The parser is resonably okay now...

onihime/src/parser/error.rs

@@ -1,19 +1,23 @@
 use crate::{lexer::LexerError, span::Span};
 
-/// Errors that can occur during parsing.
+/// Kinds of errors that can occur during parsing.
 #[derive(Debug, Clone, PartialEq)]
 pub enum ParserErrorKind {
     /// An error which ocurred during lexical analysis.
     Lexer(LexerError),
-    /// An unexpecting closing parenthesis/bracket was encountered.
+    /// Expected a value for key in map, but no value was found.
+    MissingValueInMap,
+    /// An unexpecting closing parenthesis/brace/bracket was encountered.
     UnexpectedCloseBracket,
-    /// Opening parenthesis/bracket does not have a matching closing
+    /// Unexpectedly reached the end of the input.
-    /// parenthesis/bracket.
+    UnexpectedEof,
-    UnclosedBracket,
-    /// An unmatched parenthesis/bracket was encountered.
-    UnmatchedBracket,
     /// Unexpected parser state reached.
-    Unreachable,
+    UnexpectedState,
+    /// Opening parenthesis/brace/bracket does not have a matching closing
+    /// parenthesis/brace/bracket.
+    UnclosedBracket,
+    /// An unmatched parenthesis/brace/bracket was encountered.
+    UnmatchedBracket,
 }
 
 /// Parser error, with a start and end location.
@@ -35,16 +39,19 @@ impl ParserError {
 
 impl std::error::Error for ParserError {}
 
+#[cfg(not(tarpaulin_include))]
 impl std::fmt::Display for ParserError {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         use ParserErrorKind::*;
 
         match &self.kind {
             Lexer(err) => write!(f, "{err}"),
+            MissingValueInMap => write!(f, "Key in map is missing its value"),
             UnexpectedCloseBracket => write!(f, "Unexpected closing bracket"),
-            UnclosedBracket => write!(f, "Unclosed parenthesis"),
+            UnexpectedEof => write!(f, "Unexpected reached end of input"),
+            UnexpectedState => write!(f, "Unexpected parsing state reached"),
+            UnclosedBracket => write!(f, "Unclosed bracket"),
             UnmatchedBracket => write!(f, "Unmatched bracket"),
-            Unreachable => write!(f, "Unexpected parsing state reached"),
         }
     }
 }

onihime/src/parser/mod.rs

@@ -7,7 +7,8 @@ use crate::lexer::{Lexer, TokenKind};
 mod error;
 mod node;
 
-/// A parser for the AST.
+/// Parser for converting Onihime source code into an Abstract Syntax Tree
+/// (AST).
 #[derive(Debug)]
 pub struct Parser<'parser> {
     lexer: Lexer<'parser>,
@@ -35,6 +36,7 @@ impl<'parser> Parser<'parser> {
         while let Some(token) = self.lexer.read()? {
             match token.kind {
                 TokenKind::BlockComment(_) | TokenKind::LineComment(_) => {}
+
                 TokenKind::OpenParen => {
                     let child = Node::new(NodeKind::List(Vec::new()), token.span);
                     parents.push(cur_node);
@@ -60,6 +62,47 @@ impl<'parser> Parser<'parser> {
                     parent.push_node(cur_node)?;
                     cur_node = parent;
                 }
+
+                TokenKind::OpenBrace => {
+                    let child = Node::new(NodeKind::Set(Vec::new()), token.span);
+                    parents.push(cur_node);
+                    cur_node = child;
+                }
+                TokenKind::OpenHashBrace => {
+                    let child = Node::new(NodeKind::Map(Vec::new()), token.span);
+                    parents.push(cur_node);
+                    cur_node = child;
+                }
+                TokenKind::CloseBrace => {
+                    let mut parent = parents.pop().ok_or_else(|| {
+                        ParserError::new(
+                            ParserErrorKind::UnexpectedCloseBracket,
+                            token.span.clone(),
+                        )
+                    })?;
+
+                    cur_node.span.extend(&token.span);
+
+                    if !matches!(cur_node.kind, NodeKind::Map(_) | NodeKind::Set(_)) {
+                        return Err(ParserError::new(
+                            ParserErrorKind::UnmatchedBracket,
+                            token.span,
+                        ));
+                    }
+
+                    if let NodeKind::Map(ref vec) = cur_node.kind {
+                        if vec.len() % 2 != 0 {
+                            return Err(ParserError::new(
+                                ParserErrorKind::MissingValueInMap,
+                                token.span,
+                            ));
+                        }
+                    }
+
+                    parent.push_node(cur_node)?;
+                    cur_node = parent;
+                }
+
                 TokenKind::OpenBracket => {
                     let child = Node::new(NodeKind::Vector(Vec::new()), token.span);
                     parents.push(cur_node);
@@ -86,7 +129,10 @@ impl<'parser> Parser<'parser> {
                     cur_node = parent;
                 }
 
-                _ => cur_node.push_node(Node::try_from(token)?)?,
+                _ => {
+                    let node = Node::try_from(token)?;
+                    cur_node.push_node(node)?;
+                }
             }
         }
 
@@ -100,10 +146,7 @@ impl<'parser> Parser<'parser> {
         if let NodeKind::List(body) = cur_node.kind {
             Ok(body)
         } else {
-            Err(ParserError::new(
+            unreachable!() // In theory, at least...
-                ParserErrorKind::Unreachable,
-                cur_node.span,
-            ))
         }
     }
 }
@@ -113,6 +156,7 @@ mod tests {
     use super::*;
     use crate::{
         lexer::{LexerError, LexerErrorKind, Symbol},
+        parser::node::Atom,
         span::Span,
     };
 
@@ -127,75 +171,7 @@ mod tests {
         };
     }
 
-    test!(parse_list: "(+ 1 2)", src => Ok(vec![
+    test!(empty: "", _src => Ok(vec![]));
-        Node::new(
-            NodeKind::List(vec![
-                Node::new(NodeKind::Symbol(Symbol::from("+")), Span::new(1..2, src.clone())),
-                Node::new(NodeKind::Number(1.0), Span::new(3..4, src.clone())),
-                Node::new(NodeKind::Number(2.0), Span::new(5..6, src.clone())),
-            ]),
-            Span::new(0..7, src)
-        )
-    ]));
-
-    test!(parse_nested_list: "(+ 2.5 64 (* 2 3))", src => Ok(vec![Node::new(
-        NodeKind::List(vec![
-            Node::new(NodeKind::Symbol(Symbol::from("+")), Span::new(1..2, src.clone())),
-            Node::new(NodeKind::Number(2.5), Span::new(3..6, src.clone())),
-            Node::new(NodeKind::Number(64.0), Span::new(7..9, src.clone())),
-            Node::new(
-                NodeKind::List(vec![
-                    Node::new(NodeKind::Symbol(Symbol::from("*")), Span::new(11..12, src.clone())),
-                    Node::new(NodeKind::Number(2.0), Span::new(13..14, src.clone())),
-                    Node::new(NodeKind::Number(3.0), Span::new(15..16, src.clone())),
-                ]),
-                Span::new(10..17, src.clone())
-            ),
-        ]),
-        Span::new(0..18, src)
-    )]));
-
-    test!(parse_multiple_expressions: "(/ 6 3 (+ 1 2)) (* 2 5)\n(- 10 5)", src => Ok(vec![
-        Node::new(
-            NodeKind::List(vec![
-                Node::new(NodeKind::Symbol(Symbol::from("/")), Span::new(1..2, src.clone())),
-                Node::new(NodeKind::Number(6.0), Span::new(3..4, src.clone())),
-                Node::new(NodeKind::Number(3.0), Span::new(5..6, src.clone())),
-                Node::new(
-                    NodeKind::List(vec![
-                        Node::new(NodeKind::Symbol(Symbol::from("+")), Span::new(8..9, src.clone())),
-                        Node::new(NodeKind::Number(1.0), Span::new(10..11, src.clone())),
-                        Node::new(NodeKind::Number(2.0), Span::new(12..13, src.clone())),
-                    ]),
-                    Span::new(7..14, src.clone())
-                ),
-            ]),
-            Span::new(0..15, src.clone())
-        ),
-        Node::new(
-            NodeKind::List(vec![
-                Node::new(NodeKind::Symbol(Symbol::from("*")), Span::new(17..18, src.clone())),
-                Node::new(NodeKind::Number(2.0), Span::new(19..20, src.clone())),
-                Node::new(NodeKind::Number(5.0), Span::new(21..22, src.clone())),
-            ]),
-            Span::new(16..23, src.clone())
-        ),
-        Node::new(
-            NodeKind::List(vec![
-                Node::new(NodeKind::Symbol(Symbol::from("-")), Span::new(25..26, src.clone())),
-                Node::new(NodeKind::Number(10.0), Span::new(27..29, src.clone())),
-                Node::new(NodeKind::Number(5.0), Span::new(30..31, src.clone())),
-            ]),
-            Span::new(24..32, src)
-        ),
-    ]));
-
-    test!(parse_float: "(2.500000)", src => Ok(vec![Node::new(
-        NodeKind::List(vec![Node::new(NodeKind::Number(2.5), Span::new(1..9, src.clone()))]),
-        Span::new(0..10, src)
-    )]));
-
-    test!(parse_empty: "", _src => Ok(vec![]));
 
     test!(error_invalid_number: "(+ 1.2.3)", src => Err(ParserError::new(
         ParserErrorKind::Lexer(LexerError::new(
@@ -205,8 +181,151 @@ mod tests {
         Span::new(3..8, src)
     )));
 
-    test!(error_unexpected_close_paren: ")", src => Err(ParserError::new(
+    test!(list: "(+ 1 2) ; sneaky comment :)", src => Ok(vec![
+        Node::new(
+            NodeKind::List(vec![
+                Node::new(Atom::Symbol(Symbol::from("+")).into(), Span::new(1..2, src.clone())),
+                Node::new(Atom::Integer(1).into(), Span::new(3..4, src.clone())),
+                Node::new(Atom::Integer(2).into(), Span::new(5..6, src.clone())),
+            ]),
+            Span::new(0..7, src)
+        )
+    ]));
+
+    test!(error_list_unmatched_bracket: "(]", src => Err(ParserError::new(
+        ParserErrorKind::UnmatchedBracket,
+        Span::new(1..2, src),
+    )));
+
+    test!(error_list_missing_close_paren: "(true", src => Err(ParserError::new(
+        ParserErrorKind::UnclosedBracket,
+        Span::new(0..1, src),
+    )));
+
+    test!(error_list_unexpected_close_paren: ")", src => Err(ParserError::new(
         ParserErrorKind::UnexpectedCloseBracket,
         Span::new(0..1, src)
     )));
+
+    test!(map: "#{:a 0.0 :b 1.0}", src => Ok(vec![
+        Node::new(
+            NodeKind::Map(vec![
+                Node::new(Atom::Keyword(Symbol::from("a")).into(), Span::new(2..4, src.clone())),
+                Node::new(Atom::Float(0.0).into(), Span::new(5..8, src.clone())),
+                Node::new(Atom::Keyword(Symbol::from("b")).into(), Span::new(9..11, src.clone())),
+                Node::new(Atom::Float(1.0).into(), Span::new(12..15, src.clone())),
+            ]),
+            Span::new(0..16, src)
+        )
+    ]));
+
+    test!(error_map_missing_value: "#{:x}", src => Err(ParserError::new(
+        ParserErrorKind::MissingValueInMap,
+        Span::new(4..5, src.clone())
+    )));
+
+    test!(error_map_unmatched_bracket: "#{)", src => Err(ParserError::new(
+        ParserErrorKind::UnmatchedBracket,
+        Span::new(2..3, src),
+    )));
+
+    test!(error_map_missing_close_brace: "#{", src => Err(ParserError::new(
+        ParserErrorKind::UnclosedBracket,
+        Span::new(0..2, src),
+    )));
+
+    test!(set: "{{} nil}", src => Ok(vec![
+        Node::new(
+            NodeKind::Set(vec![
+                Node::new(NodeKind::Set(vec![]), Span::new(1..3, src.clone())),
+                Node::new(NodeKind::Atom(Atom::Nil), Span::new(4..7, src.clone())),
+            ]),
+            Span::new(0..8, src),
+        )
+    ]));
+
+    test!(error_set_unmatched_bracket: "{]", src => Err(ParserError::new(
+        ParserErrorKind::UnmatchedBracket,
+        Span::new(1..2, src),
+    )));
+
+    test!(error_set_missing_close_brace: "{", src => Err(ParserError::new(
+        ParserErrorKind::UnclosedBracket,
+        Span::new(0..1, src),
+    )));
+
+    test!(error_map_set_unexpected_close_brace: "}", src => Err(ParserError::new(
+        ParserErrorKind::UnexpectedCloseBracket,
+        Span::new(0..1, src)
+    )));
+
+    test!(vector: "['a' 'b' 'c']", src => Ok(vec![
+        Node::new(
+            NodeKind::Vector(vec![
+                Node::new(NodeKind::Atom(Atom::Char('a')), Span::new(1..4, src.clone())),
+                Node::new(NodeKind::Atom(Atom::Char('b')), Span::new(5..8, src.clone())),
+                Node::new(NodeKind::Atom(Atom::Char('c')), Span::new(9..12, src.clone())),
+            ]),
+            Span::new(0..13, src),
+        )
+    ]));
+
+    test!(error_vector_unmatched_bracket: "[}", src => Err(ParserError::new(
+        ParserErrorKind::UnmatchedBracket,
+        Span::new(1..2, src),
+    )));
+
+    test!(error_vector_missing_close_bracket: "{", src => Err(ParserError::new(
+        ParserErrorKind::UnclosedBracket,
+        Span::new(0..1, src),
+    )));
+
+    test!(error_vector_unexpected_close_bracket: "]", src => Err(ParserError::new(
+        ParserErrorKind::UnexpectedCloseBracket,
+        Span::new(0..1, src)
+    )));
+
+    test!(multiple_expressions: "(/ 6 3 (+ 1 2)) (* 2 5)\n(- 10 5)", src => Ok(vec![
+        Node::new(
+            NodeKind::List(vec![
+                Node::new(Atom::Symbol(Symbol::from("/")).into(), Span::new(1..2, src.clone())),
+                Node::new(Atom::Integer(6).into(), Span::new(3..4, src.clone())),
+                Node::new(Atom::Integer(3).into(), Span::new(5..6, src.clone())),
+                Node::new(
+                    NodeKind::List(vec![
+                        Node::new(Atom::Symbol(Symbol::from("+")).into(), Span::new(8..9, src.clone())),
+                        Node::new(Atom::Integer(1).into(), Span::new(10..11, src.clone())),
+                        Node::new(Atom::Integer(2).into(), Span::new(12..13, src.clone())),
+                    ]),
+                    Span::new(7..14, src.clone())
+                ),
+            ]),
+            Span::new(0..15, src.clone())
+        ),
+        Node::new(
+            NodeKind::List(vec![
+                Node::new(Atom::Symbol(Symbol::from("*")).into(), Span::new(17..18, src.clone())),
+                Node::new(Atom::Integer(2).into(), Span::new(19..20, src.clone())),
+                Node::new(Atom::Integer(5).into(), Span::new(21..22, src.clone())),
+            ]),
+            Span::new(16..23, src.clone())
+        ),
+        Node::new(
+            NodeKind::List(vec![
+                Node::new(Atom::Symbol(Symbol::from("-")).into(), Span::new(25..26, src.clone())),
+                Node::new(Atom::Integer(10).into(), Span::new(27..29, src.clone())),
+                Node::new(Atom::Integer(5).into(), Span::new(30..31, src.clone())),
+            ]),
+            Span::new(24..32, src)
+        ),
+    ]));
+
+    test!(function_application: "(join \"foo\" \"bar\")", src => Ok(vec![Node::new(
+        NodeKind::List(vec![
+            Node::new(Atom::Symbol(Symbol::from("join")).into(), Span::new(1..5, src.clone())),
+            Node::new(Atom::String("foo".into()).into(), Span::new(6..11, src.clone())),
+            Node::new(Atom::String("bar".into()).into(), Span::new(12..17, src.clone())),
+        ]),
+        Span::new(0..18, src)
+    )]));
 }

onihime/src/parser/node.rs

@@ -4,50 +4,116 @@ use crate::{
     span::Span,
 };
 
-/// The type of a node in the AST.
+/// An atomic value.
+#[derive(Debug, Clone, PartialEq)]
+pub enum Atom {
+    /// Boolean, e.g. `true`, `false`
+    Bool(bool),
+    /// Character, e.g. `'c'`, `'\n'`
+    Char(char),
+    /// Floating-point number, e.g. `-1.0`, `2.0`, `+0.003`
+    Float(f64),
+    /// Integer, e.g. `0`, `-1`, `+200`
+    Integer(i64),
+    /// Keyword, e.g. `:baz`
+    Keyword(Symbol),
+    /// String, e.g. `"foo bar"`
+    String(String),
+    /// Symbol, e.g. `qux`, `+`
+    Symbol(Symbol),
+    /// Nil, e.g. `nil`
+    Nil,
+}
+
+#[cfg(not(tarpaulin_include))]
+impl std::fmt::Display for Atom {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        use Atom::*;
+
+        match self {
+            Bool(_) => write!(f, "BOOL"),
+            Char(_) => write!(f, "CHAR"),
+            Float(_) => write!(f, "FLOAT"),
+            Integer(_) => write!(f, "INTEGER"),
+            Keyword(_) => write!(f, "KEYWORD"),
+            String(_) => write!(f, "STRING"),
+            Symbol(_) => write!(f, "SYMBOL"),
+            Nil => write!(f, "NIL"),
+        }
+    }
+}
+
+/// An expression.
 #[derive(Debug, Clone, PartialEq)]
 pub enum NodeKind {
-    /// Bool.
+    /// An atomic value.
-    Bool(bool),
+    Atom(Atom),
-    /// Character.
+    /// A list of nodes.
-    Char(char),
-    /// Keyword.
-    Keyword(Symbol),
-    /// Number.
-    Number(f64),
-    /// String.
-    String(String),
-    /// Symbol.
-    Symbol(Symbol),
-    /// Nil.
-    Nil,
-
-    /// List.
     List(Vec<Node>),
-    /// Vector.
+    /// A map of nodes.
+    Map(Vec<Node>),
+    /// A set of nodes.
+    Set(Vec<Node>),
+    /// A vector of nodes.
     Vector(Vec<Node>),
 }
 
+impl From<Atom> for NodeKind {
+    fn from(atom: Atom) -> Self {
+        Self::Atom(atom)
+    }
+}
+
+impl TryFrom<Token> for NodeKind {
+    type Error = ParserError;
+
+    fn try_from(token: Token) -> Result<Self, Self::Error> {
+        let kind = match token.kind {
+            TokenKind::Bool(b) => Atom::Bool(b),
+            TokenKind::Char(c) => Atom::Char(c),
+            TokenKind::Float(n) => Atom::Float(n),
+            TokenKind::Integer(n) => Atom::Integer(n),
+            TokenKind::Keyword(k) => Atom::Keyword(k),
+            TokenKind::String(s) => Atom::String(s),
+            TokenKind::Symbol(s) => Atom::Symbol(s),
+            TokenKind::Nil => Atom::Nil,
+            _ => {
+                return Err(ParserError::new(
+                    ParserErrorKind::UnexpectedState,
+                    token.span,
+                ))
+            }
+        };
+
+        Ok(kind.into())
+    }
+}
+
+#[cfg(not(tarpaulin_include))]
 impl std::fmt::Display for NodeKind {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        use NodeKind::*;
+
         match self {
-            NodeKind::Bool(_) => write!(f, "BOOL"),
+            Atom(atom) => write!(f, "{atom}"),
-            NodeKind::Char(_) => write!(f, "CHAR"),
+            List(_) => write!(f, "LIST"),
-            NodeKind::Keyword(_) => write!(f, "KEYWORD"),
+            Map(_) => write!(f, "MAP"),
-            NodeKind::Number(_) => write!(f, "NUMBER"),
+            Set(_) => write!(f, "SET"),
-            NodeKind::String(_) => write!(f, "STRING"),
+            Vector(_) => write!(f, "VECTOR"),
-            NodeKind::Symbol(_) => write!(f, "SYMBOL"),
-            NodeKind::Nil => write!(f, "NIL"),
-            NodeKind::List(_) => write!(f, "LIST"),
-            NodeKind::Vector(_) => write!(f, "VECTOR"),
         }
     }
 }
 
-/// A node in the AST with a start and end location.
+/// A node in the Abstract Syntax Tree (AST).
+///
+/// `Nodes`s contain the kind of node which was found, as well as a [Span]
+/// specifying the [Source] and [Location] of the node.
+///
+/// [Source]: crate::span::Source
+/// [Location]: crate::span::Location
 #[derive(Debug, Clone, PartialEq)]
 pub struct Node {
-    /// The type of node.
+    /// The kind of node.
     pub kind: NodeKind,
     /// The span in which the node occurs.
     pub span: Span,
@@ -63,15 +129,24 @@ impl Node {
     /// Push a child node onto a list node.
     pub fn push_node(&mut self, child: Self) -> Result<(), ParserError> {
         match &mut self.kind {
-            NodeKind::List(c) | NodeKind::Vector(c) => {
+            NodeKind::List(vec)
-                c.push(child);
+            | NodeKind::Map(vec)
+            | NodeKind::Set(vec)
+            | NodeKind::Vector(vec) => {
+                vec.push(child);
+            }
+            _ => {
+                return Err(ParserError::new(
+                    ParserErrorKind::UnexpectedState,
+                    child.span,
+                ))
             }
-            _ => return Err(ParserError::new(ParserErrorKind::Unreachable, child.span)),
         }
 
         Ok(())
     }
 
+    #[cfg(not(tarpaulin_include))]
     fn display(&self, indent: usize) -> String {
         let mut text = format!(
             "{}{}@{}..{}\n",
@@ -82,48 +157,35 @@ impl Node {
         );
 
         match &self.kind {
-            NodeKind::List(vec) | NodeKind::Vector(vec) => {
+            NodeKind::Atom(_) => {}
+            NodeKind::List(vec)
+            | NodeKind::Map(vec)
+            | NodeKind::Set(vec)
+            | NodeKind::Vector(vec) => {
                 for node in vec {
-                    text.push_str(&node.display(indent + 1));
+                    text.push_str(&format!("{}\n", node.display(indent + 1)));
                 }
             }
-            _ => {}
         }
 
         text.trim_end().to_string()
     }
 }
 
-impl std::fmt::Display for Node {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.display(0))
-    }
-}
-
 impl TryFrom<Token> for Node {
     type Error = ParserError;
 
     fn try_from(token: Token) -> Result<Self, Self::Error> {
-        let kind = match token.kind {
+        let span = token.span.clone();
-            TokenKind::Bool(b) => NodeKind::Bool(b),
+        let kind = NodeKind::try_from(token)?;
-            TokenKind::Char(c) => NodeKind::Char(c),
-            TokenKind::Number(n) => NodeKind::Number(n),
-            TokenKind::String(s) => NodeKind::String(s),
-            TokenKind::Keyword(k) => NodeKind::Keyword(k),
-            TokenKind::Symbol(s) => NodeKind::Symbol(s),
-            TokenKind::Nil => NodeKind::Nil,
-            TokenKind::OpenParen
-            | TokenKind::CloseParen
-            | TokenKind::OpenBrace
-            | TokenKind::CloseBrace
-            | TokenKind::OpenBracket
-            | TokenKind::CloseBracket
-            | TokenKind::LineComment(_)
-            | TokenKind::BlockComment(_) => {
-                return Err(ParserError::new(ParserErrorKind::Unreachable, token.span))
-            }
-        };
 
-        Ok(Self::new(kind, token.span))
+        Ok(Self::new(kind, span))
+    }
+}
+
+#[cfg(not(tarpaulin_include))]
+impl std::fmt::Display for Node {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.display(0))
     }
 }

onihime/src/span.rs

@@ -87,7 +87,7 @@ impl Source {
 }
 
 /// A contiguous sequence of bytes within some source.
-#[derive(Debug, Default, Clone, Hash)]
+#[derive(Debug, Default, Clone, Eq, Hash)]
 pub struct Span {
     bytes: Range<usize>,
     source: Arc<Source>,
@@ -111,7 +111,6 @@ impl Span {
     /// Extend one span to include another.
     pub fn extend(&mut self, other: &Self) {
         debug_assert!(self.same_source(other));
-
         self.bytes.end = other.bytes.end;
     }
 
@@ -133,6 +132,7 @@ impl Span {
         Arc::ptr_eq(&self.source, &other.source)
     }
 
+    #[must_use]
     pub(crate) fn bytes(&self) -> &Range<usize> {
         &self.bytes
     }
@@ -143,3 +143,25 @@ impl PartialEq for Span {
         self.same_source(other) && self.bytes == other.bytes
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn location_partial_ord() {
+        assert!(Location::new(1, 1) < Location::new(1, 2));
+        assert!(Location::new(1, 10) < Location::new(2, 1));
+        assert!(Location::new(5, 5) == Location::new(5, 5));
+        assert!(Location::new(10, 1) > Location::new(9, 99));
+    }
+
+    #[test]
+    fn source_get_set_name() {
+        let mut src = Source::new(None, "".into());
+        assert!(src.name().is_none());
+
+        src.set_name("foo".into());
+        assert!(src.name() == Some("foo"));
+    }
+}