Create error_type! macro ✔

src/engine.rs

@@ -1,8 +1,5 @@
 //! Core typesetting engine.
 
-use std::io;
-use std::error;
-use std::fmt;
 use crate::syntax::{SyntaxTree, Node};
 use crate::doc::{Document, Size, Page, Text, TextCommand};
 use crate::font::{Font, FontConfig, FontError};
@@ -141,58 +138,25 @@ impl<'a> Engine<'a> {
     }
 }
 
-/// Result type used for typesetting.
-type TypeResult<T> = std::result::Result<T, TypesetError>;
-
 /// The error type for typesetting.
 pub enum TypesetError {
     /// There was no suitable font.
     MissingFont,
     /// An error occured while gathering font data.
     Font(FontError),
-    /// An I/O Error on occured while reading a font.
-    Io(io::Error),
 }
 
-impl error::Error for TypesetError {
-    #[inline]
-    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
-        match self {
-            TypesetError::Font(err) => Some(err),
-            TypesetError::Io(err) => Some(err),
-            _ => None,
-        }
-    }
-}
-
-impl fmt::Display for TypesetError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
+error_type! {
+    err: TypesetError,
+    res: TypeResult,
+    show: f => match err {
         TypesetError::MissingFont => write!(f, "missing font"),
         TypesetError::Font(err) => write!(f, "font error: {}", err),
-            TypesetError::Io(err) => write!(f, "io error: {}", err),
-        }
-    }
-}
-
-impl fmt::Debug for TypesetError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(self, f)
-    }
-}
-
-impl From<io::Error> for TypesetError {
-    #[inline]
-    fn from(err: io::Error) -> TypesetError {
-        TypesetError::Io(err)
-    }
-}
-
-impl From<FontError> for TypesetError {
-    #[inline]
-    fn from(err: FontError) -> TypesetError {
-        TypesetError::Font(err)
-    }
+    },
+    source: match err {
+        TypesetError::Font(err) => Some(err),
+        _ => None,
+    },
+    from: (std::io::Error, TypesetError::Font(FontError::Io(err))),
+    from: (FontError, TypesetError::Font(err)),
 }

src/error.rs

@@ -0,0 +1,38 @@
+/// Create an error type.
+macro_rules! error_type {
+    (
+        $var:ident: $err:ident,
+        $(res: $res:ident,)*
+        show: $f:ident => $show:expr,
+        $(source: $source:expr,)*
+        $(from: ($from:path, $conv:expr),)*
+    ) => {
+        $(type $res<T> = std::result::Result<T, $err>;)*
+
+        impl std::fmt::Display for $err {
+            fn fmt(&self, $f: &mut std::fmt::Formatter) -> std::fmt::Result {
+                let $var = self;
+                $show
+            }
+        }
+
+        impl std::fmt::Debug for $err {
+            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+                std::fmt::Display::fmt(self, f)
+            }
+        }
+
+        impl std::error::Error for $err {
+            $(fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+                let $var = self;
+                $source
+            })*
+        }
+
+        $(impl From<$from> for $err {
+            fn from($var: $from) -> $err {
+                $conv
+            }
+        })*
+    };
+}

src/export/pdf.rs

@@ -1,14 +1,11 @@
 //! Exporting into _PDF_ documents.
 
 use std::collections::HashSet;
-use std::fmt::{self, Display, Debug, Formatter};
 use std::io::{self, Write};
-
 use pdf::{PdfWriter, Ref, Rect, Version, Trailer, Content};
 use pdf::doc::{Catalog, PageTree, Page, Resource, Text};
 use pdf::font::{Type0Font, CIDFont, CIDFontType, CIDSystemInfo, FontDescriptor, FontFlags};
 use pdf::font::{GlyphUnit, CMapEncoding, WidthRecord, FontStream, EmbeddedFontType};
-
 use crate::doc::{Document, Size, Text as DocText, TextCommand};
 use crate::font::{Font, FontError};
 
@@ -284,9 +281,6 @@ impl std::ops::Deref for PdfFont {
     }
 }
 
-/// Result type for _PDF_ creation.
-type PdfResult<T> = std::result::Result<T, PdfExportError>;
-
 /// The error type for _PDF_ creation.
 pub enum PdfExportError {
     /// An error occured while subsetting the font for the _PDF_.
@@ -295,38 +289,17 @@ pub enum PdfExportError {
     Io(io::Error),
 }
 
-impl std::error::Error for PdfExportError {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
-        match self {
-            PdfExportError::Font(err) => Some(err),
-            PdfExportError::Io(err) => Some(err),
-        }
-    }
-}
-
-impl Display for PdfExportError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
+error_type! {
+    err: PdfExportError,
+    res: PdfResult,
+    show: f => match err {
         PdfExportError::Font(err) => write!(f, "font error: {}", err),
         PdfExportError::Io(err) => write!(f, "io error: {}", err),
-        }
-    }
-}
-
-impl Debug for PdfExportError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        Display::fmt(self, f)
-    }
-}
-
-impl From<io::Error> for PdfExportError {
-    fn from(err: io::Error) -> PdfExportError {
-        PdfExportError::Io(err)
-    }
-}
-
-impl From<FontError> for PdfExportError {
-    fn from(err: FontError) -> PdfExportError {
-        PdfExportError::Font(err)
-    }
+    },
+    source: match err {
+        PdfExportError::Font(err) => Some(err),
+        PdfExportError::Io(err) => Some(err),
+    },
+    from: (io::Error, PdfExportError::Io(err)),
+    from: (FontError, PdfExportError::Font(err)),
 }

src/font.rs

@@ -3,8 +3,6 @@
 #![macro_use]
 
 use std::collections::HashMap;
-use std::error;
-use std::fmt;
 use std::path::{Path, PathBuf};
 use std::io::{self, Cursor, Read, Seek, SeekFrom};
 use byteorder::{BE, ReadBytesExt, WriteBytesExt};
@@ -715,8 +713,6 @@ impl FontProvider for FileFontProvider<'_> {
     }
 }
 
-type FontResult<T> = Result<T, FontError>;
-
 /// The error type for font operations.
 pub enum FontError {
     /// The font file is incorrect.
@@ -731,50 +727,25 @@ pub enum FontError {
     Io(io::Error),
 }
 
-impl error::Error for FontError {
-    #[inline]
-    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
-        match self {
-            FontError::Io(err) => Some(err),
-            _ => None,
-        }
-    }
-}
-
-impl fmt::Display for FontError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        match self {
+error_type! {
+    err: FontError,
+    res: FontResult,
+    show: f => match err {
         FontError::InvalidFont(message) => write!(f, "invalid font: {}", message),
         FontError::MissingTable(table) => write!(f, "missing table: {}", table),
         FontError::UnsupportedTable(table) => write!(f, "unsupported table: {}", table),
         FontError::MissingCharacter(c) => write!(f, "missing character: '{}'", c),
         FontError::Io(err) => write!(f, "io error: {}", err),
-        }
-    }
-}
-
-impl fmt::Debug for FontError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(self, f)
-    }
-}
-
-impl From<io::Error> for FontError {
-    #[inline]
-    fn from(err: io::Error) -> FontError {
-        FontError::Io(err)
-    }
-}
-
-impl From<OpentypeError> for FontError {
-    fn from(err: OpentypeError) -> FontError {
-        match err {
+    },
+    source: match err {
+        FontError::Io(err) => Some(err),
+        _ => None,
+    },
+    from: (io::Error, FontError::Io(err)),
+    from: (OpentypeError, match err {
         OpentypeError::InvalidFont(message) => FontError::InvalidFont(message),
         OpentypeError::MissingTable(tag) => FontError::MissingTable(tag.to_string()),
         OpentypeError::Io(err) => FontError::Io(err),
         _ => panic!("unexpected extensible variant"),
-        }
-    }
+    }),
 }

src/lib.rs

@@ -38,20 +38,21 @@
 //! exporter.export(&document, &mut file).unwrap();
 //! ```
 
-use std::fmt::{self, Display, Debug, Formatter};
 use crate::syntax::SyntaxTree;
 use crate::parsing::{Tokens, Parser, ParseError};
 use crate::doc::{Document, Style};
 use crate::font::FontProvider;
 use crate::engine::{Engine, TypesetError};
 
+#[macro_use]
+mod error;
+mod utility;
 pub mod doc;
 pub mod engine;
 pub mod export;
 pub mod font;
 pub mod parsing;
 pub mod syntax;
-mod utility;
 
 
 /// Transforms source code into typesetted documents.
@@ -120,43 +121,20 @@ pub enum Error {
     Typeset(TypesetError),
 }
 
-impl std::error::Error for Error {
-    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
-        match self {
-            Error::Parse(err) => Some(err),
-            Error::Typeset(err) => Some(err),
-        }
-    }
+error_type! {
+    err: Error,
+    show: f => match err {
+        Error::Parse(e) => write!(f, "parse error: {}", e),
+        Error::Typeset(e) => write!(f, "typeset error: {}", e),
+    },
+    source: match err {
+        Error::Parse(e) => Some(e),
+        Error::Typeset(e) => Some(e),
+    },
+    from: (ParseError, Error::Parse(err)),
+    from: (TypesetError, Error::Typeset(err)),
 }
 
-impl Display for Error {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            Error::Parse(err) => write!(f, "parse error: {}", err),
-            Error::Typeset(err) => write!(f, "typeset error: {}", err),
-        }
-    }
-}
-
-impl Debug for Error {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        Display::fmt(self, f)
-    }
-}
-
-impl From<ParseError> for Error {
-    fn from(err: ParseError) -> Error {
-        Error::Parse(err)
-    }
-}
-
-impl From<TypesetError> for Error {
-    fn from(err: TypesetError) -> Error {
-        Error::Typeset(err)
-    }
-}
-
-
 #[cfg(test)]
 mod test {
     use std::fs::File;

src/parsing.rs

@@ -1,6 +1,5 @@
 //! Parsing of source code into tokens and syntax trees.
 
-use std::error;
 use std::fmt;
 use std::iter::Peekable;
 use std::mem::swap;
@@ -9,7 +8,7 @@ use crate::syntax::*;
 use crate::utility::{Splinor, Spline, Splined, StrExt};
 
 
-/// An iterator over the tokens of a text.
+/// An iterator over the tokens of source code.
 #[derive(Clone)]
 pub struct Tokens<'s> {
     source: &'s str,
@@ -211,7 +210,7 @@ impl<'s> Tokens<'s> {
     }
 }
 
-/// Parses a token stream into an abstract syntax tree.
+/// Transforms token streams to syntax trees.
 #[derive(Debug, Clone)]
 pub struct Parser<'s, T> where T: Iterator<Item = Token<'s>> {
     tokens: Peekable<T>,
@@ -355,30 +354,17 @@ impl<'s, T> Parser<'s, T> where T: Iterator<Item = Token<'s>> {
     }
 }
 
-/// Result type used for parsing.
-type ParseResult<T> = std::result::Result<T, ParseError>;
-
 /// The error type for parsing.
 pub struct ParseError {
-    /// A message describing the error.
     message: String,
 }
 
-impl error::Error for ParseError {}
-
-impl fmt::Display for ParseError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str(&self.message)
-    }
+error_type! {
+    err: ParseError,
+    res: ParseResult,
+    show: f => f.write_str(&err.message),
 }
 
-impl fmt::Debug for ParseError {
-    #[inline]
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Display::fmt(self, f)
-    }
-}
 
 #[cfg(test)]
 mod token_tests {