dataFormat.parseDataFormatXMLfile(dataFormatFileName);
		return dataFormat;
	}
	
	/**
	 * Converts an array of tokens to a dependency structure
	 * 
	 * @param tokens tokens an array of tokens
	 * @param dataFormatSpecification a data format specification
	 * @return a dependency structure
	 * @throws MaltChainedException
	 */
	public DependencyStructure toDependencyStructure(String[] tokens, DataFormatSpecification dataFormatSpecification) throws MaltChainedException {
		// Creates a symbol table handler
		SymbolTableHandler symbolTables = new HashSymbolTableHandler();
		
		// Initialize data format instance
		DataFormatInstance dataFormatInstance = dataFormatSpecification.createDataFormatInstance(symbolTables, "none");

		// Creates a dependency graph
		if (tokens == null || tokens.length == 0) {
			throw new MaltChainedException("Nothing to convert. ");
		}
		DependencyStructure outputGraph = new DependencyGraph(symbolTables);
		
		for (int i = 0; i < tokens.length; i++) {
			Iterator columns = dataFormatInstance.iterator();
			DependencyNode node = outputGraph.addDependencyNode(i+1);
			String[] items = tokens[i].split("\t");
			Edge edge = null;
			for (int j = 0; j < items.length; j++) {
				if (columns.hasNext()) {
					ColumnDescription column = columns.next();
					if (column.getCategory() == ColumnDescription.INPUT && node != null) {
						outputGraph.addLabel(node, column.getName(), items[j]);
					} else if (column.getCategory() == ColumnDescription.HEAD) {
						if (column.getCategory() != ColumnDescription.IGNORE && !items[j].equals("_")) {
							edge = ((DependencyStructure)outputGraph).addDependencyEdge(Integer.parseInt(items[j]), i+1);
						}
					} else if (column.getCategory() == ColumnDescription.DEPENDENCY_EDGE_LABEL && edge != null) {
						outputGraph.addLabel(edge, column.getName(), items[j]);
					}
				}
			}
		}
		outputGraph.setDefaultRootEdgeLabel(outputGraph.getSymbolTables().getSymbolTable("DEPREL"), "ROOT");
		return outputGraph;
	}
	
	/**
	 * Converts an array of tokens to a dependency structure
	 * 
	 * @param tokens an array of tokens
	 * @param dataFormatFileName the path to the data format file
	 * @return a dependency structure
	 * @throws MaltChainedException
	 */
	public DependencyStructure toDependencyStructure(String[] tokens, String dataFormatFileName) throws MaltChainedException {
		return toDependencyStructure(tokens, readDataFormatSpecification(dataFormatFileName));
	}
	
	/**
	 * Same as parse(String[] tokens), but instead it returns an array of tokens with a head index and a dependency type at the end of string
	 * 
	 * @param tokens an array of tokens to parse
	 * @return an array of tokens with a head index and a dependency type at the end of string
	 * @throws MaltChainedException
	 */
	public String[] parseTokens(String[] tokens) throws MaltChainedException {
		DependencyStructure outputGraph = parse(tokens);
		StringBuilder sb = new StringBuilder();
		String[] outputTokens = new String[tokens.length];
		SymbolTable deprelTable = outputGraph.getSymbolTables().getSymbolTable("DEPREL");
		for (Integer index : outputGraph.getTokenIndices()) {
			sb.setLength(0);
			if (index <= tokens.length) {
				DependencyNode node = outputGraph.getDependencyNode(index);
				sb.append(tokens[index -1]);
				sb.append('\t');
				sb.append(node.getHead().getIndex());
				sb.append('\t');
				if (node.getHeadEdge().hasLabel(deprelTable)) {
					sb.append(node.getHeadEdge().getLabelSymbol(deprelTable));
				} else {
					sb.append(outputGraph.getDefaultRootEdgeLabelSymbol(deprelTable));
				}
				outputTokens[index-1] = sb.toString();
			}
		}
		return outputTokens;
	}
	
	/**
	 * Terminates the parser model.
	 * 
	 * @throws MaltChainedException
	 */
	public void terminateParserModel() throws MaltChainedException {
		if (!initialized) {
			throw new MaltChainedException("No parser model has been initialized. Please use the method initializeParserModel() before invoking this method.");
		}
		// Runs the postprocess chart items of the "parse" flow chart
		if (flowChartInstance.hasPostProcessChartItems()) {
			flowChartInstance.postprocess();
		}
		
		// Terminate the flow chart with an option container
		engine.terminate(optionContainer);
	}
	
	private void initialize() throws MaltChainedException {
		if (OptionManager.instance().getOptionDescriptions().getOptionGroupNameSet().size() > 0) {
			return; // OptionManager is already initialized
		}
		OptionManager.instance().loadOptionDescriptionFile();
		OptionManager.instance().generateMaps();
	}
	
	
	/**
	 * Returns the option container index
	 * 
	 * @return the option container index
	 */
	public int getOptionContainer() {
		return optionContainer;
	}
}