feat(modules): add import!() expression

hydroflow/examples/modules/main.rs

@@ -0,0 +1,46 @@
+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));
+        }
+    };
+
+    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 @@
+input[0]
+    -> [0]cj1;
+
+input[1]
+    -> [1]cj1;
+
+cj1 = cross_join()
+    -> [0]cj2;
+
+input[2]
+    -> [1]cj2;
+
+cj2 = cross_join()
+    -> map(|((a, b), c)| (a, b, c))
+    -> output;

hydroflow_datalog_core/src/lib.rs

@@ -273,6 +273,7 @@ pub fn gen_hydroflow_graph(
         if !diagnostics.is_empty() {
             Err(diagnostics)
         } else {
+            flat_graph.merge_modules();
             eliminate_extra_unions_tees(&mut flat_graph);
             Ok(flat_graph)
         }

hydroflow_lang/src/graph/di_mul_graph.rs

@@ -180,6 +180,26 @@ 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.edges.values().any(|(v1, v2)| *v1 == v || *v2 == v),);
+        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()

hydroflow_lang/src/graph/flat_graph_builder.rs

@@ -3,11 +3,12 @@
 use std::borrow::Cow;
 use std::collections::btree_map::Entry;
 use std::collections::{BTreeMap, BTreeSet};
+use std::path::PathBuf;
 
 use proc_macro2::Span;
 use quote::ToTokens;
 use syn::spanned::Spanned;
-use syn::{Ident, ItemUse};
+use syn::{Error, Ident, ItemUse};
 
 use super::ops::find_op_op_constraints;
 use super::{GraphNodeId, HydroflowGraph, Node, PortIndexValue};
@@ -44,6 +45,16 @@ pub struct FlatGraphBuilder {
 
     /// Use statements.
     uses: Vec<ItemUse>,
+
+    /// In order to make import!() statements relative to the current file, we need to know where the file is that is building the flat graph.
+    macro_invocation_path: PathBuf,
+
+    /// If the flat graph is being loaded as a module, then there are some additional things that happen
+    /// 1. the varname 'input' and 'output' is reserved and used for the input and output of the module.
+    /// 2. two initial module boundary nodes are inserted into the graph before statements are processed, one input and one output.
+    is_module: bool,
+    input_node: GraphNodeId,
+    output_node: GraphNodeId,
 }
 
 impl FlatGraphBuilder {
@@ -53,8 +64,42 @@ impl FlatGraphBuilder {
     }
 
     /// Convert the Hydroflow code AST into a graph builder.
-    pub fn from_hfcode(input: HfCode) -> Self {
-        input.into()
+    pub fn from_hfcode(input: HfCode, macro_invocation_path: PathBuf) -> Self {
+        let mut builder = Self {
+            macro_invocation_path,
+            ..Default::default()
+        };
+        builder.process_statements(input.statements);
+
+        builder
+    }
+
+    /// Convert the Hydroflow code AST into a graph builder.
+    pub fn from_hfmodule(input: HfCode) -> Self {
+        let mut builder = Self::default();
+        builder.is_module = true;
+        builder.input_node = builder.flat_graph.insert_node(
+            Node::ModuleBoundary {
+                input: true,
+                import_expr: Span::call_site(),
+            },
+            Some(Ident::new("input", Span::call_site())),
+        );
+        builder.output_node = builder.flat_graph.insert_node(
+            Node::ModuleBoundary {
+                input: false,
+                import_expr: Span::call_site(),
+            },
+            Some(Ident::new("output", Span::call_site())),
+        );
+        builder.process_statements(input.statements);
+        builder
+    }
+
+    fn process_statements(&mut self, statements: impl IntoIterator<Item = HfStatement>) {
+        for stmt in statements {
+            self.add_statement(stmt);
+        }
     }
 
     /// Build into an unpartitioned [`HydroflowGraph`], returning a tuple of a `HydroflowGraph` and
@@ -77,7 +122,13 @@ impl FlatGraphBuilder {
             }
             HfStatement::Named(named) => {
                 let stmt_span = named.span();
-                let ends = self.add_pipeline(named.pipeline, Some(&named.name));
+                let ends = match self.add_pipeline(named.pipeline, Some(&named.name)) {
+                    Err(err) => {
+                        self.diagnostics.push(err.into());
+                        return;
+                    }
+                    Ok(ends) => ends,
+                };
                 match self.varname_ends.entry(named.name) {
                     Entry::Vacant(vacant_entry) => {
                         vacant_entry.insert(Ok(ends));
@@ -106,33 +157,57 @@ impl FlatGraphBuilder {
                 }
             }
             HfStatement::Pipeline(pipeline_stmt) => {
-                self.add_pipeline(pipeline_stmt.pipeline, None);
+                if let Err(err) = self.add_pipeline(pipeline_stmt.pipeline, None) {
+                    self.diagnostics.push(err.into());
+                }
             }
         }
     }
 
     /// Helper: Add a pipeline, i.e. `a -> b -> c`. Return the input and output ends for it.
-    fn add_pipeline(&mut self, pipeline: Pipeline, current_varname: Option<&Ident>) -> Ends {
+    fn add_pipeline(
+        &mut self,
+        pipeline: Pipeline,
+        current_varname: Option<&Ident>,
+    ) -> syn::Result<Ends> {
         match pipeline {
             Pipeline::Paren(ported_pipeline_paren) => {
                 let (inn_port, pipeline_paren, out_port) =
                     PortIndexValue::from_ported(ported_pipeline_paren);
-                let og_ends = self.add_pipeline(*pipeline_paren.pipeline, current_varname);
-                Self::helper_combine_ends(&mut self.diagnostics, og_ends, inn_port, out_port)
+                let og_ends = self.add_pipeline(*pipeline_paren.pipeline, current_varname)?;
+                Ok(Self::helper_combine_ends(
+                    &mut self.diagnostics,
+                    og_ends,
+                    inn_port,
+                    out_port,
+                ))
             }
             Pipeline::Name(pipeline_name) => {
                 let (inn_port, ident, out_port) = PortIndexValue::from_ported(pipeline_name);
-                // We could lookup non-forward references immediately, but easier to just have one
-                // consistent code path. -mingwei
-                Ends {
-                    inn: Some((inn_port, GraphDet::Undetermined(ident.clone()))),
-                    out: Some((out_port, GraphDet::Undetermined(ident))),
+
+                if self.is_module && ident == "input" {
+                    Ok(Ends {
+                        inn: Some((inn_port, GraphDet::Determined(self.input_node))),
+                        out: Some((out_port, GraphDet::Determined(self.input_node))),
+                    })
+                } else if self.is_module && ident == "output" {
+                    Ok(Ends {
+                        inn: Some((inn_port, GraphDet::Determined(self.output_node))),
+                        out: Some((out_port, GraphDet::Determined(self.output_node))),
+                    })
+                } else {
+                    // We could lookup non-forward references immediately, but easier to just have one
+                    // consistent code path. -mingwei
+                    Ok(Ends {
+                        inn: Some((inn_port, GraphDet::Undetermined(ident.clone()))),
+                        out: Some((out_port, GraphDet::Undetermined(ident))),
+                    })
                 }
             }
             Pipeline::Link(pipeline_link) => {
                 // Add the nested LHS and RHS of this link.
-                let lhs_ends = self.add_pipeline(*pipeline_link.lhs, current_varname);
-                let rhs_ends = self.add_pipeline(*pipeline_link.rhs, current_varname);
+                let lhs_ends = self.add_pipeline(*pipeline_link.lhs, current_varname)?;
+                let rhs_ends = self.add_pipeline(*pipeline_link.rhs, current_varname)?;
 
                 // Outer (first and last) ends.
                 let outer_ends = Ends {
@@ -145,17 +220,103 @@ impl FlatGraphBuilder {
                     inn: rhs_ends.inn,
                 };
                 self.links.push(link_ends);
-                outer_ends
+                Ok(outer_ends)
             }
             Pipeline::Operator(operator) => {
                 let op_span = Some(operator.span());
                 let nid = self
                     .flat_graph
                     .insert_node(Node::Operator(operator), current_varname.cloned());
-                Ends {
+                Ok(Ends {
                     inn: Some((PortIndexValue::Elided(op_span), GraphDet::Determined(nid))),
                     out: Some((PortIndexValue::Elided(op_span), GraphDet::Determined(nid))),
+                })
+            }
+            Pipeline::Import(import) => {
+                // TODO: https://github.com/rust-lang/rfcs/pull/3200
+                // this would be way better...
+                let mut dir = self.macro_invocation_path.clone();
+                dir.pop();
+
+                let file_contents = std::fs::read_to_string(dir.join(import.filename.value()))
+                    .map_err(|e| {
+                        Error::new(
+                            import.filename.span(),
+                            format!("filename: {}, err: {e}", import.filename.value()),
+                        )
+                    })?;
+
+                // TODO: see also above, parse_str sets all the spans in the resulting parsed token stream to the parent macro invocation span.
+                // This means that any error inside the imported module will manifest as a giant red squiggly line under the parent hydroflow_syntax!{} call.
+                let statements = match syn::parse_str::<HfCode>(&file_contents) {
+                    Ok(code) => code,
+                    Err(err) => {
+                        self.diagnostics.push(err.clone().into());
+                        return syn::Result::Err(err);
+                    }
+                };
+
+                let flat_graph_builder = crate::graph::FlatGraphBuilder::from_hfmodule(statements);
+                let (flat_graph, _uses, diagnostics) = flat_graph_builder.build();
+                diagnostics
+                    .iter()
+                    .for_each(crate::diagnostic::Diagnostic::emit);
+
+                let mut ends = Ends {
+                    inn: None,
+                    out: None,
+                };
+
+                let mut node_mapping = BTreeMap::new();
+
+                for (nid, node) in flat_graph.nodes() {
+                    match node {
+                        Node::Operator(_) => {
+                            let varname = flat_graph.node_varname(nid);
+                            let new_id = self.flat_graph.insert_node(node.clone(), varname);
+                            node_mapping.insert(nid, new_id);
+                        }
+                        Node::ModuleBoundary { input, .. } => {
+                            let new_id = self.flat_graph.insert_node(
+                                Node::ModuleBoundary {
+                                    input: *input,
+                                    import_expr: import.span(),
+                                },
+                                Some(Ident::new(
+                                    &format!("module_{}", input.to_string()),
+                                    import.span(),
+                                )),
+                            );
+                            node_mapping.insert(nid, new_id);
+
+                            if *input {
+                                ends.inn = Some((
+                                    PortIndexValue::Elided(None),
+                                    GraphDet::Determined(new_id),
+                                ));
+                            } else {
+                                ends.out = Some((
+                                    PortIndexValue::Elided(None),
+                                    GraphDet::Determined(new_id),
+                                ));
+                            }
+                        }
+                        _ => panic!(),
+                    }
+                }
+
+                for (eid, (src, dst)) in flat_graph.edges() {
+                    let (src_port, dst_port) = flat_graph.edge_ports(eid);
+
+                    self.flat_graph.insert_edge(
+                        *node_mapping.get(&src).unwrap(),
+                        src_port.clone(),
+                        *node_mapping.get(&dst).unwrap(),
+                        dst_port.clone(),
+                    );
                 }
+
+                Ok(ends)
             }
         }
     }
@@ -515,6 +676,9 @@ impl FlatGraphBuilder {
                     );
                 }
                 Node::Handoff { .. } => todo!("Node::Handoff"),
+                Node::ModuleBoundary { .. } => {
+                    // Module boundaries don't require any checking.
+                }
             }
         }
     }
@@ -577,13 +741,3 @@ impl FlatGraphBuilder {
         }
     }
 }
-
-impl From<HfCode> for FlatGraphBuilder {
-    fn from(input: HfCode) -> Self {
-        let mut builder = Self::default();
-        for stmt in input.statements {
-            builder.add_statement(stmt);
-        }
-        builder
-    }
-}