Initial commit

3 files changed, 94 insertions, 0 deletions

diff --git a/src/common/env.rs b/src/common/env.rs
new file mode 100644
index 000000000000..8b5cde49e9e4
--- /dev/null
+++ b/src/common/env.rs
@@ -0,0 +1,40 @@
+use std::collections::HashMap;
+
+use crate::ast::Ident;
+
+/// A lexical environment
+#[derive(Debug, PartialEq, Eq)]
+pub struct Env<'ast, V>(Vec<HashMap<&'ast Ident<'ast>, V>>);
+
+impl<'ast, V> Default for Env<'ast, V> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<'ast, V> Env<'ast, V> {
+    pub fn new() -> Self {
+        Self(vec![Default::default()])
+    }
+
+    pub fn push(&mut self) {
+        self.0.push(Default::default());
+    }
+
+    pub fn pop(&mut self) {
+        self.0.pop();
+    }
+
+    pub fn set(&mut self, k: &'ast Ident<'ast>, v: V) {
+        self.0.last_mut().unwrap().insert(k, v);
+    }
+
+    pub fn resolve<'a>(&'a self, k: &'ast Ident<'ast>) -> Option<&'a V> {
+        for ctx in self.0.iter().rev() {
+            if let Some(res) = ctx.get(k) {
+                return Some(res);
+            }
+        }
+        None
+    }
+}
diff --git a/src/common/error.rs b/src/common/error.rs
new file mode 100644
index 000000000000..f3f3023ceaf8
--- /dev/null
+++ b/src/common/error.rs
@@ -0,0 +1,50 @@
+use std::{io, result};
+
+use thiserror::Error;
+
+use crate::{codegen, interpreter, parser};
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    IOError(#[from] io::Error),
+
+    #[error("Error parsing input: {0}")]
+    ParseError(#[from] parser::Error),
+
+    #[error("Error evaluating expression: {0}")]
+    EvalError(#[from] interpreter::Error),
+
+    #[error("Compile error: {0}")]
+    CodegenError(#[from] codegen::Error),
+
+    #[error("{0}")]
+    Message(String),
+}
+
+impl From<String> for Error {
+    fn from(s: String) -> Self {
+        Self::Message(s)
+    }
+}
+
+impl<'a> From<nom::Err<nom::error::Error<&'a str>>> for Error {
+    fn from(e: nom::Err<nom::error::Error<&'a str>>) -> Self {
+        use nom::error::Error as NomError;
+        use nom::Err::*;
+
+        Self::ParseError(match e {
+            Incomplete(i) => Incomplete(i),
+            Error(NomError { input, code }) => Error(NomError {
+                input: input.to_owned(),
+                code,
+            }),
+            Failure(NomError { input, code }) => Failure(NomError {
+                input: input.to_owned(),
+                code,
+            }),
+        })
+    }
+}
+
+pub type Result<T> = result::Result<T, Error>;
diff --git a/src/common/mod.rs b/src/common/mod.rs
new file mode 100644
index 000000000000..af5974a116fb
--- /dev/null
+++ b/src/common/mod.rs
@@ -0,0 +1,4 @@
+pub(crate) mod env;
+pub(crate) mod error;
+
+pub use error::{Error, Result};