dsl: add dsl_words, dsl_exprs, from_literal

dsl/src/dsl.rs

@@ -289,22 +289,16 @@ fn ok_flat <T> (x: Option<DslPerhaps<T>>) -> DslPerhaps<T> {
     // Special form for numeric types
     (num |$state:ident : $State: ty| -> $Type:ty { $( $pat:tt => $body:expr ),* $(,)? }) => {
         impl<'t> DslNs<'t, $Type> for $State {
-            const WORDS: DslNsMap<'t, fn (&'t $State)->Perhaps<$Type>> =
+            const WORDS: DslNsMap<'t, fn (&$State)->Perhaps<$Type>> =
                 DslNsMap::new(&[$(dsl_ns!{@word ($state: $State) -> $Type { $pat => $body }}),*]);
-            const EXPRS: DslNsMap<'t, fn (&'t $State, &str)->Perhaps<$Type>> =
+            const EXPRS: DslNsMap<'t, fn (&$State, &str)->Perhaps<$Type>> =
                 DslNsMap::new(&[$(dsl_ns!{@exp ($state: $State) -> $Type { $pat => $body }}),*]);
-            fn from <D: Dsl> (&'t self, dsl: D) -> Perhaps<$Type> {
-                if let Ok(Some(src)) = dsl.src() {
-                    if let Ok(num) = to_number(src) {
-                        Ok(Some(num as $Type))
-                    } else if let Ok(Some(src)) = src.word() {
-                        self.from_word(src)
-                    } else {
-                        self.from_expr(src)
-                    }
+            fn from_literal <D: Dsl> (&self, dsl: &D) -> Perhaps<$Type> {
+                Ok(if let Some(src) = dsl.src()? {
+                    Some(to_number(src)? as $Type)
                 } else {
-                    Ok(None)
-                }
+                    None
+                })
             }
         }
     };
@@ -315,9 +309,9 @@ fn ok_flat <T> (x: Option<DslPerhaps<T>>) -> DslPerhaps<T> {
     // Regular form for single type
     (|$state:ident : $State: ty| -> $Type:ty { $( $pat:tt => $body:expr ),* $(,)? }) => {
         impl<'t> DslNs<'t, $Type> for $State {
-            const WORDS: DslNsMap<'t, fn (&'t $State)->Perhaps<$Type>> =
+            const WORDS: DslNsMap<'t, fn (&$State)->Perhaps<$Type>> =
                 DslNsMap::new(&[$(dsl_ns!{@word ($state: $State) -> $Type { $pat => $body }}),*]);
-            const EXPRS: DslNsMap<'t, fn (&'t $State, &str)->Perhaps<$Type>> =
+            const EXPRS: DslNsMap<'t, fn (&$State, &str)->Perhaps<$Type>> =
                 DslNsMap::new(&[$(dsl_ns!{@exp ($state: $State) -> $Type { $pat => $body }}),*]);
         }
     };
@@ -358,34 +352,36 @@ fn ok_flat <T> (x: Option<DslPerhaps<T>>) -> DslPerhaps<T> {
 
 pub trait DslNs<'t, T: 't>: 't {
     /// Known symbols.
-    const WORDS: DslNsMap<'t, fn (&'t Self)->Perhaps<T>> = DslNsMap::new(&[]);
+    const WORDS: DslNsMap<'t, fn (&Self)->Perhaps<T>> = DslNsMap::new(&[]);
     /// Known expressions.
-    const EXPRS: DslNsMap<'t, fn (&'t Self, &str)->Perhaps<T>> = DslNsMap::new(&[]);
+    const EXPRS: DslNsMap<'t, fn (&Self, &str)->Perhaps<T>> = DslNsMap::new(&[]);
     /// Resolve an expression or symbol.
-    fn from <D: Dsl> (&'t self, dsl: D) -> Perhaps<T> {
-        if let Ok(Some(src)) = dsl.src() {
-            if let Ok(Some(src)) = src.word() {
-                self.from_word(src)
-            } else {
-                self.from_expr(src)
-            }
+    fn from <D: Dsl> (&self, dsl: &D) -> Perhaps<T> {
+        if let Ok(Some(literal)) = self.from_literal(dsl) {
+            Ok(Some(literal))
+        } else if let Ok(Some(meaning)) = self.from_word(dsl) {
+            Ok(Some(meaning))
         } else {
-            Ok(None)
+            self.from_expr(dsl)
         }
     }
+    /// Resolve as literal if valid.
+    fn from_literal <D: Dsl> (&self, dsl: &D) -> Perhaps<T> {
+        Ok(None)
+    }
     /// Resolve a symbol if known.
-    fn from_word <D: Dsl> (&'t self, dsl: D) -> Perhaps<T> {
+    fn from_word <D: Dsl> (&self, dsl: &D) -> Perhaps<T> {
         if let Some(dsl) = dsl.word()? {
-            for (word, get) in Self::WORDS.0 { if dsl == *word { return get(self) } }
+            for (key, get) in Self::WORDS.0 { if dsl == *key { return get(self) } }
         }
         return Ok(None)
     }
     /// Resolve an expression if known.
-    fn from_expr <D: Dsl> (&'t self, dsl: D) -> Perhaps<T> {
-        if let Some(head) = dsl.expr().head()? {
-            for (key, value) in Self::EXPRS.0.iter() {
-                if head == *key {
-                    return value(self, dsl.expr().tail()?.unwrap_or(""))
+    fn from_expr <D: Dsl> (&self, dsl: &D) -> Perhaps<T> {
+        if let Some(expr) = dsl.expr()? {
+            for (key, get) in Self::EXPRS.0.iter() {
+                if Some(*key) == expr.head()? {
+                    return get(self, &expr.tail()?.unwrap_or(""))
                 }
             }
         }
@@ -400,3 +396,35 @@ impl<'t, T: Debug + 't> DslNsMap<'t, T> {
     /// Populate a namespace with pre-existing values.
     pub const fn new (data: &'t [(&'t str, T)]) -> Self { Self(data) /* TODO a search trie */ }
 }
+
+#[macro_export] macro_rules!dsl_words((|$state:ident|->$Type:ty$({
+    $($word:literal => $body:expr),* $(,)?
+})?)=>{
+    const WORDS: DslNsMap<'t, fn (&Self)->Perhaps<$Type>> = DslNsMap::new(&[$(
+        $(($word, |$state: &Self|{Ok(Some($body))})),*
+    )? ]);
+});
+
+
+#[macro_export] macro_rules!dsl_exprs((|$state:ident|->$Type:ty$({
+    $($name:literal ($($arg:ident:$ty:ty),* $(,)?) => $body:expr),* $(,)?
+})?)=>{
+    const EXPRS: DslNsMap<'t, fn (&Self, &str)->Perhaps<$Type>> = DslNsMap::new(&[$(
+        $(($name, |$state: &Self, tail: &str|{
+            $(
+                let head = tail.head()?.unwrap_or_default();
+                let tail = tail.tail()?.unwrap_or_default();
+                let $arg: $ty = if let Some(arg) = $state.from(&head)? {
+                    arg
+                } else {
+                    return Err(format!("{}: arg \"{}\" ({}) got: {head} {tail}",
+                        $name,
+                        stringify!($arg),
+                        stringify!($ty),
+                    ).into())
+                };
+            )*
+            Ok(Some($body))
+        })),*
+    )? ]);
+});