Merge pull request #2 from typst/expressions

Add parsing capabilities for mathematical expressions

1 files changed, 37 insertions, 19 deletions

diff --git a/src/syntax/expr.rs b/src/syntax/expr.rs
index 9d690266..1dc47d03 100644
--- a/src/syntax/expr.rs
+++ b/src/syntax/expr.rs
@@ -1,6 +1,6 @@
 //! Expressions in function headers.
 
-use std::fmt::{self, Write, Debug, Formatter};
+use std::fmt::{self, Debug, Formatter};
 use std::iter::FromIterator;
 use std::ops::Deref;
 use std::str::FromStr;
@@ -26,7 +26,7 @@ pub enum Expr {
     Size(Size),
     /// A bool: `true, false`.
     Bool(bool),
-    /// A color value, including the alpha channel: `#f79143ff`
+    /// A color value, including the alpha channel: `#f79143ff`.
     Color(RgbaColor),
     /// A tuple: `(false, 12cm, "hi")`.
     Tuple(Tuple),
@@ -34,6 +34,16 @@ pub enum Expr {
     NamedTuple(NamedTuple),
     /// An object: `{ fit: false, size: 12pt }`.
     Object(Object),
+    /// An operator that negates the contained expression.
+    Neg(Box<Spanned<Expr>>),
+    /// An operator that adds the contained expressions.
+    Add(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    /// An operator that subtracts contained expressions.
+    Sub(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    /// An operator that multiplies the contained expressions.
+    Mul(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
+    /// An operator that divides the contained expressions.
+    Div(Box<Spanned<Expr>>, Box<Spanned<Expr>>),
 }
 
 impl Expr {
@@ -50,6 +60,11 @@ impl Expr {
             Tuple(_) => "tuple",
             NamedTuple(_) => "named tuple",
             Object(_) => "object",
+            Neg(_) => "negation",
+            Add(_, _) => "addition",
+            Sub(_, _) => "subtraction",
+            Mul(_, _) => "multiplication",
+            Div(_, _) => "division",
         }
     }
 }
@@ -67,6 +82,11 @@ impl Debug for Expr {
             Tuple(t) => t.fmt(f),
             NamedTuple(t) => t.fmt(f),
             Object(o) => o.fmt(f),
+            Neg(e) => write!(f, "-{:?}", e),
+            Add(a, b) => write!(f, "({:?} + {:?})", a, b),
+            Sub(a, b) => write!(f, "({:?} - {:?})", a, b),
+            Mul(a, b) => write!(f, "({:?} * {:?})", a, b),
+            Div(a, b) => write!(f, "({:?} / {:?})", a, b),
         }
     }
 }
@@ -102,9 +122,7 @@ impl Ident {
 
 impl Debug for Ident {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.write_char('`')?;
-        f.write_str(&self.0)?;
-        f.write_char('`')
+        write!(f, "`{}`", self.0)
     }
 }
 
@@ -346,7 +364,7 @@ impl Deref for NamedTuple {
 #[derive(Default, Clone, PartialEq)]
 pub struct Object {
     /// The key-value pairs of the object.
-    pub pairs: Vec<Pair>,
+    pub pairs: Vec<Spanned<Pair>>,
 }
 
 /// A key-value pair in an object.
@@ -373,7 +391,7 @@ impl Object {
     }
 
     /// Add a pair to object.
-    pub fn add(&mut self, pair: Pair) {
+    pub fn add(&mut self, pair: Spanned<Pair>) {
         self.pairs.push(pair);
     }
 
@@ -383,7 +401,7 @@ impl Object {
     /// Inserts an error if the value does not match. If the key is not
     /// contained, no error is inserted.
     pub fn get<V: Value>(&mut self, errors: &mut Errors, key: &str) -> Option<V> {
-        let index = self.pairs.iter().position(|pair| pair.key.v.as_str() == key)?;
+        let index = self.pairs.iter().position(|pair| pair.v.key.v.as_str() == key)?;
         self.get_index::<V>(errors, index)
     }
 
@@ -396,7 +414,7 @@ impl Object {
         errors: &mut Errors,
     ) -> Option<(K, V)> {
         for (index, pair) in self.pairs.iter().enumerate() {
-            let key = Spanned { v: pair.key.v.as_str(), span: pair.key.span };
+            let key = Spanned { v: pair.v.key.v.as_str(), span: pair.v.key.span };
             if let Some(key) = K::parse(key) {
                 return self.get_index::<V>(errors, index).map(|value| (key, value));
             }
@@ -414,7 +432,7 @@ impl Object {
         let mut index = 0;
         std::iter::from_fn(move || {
             if index < self.pairs.len() {
-                let key = &self.pairs[index].key;
+                let key = &self.pairs[index].v.key;
                 let key = Spanned { v: key.v.as_str(), span: key.span };
 
                 Some(if let Some(key) = K::parse(key) {
@@ -447,7 +465,7 @@ impl Object {
     /// Extract the argument at the given index and insert an error if the value
     /// does not match.
     fn get_index<V: Value>(&mut self, errors: &mut Errors, index: usize) -> Option<V> {
-        let expr = self.pairs.remove(index).value;
+        let expr = self.pairs.remove(index).v.value;
         let span = expr.span;
         match V::parse(expr) {
             Ok(output) => Some(output),
@@ -456,14 +474,14 @@ impl Object {
     }
 
     /// Iterate over the pairs of this object.
-    pub fn iter<'a>(&'a self) -> std::slice::Iter<'a, Pair> {
+    pub fn iter<'a>(&'a self) -> std::slice::Iter<'a, Spanned<Pair>> {
         self.pairs.iter()
     }
 }
 
 impl IntoIterator for Object {
-    type Item = Pair;
-    type IntoIter = std::vec::IntoIter<Pair>;
+    type Item = Spanned<Pair>;
+    type IntoIter = std::vec::IntoIter<Spanned<Pair>>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.pairs.into_iter()
@@ -471,16 +489,16 @@ impl IntoIterator for Object {
 }
 
 impl<'a> IntoIterator for &'a Object {
-    type Item = &'a Pair;
-    type IntoIter = std::slice::Iter<'a, Pair>;
+    type Item = &'a Spanned<Pair>;
+    type IntoIter = std::slice::Iter<'a, Spanned<Pair>>;
 
     fn into_iter(self) -> Self::IntoIter {
         self.iter()
     }
 }
 
-impl FromIterator<Pair> for Object {
-    fn from_iter<I: IntoIterator<Item=Pair>>(iter: I) -> Self {
+impl FromIterator<Spanned<Pair>> for Object {
+    fn from_iter<I: IntoIterator<Item=Spanned<Pair>>>(iter: I) -> Self {
         Object { pairs: iter.into_iter().collect() }
     }
 }
@@ -488,7 +506,7 @@ impl FromIterator<Pair> for Object {
 impl Debug for Object {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         f.debug_map()
-            .entries(self.pairs.iter().map(|p| (&p.key.v, &p.value.v)))
+            .entries(self.pairs.iter().map(|p| (&p.v.key.v, &p.v.value.v)))
             .finish()
     }
 }