[evolution] Add e_table_column_specification_equal().

[Matthew Barnes <mbarnes src gnome org>]

commit 46b7a9961fc0606941dc0e2a2edf4a1383e3fa25
Author: Matthew Barnes <mbarnes redhat com>
Date:   Fri Jun 28 11:44:27 2013 -0400

    Add e_table_column_specification_equal().
    
    Compares two ETableColumnSpecification instances for equality, which
    just means they both refer to the same model column number.

 .../evolution-util/evolution-util-sections.txt     |    1 +
 e-util/e-table-column-specification.c              |   28 ++++++++++++++++++++
 e-util/e-table-column-specification.h              |    3 ++
 3 files changed, 32 insertions(+), 0 deletions(-)
---
diff --git a/doc/reference/evolution-util/evolution-util-sections.txt 
b/doc/reference/evolution-util/evolution-util-sections.txt
index 4cfcb81..039667a 100644
--- a/doc/reference/evolution-util/evolution-util-sections.txt
+++ b/doc/reference/evolution-util/evolution-util-sections.txt
@@ -3397,6 +3397,7 @@ e_table_col_get_type
 <TITLE>ETableColumnSpecification</TITLE>
 ETableColumnSpecification
 e_table_column_specification_new
+e_table_column_specification_equal
 e_table_column_specification_load_from_node
 <SUBSECTION Standard>
 E_TABLE_COLUMN_SPECIFICATION
diff --git a/e-util/e-table-column-specification.c b/e-util/e-table-column-specification.c
index a5d68b4..a770bdc 100644
--- a/e-util/e-table-column-specification.c
+++ b/e-util/e-table-column-specification.c
@@ -98,6 +98,34 @@ e_table_column_specification_new (void)
        return g_object_new (E_TYPE_TABLE_COLUMN_SPECIFICATION, NULL);
 }
 
+/**
+ * e_table_column_specification_equal:
+ * @spec_a: an #ETableColumnSpecification
+ * @spec_b: another #ETableColumnSpecification
+ *
+ * Convenience function compares @spec_a and @spec_b for equality, which
+ * simply means they share the same model column number.
+ *
+ * <note>
+ *   <para>
+ *     We should strive to get rid of this function by ensuring only one
+ *     #ETableSpecification instance exists per table specification file.
+ *     Then we could compare for equality by simply comparing pointers.
+ *   </para>
+ * </note>
+ *
+ * Returns: %TRUE if @spec_a and @spec_b describe the same column
+ **/
+gboolean
+e_table_column_specification_equal (ETableColumnSpecification *spec_a,
+                                    ETableColumnSpecification *spec_b)
+{
+       g_return_val_if_fail (E_IS_TABLE_COLUMN_SPECIFICATION (spec_a), FALSE);
+       g_return_val_if_fail (E_IS_TABLE_COLUMN_SPECIFICATION (spec_b), FALSE);
+
+       return (spec_a->model_col == spec_b->model_col);
+}
+
 void
 e_table_column_specification_load_from_node (ETableColumnSpecification *etcs,
                                              const xmlNode *node)
diff --git a/e-util/e-table-column-specification.h b/e-util/e-table-column-specification.h
index 68ded2e..1790d2a 100644
--- a/e-util/e-table-column-specification.h
+++ b/e-util/e-table-column-specification.h
@@ -81,6 +81,9 @@ struct _ETableColumnSpecificationClass {
 GType          e_table_column_specification_get_type   (void) G_GNUC_CONST;
 ETableColumnSpecification *
                e_table_column_specification_new        (void);
+gboolean       e_table_column_specification_equal
+                                       (ETableColumnSpecification *spec_a,
+                                        ETableColumnSpecification *spec_b);
 void           e_table_column_specification_load_from_node
                                        (ETableColumnSpecification *state,
                                         const xmlNode *node);