Reorganise lex and parse under single read module

src/lib.rs

@@ -2,8 +2,8 @@ pub mod token;
 pub mod expression;
 pub mod binding;
 
-pub mod lex;
-pub mod parse;
-pub mod print;
+pub mod read;
 pub mod eval;
+pub mod print;
+
 pub mod repl;

src/read.rs

@@ -0,0 +1,34 @@
+mod lex;
+mod parse;
+
+use crate::expression::Expression;
+use parse::parse;
+
+impl std::str::FromStr for Expression {
+	type Err = parse::Error;
+
+	fn from_str(s: &str) -> Result<Self, Self::Err> {
+		parse(lex::TokenSource::new(std::io::Cursor::new(s)))
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	#[test]
+	fn expressions_can_be_read_from_string() {
+		let expr = "x - y".parse::<Expression>().unwrap();
+		assert_eq!(
+			expr,
+			Expression::difference(
+				Expression::Symbol('x'),
+				Expression::Symbol('y')));
+	}
+
+	#[test]
+	fn reading_string_with_invalid_syntax_yields_error() {
+		let result = "(x + 1".parse::<Expression>();
+		assert!(matches!(result, Err(parse::Error::InvalidSyntax)));
+	}
+}

src/read/parse.rs

@@ -1,7 +1,6 @@
 use crate::token::Token;
 use crate::expression::Expression;
 use crate::binding::{Binding, Power};
-use crate::lex::TokenSource;
 
 #[derive(Debug)]
 pub enum Error {
@@ -18,14 +17,6 @@ impl std::fmt::Display for Error {
 	}
 }
 
-impl std::str::FromStr for Expression {
-	type Err = Error;
-
-	fn from_str(s: &str) -> Result<Self, Self::Err> {
-		parse(TokenSource::new(std::io::Cursor::new(s)))
-	}
-}
-
 pub fn parse<I>(input: I) -> Result<Expression, Error>
 where I: Iterator<Item = Result<Token, std::io::Error>>
 {
@@ -502,20 +493,4 @@ mod tests {
 		let result = parse(tokens.into_iter().map(|t| Ok(t)));
 		std::assert_matches!(result, Err(Error::InvalidSyntax));
 	}
-
-	#[test]
-	fn expressions_can_be_read_from_string() {
-		let expr = "x - y".parse::<Expression>().unwrap();
-		assert_eq!(
-			expr,
-			Expression::difference(
-				Expression::Symbol('x'),
-				Expression::Symbol('y')));
-	}
-
-	#[test]
-	fn reading_string_with_invalid_syntax_yields_error() {
-		let result = "(x + 1".parse::<Expression>();
-		assert!(matches!(result, Err(Error::InvalidSyntax)));
-	}
 }