Merge pull request #3241 from Skgland/parse-error-improvements

change `ParserError` type

src/debray_allocator.rs

@@ -106,7 +106,7 @@ impl BranchStack {
         let branch_num = self
             .last()
             .map(|occurrences| occurrences.current_branch_num.clone())
-            .unwrap_or_else(|| BranchNumber::default());
+            .unwrap_or_default();
 
         BranchDesignator { branch_num }
     }

src/machine/machine_errors.rs

@@ -20,7 +20,7 @@ pub type MachineStubGen = Box<dyn Fn(&mut MachineState) -> MachineStub>;
 #[derive(Debug)]
 pub(crate) struct MachineError {
     stub: MachineStub,
-    location: Option<(usize, usize)>, // line_num, col_num
+    location: Option<Location>,
 }
 
 // from 7.12.2 b) of 13211-1:1995
@@ -753,14 +753,15 @@ impl MachineState {
     }
 
     pub(super) fn error_form(&mut self, err: MachineError, src: MachineStub) -> MachineStub {
-        if let Some((line_num, _col_num)) = err.location {
+        if let Some(location) = err.location {
+            let line = location.line();
             functor!(
                 atom!("error"),
                 [
                     functor((err.stub)),
                     functor(
                         (atom!(":")),
-                        [functor(src), number(line_num, (&mut self.arena))]
+                        [functor(src), number(line, (&mut self.arena))]
                     )
                 ]
             )
@@ -853,9 +854,9 @@ impl From<ParserError> for CompilationError {
 }
 
 impl CompilationError {
-    pub(crate) fn line_and_col_num(&self) -> Option<(usize, usize)> {
+    pub(crate) fn line_and_col_num(&self) -> Option<Location> {
         match self {
-            CompilationError::ParserError(err) => err.line_and_col_num(),
+            CompilationError::ParserError(err) => err.location(),
             _ => None,
         }
     }

src/machine/streams.rs

@@ -1952,7 +1952,7 @@ impl MachineState {
     ) -> Result<Stream, ParserError> {
         match stream.peek_char() {
             None => Ok(stream), // empty stream is handled gracefully by Lexer::eof
-            Some(Err(e)) => Err(ParserError::IO(e)),
+            Some(Err(e)) => Err(ParserError::from(e)),
             Some(Ok(c)) => {
                 if c == '\u{feff}' {
                     // skip UTF-8 BOM

src/machine/system_calls.rs

@@ -1016,7 +1016,7 @@ impl MachineState {
                             self.unify_fixnum(n, nx);
                         }
                         _ => {
-                            let err = ParserError::ParseBigInt(0, 0);
+                            let err = parser.lexer.parse_big_int_error();
                             let err = self.syntax_error(err);
 
                             return Err(self.error_form(err, stub_gen()));
@@ -1026,9 +1026,7 @@ impl MachineState {
                     return Ok(());
                 }
                 Ok(c) => {
-                    let (line_num, col_num) = (lexer.line_num, lexer.col_num);
+                    let err = lexer.unexpected_char(c);
-
-                    let err = ParserError::UnexpectedChar(c, line_num, col_num);
                     let err = self.syntax_error(err);
 
                     return Err(self.error_form(err, stub_gen()));
@@ -9214,7 +9212,7 @@ impl Machine {
                 stream.add_lines_read(parser.lines_read());
             }
             Ok(true) => {
-                stream.add_lines_read(parser.lexer.line_num);
+                stream.add_lines_read(parser.lexer.location.line());
                 self.machine_st.fail = true;
             }
             Err(err) => {

src/parser/ast.rs

@@ -4,7 +4,6 @@
 use crate::arena::*;
 use crate::atom_table::*;
 use crate::offset_table::*;
-use crate::parser::char_reader::*;
 use crate::types::HeapCellValueTag;
 
 use std::cell::{Cell, Ref, RefCell, RefMut};
@@ -426,72 +425,92 @@ pub enum ArithmeticError {
     UninstantiatedVar,
 }
 
+#[derive(Debug, Clone)]
+pub struct Location {
+    pub(super) line: usize,
+    pub(super) column: usize,
+}
+
+impl Location {
+    // beginning of file
+    pub(crate) const BOF: Self = Self { line: 0, column: 0 };
+
+    pub fn line(&self) -> usize {
+        self.line
+    }
+
+    pub fn column(&self) -> usize {
+        self.column
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Debug)]
-pub enum ParserError {
+pub struct ParserError {
-    BackQuotedString(usize, usize),
+    pub(crate) location: Option<Location>,
+    pub(crate) kind: ParserErrorKind,
+}
+
+#[allow(dead_code)]
+#[derive(Debug)]
+#[non_exhaustive]
+pub(crate) enum ParserErrorKind {
+    BackQuotedString,
     IO(IOError),
-    IncompleteReduction(usize, usize),
+    IncompleteReduction,
-    InfiniteFloat(usize, usize),
+    InfiniteFloat,
     InvalidSingleQuotedCharacter(char),
-    LexicalError(lexical::Error),
+    ParseFloat,
-    MissingQuote(usize, usize),
+    MissingQuote,
-    NonPrologChar(usize, usize),
+    NonPrologChar,
-    ParseBigInt(usize, usize),
+    ParseBigInt,
-    UnexpectedChar(char, usize, usize),
+    UnexpectedChar(char),
     // UnexpectedEOF,
-    Utf8Error(usize, usize),
+    Utf8Error,
 }
 
 impl ParserError {
-    pub fn line_and_col_num(&self) -> Option<(usize, usize)> {
+    pub(crate) fn location(&self) -> Option<Location> {
-        match self {
+        self.location.as_ref().cloned()
-            &ParserError::BackQuotedString(line_num, col_num)
-            | &ParserError::IncompleteReduction(line_num, col_num)
-            | &ParserError::InfiniteFloat(line_num, col_num)
-            | &ParserError::MissingQuote(line_num, col_num)
-            | &ParserError::NonPrologChar(line_num, col_num)
-            | &ParserError::ParseBigInt(line_num, col_num)
-            | &ParserError::UnexpectedChar(_, line_num, col_num)
-            | &ParserError::Utf8Error(line_num, col_num) => Some((line_num, col_num)),
-            _ => None,
-        }
     }
 
-    pub fn as_atom(&self) -> Atom {
+    pub(crate) fn as_atom(&self) -> Atom {
-        match self {
+        match &self.kind {
-            ParserError::BackQuotedString(..) => atom!("back_quoted_string"),
+            ParserErrorKind::BackQuotedString => atom!("back_quoted_string"),
-            ParserError::IncompleteReduction(..) => atom!("incomplete_reduction"),
+            ParserErrorKind::IncompleteReduction => atom!("incomplete_reduction"),
-            ParserError::InvalidSingleQuotedCharacter(..) => {
+            ParserErrorKind::InvalidSingleQuotedCharacter(..) => {
                 atom!("invalid_single_quoted_character")
             }
-            ParserError::InfiniteFloat(..) => {
+            ParserErrorKind::InfiniteFloat => {
                 atom!("infinite_float")
             }
-            ParserError::IO(e) if e.kind() == ErrorKind::UnexpectedEof => {
+            ParserErrorKind::IO(e) if e.kind() == ErrorKind::UnexpectedEof => {
                 atom!("unexpected_end_of_file")
             }
-            ParserError::IO(e) if e.kind() == ErrorKind::InvalidData => {
+            ParserErrorKind::IO(e) if e.kind() == ErrorKind::InvalidData => {
                 atom!("invalid_data")
             }
-            ParserError::IO(_) => atom!("input_output_error"),
+            ParserErrorKind::IO(_) => atom!("input_output_error"),
-            ParserError::LexicalError(_) => atom!("lexical_error"),
+            ParserErrorKind::ParseFloat => atom!("parse_float"),
-            ParserError::MissingQuote(..) => atom!("missing_quote"),
+            ParserErrorKind::MissingQuote => atom!("missing_quote"),
-            ParserError::NonPrologChar(..) => atom!("non_prolog_character"),
+            ParserErrorKind::NonPrologChar => atom!("non_prolog_character"),
-            ParserError::ParseBigInt(..) => atom!("cannot_parse_big_int"),
+            ParserErrorKind::ParseBigInt => atom!("cannot_parse_big_int"),
-            ParserError::UnexpectedChar(..) => atom!("unexpected_char"),
+            ParserErrorKind::UnexpectedChar(..) => atom!("unexpected_char"),
-            ParserError::Utf8Error(..) => atom!("utf8_conversion_error"),
+            ParserErrorKind::Utf8Error => atom!("utf8_conversion_error"),
         }
     }
 
     #[inline]
-    pub fn unexpected_eof() -> Self {
+    pub(crate) fn unexpected_eof() -> Self {
-        ParserError::IO(std::io::Error::from(ErrorKind::UnexpectedEof))
+        ParserError {
+            location: None,
+            kind: ParserErrorKind::IO(std::io::Error::from(ErrorKind::UnexpectedEof)),
+        }
     }
 
     #[inline]
-    pub fn is_unexpected_eof(&self) -> bool {
+    pub(crate) fn is_unexpected_eof(&self) -> bool {
-        if let ParserError::IO(e) = self {
+        if let ParserErrorKind::IO(e) = &self.kind {
             e.kind() == ErrorKind::UnexpectedEof
         } else {
             false
@@ -499,24 +518,11 @@ impl ParserError {
     }
 }
 
-impl From<lexical::Error> for ParserError {
-    fn from(e: lexical::Error) -> ParserError {
-        ParserError::LexicalError(e)
-    }
-}
-
 impl From<IOError> for ParserError {
     fn from(e: IOError) -> ParserError {
-        ParserError::IO(e)
+        ParserError {
-    }
+            location: None,
-}
+            kind: ParserErrorKind::IO(e),
-
-impl From<&IOError> for ParserError {
-    fn from(error: &IOError) -> ParserError {
-        if error.get_ref().filter(|e| e.is::<BadUtf8Error>()).is_some() {
-            ParserError::Utf8Error(0, 0)
-        } else {
-            ParserError::IO(error.kind().into())
         }
     }
 }

src/parser/lexer.rs

@@ -16,7 +16,10 @@ macro_rules! consume_chars_with {
             match $e {
                 Ok(Some(c)) => $token.push(c),
                 Ok(None) => continue,
-                Err($crate::parser::ast::ParserError::UnexpectedChar(..)) => break,
+                Err($crate::parser::ast::ParserError {
+                    kind: $crate::parser::ast::ParserErrorKind::UnexpectedChar(..),
+                    ..
+                }) => break,
                 Err(e) => return Err(e),
             }
         }
@@ -91,27 +94,45 @@ macro_rules! try_nt {
 pub(crate) struct Lexer<'a, R> {
     pub(crate) reader: R,
     pub(crate) machine_st: &'a mut MachineState,
-    pub(crate) line_num: usize,
+    pub(crate) location: Location,
-    pub(crate) col_num: usize,
 }
 
 impl<'a, R: fmt::Debug> fmt::Debug for Lexer<'a, R> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("LexerParser")
             .field("reader", &"&'a mut R") // Hacky solution.
-            .field("line_num", &self.line_num)
+            .field("location", &self.location)
-            .field("col_num", &self.col_num)
             .finish()
     }
 }
 
+impl<R> Lexer<'_, R> {
+    pub(crate) fn located_error(&self, kind: ParserErrorKind) -> ParserError {
+        ParserError {
+            location: Some(self.location.clone()),
+            kind,
+        }
+    }
+
+    pub(crate) fn parse_big_int_error(&self) -> ParserError {
+        self.located_error(ParserErrorKind::ParseBigInt)
+    }
+
+    pub(crate) fn incomplete_reduction(&self) -> ParserError {
+        self.located_error(ParserErrorKind::IncompleteReduction)
+    }
+
+    pub(crate) fn unexpected_char(&self, c: char) -> ParserError {
+        self.located_error(ParserErrorKind::UnexpectedChar(c))
+    }
+}
+
 impl<'a, R: CharRead> Lexer<'a, R> {
     pub fn new(src: R, machine_st: &'a mut MachineState) -> Self {
         Self {
             reader: src,
             machine_st,
-            line_num: 0,
+            location: Location::BOF,
-            col_num: 0,
         }
     }
 
@@ -138,10 +159,10 @@ impl<'a, R: CharRead> Lexer<'a, R> {
         self.reader.consume(c.len_utf8());
 
         if new_line_char!(c) {
-            self.line_num += 1;
+            self.location.line += 1;
-            self.col_num = 0;
+            self.location.column = 0;
         } else {
-            self.col_num += 1;
+            self.location.column += 1;
         }
     }
 
@@ -200,10 +221,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
 
             match comment_loop() {
                 Err(e) if e.is_unexpected_eof() => {
-                    return Err(ParserError::IncompleteReduction(
+                    return Err(self.incomplete_reduction());
-                        self.line_num,
-                        self.col_num,
-                    ));
                 }
                 Err(e) => {
                     return Err(e);
@@ -215,7 +233,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 self.skip_char(c);
                 Ok(true)
             } else {
-                Err(ParserError::NonPrologChar(self.line_num, self.col_num))
+                Err(self.located_error(ParserErrorKind::NonPrologChar))
             }
         } else {
             self.return_char('/');
@@ -232,7 +250,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
 
             if !back_quote_char!(c2) {
                 self.return_char(c);
-                Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num))
+                Err(self.unexpected_char(c))
             } else {
                 self.skip_char(c2);
                 Ok(c2)
@@ -257,7 +275,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 Ok(None)
             } else {
                 self.return_char(c);
-                Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num))
+                Err(self.unexpected_char(c))
             }
         } else {
             self.get_back_quoted_char().map(Some)
@@ -279,10 +297,13 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 self.skip_char(c);
                 Ok(token)
             } else {
-                Err(ParserError::MissingQuote(self.line_num, self.col_num))
+                Err({
+                    let this = &self;
+                    this.located_error(ParserErrorKind::MissingQuote)
+                })
             }
         } else {
-            Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num))
+            Err(self.unexpected_char(c))
         }
     }
 
@@ -313,7 +334,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
 
             if !single_quote_char!(c2) {
                 self.return_char(c);
-                Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num))
+                Err(self.unexpected_char(c))
             } else {
                 self.skip_char(c2);
                 Ok(c2)
@@ -354,7 +375,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
 
             if !double_quote_char!(c2) {
                 self.return_char(c);
-                Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num))
+                Err(self.unexpected_char(c))
             } else {
                 self.skip_char(c2);
                 Ok(c2)
@@ -378,7 +399,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             't' => '\t',
             'n' => '\n',
             'r' => '\r',
-            c => return Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num)),
+            c => return Err(self.unexpected_char(c)),
         };
 
         self.skip_char(c);
@@ -396,10 +417,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
         if hexadecimal_digit_char!(c) {
             self.escape_sequence_to_char(|c| hexadecimal_digit_char!(c), 16)
         } else {
-            Err(ParserError::IncompleteReduction(
+            Err(self.incomplete_reduction())
-                self.line_num,
-                self.col_num,
-            ))
         }
     }
 
@@ -425,17 +443,11 @@ impl<'a, R: CharRead> Lexer<'a, R> {
         if backslash_char!(c) {
             self.skip_char(c);
             u32::from_str_radix(&token, radix).map_or_else(
-                |_| Err(ParserError::ParseBigInt(self.line_num, self.col_num)),
+                |_| Err(self.parse_big_int_error()),
-                |n| {
+                |n| char::try_from(n).map_err(|_| self.located_error(ParserErrorKind::Utf8Error)),
-                    char::try_from(n)
-                        .map_err(|_| ParserError::Utf8Error(self.line_num, self.col_num))
-                },
             )
         } else {
-            Err(ParserError::IncompleteReduction(
+            Err(self.incomplete_reduction())
-                self.line_num,
-                self.col_num,
-            ))
         }
     }
 
@@ -447,7 +459,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             Ok(c)
         } else {
             if !backslash_char!(c) {
-                return Err(ParserError::UnexpectedChar(c, self.line_num, self.col_num));
+                return Err(self.unexpected_char(c));
             }
 
             self.skip_char(c);
@@ -478,7 +490,10 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             self.skip_char(c);
             Ok(token)
         } else {
-            Err(ParserError::MissingQuote(self.line_num, self.col_num))
+            Err({
+                let this = &self;
+                this.located_error(ParserErrorKind::MissingQuote)
+            })
         }
     }
 
@@ -509,7 +524,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 .map(NumberToken::Integer)
         } else {
             self.return_char(start);
-            Err(ParserError::ParseBigInt(self.line_num, self.col_num))
+            Err(self.parse_big_int_error())
         }
     }
 
@@ -540,7 +555,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 .map(NumberToken::Integer)
         } else {
             self.return_char(start);
-            Err(ParserError::ParseBigInt(self.line_num, self.col_num))
+            Err(self.parse_big_int_error())
         }
     }
 
@@ -571,7 +586,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 .map(NumberToken::Integer)
         } else {
             self.return_char(start);
-            Err(ParserError::ParseBigInt(self.line_num, self.col_num))
+            Err(self.parse_big_int_error())
         }
     }
 
@@ -644,11 +659,11 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                     }
                 }
             } else {
-                return Err(ParserError::InvalidSingleQuotedCharacter(c));
+                return Err(self.located_error(ParserErrorKind::InvalidSingleQuotedCharacter(c)));
             }
         } else {
             match self.get_back_quoted_string() {
-                Ok(_) => return Err(ParserError::BackQuotedString(self.line_num, self.col_num)),
+                Ok(_) => return Err(self.located_error(ParserErrorKind::BackQuotedString)),
                 Err(e) => return Err(e),
             }
         }
@@ -669,7 +684,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
     ) -> Result<(F64Offset, OrderedFloat<f64>), ParserError> {
         self.return_char(token.pop().unwrap());
 
-        let n = parse_float_lossy(&token)?;
+        let n = self.parse_float_lossy(&token)?;
         let offset = float_alloc!(n, self.machine_st.arena);
 
         Ok((offset, OrderedFloat(n)))
@@ -686,7 +701,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             if decimal_digit_char!(c) {
                 Ok(c)
             } else {
-                Err(ParserError::ParseBigInt(self.line_num, self.col_num))
+                Err(self.parse_big_int_error())
             }
         } else {
             Ok(c)
@@ -708,7 +723,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             .or_else(|_| {
                 Integer::from_str_radix(token, radix)
                     .map(|n| GInteger::Integer(arena_alloc!(n, &mut self.machine_st.arena)))
-                    .map_err(|_| ParserError::ParseBigInt(self.line_num, self.col_num))
+                    .map_err(|_| self.parse_big_int_error())
             })
     }
 
@@ -806,7 +821,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                             }
                         }
 
-                        let n = parse_float_lossy(&token)?;
+                        let n = self.parse_float_lossy(&token)?;
                         let offset = float_alloc!(n, self.machine_st.arena);
 
                         Ok(NumberToken::Float(offset, OrderedFloat(n)))
@@ -815,7 +830,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                             .map(|(offset, fl)| NumberToken::Float(offset, fl))
                     }
                 } else {
-                    let n = parse_float_lossy(&token)?;
+                    let n = self.parse_float_lossy(&token)?;
                     let offset = float_alloc!(n, self.machine_st.arena);
                     Ok(NumberToken::Float(offset, OrderedFloat(n)))
                 }
@@ -826,7 +841,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
         } else if token.starts_with('0') && token.len() == 1 {
             if c == 'x' {
                 self.hexadecimal_constant(c).or_else(|e| {
-                    if let ParserError::ParseBigInt(..) = e {
+                    if let ParserErrorKind::ParseBigInt = e.kind {
                         self.parse_integer(&token).map(NumberToken::Integer)
                     } else {
                         Err(e)
@@ -834,7 +849,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 })
             } else if c == 'o' {
                 self.octal_constant(c).or_else(|e| {
-                    if let ParserError::ParseBigInt(..) = e {
+                    if let ParserErrorKind::ParseBigInt = e.kind {
                         self.parse_integer(&token).map(NumberToken::Integer)
                     } else {
                         Err(e)
@@ -842,7 +857,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 })
             } else if c == 'b' {
                 self.binary_constant(c).or_else(|e| {
-                    if let ParserError::ParseBigInt(..) = e {
+                    if let ParserErrorKind::ParseBigInt = e.kind {
                         self.parse_integer(&token).map(NumberToken::Integer)
                     } else {
                         Err(e)
@@ -871,9 +886,9 @@ impl<'a, R: CharRead> Lexer<'a, R> {
                 self.get_single_quoted_char()
                     .map(|c| NumberToken::Integer(GInteger::Fixnum(Fixnum::build_with(c))))
                     .or_else(|err| {
-                        match err {
+                        match &err.kind {
-                            ParserError::UnexpectedChar('\'', ..) => {}
+                            ParserErrorKind::UnexpectedChar('\'', ..) => {}
-                            err => return Err(err),
+                            _ => return Err(err),
                         }
 
                         self.return_char(c);
@@ -954,7 +969,7 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             Ok(NumberToken::Partial(token_string)) => match self.parse_integer(&token_string) {
                 Ok(n) => Ok(Token::Literal(n.to_literal())),
                 Err(_) => {
-                    let n = parse_float_lossy(&token_string)?;
+                    let n = self.parse_float_lossy(&token_string)?;
                     let offset = float_alloc!(n, self.machine_st.arena);
                     Ok(Token::Literal(Literal::F64(offset, OrderedFloat(n))))
                 }
@@ -1068,14 +1083,17 @@ impl<'a, R: CharRead> Lexer<'a, R> {
             Err(e) => Err(e),
         }
     }
-}
 
-fn parse_float_lossy(token: &str) -> Result<f64, ParserError> {
+    fn parse_float_lossy(&self, token: &str) -> Result<f64, ParserError> {
-    const FORMAT: u128 = lexical::format::STANDARD;
+        const FORMAT: u128 = lexical::format::STANDARD;
-    let options = lexical::ParseFloatOptions::builder()
+        let Ok(options) = lexical::ParseFloatOptions::builder().lossy(true).build() else {
-        .lossy(true)
+            return Err(self.located_error(ParserErrorKind::ParseFloat));
-        .build()
+        };
-        .unwrap();
+
-    let n = lexical::parse_with_options::<f64, _, FORMAT>(token.as_bytes(), &options)?;
+        let Ok(n) = lexical::parse_with_options::<f64, _, FORMAT>(token.as_bytes(), &options)
-    Ok(n)
+        else {
+            return Err(self.located_error(ParserErrorKind::ParseFloat));
+        };
+        Ok(n)
+    }
 }

src/parser/parser.rs

@@ -254,10 +254,7 @@ pub fn read_tokens<R: CharRead>(lexer: &mut Lexer<'_, R>) -> Result<Vec<Token>,
                 }
             }
             Err(e) if e.is_unexpected_eof() && !tokens.is_empty() => {
-                return Err(ParserError::IncompleteReduction(
+                return Err(lexer.incomplete_reduction());
-                    lexer.line_num,
-                    lexer.col_num,
-                ));
             }
             Err(e) => {
                 return Err(e);
@@ -700,12 +697,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
         } else {
             let term = match self.terms.pop() {
                 Some(term) => term,
-                _ => {
+                _ => return Err(self.lexer.incomplete_reduction()),
-                    return Err(ParserError::IncompleteReduction(
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ))
-                }
             };
 
             if self.stack[idx].priority > 1000 {
@@ -718,10 +710,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
         };
 
         if arity > self.terms.len() {
-            return Err(ParserError::IncompleteReduction(
+            return Err(self.lexer.incomplete_reduction());
-                self.lexer.line_num,
-                self.lexer.col_num,
-            ));
         }
 
         let idx = self.terms.len() - arity;
@@ -789,12 +778,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
 
                         let term = match self.terms.pop() {
                             Some(term) => term,
-                            _ => {
+                            _ => return Err(self.lexer.incomplete_reduction()),
-                                return Err(ParserError::IncompleteReduction(
-                                    self.lexer.line_num,
-                                    self.lexer.col_num,
-                                ))
-                            }
                         };
 
                         self.terms
@@ -972,10 +956,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
                 self.negate_number(n, negate_rat_rc, Literal::Rational)
             }
             Token::Literal(Literal::F64(_offset, n)) if n.is_infinite() => {
-                return Err(ParserError::InfiniteFloat(
+                return Err(self.lexer.located_error(ParserErrorKind::InfiniteFloat));
-                    self.lexer.line_num,
-                    self.lexer.col_num,
-                ));
             }
             Token::Literal(Literal::F64(offset, n)) => {
                 self.negate_number((offset, n), negate_f64, |(offset, n)| {
@@ -997,28 +978,19 @@ impl<'a, R: CharRead> Parser<'a, R> {
             Token::OpenCT => self.shift(Token::OpenCT, 1300, DELIMITER),
             Token::Close => {
                 if !self.reduce_term() && !self.reduce_brackets() {
-                    return Err(ParserError::IncompleteReduction(
+                    return Err(self.lexer.incomplete_reduction());
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ));
                 }
             }
             Token::OpenList => self.shift(Token::OpenList, 1300, DELIMITER),
             Token::CloseList => {
                 if !self.reduce_list()? {
-                    return Err(ParserError::IncompleteReduction(
+                    return Err(self.lexer.incomplete_reduction());
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ));
                 }
             }
             Token::OpenCurly => self.shift(Token::OpenCurly, 1300, DELIMITER),
             Token::CloseCurly => {
                 if !self.reduce_curly()? {
-                    return Err(ParserError::IncompleteReduction(
+                    return Err(self.lexer.incomplete_reduction());
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ));
                 }
             }
             Token::HeadTailSeparator => {
@@ -1051,12 +1023,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
                 | Some(TokenType::OpenList)
                 | Some(TokenType::OpenCurly)
                 | Some(TokenType::HeadTailSeparator)
-                | Some(TokenType::Comma) => {
+                | Some(TokenType::Comma) => return Err(self.lexer.incomplete_reduction()),
-                    return Err(ParserError::IncompleteReduction(
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ))
-                }
                 _ => {}
             },
         }
@@ -1066,12 +1033,12 @@ impl<'a, R: CharRead> Parser<'a, R> {
 
     #[inline]
     pub fn add_lines_read(&mut self, lines_read: usize) {
-        self.lexer.line_num += lines_read;
+        self.lexer.location.line += lines_read;
     }
 
     #[inline]
     pub fn lines_read(&self) -> usize {
-        self.lexer.line_num
+        self.lexer.location.line
     }
 
     // on success, returns the parsed term and the number of lines read.
@@ -1092,10 +1059,7 @@ impl<'a, R: CharRead> Parser<'a, R> {
         self.reduce_op(1400);
 
         if self.terms.len() > 1 || self.stack.len() > 1 {
-            return Err(ParserError::IncompleteReduction(
+            return Err(self.lexer.incomplete_reduction());
-                self.lexer.line_num,
-                self.lexer.col_num,
-            ));
         }
 
         match self.terms.pop() {
@@ -1103,16 +1067,10 @@ impl<'a, R: CharRead> Parser<'a, R> {
                 if self.terms.is_empty() {
                     Ok(term)
                 } else {
-                    Err(ParserError::IncompleteReduction(
+                    Err(self.lexer.incomplete_reduction())
-                        self.lexer.line_num,
-                        self.lexer.col_num,
-                    ))
                 }
             }
-            _ => Err(ParserError::IncompleteReduction(
+            _ => Err(self.lexer.incomplete_reduction()),
-                self.lexer.line_num,
-                self.lexer.col_num,
-            )),
         }
     }
 }

src/read.rs

@@ -48,12 +48,11 @@ pub(crate) fn error_after_read_term<R>(
     parser: &Parser<R>,
 ) -> CompilationError {
     if err.is_unexpected_eof() {
-        let line_num = parser.lexer.line_num;
+        let location = &parser.lexer.location;
-        let col_num = parser.lexer.col_num;
 
         // rough overlap with errors 8.14.1.3 k) & l) of the ISO standard here
-        if !(line_num == prior_num_lines_read && col_num == 0) {
+        if !(location.line() == prior_num_lines_read && location.column() == 0) {
-            return CompilationError::from(ParserError::IncompleteReduction(line_num, col_num));
+            return CompilationError::from(parser.lexer.incomplete_reduction());
         }
     }