dsl: add ns

dsl/src/dsl.rs

@@ -81,7 +81,7 @@ pub const fn peek_tail (src: &str) -> DslPerhaps<&str> {
         Ok(None) => Ok(None),
         Ok(Some((start, length))) => {
             let tail = str_range(src, start + length, src.len());
-            for_each!((i, c) in char_indices(tail) => if !is_space(c) { return Ok(Some(tail)) });
+            for_each!((_i, c) in char_indices(tail) => if !is_space(c) { return Ok(Some(tail)) });
             Ok(None)
         },
     }

dsl/src/dsl_conv.rs

@@ -1,5 +1,43 @@
 use crate::*;
 
+/// Namespace. Currently linearly searched.
+pub struct DslNs<'t, T: 't>(pub &'t [(&'t str, T)]);
+
+/// Namespace where keys are symbols.
+pub trait DslSymNs<'t, T: 't>: 't {
+    const SYMS: DslNs<'t, fn (&'t Self)->T>;
+    fn from_sym <D: Dsl> (&'t self, dsl: D) -> Usually<T> {
+        if let Some(dsl) = dsl.sym()? {
+            for (sym, get) in Self::SYMS.0 {
+                if dsl == *sym {
+                    return Ok(get(self))
+                }
+            }
+        }
+        return Err(format!("not found: sym: {dsl:?}").into())
+    }
+}
+
+#[macro_export] macro_rules! dsl_sym (
+    (|$state:ident:$State:ty| -> $type:ty {$($lit:literal => $exp:expr),* $(,)?})=>{
+        impl<'t> DslSymNs<'t, $type> for $State {
+            const SYMS: DslNs<'t, fn (&'t $State)->$type> =
+                DslNs(&[$(($lit, |$state: &$State|$exp)),*]); } });
+
+pub trait DslExpNs<'t, T: 't>: 't {
+    const EXPS: DslNs<'t, fn (&'t Self, &str)->T>;
+}
+
+#[macro_export] macro_rules! dsl_exp (
+    (|$state:ident:$State:ty|->$type:ty { $(
+        [$key:literal $(/ $sub:ident: $Sub:ty)? $(, $arg:ident $(?)? :$argtype:ty)*] => $body:expr
+    ),* $(,)? }) => {
+        impl<'t> DslExpNs<'t, $type> for $State {
+            const EXPS: DslNs<'t, fn (&'t $State, &str)->$type> =
+                DslNs(&[]); } });
+
+// TODO DEPRECATE:
+
 /// `T` + [Dsl] -> `Self`.
 pub trait FromDsl<T>: Sized {
     fn from_dsl (state: &T, dsl: &impl Dsl) -> Perhaps<Self>;