refactor some common code for encoding/decoding uncompressed strings

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@277 f203690c-595d-4dc9-a70b-905162fa7fd2

2 files changed, 75 insertions, 44 deletions

diff --git a/src/java/com/healthmarketscience/jackcess/Column.java b/src/java/com/healthmarketscience/jackcess/Column.java
index 312c141..474cc54 100644
--- a/src/java/com/healthmarketscience/jackcess/Column.java
+++ b/src/java/com/healthmarketscience/jackcess/Column.java
@@ -907,7 +907,7 @@ public class Column implements Comparable<Column> {
         if (text.length() > maxChars) {
           throw new IOException("Text is too big for column");
         }
-        byte[] encodedData = encodeUncompressedText(text).array();
+        byte[] encodedData = encodeUncompressedText(text, getFormat()).array();
         obj = encodedData;
         break;
         
@@ -930,7 +930,7 @@ public class Column implements Comparable<Column> {
       // should already be "encoded"
       break;
     case MEMO:
-      obj = encodeUncompressedText(toCharSequence(obj)).array();
+      obj = encodeUncompressedText(toCharSequence(obj), getFormat()).array();
       break;
     default:
       throw new RuntimeException("unexpected var length, long value type: " +
@@ -1046,7 +1046,7 @@ public class Column implements Comparable<Column> {
         
       }
       
-      return decodeUncompressedText(data);
+      return decodeUncompressedText(data, getFormat());
       
     } catch (IllegalInputException e) {
       throw (IOException)
@@ -1079,34 +1079,19 @@ public class Column implements Comparable<Column> {
       textBuf.append(expander.expand(tmpData));
     } else {
       // handle uncompressed data
-      textBuf.append(decodeUncompressedText(data, dataStart, dataLength));
+      textBuf.append(decodeUncompressedText(data, dataStart, dataLength,
+                                            getFormat()));
     }
   }
 
   /**
-   * @param text Text to encode
-   * @return A buffer with the text encoded
-   */
-  private ByteBuffer encodeUncompressedText(CharSequence text) {
-    return getFormat().CHARSET.encode(CharBuffer.wrap(text));
-  }
-
-  /**
-   * @param textBytes bytes of text to decode
-   * @return the decoded string
-   */
-  private String decodeUncompressedText(byte[] textBytes) {
-    return decodeUncompressedText(textBytes, 0, textBytes.length).toString();
-  }
-  
-  /**
    * @param textBytes bytes of text to decode
    * @return the decoded string
    */
-  private CharBuffer decodeUncompressedText(byte[] textBytes, int startPost,
-                                            int length) {
-    return getFormat().CHARSET.decode(ByteBuffer.wrap(textBytes, startPost,
-                                                  length));
+  private static CharBuffer decodeUncompressedText(
+      byte[] textBytes, int startPos, int length, JetFormat format)
+  {
+    return format.CHARSET.decode(ByteBuffer.wrap(textBytes, startPos, length));
   }  
 
   @Override
@@ -1128,6 +1113,30 @@ public class Column implements Comparable<Column> {
     return rtn.toString();
   }
   
+  /**
+   * @param textBytes bytes of text to decode
+   * @param format relevant db format
+   * @return the decoded string
+   */
+  public static String decodeUncompressedText(byte[] textBytes,
+                                              JetFormat format)
+  {
+    return decodeUncompressedText(textBytes, 0, textBytes.length, format)
+      .toString();
+  }
+
+  /**
+   * @param text Text to encode
+   * @param format relevant db format
+   * @return A buffer with the text encoded
+   */
+  public static ByteBuffer encodeUncompressedText(CharSequence text,
+                                                  JetFormat format)
+  {
+    return format.CHARSET.encode(CharBuffer.wrap(text));
+  }
+
+  
   public int compareTo(Column other) {
     if (_columnNumber > other.getColumnNumber()) {
       return 1;
diff --git a/src/java/com/healthmarketscience/jackcess/Table.java b/src/java/com/healthmarketscience/jackcess/Table.java
index 0c30d79..9f07f36 100644
--- a/src/java/com/healthmarketscience/jackcess/Table.java
+++ b/src/java/com/healthmarketscience/jackcess/Table.java
@@ -842,13 +842,24 @@ public class Table
       }
     }
     for (Column col : columns) {
-      ByteBuffer colName = format.CHARSET.encode(col.getName());
-      buffer.putShort((short) colName.remaining());
-      buffer.put(colName);
+      writeName(buffer, col.getName(), format);
     }
   }
 
   /**
+   * Writes the given name into the given buffer in the format as expected by
+   * {@link #readName}.
+   */
+  private static void writeName(ByteBuffer buffer, String name,
+                                JetFormat format)
+  {
+      ByteBuffer encName = Column.encodeUncompressedText(
+          name, format);
+      buffer.putShort((short) encName.remaining());
+      buffer.put(encName);
+  }
+
+  /**
    * Constructs a byte containing the flags for the given column.
    */
   private static byte getColumnBitFlags(Column col) {
@@ -936,11 +947,11 @@ public class Table
           i * getFormat().SIZE_INDEX_DEFINITION + 4));
     }
     
-    int offset = getFormat().OFFSET_INDEX_DEF_BLOCK +
+    int colOffset = getFormat().OFFSET_INDEX_DEF_BLOCK +
         _indexCount * getFormat().SIZE_INDEX_DEFINITION;
     for (int i = 0; i < columnCount; i++) {
       Column column = new Column(this, tableBuffer,
-          offset + i * getFormat().SIZE_COLUMN_HEADER);
+          colOffset + (i * getFormat().SIZE_COLUMN_HEADER));
       _columns.add(column);
       if(column.isVariableLength()) {
         // also shove it in the variable columns list, which is ordered
@@ -948,16 +959,11 @@ public class Table
         _varColumns.add(column);
       }
     }
-    offset += columnCount * getFormat().SIZE_COLUMN_HEADER;
+    tableBuffer.position(colOffset +
+                         (columnCount * getFormat().SIZE_COLUMN_HEADER));
     for (int i = 0; i < columnCount; i++) {
       Column column = _columns.get(i);
-      short nameLength = tableBuffer.getShort(offset);
-      offset += 2;
-      byte[] nameBytes = new byte[nameLength];
-      tableBuffer.position(offset);
-      tableBuffer.get(nameBytes, 0, nameLength);
-      column.setName(getFormat().CHARSET.decode(ByteBuffer.wrap(nameBytes)).toString());
-      offset += nameLength;
+      column.setName(readName(tableBuffer));
     }    
     Collections.sort(_columns);
 
@@ -1000,20 +1006,15 @@ public class Table
 
     // read actual index names
     for (int i = 0; i < _indexSlotCount; i++) {
-      int nameLen = tableBuffer.getShort();
-
       if(i < firstRealIdx) {
         // for each empty index slot, there is some weird sort of name, skip
         // it
-        tableBuffer.position(tableBuffer.position() + nameLen);
+        skipName(tableBuffer);
         continue;
       }
         
-      byte[] nameBytes = new byte[nameLen];
-      tableBuffer.get(nameBytes);
       _indexes.get(i - firstRealIdx)
-        .setName(getFormat().CHARSET.decode(
-                     ByteBuffer.wrap(nameBytes)).toString());
+        .setName(readName(tableBuffer));
     }
     int idxEndOffset = tableBuffer.position();
     
@@ -1046,6 +1047,27 @@ public class Table
   }
 
   /**
+   * Returns a name read from the buffer at the current position.  The
+   * expected name format is the name length as a short followed by (length *
+   * 2) bytes encoded using the {@link JetFormat#CHARSET}
+   */
+  private String readName(ByteBuffer buffer) {
+    short nameLength = buffer.getShort();
+    byte[] nameBytes = new byte[nameLength];
+    buffer.get(nameBytes);
+    return Column.decodeUncompressedText(nameBytes, getFormat());
+  }
+  
+  /**
+   * Skips past a name int the buffer at the current position.  The
+   * expected name format is the same as that for {@link #readName}.
+   */
+  private void skipName(ByteBuffer buffer) {
+    short nameLength = buffer.getShort();
+    buffer.position(buffer.position() + nameLength);
+  }
+  
+  /**
    * Converts a map of columnName -> columnValue to an array of row values
    * appropriate for a call to {@link #addRow(Object...)}.
    */