UnitSystem string-description of a unit

Analoguous to to/from_si but for string-representation of the unit in
question.

opm/parser/eclipse/Units/UnitSystem.cpp

@@ -77,6 +77,29 @@ namespace {
         Metric::ReservoirVolume / Metric::Time,
         Metric::Transmissibility,
         Metric::Mass,
+        1, /* gas-oil ratio */
+        1, /* oil-gas ratio */
+        1, /* water cut */
+    };
+
+    static constexpr const char* metric_names[] = {
+        "",
+        "M",
+        "DAY",
+        "KG/M3",
+        "BARSA",
+        "K",
+        "C",
+        "CP",
+        "MD",
+        "SM3",
+        "SM3",
+        "RM3",
+        "SM3/DAY",
+        "SM3/DAY",
+        "RM3/DAY",
+        "CPR3/DAY/BARS",
+        "KG"
     };
 
     static const double to_field[] = {
@@ -119,6 +142,25 @@ namespace {
          Field::Mass,
     };
 
+    static constexpr const char* field_names[] = {
+        "",
+        "FT",
+        "DAY",
+        "LB/FT3",
+        "PSIA",
+        "R",
+        "F",
+        "CP",
+        "MD",
+        "STB",
+        "MSCF",
+        "RB",
+        "STB/DAY",
+        "MSCF/DAY",
+        "RB/DAY",
+        "CPRB/DAY/PSI",
+        "LB"
+    };
 }
 
     UnitSystem::UnitSystem(const UnitType unit) :
@@ -129,11 +171,13 @@ namespace {
                 m_name = "Metric";
                 this->measure_table_from_si = to_metric;
                 this->measure_table_to_si = from_metric;
+                this->unit_name_table = metric_names;
                 break;
             case(UNIT_TYPE_FIELD):
                 m_name = "Field";
                 this->measure_table_from_si = to_field;
                 this->measure_table_to_si = from_field;
+                this->unit_name_table = field_names;
                 break;
             case(UNIT_TYPE_LAB):
                 m_name = "Lab";
@@ -263,6 +307,10 @@ namespace {
         return this->measure_table_to_si[ static_cast< int >( m ) ] * val;
     }
 
+    const char* UnitSystem::name( measure m ) const {
+        return this->unit_name_table[ static_cast< int >( m ) ];
+    }
+
     UnitSystem * UnitSystem::newMETRIC() {
         UnitSystem * system = new UnitSystem(UNIT_TYPE_METRIC);
 

opm/parser/eclipse/Units/UnitSystem.hpp

@@ -72,6 +72,7 @@ namespace Opm {
 
         double from_si( measure, double ) const;
         double to_si( measure, double ) const;
+        const char* name( measure ) const;
 
         static UnitSystem * newMETRIC();
         static UnitSystem * newFIELD();
@@ -83,6 +84,7 @@ namespace Opm {
         std::map<std::string , std::shared_ptr<const Dimension> > m_dimensions;
         const double* measure_table_from_si;
         const double* measure_table_to_si;
+        const char* const*  unit_name_table;
     };
 }