cleanup

src/config.rs

@@ -1,9 +1,14 @@
-use std::{collections::HashMap, iter::FromIterator};
-
-use super::*;
-use crate::error::*;
+use crate::{
+    error::*,
+    expr::{Expr, ExprIterator, ExprType, Span},
+    parser, spanned,
+};
 use itertools::Itertools;
-use std::collections::LinkedList;
+use std::{
+    collections::{HashMap, LinkedList},
+    iter::FromIterator,
+    str::FromStr,
+};
 
 type VarName = String;
 type AttrValue = String;
@@ -24,15 +29,13 @@ pub enum DefType {
     Widget,
 }
 
-impl FromExpr for DefType {
-    fn from_expr(e: Expr) -> AstResult<Self> {
-        if let Expr::Symbol(span, sym) = e {
-            match sym.as_str() {
+impl FromStr for DefType {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
             "defwidget" => Ok(DefType::Widget),
-                _ => Err(AstError::InvalidDefinition(Some(span))),
-            }
-        } else {
-            Err(AstError::WrongExprType(Some(e.span()), ExprType::Symbol, e))
+            _ => Err(()),
         }
     }
 }
@@ -51,13 +54,13 @@ impl<C: FromExpr, A: FromExpr> FromExpr for Definitional<C, A> {
         let span = e.span();
         spanned!(e.span(), {
             let list = e.as_list()?;
-            let mut iter = itertools::put_back(list.into_iter());
+            let mut iter = ExprIterator::new(list.into_iter());
+            let (span, def_type) = iter.next_symbol()?;
+            let def_type = def_type.parse().map_err(|_| AstError::InvalidDefinition(Some(span)))?;
 
-            let def_type = DefType::from_expr(iter.next().or_missing(ExprType::Symbol)?)?;
-            let name = iter.next().or_missing(ExprType::Symbol)?.as_symbol()?;
-            let attrs = parse_key_values(&mut iter)?;
+            let (_, name) = iter.next_symbol()?;
+            let attrs = iter.key_values()?;
             let children = iter.map(|x| C::from_expr(x)).collect::<AstResult<Vec<_>>>()?;
-
             Definitional { span, def_type, name, attrs, children }
         })
     }
@@ -76,40 +79,15 @@ impl<C: FromExpr, A: FromExpr> FromExpr for Element<C, A> {
         let span = e.span();
         spanned!(e.span(), {
             let list = e.as_list()?;
-            let mut iter = itertools::put_back(list.into_iter());
-
-            let name = iter.next().or_missing(ExprType::Str)?.as_symbol()?;
-            let attrs = parse_key_values(&mut iter)?;
-            let children = iter.map(C::from_expr).collect::<AstResult<Vec<_>>>()?;
-
+            let mut iter = ExprIterator::new(list.into_iter());
+            let (_, name) = iter.next_symbol()?;
+            let attrs = iter.key_values()?;
+            let children = iter.map(|x| C::from_expr(x)).collect::<AstResult<Vec<_>>>()?;
             Element { span, name, attrs, children }
         })
     }
 }
 
-/// Parse consecutive `:keyword value` pairs from an expression iterator into a HashMap. Transforms the keys using the FromExpr trait.
-fn parse_key_values<T: FromExpr, I: Iterator<Item = Expr>>(iter: &mut itertools::PutBack<I>) -> AstResult<HashMap<String, T>> {
-    let mut data = HashMap::new();
-    loop {
-        match iter.next() {
-            Some(Expr::Keyword(span, kw)) => match iter.next() {
-                Some(value) => {
-                    data.insert(kw, T::from_expr(value)?);
-                }
-                None => {
-                    iter.put_back(Expr::Keyword(span, kw));
-                    return Ok(data);
-                }
-            },
-            Some(expr) => {
-                iter.put_back(expr);
-                return Ok(data);
-            }
-            None => return Ok(data),
-        }
-    }
-}
-
 #[cfg(test)]
 mod test {
 

src/error.rs

@@ -1,4 +1,4 @@
-use crate::{Expr, ExprType, Span};
+use crate::expr::{Expr, ExprType, Span};
 use thiserror::Error;
 
 pub type AstResult<T> = Result<T, AstError>;
@@ -10,7 +10,7 @@ pub enum AstError {
     #[error("Expected a {1}, but got nothing")]
     MissingNode(Option<Span>, ExprType),
     #[error("Wrong type of expression: Expected {1} but got {2}")]
-    WrongExprType(Option<Span>, ExprType, Expr),
+    WrongExprType(Option<Span>, ExprType, ExprType),
 }
 
 pub fn spanned(span: Span, err: impl Into<AstError>) -> AstError {

src/expr.rs

@@ -0,0 +1,173 @@
+use itertools::Itertools;
+use std::collections::HashMap;
+
+use crate::{config::FromExpr, error::*};
+use std::fmt::Display;
+
+#[derive(Eq, PartialEq, Clone, Copy)]
+pub struct Span(pub usize, pub usize);
+
+impl std::fmt::Display for Span {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}..{}", self.0, self.1)
+    }
+}
+
+impl std::fmt::Debug for Span {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self)
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+pub enum ExprType {
+    List,
+    Table,
+    Keyword,
+    Symbol,
+    Str,
+    Number,
+    Comment,
+}
+
+impl Display for ExprType {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum Expr {
+    List(Span, Vec<Expr>),
+    Table(Span, Vec<(Expr, Expr)>),
+    Keyword(Span, String),
+    Symbol(Span, String),
+    Str(Span, String),
+    Number(Span, i32),
+    Comment(Span),
+}
+
+macro_rules! as_func {
+    ($exprtype:expr, $name:ident < $t:ty > = $p:pat => $value:expr) => {
+        pub fn $name(self) -> Result<$t, AstError> {
+            match self {
+                $p => Ok($value),
+                x => Err(AstError::WrongExprType(Some(x.span()), $exprtype, x.expr_type())),
+            }
+        }
+    };
+}
+
+impl Expr {
+    as_func!(ExprType::Str, as_str<String> = Expr::Str(_, x) => x);
+
+    as_func!(ExprType::Symbol, as_symbol<String> = Expr::Symbol(_, x) => x);
+
+    as_func!(ExprType::List, as_list<Vec<Expr>> = Expr::List(_, x) => x);
+
+    pub fn expr_type(&self) -> ExprType {
+        match self {
+            Expr::List(..) => ExprType::List,
+            Expr::Table(..) => ExprType::Table,
+            Expr::Keyword(..) => ExprType::Keyword,
+            Expr::Symbol(..) => ExprType::Symbol,
+            Expr::Str(..) => ExprType::Str,
+            Expr::Number(..) => ExprType::Number,
+            Expr::Comment(_) => ExprType::Number,
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        match self {
+            Expr::List(span, _) => *span,
+            Expr::Table(span, _) => *span,
+            Expr::Keyword(span, _) => *span,
+            Expr::Symbol(span, _) => *span,
+            Expr::Str(span, _) => *span,
+            Expr::Number(span, _) => *span,
+            Expr::Comment(span) => *span,
+        }
+    }
+}
+
+impl std::fmt::Display for Expr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        use Expr::*;
+        match self {
+            Number(_, x) => write!(f, "{}", x),
+            List(_, x) => write!(f, "({})", x.iter().map(|e| format!("{}", e)).join(" ")),
+            Table(_, x) => write!(f, "{{{}}}", x.iter().map(|(k, v)| format!("{} {}", k, v)).join(" ")),
+            Keyword(_, x) => write!(f, "{}", x),
+            Symbol(_, x) => write!(f, "{}", x),
+            Str(_, x) => write!(f, "{}", x),
+            Comment(_) => write!(f, ""),
+        }
+    }
+}
+
+pub struct ExprIterator<I: Iterator<Item = Expr>> {
+    iter: itertools::PutBack<I>,
+}
+
+macro_rules! return_or_put_back {
+    ($name:ident, $expr_type:expr, $t:ty = $p:pat => $ret:expr) => {
+        pub fn $name(&mut self) -> AstResult<$t> {
+            let expr_type = $expr_type;
+            match self.next() {
+                Some($p) => Ok($ret),
+                Some(other) => {
+                    let span = other.span();
+                    let actual_type = other.expr_type();
+                    self.iter.put_back(other);
+                    Err(AstError::WrongExprType(Some(span), expr_type, actual_type))
+                }
+                None => Err(AstError::MissingNode(None, expr_type)),
+            }
+        }
+    };
+}
+
+impl<I: Iterator<Item = Expr>> ExprIterator<I> {
+    return_or_put_back!(next_symbol, ExprType::Symbol, (Span, String) = Expr::Symbol(span, x) => (span, x));
+
+    return_or_put_back!(next_string, ExprType::Str, (Span, String) = Expr::Str(span, x) => (span, x));
+
+    pub fn new(iter: I) -> Self {
+        ExprIterator { iter: itertools::put_back(iter) }
+    }
+
+    pub fn key_values<T: FromExpr>(&mut self) -> AstResult<HashMap<String, T>> {
+        parse_key_values(&mut self.iter)
+    }
+}
+
+impl<I: Iterator<Item = Expr>> Iterator for ExprIterator<I> {
+    type Item = Expr;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next()
+    }
+}
+
+/// Parse consecutive `:keyword value` pairs from an expression iterator into a HashMap. Transforms the keys using the FromExpr trait.
+fn parse_key_values<T: FromExpr, I: Iterator<Item = Expr>>(iter: &mut itertools::PutBack<I>) -> AstResult<HashMap<String, T>> {
+    let mut data = HashMap::new();
+    loop {
+        match iter.next() {
+            Some(Expr::Keyword(span, kw)) => match iter.next() {
+                Some(value) => {
+                    data.insert(kw, T::from_expr(value)?);
+                }
+                None => {
+                    iter.put_back(Expr::Keyword(span, kw));
+                    return Ok(data);
+                }
+            },
+            Some(expr) => {
+                iter.put_back(expr);
+                return Ok(data);
+            }
+            None => return Ok(data),
+        }
+    }
+}

src/main.rs

@@ -4,6 +4,7 @@
 
 mod config;
 mod error;
+mod expr;
 use error::AstError;
 
 use std::{fmt::Display, ops::Deref};
@@ -16,109 +17,6 @@ use lalrpop_util::lalrpop_mod;
 
 lalrpop_mod!(pub parser);
 
-#[derive(Eq, PartialEq, Clone, Copy)]
-pub struct Span(pub usize, pub usize);
-
-impl std::fmt::Display for Span {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}..{}", self.0, self.1)
-    }
-}
-
-impl std::fmt::Debug for Span {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self)
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-pub enum ExprType {
-    List,
-    Table,
-    Keyword,
-    Symbol,
-    Str,
-    Number,
-    Comment,
-}
-
-impl Display for ExprType {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{:?}", self)
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Clone)]
-pub enum Expr {
-    List(Span, Vec<Expr>),
-    Table(Span, Vec<(Expr, Expr)>),
-    Keyword(Span, String),
-    Symbol(Span, String),
-    Str(Span, String),
-    Number(Span, i32),
-    Comment(Span),
-}
-
-impl From<Expr> for ExprType {
-    fn from(x: Expr) -> Self {
-        match x {
-            Expr::List(..) => ExprType::List,
-            Expr::Table(..) => ExprType::Table,
-            Expr::Keyword(..) => ExprType::Keyword,
-            Expr::Symbol(..) => ExprType::Symbol,
-            Expr::Str(..) => ExprType::Str,
-            Expr::Number(..) => ExprType::Number,
-            Expr::Comment(_) => ExprType::Number,
-        }
-    }
-}
-
-macro_rules! as_func {
-    ($exprtype:expr, $name:ident < $t:ty > = $p:pat => $value:expr) => {
-        fn $name(self) -> Result<$t, AstError> {
-            match self {
-                $p => Ok($value),
-                x => Err(AstError::WrongExprType(Some(x.span()), $exprtype, x)),
-            }
-        }
-    };
-}
-
-impl Expr {
-    as_func!(ExprType::Str, as_str<String> = Expr::Str(_, x) => x);
-
-    as_func!(ExprType::Symbol, as_symbol<String> = Expr::Symbol(_, x) => x);
-
-    as_func!(ExprType::List, as_list<Vec<Expr>> = Expr::List(_, x) => x);
-
-    pub fn span(&self) -> Span {
-        match self {
-            Expr::List(span, _) => *span,
-            Expr::Table(span, _) => *span,
-            Expr::Keyword(span, _) => *span,
-            Expr::Symbol(span, _) => *span,
-            Expr::Str(span, _) => *span,
-            Expr::Number(span, _) => *span,
-            Expr::Comment(span) => *span,
-        }
-    }
-}
-
-impl std::fmt::Display for Expr {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        use Expr::*;
-        match self {
-            Number(_, x) => write!(f, "{}", x),
-            List(_, x) => write!(f, "({})", x.iter().map(|e| format!("{}", e)).join(" ")),
-            Table(_, x) => write!(f, "{{{}}}", x.iter().map(|(k, v)| format!("{} {}", k, v)).join(" ")),
-            Keyword(_, x) => write!(f, "{}", x),
-            Symbol(_, x) => write!(f, "{}", x),
-            Str(_, x) => write!(f, "{}", x),
-            Comment(_) => write!(f, ""),
-        }
-    }
-}
-
 fn main() {}
 
 #[allow(unused_macros)]

src/parser.lalrpop

@@ -1,7 +1,6 @@
 use std::str::FromStr;
 //use crate::lexer;
-use crate::Expr;
-use crate::Span;
+use crate::expr::{Expr, Span};
 
 grammar;