[doc][algorithms][is_empty] add documentation for is_empty algorithm

doc/doxy/doxygen_input/groups/groups.hpp

@@ -40,6 +40,7 @@
 \defgroup interior_rings interior_rings: interior_rings
 \defgroup intersection intersection: calculate new geometry
 \defgroup intersects intersects: detect if a geometry self-intersects or if two geometries intersect
+\defgroup is_empty is_empty: detect if a geometry is the empty set
 \defgroup is_simple is_simple: detect if a geometry is simple
 \defgroup is_valid is_valid: detect if a geometry is valid
 \defgroup iterators iterators: iterators

doc/imports.qbk

@@ -45,6 +45,7 @@
 [import src/examples/algorithms/intersection_segment.cpp]
 [import src/examples/algorithms/intersection_poly_poly.cpp]
 [import src/examples/algorithms/intersects_linestring.cpp]
+[import src/examples/algorithms/is_empty.cpp]
 [import src/examples/algorithms/is_simple.cpp]
 [import src/examples/algorithms/is_valid.cpp]
 [import src/examples/algorithms/is_valid_failure.cpp]

doc/make_qbk.py

@@ -86,10 +86,11 @@ call_doxygen()
 algorithms = ["append", "assign", "make", "clear"
     , "area", "buffer", "centroid", "convert", "correct", "covered_by"
     , "convex_hull", "crosses", "difference", "disjoint", "distance" 
-    , "envelope", "equals", "expand", "for_each", "is_simple", "is_valid"
-    , "intersection", "intersects", "length", "num_geometries"
-    , "num_interior_rings", "num_points", "num_segments", "overlaps"
-    , "perimeter", "relate", "relation", "reverse", "simplify", "sym_difference", "touches"
+    , "envelope", "equals", "expand", "for_each", "is_empty"
+    , "is_simple", "is_valid", "intersection", "intersects", "length"
+    , "num_geometries", "num_interior_rings", "num_points"
+    , "num_segments", "overlaps", "perimeter", "relate", "relation"
+    , "reverse", "simplify", "sym_difference", "touches"
     , "transform", "union", "unique", "within"]
 
 access_functions = ["get", "set", "exterior_ring", "interior_rings"

doc/quickref.xml

@@ -329,6 +329,7 @@
      <member><link linkend="geometry.reference.algorithms.disjoint">disjoint</link></member>
      <member><link linkend="geometry.reference.algorithms.equals">equals</link></member>
      <member><link linkend="geometry.reference.algorithms.intersects">intersects</link></member>
+     <member><link linkend="geometry.reference.algorithms.is_empty">is_empty</link></member>
      <member><link linkend="geometry.reference.algorithms.is_simple">is_simple</link></member>
      <member><link linkend="geometry.reference.algorithms.is_valid">is_valid</link></member>
      <member><link linkend="geometry.reference.algorithms.overlaps">overlaps</link></member>

doc/reference.qbk

@@ -122,6 +122,8 @@
 [include generated/intersects.qbk]
 [endsect]
 
+[include generated/is_empty.qbk]
+
 [include generated/is_simple.qbk]
 
 [section:is_valid is_valid]

doc/reference/algorithms/is_empty.qbk

@@ -0,0 +1,26 @@
+[/============================================================================
+  Boost.Geometry (aka GGL, Generic Geometry Library)
+
+  Copyright (c) 2015, Oracle and/or its affiliates.
+
+  Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
+
+  Licensed under the Boost Software License version 1.0.
+  http://www.boost.org/users/license.html
+=============================================================================/]
+
+[def __this_function__ is_empty]
+
+[heading_conformance_no_ogc __this_function__]
+
+[include reference/status/is_empty_status.qbk]
+
+[heading Complexity]
+Constant-time
+
+[heading Example]
+[is_empty]
+[is_empty_output]
+
+[heading See also]
+* [link geometry.reference.algorithms.num_points num_points]

doc/reference/status/is_empty_status.qbk

@@ -0,0 +1,14 @@
+[heading Supported geometries]
+[table
+[[Geometry][Status]]
+[[Point][ [$img/ok.png] ]]
+[[Segment][ [$img/ok.png] ]]
+[[Box][ [$img/ok.png] ]]
+[[Linestring][ [$img/ok.png] ]]
+[[Ring][ [$img/ok.png] ]]
+[[Polygon][ [$img/ok.png] ]]
+[[MultiPoint][ [$img/ok.png] ]]
+[[MultiLinestring][ [$img/ok.png] ]]
+[[MultiPolygon][ [$img/ok.png] ]]
+[[Variant][ [$img/ok.png] ]]
+]

doc/src/docutils/tools/support_status/support_status.cpp

@@ -34,6 +34,7 @@
 #include <boost/geometry/algorithms/equals.hpp>
 #include <boost/geometry/algorithms/expand.hpp>
 #include <boost/geometry/algorithms/for_each.hpp>
+#include <boost/geometry/algorithms/is_empty.hpp>
 #include <boost/geometry/algorithms/is_simple.hpp>
 #include <boost/geometry/algorithms/is_valid.hpp>
 #include <boost/geometry/algorithms/length.hpp>
@@ -109,6 +110,7 @@ DECLARE_BINARY_ALGORITHM(equals)
 DECLARE_BINARY_ALGORITHM(expand)
 DECLARE_UNARY_ALGORITHM(for_each_point)
 DECLARE_UNARY_ALGORITHM(for_each_segment)
+DECLARE_UNARY_ALGORITHM(is_empty)
 DECLARE_UNARY_ALGORITHM(is_simple)
 DECLARE_UNARY_ALGORITHM(is_valid)
 DECLARE_UNARY_ALGORITHM(length)
@@ -248,6 +250,7 @@ void support_status()
     test_binary_algorithm<expand, all_types, all_types, OutputFactory>("expand");
     test_unary_algorithm<for_each_point, all_types, OutputFactory>("for_each_point");
     test_unary_algorithm<for_each_segment, all_types, OutputFactory>("for_each_segment");
+    test_unary_algorithm<is_empty, all_types, OutputFactory>("is_empty");
     test_unary_algorithm<is_simple, all_types, OutputFactory>("is_simple");
     test_unary_algorithm<is_valid, all_types, OutputFactory>("is_valid");
     test_unary_algorithm<length, all_types, OutputFactory>("length");

doc/src/examples/algorithms/is_empty.cpp

@@ -0,0 +1,47 @@
+// Boost.Geometry (aka GGL, Generic Geometry Library)
+// QuickBook Example
+
+// Copyright (c) 2015, Oracle and/or its affiliates
+
+// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+//[is_empty
+//` Check if a geometry is the empty set
+
+#include <iostream>
+
+#include <boost/geometry.hpp>
+#include <boost/geometry/geometries/point_xy.hpp>
+
+
+int main()
+{
+    boost::geometry::model::multi_linestring
+        <
+            boost::geometry::model::linestring
+                <
+                    boost::geometry::model::d2::point_xy<double>
+                >
+        > mls;
+    boost::geometry::read_wkt("MULTILINESTRING((0 0,0 10,10 0),(1 1,8 1,1 8))", mls);
+    std::cout << "Is empty? " << (boost::geometry::is_empty(mls) ? "yes" : "no") << std::endl;
+    boost::geometry::clear(mls);
+    std::cout << "Is empty (after clearing)? " << (boost::geometry::is_empty(mls) ? "yes" : "no") << std::endl;
+    return 0;
+}
+
+//]
+
+
+//[is_empty_output
+/*`
+Output:
+[pre
+Is empty? no
+Is empty (after clearing)? yes
+]
+*/
+//]