output: more big refactors

dsl/src/dsl_expr.rs

@@ -63,7 +63,7 @@ dsl_type!(DslExpr {
                     ).into())
                 };
             )*
-            Ok(Some($body as $Type))
+            Ok(Some($body/* as $Type*/))
         };
         ($name, get)
     }),* )? ];
@@ -74,12 +74,14 @@ pub trait DslNsExprs<'a, T: 'a>: 'a {
     const EXPRS: DslExprs<'a, Self, T> = &[];
     /// Resolve an expression if known.
     fn from_expr (&'a self, dsl: impl DslExpr + 'a) -> Perhaps<T> {
-        let head = dsl.head()?;
-        for (key, get) in Self::EXPRS.iter() {
-            if Some(*key) == head {
-                return get(self, dsl.tail()?.unwrap_or(""))
+        if let Some(dsl) = dsl.expr()? {
+            let head = dsl.head()?;
+            for (key, get) in Self::EXPRS.iter() {
+                if Some(*key) == head {
+                    return get(self, dsl.tail()?.unwrap_or(""))
+                }
             }
         }
-        return Ok(None)
+        Ok(None)
     }
 }

dsl/src/dsl_ns.rs

@@ -16,3 +16,31 @@ pub trait DslNs<'a, T: 'a>: DslNsWords<'a, T> + DslNsExprs<'a, T> {
         Ok(None)
     }
 }
+
+#[macro_export] macro_rules! dsl_ns {
+    ($State:ty: $Type:ty {
+        $(literal = |$dsl:ident| $literal:expr;)?
+        $(word = |$state_w:ident| {
+            $($word:literal => $body_w:expr),* $(,)?
+        };)?
+        $(expr = |$state_e:ident| {
+            $($head:literal $args:tt => $body_e:expr),* $(,)?
+        };)?
+    }) => {
+        impl<'a> DslNs<'a, $Type> for $State {
+            $(fn from_literal (&self, $dsl: impl Dsl) -> Perhaps<$Type> {
+                $literal
+            })?
+        }
+        impl<'a> DslNsWords<'a, $Type> for $State {
+            $(dsl_words! { 'a |$state_w| -> $Type {
+                $($word => $body_w),*
+            } })?
+        }
+        impl<'a> DslNsExprs<'a, $Type> for $State {
+            $(dsl_exprs! { 'a |$state_e| -> $Type {
+                $($head $args => $body_e),*
+            } })?
+        }
+    }
+}