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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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/*

 * Copyright (C) 2004-2011

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

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 * THE SOFTWARE.

 */

package com.sun.xml.internal.rngom.parse.compact;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.PushbackInputStream;

import java.io.Reader;

import java.net.URL;

import com.sun.xml.internal.rngom.ast.builder.BuildException;

import com.sun.xml.internal.rngom.ast.builder.IncludedGrammar;

import com.sun.xml.internal.rngom.ast.builder.SchemaBuilder;

import com.sun.xml.internal.rngom.ast.builder.Scope;

import com.sun.xml.internal.rngom.ast.om.ParsedPattern;

import com.sun.xml.internal.rngom.parse.IllegalSchemaException;

import com.sun.xml.internal.rngom.parse.Parseable;

import com.sun.xml.internal.rngom.xml.util.EncodingMap;

import org.xml.sax.ErrorHandler;

import org.xml.sax.InputSource;

/**

 * RELAX NG schema in the compact syntax.

 */

public class CompactParseable implements Parseable {

  private final InputSource in;

  private final ErrorHandler eh;

  public CompactParseable(InputSource in, ErrorHandler eh) {

    this.in = in;

    this.eh = eh;

  }

  public ParsedPattern parse(SchemaBuilder sb) throws BuildException, IllegalSchemaException {

      ParsedPattern p = new CompactSyntax(this, makeReader(in), in.getSystemId(), sb, eh, "").parse(null);

      return sb.expandPattern(p);

  }

  public ParsedPattern parseInclude(String uri, SchemaBuilder sb, IncludedGrammar g, String inheritedNs)

          throws BuildException, IllegalSchemaException {

    InputSource tem = new InputSource(uri);

    tem.setEncoding(in.getEncoding());

    return new CompactSyntax(this, makeReader(tem), uri, sb, eh, inheritedNs).parseInclude(g);

  }

  public ParsedPattern parseExternal(String uri, SchemaBuilder sb, Scope scope, String inheritedNs)

          throws BuildException, IllegalSchemaException {

    InputSource tem = new InputSource(uri);

    tem.setEncoding(in.getEncoding());

    return new CompactSyntax(this, makeReader(tem), uri, sb, eh, inheritedNs).parse(scope);

  }

  private static final String UTF8 = EncodingMap.getJavaName("UTF-8");

  private static final String UTF16 = EncodingMap.getJavaName("UTF-16");

  private static Reader makeReader(InputSource is) throws BuildException {

    try {

      Reader r = is.getCharacterStream();

      if (r == null) {

        InputStream in = is.getByteStream();

        if (in == null) {

          String systemId = is.getSystemId();

          in = new URL(systemId).openStream();

        }

        String encoding = is.getEncoding();

        if (encoding == null) {

          PushbackInputStream pb = new PushbackInputStream(in, 2);

          encoding = detectEncoding(pb);

          in = pb;

        }

        r = new InputStreamReader(in, encoding);

      }

      return r;

    }

    catch (IOException e) {

      throw new BuildException(e);

    }

  }

  static private String detectEncoding(PushbackInputStream in) throws IOException {

    String encoding = UTF8;

    int b1 = in.read();

    if (b1 != -1) {

      int b2 = in.read();

      if (b2 != -1) {

        in.unread(b2);

        if ((b1 == 0xFF && b2 == 0xFE) || (b1 == 0xFE && b2 == 0xFF))

          encoding = UTF16;

      }

      in.unread(b1);

    }

    return encoding;

  }

}