better usability for ast::Constant

src/ast.rs

@@ -54,3 +54,57 @@ pub enum Constant {
 	Number(i64),
 	String(String),
 }
+
+impl Expression {
+	pub fn new_constant(value: impl Into<Constant>) -> Self {
+		Self::Constant(value.into())
+	}
+}
+
+impl From<()> for Constant {
+	fn from(_value: ()) -> Self {
+		Self::Nil
+	}
+}
+
+macro_rules! impl_from {
+	($as: ident, $from: ty) => {
+		impl From<$from> for Constant {
+			fn from(value: $from) -> Self {
+				Self::$as(value.into())
+			}
+		}
+	};
+	(try $as: ident, $from: ty) => {
+		impl TryFrom<$from> for Constant {
+			type Error = ::std::num::TryFromIntError;
+			fn try_from(value: $from) -> Result<Self, Self::Error> {
+				Ok(Self::$as(value.try_into()?))
+			}
+		}
+	};
+}
+
+impl_from!(Boolean, bool);
+impl_from!(try Number, isize);
+impl_from!(try Number, usize);
+impl_from!(try Number, i64);
+impl_from!(try Number, u64);
+impl_from!(Number, u32);
+impl_from!(Number, i32);
+impl_from!(String, String);
+impl_from!(String, &str);
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn test_into() {
+		// test that this compiles
+		Expression::new_constant(());
+		Expression::new_constant(true);
+		Expression::new_constant(42);
+		Expression::new_constant("foobar");
+	}
+}