com.github.jknack.handlebars.internal.HbsParserFactory Maven / Gradle / Ivy

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/*
 * Handlebars.java: https://github.com/jknack/handlebars.java
 * Apache License Version 2.0 http://www.apache.org/licenses/LICENSE-2.0
 * Copyright (c) 2012 Edgar Espina
 */
package com.github.jknack.handlebars.internal;

import java.io.IOException;
import java.util.Optional;

import org.antlr.v4.runtime.ANTLRErrorListener;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.CharStreams;
import org.antlr.v4.runtime.CommonToken;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.LexerNoViableAltException;
import org.antlr.v4.runtime.Recognizer;
import org.antlr.v4.runtime.atn.PredictionMode;
import org.antlr.v4.runtime.misc.Interval;
import org.antlr.v4.runtime.tree.ParseTree;
import org.antlr.v4.runtime.tree.ParseTreeWalker;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.github.jknack.handlebars.Handlebars;
import com.github.jknack.handlebars.Parser;
import com.github.jknack.handlebars.ParserFactory;
import com.github.jknack.handlebars.Template;
import com.github.jknack.handlebars.io.TemplateSource;

/**
 * The default {@link ParserFactory}.
 *
 * @author edgar.espina
 * @since 0.10.0
 */
public class HbsParserFactory implements ParserFactory {

  /** The logging system. */
  private final Logger logger = LoggerFactory.getLogger(getClass());

  /**
   * Creates a new {@link Parser}.
   *
   * @param handlebars The parser owner.
   * @param startDelimiter The start delimiter.
   * @param endDelimiter The end delimiter.
   * @return A new {@link Parser}.
   */
  @Override
  public Parser create(
      final Handlebars handlebars, final String startDelimiter, final String endDelimiter) {
    return new Parser() {

      @Override
      public Template parse(final TemplateSource source) throws IOException {
        logger.debug("About to parse: {}", source);
        String sourceName = source.filename();
        final ANTLRErrorListener errorReporter = new HbsErrorReporter(sourceName);

        // 1. Lexer
        String content = Optional.ofNullable(source.content(handlebars.getCharset())).orElse("");
        final HbsLexer lexer =
            newLexer(CharStreams.fromString(content, sourceName), startDelimiter, endDelimiter);
        configure(lexer, errorReporter);

        // 2. Parser
        final HbsParser parser = newParser(lexer);
        configure(parser, errorReporter);

        logger.debug("Building AST");
        // 3. Parse
        ParseTree tree = parser.template();

        // remove unnecessary spaces and new lines?
        if (handlebars.prettyPrint()) {
          logger.debug("Applying Mustache spec");
          new ParseTreeWalker().walk(new MustacheSpec(), tree);
        }

        if (lexer.whiteSpaceControl) {
          logger.debug("Applying white spaces control");
          new ParseTreeWalker()
              .walk(new WhiteSpaceControl((CommonTokenStream) parser.getTokenStream()), tree);
        }

        /** Build the AST. */
        TemplateBuilder builder =
            new TemplateBuilder(handlebars, source) {
              @Override
              protected void reportError(
                  final CommonToken offendingToken,
                  final int line,
                  final int column,
                  final String message) {
                errorReporter.syntaxError(parser, offendingToken, line, column, message, null);
              }
            };
        logger.debug("Creating templates");
        Template template = builder.visit(tree);
        return template;
      }
    };
  }

  /**
   * Creates a new {@link HbsLexer}.
   *
   * @param stream The input stream.
   * @param startDelimiter The start delimiter.
   * @param endDelimiter The end delimiter.
   * @return A new {@link HbsLexer}.
   */
  private HbsLexer newLexer(
      final CharStream stream, final String startDelimiter, final String endDelimiter) {
    return new HbsLexer(stream, startDelimiter, endDelimiter) {

      @Override
      public void notifyListeners(final LexerNoViableAltException e) {
        String text = _input.getText(Interval.of(_tokenStartCharIndex, _input.index()));
        String msg = "found: '" + getErrorDisplay(text) + "'";
        ANTLRErrorListener listener = getErrorListenerDispatch();
        listener.syntaxError(this, null, _tokenStartLine, _tokenStartCharPositionInLine, msg, e);
      }

      @Override
      public void recover(final LexerNoViableAltException e) {
        throw new IllegalArgumentException(e);
      }
    };
  }

  /**
   * Creates a new {@link HbsParser}.
   *
   * @param lexer The {@link HbsLexer}.
   * @return A new {@link HbsParser}.
   */
  private HbsParser newParser(final HbsLexer lexer) {
    return new HbsParser(new CommonTokenStream(lexer)) {
      @Override
      void setStart(final String start) {
        lexer.start = start;
      }

      @Override
      void setEnd(final String end) {
        lexer.end = end;
      }
    };
  }

  /**
   * Configure a {@link HbsParser}.
   *
   * @param parser The {@link HbsParser}.
   * @param errorReporter The error reporter.
   */
  @SuppressWarnings("rawtypes")
  private void configure(final HbsParser parser, final ANTLRErrorListener errorReporter) {
    configure((Recognizer) parser, errorReporter);

    parser.setErrorHandler(new HbsErrorStrategy());
    parser.getInterpreter().setPredictionMode(PredictionMode.SLL);
  }

  /**
   * Configure a recognizer with an error reporter.
   *
   * @param recognizer A recognizer.
   * @param errorReporter The error reporter.
   */
  private void configure(
      final Recognizer recognizer, final ANTLRErrorListener errorReporter) {
    recognizer.removeErrorListeners();
    recognizer.addErrorListener(errorReporter);
  }
}