Statement scheduler (WIP)

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

tests/scheduler/mod.rs

@@ -0,0 +1,104 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+use anyhow::{bail, Result};
+
+use regorus::scheduler::*;
+
+fn make_info<'a>(definitions: &[(&'a str, &[&'a str])]) -> StmtInfo<'a> {
+    StmtInfo {
+        definitions: definitions
+            .iter()
+            .map(|d| Definition {
+                var: d.0,
+                used_vars: d.1.to_vec(),
+            })
+            .collect(),
+    }
+}
+
+fn print_stmts(stmts: &[&str], order: &[usize]) {
+    for idx in order.iter().cloned() {
+        println!("{}", stmts[idx]);
+    }
+}
+
+fn check_result(stmts: &[&str], expected: &[&str], r: SortResult) -> Result<()> {
+    match r {
+        SortResult::Order(order) => {
+            print_stmts(stmts, &order);
+            for (i, o) in order.iter().cloned().enumerate() {
+                assert_eq!(stmts[o], expected[i]);
+            }
+            Ok(())
+        }
+        _ => bail!("scheduling failed"),
+    }
+}
+
+#[test]
+fn case1() -> Result<()> {
+    let stmts = vec![
+        "v = x",
+        "x > 10",
+        "x = y + z",
+        "y = [1, 2, 4][_]",
+        "z = [4, 8][_]",
+        "x = 5",
+        "v = 1",
+    ];
+
+    let expected = vec![
+        "v = 1",
+        "v = x",
+        "x = 5",
+        "x > 10",
+        "y = [1, 2, 4][_]",
+        "z = [4, 8][_]",
+        "x = y + z",
+    ];
+
+    let mut infos = vec![
+        make_info(&[("v", &["x"]), ("x", &["v"])]),
+        make_info(&[("", &["x"])]),
+        make_info(&[("x", &["y", "z"])]),
+        make_info(&[("y", &[])]),
+        make_info(&[("z", &[])]),
+        make_info(&[("x", &[])]),
+        make_info(&[("v", &[])]),
+    ];
+
+    check_result(&stmts[..], &expected[..], schedule(&mut infos)?)
+}
+
+#[test]
+#[ignore = "destructing needs more thought. Hoist exprs and introduce new assignments?"]
+fn case2() -> Result<()> {
+    let stmts = vec!["[x, y+1] = [y, p]", "value = x + p", "y = 5"];
+
+    let expected = vec!["y = 5", "[x, y+1] = [y, p]", "value = x + p"];
+
+    let mut infos = vec![
+        make_info(&[("y", &[])]),
+        make_info(&[("value", &["x", "p"])]),
+        make_info(&[("x", &["y"]), ("y", &["x"]), ("p", &["y"])]),
+    ];
+
+    check_result(&stmts[..], &expected[..], schedule(&mut infos)?)
+}
+
+#[test]
+fn case2_rewritten() -> Result<()> {
+    let stmts = vec!["y+1 = p", "x = y", "value = x + p", "y = 5"];
+
+    let expected = vec!["y = 5", "y+1 = p", "x = y", "value = x + p"];
+
+    let mut infos = vec![
+        make_info(&[("p", &["y"])]),
+        make_info(&[("x", &["y"])]),
+        make_info(&[("value", &["x", "p"])]),
+        make_info(&[("y", &[])]),
+    ];
+
+    check_result(&stmts[..], &expected[..], schedule(&mut infos)?)
+}

tests/tests.rs

@@ -4,4 +4,5 @@
 mod interpreter;
 mod lexer;
 mod parser;
+mod scheduler;
 mod value;