[lmi-commits] [lmi] odd/any_member-opt cdfc8d5 4/5: Allow computing MemberSymbolTable member index and reusing it

[Greg Chicares]

branch: odd/any_member-opt
commit cdfc8d5054d675cdf4e562baf62cf5a4a94f3a09
Author: Vadim Zeitlin <vadim@tt-solutions.com>
Commit: Gregory W. Chicares <gchicares@sbcglobal.net>

    Allow computing MemberSymbolTable member index and reusing it
    
    Looking up the member by name once and then reusing the index to access
    it results in a big performance gain when doing it many times in a row,
    e.g. CensusView::column_value_varies_across_cells() now takes less than
    30% of the time it took before for a census with ~4000 rows.
---
 any_member.hpp  | 25 +++++++++++++++++++++----
 census_view.cpp | 20 ++++++++++++++++++--
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/any_member.hpp b/any_member.hpp
index cdca2c9..b01f6df 100644
--- a/any_member.hpp
+++ b/any_member.hpp
@@ -63,6 +63,7 @@
 #include "any_entity.hpp"
 
 #include "assert_lmi.hpp"
+#include "bourn_cast.hpp"
 #include "rtti_lmi.hpp"
 #include "value_cast.hpp"
 
@@ -553,6 +554,9 @@ class MemberSymbolTable
     bool equals(MemberSymbolTable<ClassType> const&) const;
     std::vector<std::string> const& member_names() const;
 
+    int get_member_index(std::string const&) const;
+    any_member<ClassType> const& get_member_by_index(int) const;
+
   protected:
     MemberSymbolTable();
 
@@ -599,16 +603,29 @@ void 
MemberSymbolTable<ClassType>::complain_that_no_such_member_is_ascribed
 }
 
 template<typename ClassType>
-any_member<ClassType>& MemberSymbolTable<ClassType>::operator[]
-    (std::string const& s
-    )
+int MemberSymbolTable<ClassType>::get_member_index(std::string const& s) const
 {
     auto const i = std::lower_bound(member_names_.begin(), 
member_names_.end(), s);
     if(i == member_names_.end() || (*i != s))
         {
         complain_that_no_such_member_is_ascribed(s);
         }
-    return member_values_[i - member_names_.begin()];
+    return bourn_cast<int>(i - member_names_.begin());
+}
+
+template<typename ClassType>
+any_member<ClassType> const&
+MemberSymbolTable<ClassType>::get_member_by_index(int n) const
+{
+    return member_values_[n];
+}
+
+template<typename ClassType>
+any_member<ClassType>& MemberSymbolTable<ClassType>::operator[]
+    (std::string const& s
+    )
+{
+    return member_values_[get_member_index(s)];
 }
 
 template<typename ClassType>
diff --git a/census_view.cpp b/census_view.cpp
index 9ee061d..f8ccd3c 100644
--- a/census_view.cpp
+++ b/census_view.cpp
@@ -1077,8 +1077,24 @@ Input* 
CensusView::class_parms_from_class_name(std::string const& class_name)
 bool CensusView::column_value_varies_across_cells(std::string const& header) 
const
 {
     auto const z = case_parms()[0][header];
-    for(auto const& j : class_parms()) {if(z != j[header]) return true;}
-    for(auto const& j : cell_parms() ) {if(z != j[header]) return true;}
+
+    auto const class_header_index = 
class_parms().begin()->get_member_index(header);
+    for(auto const& j : class_parms())
+        {
+        if(z != j.get_member_by_index(class_header_index))
+            {
+            return true;
+            }
+        }
+
+    auto const cell_header_index = 
cell_parms().begin()->get_member_index(header);
+    for(auto const& j : cell_parms())
+        {
+        if(z != j.get_member_by_index(cell_header_index))
+            {
+            return true;
+            }
+        }
     return false;
 }