more specific error

src/config/error.rs

@@ -11,10 +11,26 @@ pub enum Error {
     Syntax(sexp::Error),
     NotFound(PathBuf),
     InvalidUtf8,
-    InvalidSexp,
+    TypeError{expected:LispType, got: LispType},
+    BadLength,
     Unknown,
 }
 
+impl Error
+{
+    /// Helper function for type errors
+    #[inline]
+    pub fn bad_type<T,U>(expected: T, got: U) -> Self
+    where T: Into<LispType>,
+	  U: Into<LispType>
+    {
+	Self::TypeError {
+	    expected: expected.into(),
+	    got: got.into()
+	}
+    }
+}
+
 impl std::error::Error for Error
 {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)>
@@ -35,7 +51,8 @@ impl std::fmt::Display for Error
 	    Self::Syntax(sy) => write!(f, "s-expression syntax error: {}", sy),
             Self::NotFound(path) => write!(f, "File not found: {:?}", path),
 	    Self::InvalidUtf8 => write!(f, "Invalid UTF8 decoded string or some such"),
-                    Self::InvalidSexp => write!(f, "Invalid s-expression"),
+            Self::TypeError{expected, got} => write!(f, "Type mismatch: Expected {}, got {}", expected, got),
+	    Self::BadLength => write!(f, "expected at least 1 element"),
 	    _ => write!(f, "unknown error")
 	}
     }
@@ -67,7 +84,7 @@ impl From<Box<sexp::Error>> for Error
 
 impl From<std::str::Utf8Error> for Error
 {
-    fn from(from: std::str::Utf8Error) -> Self
+    fn from(_: std::str::Utf8Error) -> Self
     {
         Self::InvalidUtf8
     }

src/config/format.rs

@@ -0,0 +1,177 @@
+//! Formatting specifiers for the config file format
+use super::*;
+use sexp::{
+    Sexp,
+    Atom,
+};
+
+/// A valid type in the config file
+#[derive(Debug)]
+pub enum LispType
+{
+    List,
+    String,
+    Integer,
+    Float,
+    Atom,
+}
+
+impl From<Sexp> for LispType
+{
+    fn from(from: Sexp) -> Self
+    {
+	match from {
+	    Sexp::Atom(atom) => atom.into(),
+	    Sexp::List(_) => Self::List
+	}
+    }
+}
+
+impl From<Atom> for LispType
+{
+    fn from(from: Atom) -> Self
+    {
+	match from {
+	    Atom::F(_) => Self::Float,
+	    Atom::I(_) => Self::Integer,
+	    Atom::S(_) => Self::String,
+	}
+    }
+}
+
+impl<T> From<Result<T, Error>> for LispType
+where T: Into<LispType>
+{
+    fn from(from: Result<T, Error>) -> Self
+    {
+	match from {
+	    Ok(value) => value.into(),
+	    Err(Error::TypeError{got,..}) => got,
+	    _ => unreachable!("you shouldn't use this here"),
+	}
+    }
+}
+
+impl std::fmt::Display for LispType
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	f.write_str(match self {
+	    Self::List => "list",
+	    Self::String => "string",
+	    Self::Integer => "integer",
+	    Self::Float => "float",
+	    Self::Atom => "atom",
+	})
+    }
+}
+
+pub trait LispExt
+{
+    /// Try to get `car` and `cdr`
+    fn try_split<'a>(&'a self) -> Result<(&'a Sexp, &'a [Sexp]), Error>;
+}
+
+impl LispExt for Vec<Sexp>
+{
+    fn try_split<'a>(&'a self) -> Result<(&'a Sexp, &'a [Sexp]), Error>
+    {
+	if self.len() > 1 {
+	    Ok((&self[0], &self[1..]))
+	} else if self.len() > 0{
+	    Ok((&self[0], &[]))
+	} else {
+	    Err(Error::BadLength)
+	}
+    }
+}
+
+// Sexp doesn't use try_from(), so...
+pub trait TryIntoExt: Sized
+{
+    fn try_into_list(self) -> Result<Vec<Sexp>, Error>;
+    fn try_into_atom(self) -> Result<Atom, Error>;
+
+    fn try_into_string(self) -> Result<String, Error>;
+    fn try_into_int(self) -> Result<i64, Error>;
+    fn try_into_float(self) -> Result<f64, Error>;
+}
+
+impl TryIntoExt for Sexp
+{
+    fn try_into_list(self) -> Result<Vec<Sexp>, Error>
+    {
+	match self {
+	    Sexp::List(this) => Ok(this),
+	    other => Err(Error::bad_type(LispType::List, other)),
+	}
+    }
+    fn try_into_atom(self) -> Result<Atom, Error>
+    {
+	match self {
+	    Sexp::Atom(this) => Ok(this),
+	    other => Err(Error::bad_type(LispType::Atom, other)),
+	}
+    }
+
+    fn try_into_string(self) -> Result<String, Error>
+    {
+	match self.try_into_atom() {
+	    Ok(Atom::S(this)) => Ok(this),
+	    other => Err(Error::bad_type(LispType::String, other)),
+	}
+    }
+    
+    fn try_into_int(self) -> Result<i64, Error>
+    {	
+	match self.try_into_atom() {
+	    Ok(Atom::I(this)) => Ok(this),
+	    other => Err(Error::bad_type(LispType::Integer, other)),
+	}
+    }
+    fn try_into_float(self) -> Result<f64, Error>
+    {
+	match self.try_into_atom() {
+	    Ok(Atom::F(this)) => Ok(this),
+	    other => Err(Error::bad_type(LispType::Float, other)),
+	}
+    }
+}
+
+impl TryIntoExt for Atom
+{
+    #[inline]
+    fn try_into_list(self) -> Result<Vec<Sexp>, Error>
+    {
+	Err(Error::bad_type(LispType::List, self))
+    }
+    #[inline]
+    fn try_into_atom(self) -> Result<Atom, Error>
+    {
+	Ok(self)
+    }
+
+    fn try_into_string(self) -> Result<String, Error>
+    {
+	match self {
+	    Atom::S(this) => Ok(this),
+	    other => Err(Error::bad_type(LispType::String, other)),
+	}
+    }
+    
+    fn try_into_int(self) -> Result<i64, Error>
+    {
+	match self {
+	    Atom::I(this) => Ok(this),
+	    other => Err(Error::bad_type(LispType::Integer, other)),
+	}
+    }
+    fn try_into_float(self) -> Result<f64, Error>
+    {
+	match self {
+	    Atom::F(this) => Ok(this),
+	    other => Err(Error::bad_type(LispType::Float, other)),
+	}
+    }
+    
+}

src/config/mod.rs

@@ -9,6 +9,10 @@ use std::{
 };
 
 mod parse;
+
+mod format;
+pub use format::*;
+
 mod error;
 pub use error::*;
 

src/config/parse.rs

@@ -1,10 +1,13 @@
 //! Parses the config files
 use super::*;
-
-use tokio::fs::File;
-use tokio::prelude::*;
+use std::{
+    convert::TryFrom,
+};
+use tokio::{
+    prelude::*,
+    fs::File,
+};
 use sexp::{
-    parse,
     Sexp,
     Atom,
 };
@@ -13,7 +16,7 @@ fn get_atom_string<'a>(maybe_atom: &'a Sexp) -> Result<&'a String, Error>
 {
     match &maybe_atom {
         Sexp::Atom(Atom::S(string)) => Ok(string),
-        _ => Err(Error::InvalidSexp),
+        &opt => Err(Error::bad_type(LispType::String, opt.to_owned())),
     }
 }
 
@@ -44,6 +47,7 @@ fn set_debug(to: &mut Config, cdr: &[Sexp]) -> Result<(), Error> {
 #[inline]
 fn mwee(to: &mut Config, cdr: &[Sexp]) -> Result<(), Error> {
     println!("{:?}", cdr);
+    //todo!()
     Ok(())
 }
 
@@ -54,21 +58,23 @@ pub async fn global(to: &mut Config, path: impl AsRef<Path>) -> Result<(), error
 
     if path.exists() {
         let mut file = File::open(path).await?;
-        let mut contents = vec![];
+        let mut contents = if let Ok(Ok(wv)) = file.metadata().await
+	    .map(|x| x.len())
+	    .map(|x| usize::try_from(x)) {
+		Vec::with_capacity(wv)
+	    } else {
+		Vec::new()
+	    };
         file.read_to_end(&mut contents).await?;
 
         let parsed = sexp::parse(std::str::from_utf8(&contents[..])?)?;
 
-        if let Sexp::List(sexp) = parsed {
+	let sexp = parsed.try_into_list()?;
         for sexp in sexp.into_iter() {
-                if let Sexp::List(sexp) = sexp {
+	    let sexp = sexp.try_into_list()?;
 
-                    let car = &sexp[0];
-                    let cdr = &sexp[1..];
-                    match car {
-                        Sexp::List(_) => return Err(Error::InvalidSexp),
-                        Sexp::Atom(car) => {
-                            if let Atom::S(car) = car {
+	    let (car,cdr) = sexp.try_split()?;
+	    let car = car.clone()/* <- i'm too lazy to make ref versions of these `try_into_*` functions, so this will do*/.try_into_string()?;
             match car.to_lowercase().trim() {
                 "jobs-dir" => add_job(to, cdr),
                 "debug" => set_debug(to ,cdr),
@@ -76,22 +82,11 @@ pub async fn global(to: &mut Config, path: impl AsRef<Path>) -> Result<(), error
                 "deny" => mwee(to, cdr),
                 _ => return Err(Error::Unknown),
             }?;
-                            } else {
-                                return Err(Error::InvalidSexp);
-                            }
-                        }
         }
-                }
-                else {
-                    return Err(Error::InvalidSexp);
-                }
-            }
-        } else {
-            return Err(Error::InvalidSexp);
-        }
-        
 	Ok(())
+            
+            
     } else {
-        return Err(Error::NotFound(path.to_owned()));
+        Err(Error::NotFound(path.to_owned()))
     }
 }

src/main.rs

@@ -62,7 +62,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     
     debug!("Initialised");
 
-    println!("{:?}", config::parse_global_single("/home/manx/flon.txt").await.expect("Waaaaaah"));
+    println!("{:?}", config::parse_global_single("example.rori").await.expect("Waaaaaah"));
     
     //let (mut tx, h) = do_thing_every().await?;