[Rust] impl FromStr for generated enum items

Author: wbprime

rust/tests/baseline_enum_from_str.rs

@@ -0,0 +1,21 @@
+use examples_baseline::{
+    boost_type::BoostType,
+};
+
+#[test]
+fn test_boost_type_from_str() -> Result<(), ()> {
+    assert_eq!("TURBO".parse::<BoostType>()?, BoostType::TURBO, "Parse \"TURBO\" as BoostType");
+    assert_eq!("SUPERCHARGER".parse::<BoostType>()?, BoostType::SUPERCHARGER, "Parse \"SUPERCHARGER\" as BoostType");
+    assert_eq!("NITROUS".parse::<BoostType>()?, BoostType::NITROUS, "Parse \"NITROUS\" as BoostType");
+    assert_eq!("KERS".parse::<BoostType>()?, BoostType::KERS, "Parse \"KERS\" as BoostType");
+
+    assert_eq!("Turbo".parse::<BoostType>()?, BoostType::NullVal, "Parse \"Turbo\" as BoostType");
+    assert_eq!("Supercharger".parse::<BoostType>()?, BoostType::NullVal, "Parse \"Supercharger\" as BoostType");
+    assert_eq!("Nitrous".parse::<BoostType>()?, BoostType::NullVal, "Parse \"Nitrous\" as BoostType");
+    assert_eq!("Kers".parse::<BoostType>()?, BoostType::NullVal, "Parse \"Kers\" as BoostType");
+
+    assert_eq!("AA".parse::<BoostType>()?, BoostType::NullVal, "Parse \"AA\" as BoostType");
+    assert_eq!("".parse::<BoostType>().unwrap(), BoostType::NullVal, "Parse \"\" as BoostType");
+
+    Ok(())
+}

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustGenerator.java

@@ -1283,6 +1283,22 @@ private static void generateEnum(
         indent(writer, 2, "}\n");
         indent(writer, 1, "}\n");
         indent(writer, 0, "}\n");
+
+        // FromStr impl
+        indent(writer, 0, "impl core::str::FromStr for %s {\n", enumRustName);
+        indent(writer, 1, "type Err = ();\n\n");
+        indent(writer, 1, "#[inline]\n");
+        indent(writer, 1, "fn from_str(v: &str) -> core::result::Result<Self, Self::Err> {\n", primitiveType);
+        indent(writer, 2, "match v {\n");
+        for (final Token token : messageBody)
+        {
+            indent(writer, 3, "\"%1$s\" => core::result::Result::Ok(Self::%1$s), \n", token.name());
+        }
+        // default => NullVal
+        indent(writer, 3, "_ => core::result::Result::Ok(Self::NullVal),\n");
+        indent(writer, 2, "}\n");
+        indent(writer, 1, "}\n");
+        indent(writer, 0, "}\n");
     }
 
     private static void generateComposites(