feat: Expand the Command API with iterators and helpers. (#100)

- Uses the `Units` iterator from #96 to provide multiple iterators over
the units of a command.
- Adds helper methods in `Command` to query the `nodetype` and `optype`,
unit counts, etc.

Closes #85

compile-matcher/src/main.rs

@@ -2,9 +2,6 @@ use std::fs;
 use std::path::Path;
 
 use clap::Parser;
-use hugr::hugr::views::{HierarchyView, SiblingGraph};
-use hugr::ops::handle::DfgID;
-use hugr::HugrView;
 use itertools::Itertools;
 
 use tket2::json::load_tk1_json_file;
@@ -65,9 +62,8 @@ fn main() {
     let patterns = all_circs
         .iter()
         .filter_map(|circ| {
-            let circ: SiblingGraph<'_, DfgID> = SiblingGraph::new(circ, circ.root());
             // Fail silently on empty or disconnected patterns
-            CircuitPattern::try_from_circuit(&circ).ok()
+            CircuitPattern::try_from_circuit(circ).ok()
         })
         .collect_vec();
     println!("Loaded {} patterns.", patterns.len());

src/circuit.rs

@@ -7,7 +7,6 @@ mod units;
 pub use command::{Command, CommandIterator};
 pub use hash::CircuitHash;
 
-use hugr::hugr::NodeType;
 use hugr::HugrView;
 
 pub use hugr::ops::OpType;
@@ -119,16 +118,6 @@ pub trait Circuit: HugrView {
         // Traverse the circuit in topological order.
         CommandIterator::new(self)
     }
-
-    /// Returns the [`NodeType`] of a command.
-    fn command_nodetype(&self, command: &Command) -> &NodeType {
-        self.get_nodetype(command.node())
-    }
-
-    /// Returns the [`OpType`] of a command.
-    fn command_optype(&self, command: &Command) -> &OpType {
-        self.get_optype(command.node())
-    }
 }
 
 impl<T> Circuit for T where T: HugrView {}