1 files changed, 59 insertions, 0 deletions
diff --git a/users/tazjin/rlox/src/treewalk/errors.rs b/users/tazjin/rlox/src/treewalk/errors.rs
new file mode 100644
index 000000000000..391663d51b18
--- /dev/null
+++ b/users/tazjin/rlox/src/treewalk/errors.rs
@@ -0,0 +1,59 @@
+use crate::scanner::ScannerError;
+use crate::treewalk::interpreter::Value;
+
+use std::fmt;
+
+#[derive(Debug)]
+pub enum ErrorKind {
+    UnexpectedChar(char),
+    UnterminatedString,
+    UnmatchedParens,
+    ExpectedExpression(String),
+    ExpectedSemicolon,
+    ExpectedClosingBrace,
+    ExpectedToken(&'static str),
+    TypeError(String),
+    UndefinedVariable(String),
+    InternalError(String),
+    InvalidAssignmentTarget(String),
+    RuntimeError(String),
+    StaticError(String),
+
+    // This variant is not an error, rather it is used for
+    // short-circuiting out of a function body that hits a `return`
+    // statement.
+    //
+    // It's implemented this way because in the original book the
+    // author uses exceptions for control flow, and this is the
+    // closest equivalent that I had available without diverging too
+    // much.
+    FunctionReturn(Value),
+}
+
+#[derive(Debug)]
+pub struct Error {
+    pub line: usize,
+    pub kind: ErrorKind,
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "[line {}] Error: {:?}", self.line, self.kind)
+    }
+}
+
+impl From<ScannerError> for Error {
+    fn from(err: ScannerError) -> Self {
+        match err {
+            ScannerError::UnexpectedChar { line, unexpected } => Error {
+                line,
+                kind: ErrorKind::UnexpectedChar(unexpected),
+            },
+
+            ScannerError::UnterminatedString { line } => Error {
+                line,
+                kind: ErrorKind::UnterminatedString,
+            },
+        }
+    }
+}