first pass at prefix rules

codex-rs/execpolicy2/src/error.rs

@@ -0,0 +1,19 @@
+use thiserror::Error;
+
+pub type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("invalid decision: {0}")]
+    InvalidDecision(String),
+    #[error("invalid pattern element: {0}")]
+    InvalidPattern(String),
+    #[error("failed to tokenize example `{example}`: {reason}")]
+    TokenizationFailed { example: String, reason: String },
+    #[error("expected example to match rule `{rule_id}`: {example}")]
+    ExampleDidNotMatch { rule_id: String, example: String },
+    #[error("expected example to not match rule `{rule_id}`: {example}")]
+    ExampleDidMatch { rule_id: String, example: String },
+    #[error("starlark error: {0}")]
+    Starlark(String),
+}