javatokenizerfile.java

Grammatica是一个C#和Java的语法分析程序生成器(编译器的编译器)。它可以用LL(k)语法创建可读的和带有注释的源代码。它也支持创建一个运行时语法分析器

/*
 * JavaTokenizerFile.java
 *
 * This work is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * This work is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 * As a special exception, the copyright holders of this library give
 * you permission to link this library with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also meet,
 * for each linked independent module, the terms and conditions of the
 * license of that module. An independent module is a module which is
 * not derived from or based on this library. If you modify this
 * library, you may extend this exception to your version of the
 * library, but you are not obligated to do so. If you do not wish to
 * do so, delete this exception statement from your version.
 *
 * Copyright (c) 2003 Per Cederberg. All rights reserved.
 */

package net.percederberg.grammatica.output;

import java.io.IOException;

import net.percederberg.grammatica.code.java.JavaClass;
import net.percederberg.grammatica.code.java.JavaComment;
import net.percederberg.grammatica.code.java.JavaConstructor;
import net.percederberg.grammatica.code.java.JavaFile;
import net.percederberg.grammatica.code.java.JavaImport;
import net.percederberg.grammatica.code.java.JavaMethod;
import net.percederberg.grammatica.parser.TokenPattern;

/**
 * The Java tokenizer file generator. This class encapsulates all the
 * Java code necessary for creating a tokenizer.
 *
 * @author   Per Cederberg, <per at percederberg dot net>
 * @version  1.0
 */
class JavaTokenizerFile {

    /**
     * The tokenizer class comment.
     */
    private static final String CLASS_COMMENT =
        "A character stream tokenizer.";

    /**
     * The tokenizer constructor comment.
     */
    private static final String CONSTRUCTOR_COMMENT =
        "Creates a new tokenizer for the specified input stream.\n\n" +
        "@param input          the input stream to read\n\n" +
        "@throws ParserCreationException if the tokenizer couldn't be\n" + 
        "            initialized correctly";

    /**
     * The init method comment.
     */
    private static final String INIT_METHOD_COMMENT =
        "Initializes the tokenizer by creating all the token patterns.\n\n" +
        "@throws ParserCreationException if the tokenizer couldn't be\n" + 
        "            initialized correctly";

    /**
     * The Java parser generator.
     */
    private JavaParserGenerator gen;

    /**
     * The Java file to write.
     */
    private JavaFile file;
    
    /**
     * The Java class to write.
     */
    private JavaClass cls;
    
    /**
     * The Java class initializer method.
     */
    private JavaMethod initMethod;
    
    /**
     * Creates a new tokenizer file.
     * 
     * @param gen            the parser generator to use
     */
    public JavaTokenizerFile(JavaParserGenerator gen) {
        int  modifiers;

        this.gen = gen;
        this.file = gen.createJavaFile();
        if (gen.getPublicAccess()) {
            modifiers = JavaClass.PUBLIC;
        } else {
            modifiers = JavaClass.PACKAGE_LOCAL;
        }
        this.cls = new JavaClass(modifiers, 
                                 gen.getBaseName() + "Tokenizer", 
                                 "Tokenizer");
        this.initMethod = new JavaMethod(JavaMethod.PRIVATE,
                                         "createPatterns",
                                         "",
                                         "void");
        initializeCode();
    }

    /**
     * Initializes the source code objects.
     */    
    private void initializeCode() {
        JavaConstructor  constr;
        String           str;

        // Add imports
        file.addImport(new JavaImport("java.io", "Reader"));
        file.addImport(new JavaImport("net.percederberg.grammatica.parser", 
                                      "ParserCreationException"));
        file.addImport(new JavaImport("net.percederberg.grammatica.parser", 
                                      "TokenPattern"));
        file.addImport(new JavaImport("net.percederberg.grammatica.parser", 
                                      "Tokenizer"));

        // Add class
        file.addClass(cls);
        str = CLASS_COMMENT;
        if (gen.getClassComment() != null) {
            str += "\n\n" + gen.getClassComment();
        }
        cls.addComment(new JavaComment(str));
        
        // Add file comment
        str = file.toString() + "\n\n" + gen.getFileComment();
        file.addComment(new JavaComment(JavaComment.BLOCK, str));

        // Add constructor
        constr = new JavaConstructor("Reader input");
        cls.addConstructor(constr);
        constr.addComment(new JavaComment(CONSTRUCTOR_COMMENT));
        constr.addThrows("ParserCreationException");
        constr.addCode("super(input);");
        constr.addCode("createPatterns();");
        
        // Add init method
        cls.addMethod(initMethod);
        initMethod.addComment(new JavaComment(INIT_METHOD_COMMENT));
        initMethod.addThrows("ParserCreationException");
        initMethod.addCode("TokenPattern  pattern;");
    }
    
    /**
     * Adds a token pattern definition to this file.
     * 
     * @param pattern        the token pattern
     * @param constants      the constants file generator
     */
    public void addToken(TokenPattern pattern, JavaConstantsFile constants) {
        StringBuffer  code = new StringBuffer();
        String        str;
        
        // Create new pattern
        code.append("pattern = new TokenPattern(");
        code.append(constants.getConstant(pattern.getId()));
        code.append(",\n");
        code.append("                           \"");
        code.append(pattern.getName());
        code.append("\",\n"); 
        code.append("                           TokenPattern.");
        switch (pattern.getType()) {
        case TokenPattern.STRING_TYPE:
            code.append("STRING_TYPE");
            break;
        case TokenPattern.REGEXP_TYPE:
            code.append("REGEXP_TYPE");
            break;
        }
        code.append(",\n"); 
        code.append("                           ");
        str = pattern.getPattern();
        code.append(gen.getCodeStyle().getStringConstant(str));
        code.append(");\n");

        // Add error and ignore messages
        if (pattern.isError()) {
            code.append("pattern.setError(");
            if (pattern.getErrorMessage() != null) {
                str = pattern.getErrorMessage();
                code.append(gen.getCodeStyle().getStringConstant(str));
            }
            code.append(");\n");            
        }
        if (pattern.isIgnore()) {
            code.append("pattern.setIgnore(");
            if (pattern.getIgnoreMessage() != null) {
                str = pattern.getIgnoreMessage();
                code.append(gen.getCodeStyle().getStringConstant(str));
            }
            code.append(");\n");            
        }

        // Add pattern to tokenizer
        code.append("addPattern(pattern);");
        initMethod.addCode("");
        initMethod.addCode(code.toString());
    }

    /**
     * Creates source code performing a call to the constructor for
     * the tokenizer.
     * 
     * @param param          the input parameters
     * 
     * @return the source code for the call
     */
    protected String getConstructorCall(String param) {
        return "new " + gen.getBaseName() + "Tokenizer(" + param + ")";
    }

    /**
     * Writes the file source code.
     * 
     * @throws IOException if the output file couldn't be created 
     *             correctly 
     */
    public void writeCode() throws IOException {
        file.writeCode(gen.getCodeStyle());
    }
}