[Units] Simplify Units::str()

Cantera · Jul 27, 2021 · 01c2ba1 · 01c2ba1
1 parent ebd5311
commit 01c2ba1
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Showing 2 changed files with 20 additions and 9 deletions.
diff --git a/src/base/Units.cpp b/src/base/Units.cpp
@@ -246,19 +246,30 @@ std::string Units::str() const {
         {"kmol", m_quantity_dim},
     };
 
+    std::string num = "";
     std::string out = "";
     for (auto const& dim : dims) {
         int rounded = roundf(dim.second);
-        if (dim.second == 1.) {
-            out.append(fmt::format(" * {}", dim.first));
-        } else if (dim.second == 0.) {
+        if (dim.second == 0.) {
             // skip
+        } else if (dim.second == 1.) {
+            num.append(fmt::format(" * {}", dim.first));
+        } else if (dim.second == -1.) {
+            out.append(fmt::format(" / {}", dim.first));
+        } else if (dim.second == rounded && rounded > 0) {
+            num.append(fmt::format(" * {}^{}", dim.first, rounded));
         } else if (dim.second == rounded) {
-            out.append(fmt::format(" * {}^{}", dim.first, rounded));
+            out.append(fmt::format(" / {}^{}", dim.first, -rounded));
+        } else if (dim.second > 0) {
+            num.append(fmt::format(" * {}^{}", dim.first, dim.second));
         } else {
-            out.append(fmt::format(" * {}^{}", dim.first, dim.second));
+            out.append(fmt::format(" / {}^{}", dim.first, -dim.second));
         }
     }
+    if (num.size()) {
+        // concatenate numerator and denominator (skipping leading '*')
+        out = fmt::format("{}{}", num.substr(2), out);
+    }
 
     std::string factor;
     if (m_factor == roundf(m_factor)) {
@@ -269,7 +280,7 @@ std::string Units::str() const {
     }
 
     if (out.size()) {
-        return fmt::format("{} {}", factor, out.substr(3));
+        return fmt::format("{}{}", factor, out);
     }
     return factor;
 }

diff --git a/test/general/test_units.cpp b/test/general/test_units.cpp
@@ -10,7 +10,7 @@ TEST(Units, from_string) {
     EXPECT_EQ(Units("2").str(), "2.0");
     EXPECT_EQ(Units("kg").str(), "1.0 kg");
     EXPECT_EQ(Units("1.0 kg^0.5").str(), "1.0 kg^0.5");
-    EXPECT_EQ(Units("kg / m^3").str(), "1.0 kg * m^-3");
+    EXPECT_EQ(Units("kg / m^3").str(), "1.0 kg / m^3");
     EXPECT_EQ(Units("0.001 m^3").str(), "0.001 m^3");
 }
 
@@ -19,8 +19,8 @@ TEST(Units, copy_construct) {
     EXPECT_EQ(Units(Units(1., 1.)).str(), "1.0 kg");
     EXPECT_EQ(Units(Units(1., 2.)).str(), "1.0 kg^2");
     EXPECT_EQ(Units(Units(1., .5)).str(), "1.0 kg^0.5");
-    EXPECT_EQ(Units(Units(1., -1.)).str(), "1.0 kg^-1");
-    EXPECT_EQ(Units(Units(1., 1., -3.)).str(), "1.0 kg * m^-3");
+    EXPECT_EQ(Units(Units(1., -1.)).str(), "1.0 / kg");
+    EXPECT_EQ(Units(Units(1., 1., -3.)).str(), "1.0 kg / m^3");
     EXPECT_EQ(Units(Units(.001, 0., 3.)).str(), "0.001 m^3");
 }