From ed8c8df73855edffd7676292dd69e9d4d6b6a358 Mon Sep 17 00:00:00 2001
From: Mickey Rose <mickey.rose@seznam.cz>
Date: Sat, 6 Feb 2016 18:39:56 +0100
Subject: [PATCH] expression_grammar: use one symbol table for all constants

---
 include/mapnik/expression_grammar.hpp      | 41 +---------------------
 include/mapnik/expression_grammar_impl.hpp | 24 +++++++++----
 2 files changed, 19 insertions(+), 46 deletions(-)

diff --git a/include/mapnik/expression_grammar.hpp b/include/mapnik/expression_grammar.hpp
index ff9423ea3..ea65425a0 100644
--- a/include/mapnik/expression_grammar.hpp
+++ b/include/mapnik/expression_grammar.hpp
@@ -107,43 +107,6 @@ struct regex_replace_impl
     mapnik::transcoder const& tr_;
 };
 
-struct geometry_types : qi::symbols<char, mapnik::value_integer>
-{
-    geometry_types()
-    {
-        add
-            ("point", 1)
-            ("linestring", 2)
-            ("polygon",3)
-            ("collection",4)
-            ;
-    }
-};
-
-struct boolean_constants :  qi::symbols<char,mapnik::value_bool>
-{
-    boolean_constants()
-    {
-        add
-            ("true", true)
-            ("false", false)
-            ;
-    }
-};
-
-struct floating_point_constants :  qi::symbols<char,mapnik::value_double>
-{
-    floating_point_constants()
-    {
-        add
-            ("pi", 3.1415926535897932384626433832795)
-            ("deg_to_rad",0.017453292519943295769236907684886)
-            ("rad_to_deg",57.295779513082320876798154814105)
-            ;
-    }
-};
-
-
 template <typename T>
 struct integer_parser
 {
@@ -200,9 +163,7 @@ struct expression_grammar : qi::grammar<Iterator, expr_node(), space_type>
 
     qi::symbols<char const, char const> unesc_char;
     qi::rule<Iterator, char() > quote_char;
-    geometry_types geom_type;
-    boolean_constants bool_const;
-    floating_point_constants float_const;
+    qi::symbols<char, expr_node> constant;
     unary_function_types unary_func_type;
     binary_function_types binary_func_type;
 
diff --git a/include/mapnik/expression_grammar_impl.hpp b/include/mapnik/expression_grammar_impl.hpp
index 9c82cb8c5..c2c23e050 100644
--- a/include/mapnik/expression_grammar_impl.hpp
+++ b/include/mapnik/expression_grammar_impl.hpp
@@ -103,6 +103,20 @@ expression_grammar<Iterator>::expression_grammar(std::string const& encoding)
     standard_wide::char_type char_;
     standard_wide::no_case_type no_case;
     using boost::phoenix::construct;
+    using boost::phoenix::if_else;
+
+    constant.add
+        ("null",        mapnik::value_null())
+        ("false",       mapnik::value_bool(false))
+        ("true",        mapnik::value_bool(true))
+        ("point",       mapnik::value_integer(1))
+        ("linestring",  mapnik::value_integer(2))
+        ("polygon",     mapnik::value_integer(3))
+        ("collection",  mapnik::value_integer(4))
+        ("pi",          mapnik::value_double(3.1415926535897932384626433832795))
+        ("deg_to_rad",  mapnik::value_double(0.017453292519943295769236907684886))
+        ("rad_to_deg",  mapnik::value_double(57.295779513082320876798154814105))
+        ;
 
     expr = logical_expr.alias();
 
@@ -180,13 +194,11 @@ expression_grammar<Iterator>::expression_grammar(std::string const& encoding)
 
     primary_expr = strict_double [_val = _1]
         | int__[_val = _1]
-        | no_case[bool_const][_val = _1]
-        | no_case[lit("null")] [_val = value_null() ]
-        | no_case[geom_type][_val = _1 ]
-        | no_case[float_const] [_val = _1 ]
+        | no_case[constant] [_val = _1]
         | quoted_ustring [_val = unicode_(_1)]
-        | lit("[mapnik::geometry_type]")[_val = construct<mapnik::geometry_type_attribute>()]
-        | attr [_val = construct<mapnik::attribute>( _1 ) ]
+        | attr [if_else(_1 == "mapnik::geometry_type",
+                        _val = construct<mapnik::geometry_type_attribute>(),
+                        _val = construct<mapnik::attribute>(_1))]
         | global_attr [_val = construct<mapnik::global_attribute>( _1 )]
         | lit("not") >> expr [_val =  !_1]
         | unary_function_expr [_val = _1]