feat(modules): add import!() expression (#898)

hydroflow/examples/modules/main.rs

@@ -0,0 +1,48 @@
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use hydroflow::hydroflow_syntax;
+use hydroflow::scheduled::graph::Hydroflow;
+use hydroflow::util::multiset::HashMultiSet;
+
+pub fn main() {
+    let output = Rc::new(RefCell::new(
+        HashMultiSet::<(usize, usize, usize)>::default(),
+    ));
+
+    let mut df: Hydroflow = {
+        let output = output.clone();
+        hydroflow_syntax! {
+            source_iter(0..2) -> [0]cj;
+            source_iter(0..2) -> [1]cj;
+            source_iter(0..2) -> [2]cj;
+
+            cj = import!("triple_cross_join.hf")
+                -> for_each(|x| output.borrow_mut().insert(x));
+        }
+    };
+
+    println!("{}", df.meta_graph().unwrap().to_mermaid());
+
+    df.run_available();
+
+    #[rustfmt::skip]
+    assert_eq!(
+        *output.borrow(),
+        HashMultiSet::from_iter([
+            (0, 0, 0),
+            (0, 0, 1),
+            (0, 1, 0),
+            (0, 1, 1),
+            (1, 0, 0),
+            (1, 0, 1),
+            (1, 1, 0),
+            (1, 1, 1),
+        ])
+    );
+}
+
+#[test]
+fn test() {
+    main();
+}

hydroflow/examples/modules/triple_cross_join.hf

@@ -0,0 +1,15 @@
+mod[0]
+    -> [0]cj1;
+
+mod[1]
+    -> [1]cj1;
+
+cj1 = cross_join()
+    -> [0]cj2;
+
+mod[2]
+    -> [1]cj2;
+
+cj2 = cross_join()
+    -> map(|((a, b), c)| (a, b, c))
+    -> mod;

hydroflow/tests/compile-fail/surface_syntax_eol_arrow.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected one of: square brackets, identifier, parentheses
+error: unexpected end of input, expected one of: square brackets, `mod`, identifier, parentheses
  --> tests/compile-fail/surface_syntax_eol_arrow.rs:4:18
   |
 4 |       let mut df = hydroflow_syntax! {

hydroflow/tests/compile-fail/surface_syntax_eol_indexing.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected parentheses or identifier
+error: unexpected end of input, expected one of: parentheses, identifier, `mod`
  --> tests/compile-fail/surface_syntax_eol_indexing.rs:4:18
   |
 4 |       let mut df = hydroflow_syntax! {

hydroflow/tests/compile-fail/surface_syntax_eol_missingop.stderr

@@ -1,4 +1,4 @@
-error: expected one of: square brackets, identifier, parentheses
+error: expected one of: square brackets, `mod`, identifier, parentheses
  --> tests/compile-fail/surface_syntax_eol_missingop.rs:5:31
   |
 5 |         source_iter(0..10) -> ;

hydroflow/tests/compile-fail/surface_syntax_indexing_empty.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected one of: square brackets, identifier, parentheses
+error: unexpected end of input, expected one of: square brackets, `mod`, identifier, parentheses
  --> tests/compile-fail/surface_syntax_indexing_empty.rs:5:35
   |
 5 |         source_iter(0..10) -> [0]();

hydroflow/tests/compile-fail/surface_syntax_paren_arrow.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected one of: square brackets, identifier, parentheses
+error: unexpected end of input, expected one of: square brackets, `mod`, identifier, parentheses
  --> tests/compile-fail/surface_syntax_paren_arrow.rs:5:31
   |
 5 |         (source_iter(0..10) ->);

hydroflow/tests/compile-fail/surface_syntax_paren_indexing.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected parentheses or identifier
+error: unexpected end of input, expected one of: parentheses, identifier, `mod`
  --> tests/compile-fail/surface_syntax_paren_indexing.rs:5:35
   |
 5 |         (source_iter(0..10) -> [0]);

hydroflow/tests/compile-fail/surface_syntax_paren_missingop.stderr

@@ -1,4 +1,4 @@
-error: unexpected end of input, expected one of: square brackets, identifier, parentheses
+error: unexpected end of input, expected one of: square brackets, `mod`, identifier, parentheses
  --> tests/compile-fail/surface_syntax_paren_missingop.rs:5:32
   |
 5 |         (source_iter(0..10) -> );

hydroflow_datalog_core/src/lib.rs

@@ -266,17 +266,22 @@ pub fn gen_hydroflow_graph(
     }
 
     if !diagnostics.is_empty() {
-        Err(diagnostics)
-    } else {
-        let (mut flat_graph, _uses, mut diagnostics) = flat_graph_builder.build();
-        diagnostics.retain(Diagnostic::is_error);
-        if !diagnostics.is_empty() {
-            Err(diagnostics)
-        } else {
-            eliminate_extra_unions_tees(&mut flat_graph);
-            Ok(flat_graph)
-        }
+        return Err(diagnostics);
     }
+
+    let (mut flat_graph, _uses, mut diagnostics) = flat_graph_builder.build();
+    diagnostics.retain(Diagnostic::is_error);
+    if !diagnostics.is_empty() {
+        return Err(diagnostics);
+    }
+
+    if let Err(err) = flat_graph.merge_modules() {
+        diagnostics.push(err);
+        return Err(diagnostics);
+    }
+
+    eliminate_extra_unions_tees(&mut flat_graph);
+    Ok(flat_graph)
 }
 
 fn handle_errors(

hydroflow_lang/src/graph/di_mul_graph.rs

@@ -180,6 +180,27 @@ where
         Some((new_edge, (pred_edge, succ_edge)))
     }
 
+    /// Remove an edge from the graph. If the edgeId is found then the edge is removed from the graph and returned.
+    /// If the edgeId was not found in the graph then nothing is returned and nothing is done.
+    pub fn remove_edge(&mut self, e: E) -> Option<(V, V)> {
+        let Some((src, dst)) = self.edges.remove(e) else {
+            return None;
+        };
+
+        self.succs[src].retain(|x| *x != e);
+        self.preds[dst].retain(|x| *x != e);
+
+        Some((src, dst))
+    }
+
+    /// Remove a vertex from the graph, it must have no edges to or from it when doing this.
+    pub fn remove_vertex(&mut self, v: V) {
+        assert!(self.preds[v].is_empty() && self.succs[v].is_empty());
+
+        self.preds.remove(v);
+        self.succs.remove(v);
+    }
+
     /// Get the source and destination vertex IDs for the given edge ID.
     pub fn edge(&self, e: E) -> Option<(V, V)> {
         self.edges.get(e).copied()