add a few util methods related to indexes and joins

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@566 f203690c-595d-4dc9-a70b-905162fa7fd2

2 files changed, 61 insertions, 2 deletions

diff --git a/src/java/com/healthmarketscience/jackcess/Joiner.java b/src/java/com/healthmarketscience/jackcess/Joiner.java
index afe445d..89da959 100644
--- a/src/java/com/healthmarketscience/jackcess/Joiner.java
+++ b/src/java/com/healthmarketscience/jackcess/Joiner.java
@@ -47,9 +47,24 @@ public class Joiner
   }
 
   /**
+   * Creates a new Joiner based on the foreign-key relationship between the
+   * given "from"" table and the given "to"" table.
+   *
+   * @param fromTable the "from" side of the relationship
+   * @param toTable the "to" side of the relationship
+   * @throws IllegalArgumentException if there is no relationship between the
+   *         given tables
+   */
+  public static Joiner create(Table fromTable, Table toTable)
+    throws IOException
+  {
+    return create(fromTable.getForeignKeyIndex(toTable));
+  }
+  
+  /**
    * Creates a new Joiner based on the given index which backs a foreign-key
    * relationship.  The table of the given index will be the "from" table and
-   * the table on the other end of the relationsip is the "to" table.
+   * the table on the other end of the relationship will be the "to" table.
    *
    * @param fromIndex the index backing one side of a foreign-key relationship
    */
@@ -63,6 +78,16 @@ public class Joiner
     toCursor.setColumnMatcher(CaseInsensitiveColumnMatcher.INSTANCE);
     return new Joiner(fromIndex, toCursor);
   }
+
+  /**
+   * Creates a new Joiner that is the reverse of this Joiner (the "from" and
+   * "to" tables are swapped).
+   */ 
+  public Joiner createReverse()
+    throws IOException
+  {
+    return create(getToTable(), getFromTable());
+  }
   
   public Table getFromTable()
   {
diff --git a/src/java/com/healthmarketscience/jackcess/Table.java b/src/java/com/healthmarketscience/jackcess/Table.java
index 1d1c7a3..34b3c27 100644
--- a/src/java/com/healthmarketscience/jackcess/Table.java
+++ b/src/java/com/healthmarketscience/jackcess/Table.java
@@ -367,6 +367,7 @@ public class Table
 
   /**
    * @return the index with the given name
+   * @throws IllegalArgumentException if there is no index with the given name
    */
   public Index getIndex(String name) {
     for(Index index : _indexes) {
@@ -377,7 +378,40 @@ public class Table
     throw new IllegalArgumentException("Index with name " + name +
                                        " does not exist on this table");
   }
-    
+
+  /**
+   * @return the primary key index for this table
+   * @throws IllegalArgumentException if there is no primary key index on this
+   *         table
+   */
+  public Index getPrimaryKeyIndex() {
+    for(Index index : _indexes) {
+      if(index.isPrimaryKey()) {
+        return index;
+      }
+    }
+    throw new IllegalArgumentException("Table " + getName() +
+                                       " does not have a primary key index");
+  }
+  
+  /**
+   * @return the foreign key index joining this table to the given other table
+   * @throws IllegalArgumentException if there is no relationship between this
+   *         table and the given table
+   */
+  public Index getForeignKeyIndex(Table otherTable) {
+    for(Index index : _indexes) {
+      if(index.isForeignKey() && (index.getReference() != null) &&
+         (index.getReference().getOtherTablePageNumber() ==
+          otherTable.getTableDefPageNumber())) {
+        return index;
+      }
+    }
+    throw new IllegalArgumentException(
+        "Table " + getName() + " does not have a foreign key reference to " +
+        otherTable.getName());
+  }
+  
   /**
    * @return All of the IndexData on this table (unmodifiable List)
    */