implement vm-based engine

1 files changed, 36 insertions, 0 deletions

diff --git a/src/vm.rs b/src/vm.rs
new file mode 100644
index 0000000..e780e96
--- /dev/null
+++ b/src/vm.rs
@@ -0,0 +1,36 @@
+use crate::syntax::ast::Regex;
+
+pub mod compile;
+pub mod instr;
+pub mod vm;
+
+pub fn is_match(re: Regex, s: &str) -> bool {
+    let instrs = compile::compile(&re);
+    vm::run(&instrs, s.as_bytes())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn re(p: &str) -> Regex {
+        use crate::syntax::parse::parse;
+        parse(p).unwrap()
+    }
+
+    #[test]
+    fn matches() {
+        assert!(is_match(re("a"), "a"));
+        assert!(is_match(re("a*"), ""));
+        assert!(is_match(re("a*"), "a"));
+        assert!(is_match(re("a|b*"), "a"));
+        assert!(is_match(re("a|b*"), "bb"));
+        assert!(is_match(re("(a|b)*"), "abababaa"));
+        assert!(is_match(re("a*b*"), "abb"));
+    }
+
+    #[test]
+    fn does_not_match() {
+        assert!(!is_match(re("a"), "b"));
+    }
+}