first pass at prefix rules

codex-rs/execpolicy2/src/policy.rs

@@ -0,0 +1,59 @@
+use crate::decision::Decision;
+use crate::rule::Rule;
+use crate::rule::RuleMatch;
+use serde::Deserialize;
+use serde::Serialize;
+
+#[derive(Clone, Debug)]
+pub struct Policy {
+    rules: Vec<Rule>,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
+pub struct Evaluation {
+    pub rule_id: String,
+    pub decision: Decision,
+    pub matched_prefix: Vec<String>,
+    pub remainder: Vec<String>,
+}
+
+impl From<RuleMatch> for Evaluation {
+    fn from(value: RuleMatch) -> Self {
+        Self {
+            rule_id: value.rule_id,
+            decision: value.decision,
+            matched_prefix: value.matched_prefix,
+            remainder: value.remainder,
+        }
+    }
+}
+
+impl Policy {
+    pub fn new(rules: Vec<Rule>) -> Self {
+        Self { rules }
+    }
+
+    pub fn rules(&self) -> &[Rule] {
+        &self.rules
+    }
+
+    pub fn evaluate(&self, cmd: &[String]) -> Option<Evaluation> {
+        let mut best: Option<Evaluation> = None;
+        for rule in &self.rules {
+            if let Some(matched) = rule.matches(cmd) {
+                let eval = Evaluation::from(matched);
+                best = match best {
+                    None => Some(eval),
+                    Some(current) => {
+                        if eval.decision.is_stricter_than(current.decision) {
+                            Some(eval)
+                        } else {
+                            Some(current)
+                        }
+                    }
+                };
+            }
+        }
+        best
+    }
+}