content: /*
   * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code 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
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package openjdk.tools.javac.util;
  
  import java.io.IOException;
  import java.lang.ref.SoftReference;
  import java.nio.CharBuffer;
  import jdkx.tools.JavaFileObject;
  
  import openjdk.tools.javac.file.JavacFileManager;
  import openjdk.tools.javac.tree.EndPosTable;
  
  import static openjdk.tools.javac.util.LayoutCharacters.*;
  
  /**
   * A simple abstraction of a source file, as needed for use in a diagnostic message.
   * Provides access to the line and position in a line for any given character offset.
   *
   *  <p><b>This is NOT part of any supported API.
   *  If you write code that depends on this, you do so at your own risk.
   *  This code and its internal interfaces are subject to change or
   *  deletion without notice.</b>
   */
  public class DiagnosticSource {
  
      /* constant DiagnosticSource to be used when sourcefile is missing */
      public static final DiagnosticSource NO_SOURCE = new DiagnosticSource() {
          @Override
          protected boolean findLine(int pos) {
              return false;
          }
      };
  
      public DiagnosticSource(JavaFileObject fo, AbstractLog log) {
          this.fileObject = fo;
          this.log = log;
      }
  
      private DiagnosticSource() {}
  
      /** Return the underlying file object handled by this
       *  DiagnosticSource object.
       */
      public JavaFileObject getFile() {
          return fileObject;
      }
  
      /** Return the one-based line number associated with a given pos
       * for the current source file.  Zero is returned if no line exists
       * for the given position.
       */
      public int getLineNumber(int pos) {
          try {
              if (findLine(pos)) {
                  return line;
              }
              return 0;
          } finally {
              buf = null;
          }
      }
  
      /** Return the one-based column number associated with a given pos
       * for the current source file.  Zero is returned if no column exists
       * for the given position.
       */
      public int getColumnNumber(int pos, boolean expandTabs) {
          try {
              if (findLine(pos)) {
                  int column = 0;
                  for (int bp = lineStart; bp < pos; bp++) {
                      if (bp >= bufLen) {
                          return 0;
                      }
                      if (buf[bp] == '\t' && expandTabs) {
                          column = tabulate(column);
                      } else {
                          column++;
                      }
                  }
                  return column + 1; // positions are one-based
              }
              return 0;
          } finally {
              buf = null;
          }
      }
  
      /** Return the content of the line containing a given pos.
       */
      public String getLine(int pos) {
          try {
              if (!findLine(pos))
                  return null;
  
              int lineEnd = lineStart;
              while (lineEnd < bufLen && buf[lineEnd] != CR && buf[lineEnd] != LF)
                  lineEnd++;
              if (lineEnd - lineStart == 0)
                  return null;
              return new String(buf, lineStart, lineEnd - lineStart);
          } finally {
              buf = null;
          }
      }
  
      public EndPosTable getEndPosTable() {
          return endPosTable;
      }
  
      public void setEndPosTable(EndPosTable t) {
          if (endPosTable != null && endPosTable != t)
              throw new IllegalStateException("endPosTable already set for : " + fileObject.toUri(), thr);
          endPosTable = t;
          thr = new Throwable();
      }
  
      /** Find the line in the buffer that contains the current position
       * @param pos      Character offset into the buffer
       */
      protected boolean findLine(int pos) {
          if (pos == Position.NOPOS)
              return false;
  
          try {
              // try and recover buffer from soft reference cache
              if (buf == null && refBuf != null)
                  buf = refBuf.get();
  
              if (buf == null) {
                  buf = initBuf(fileObject);
                  lineStart = 0;
                  line = 1;
              } else if (lineStart > pos) { // messages don't come in order
                  lineStart = 0;
                  line = 1;
              }
  
              int bp = lineStart;
              while (bp < bufLen && bp < pos) {
                  switch (buf[bp++]) {
                  case CR:
                      if (bp < bufLen && buf[bp] == LF) bp++;
                      line++;
                      lineStart = bp;
                      break;
                  case LF:
                      line++;
                      lineStart = bp;
                      break;
                  }
              }
              return bp <= bufLen;
          } catch (IOException e) {
              log.directError("source.unavailable");
              buf = new char[0];
              return false;
          }
      }
  
      protected char[] initBuf(JavaFileObject fileObject) throws IOException {
          char[] buf;
          CharSequence cs = fileObject.getCharContent(true);
          if (cs instanceof CharBuffer) {
              CharBuffer charBuffer = (CharBuffer)cs;
              buf = JavacFileManager.toArray(charBuffer);
              bufLen = charBuffer.limit();
          } else {
              buf = cs.toString().toCharArray();
              bufLen = buf.length;
          }
          refBuf = new SoftReference<>(buf);
          return buf;
      }
  
      /** The underlying file object. */
      protected JavaFileObject fileObject;
  
      protected EndPosTable endPosTable;
  
      /** A soft reference to the content of the file object. */
      protected SoftReference<char[]> refBuf;
  
      /** A temporary hard reference to the content of the file object. */
      protected char[] buf;
  
      /** The length of the content. */
      protected int bufLen;
  
      /** The start of a line found by findLine. */
      protected int lineStart;
  
      /** The line number of a line found by findLine. */
      protected int line;
  
      /** A log for reporting errors, such as errors accessing the content. */
      protected AbstractLog log;
  
      private Throwable thr;
  }
  