add all_variants, from_constant_name to trait Enum

CHANGELOG.md

@@ -12,6 +12,11 @@ JMdict was updated to 2021-09-17. This requires the following changes in enum va
 - added `SenseTopic::Psychiatry`
 - added `SenseTopic::Railway`
 
+Further changes:
+
+- The `all_variants()` method was added to `trait Enum`.
+- The `from_constant_name()` method was added to `trait Enum`.
+
 # v1.0.0 (2021-04-18)
 
 Initial stable release. No changes from v0.99.1.

jmdict-enums/build.rs

@@ -439,6 +439,28 @@ fn process(e: Enum) -> String {
     lines.push("        }".into());
     lines.push("    }\n".into());
 
+    //fn from_constant_name(&str) -> Self
+    lines.push("    fn from_constant_name(text: &str) -> Option<Self> {".into());
+    lines.push("        match text {".into());
+    for v in e.variants.iter().filter(|v| v.enabled) {
+        lines.push(format!(
+            "            \"{}\" => Some({}::{}),",
+            v.name, e.name, v.name
+        ));
+    }
+    lines.push("            _ => None,".into());
+    lines.push("        }".into());
+    lines.push("    }\n".into());
+
+    //fn all_variants() -> &'static [Self]
+    lines.push("    fn all_variants() -> &'static [Self] {".into());
+    lines.push("        &[".into());
+    for v in e.variants.iter().filter(|v| v.enabled) {
+        lines.push(format!("            {}::{},", e.name, v.name));
+    }
+    lines.push("        ]".into());
+    lines.push("    }\n".into());
+
     //end impl Enum
     lines.push("}\n".into());
 

jmdict-enums/src/lib.rs

@@ -43,6 +43,10 @@ pub trait EnumPayload {
 
 ///Common methods provided by all enums in this crate.
 pub trait Enum: Sized {
+    ///Returns a list of all variant values in this enum. No particular order is guaranteed or
+    ///implied.
+    fn all_variants() -> &'static [Self];
+
     ///Returns the string that marks this enum variant in the JMdict. For values that JMdict
     ///represents as XML entities, only the entity name is returned, e.g. `adj-n` instead of
     ///`&adj-n;`.
@@ -55,6 +59,11 @@ pub trait Enum: Sized {
     ///Returns the variant name. This is used to generate Rust code for this enum. The `impl
     ///Display` for enums uses this same representation.
     fn constant_name(&self) -> &'static str;
+
+    ///Returns the variant that is identified the given name in Rust code, or `None` if there is no
+    ///such variant. This is the reverse of `self.constant_name()`, i.e.
+    ///`Self::from_constant_name(self.constant_name()) == Some(self)`.
+    fn from_constant_name(name: &str) -> Option<Self>;
 }
 
 ///PriorityInCorpus appears in struct [Priority]. It describes how often a dictionary entry