Evaluate expressions 🧮

6 files changed, 246 insertions, 48 deletions

diff --git a/src/eval/dict.rs b/src/eval/dict.rs
index 7f4426ff..b0d5fb82 100644
--- a/src/eval/dict.rs
+++ b/src/eval/dict.rs
@@ -2,6 +2,7 @@
 
 use std::collections::BTreeMap;
 use std::fmt::{self, Debug, Display, Formatter};
+use std::iter::Extend;
 use std::ops::Index;
 
 use crate::syntax::{Span, Spanned};
@@ -117,9 +118,7 @@ impl<V> Dict<V> {
 
     /// Iterator over all borrowed keys and values.
     pub fn iter(&self) -> impl Iterator<Item = (RefKey, &V)> {
-        self.nums()
-            .map(|(&k, v)| (RefKey::Num(k), v))
-            .chain(self.strs().map(|(k, v)| (RefKey::Str(k), v)))
+        self.into_iter()
     }
 
     /// Iterate over all values in the dictionary.
@@ -137,14 +136,6 @@ impl<V> Dict<V> {
         self.strs.iter()
     }
 
-    /// Move into an owned iterator over owned keys and values.
-    pub fn into_iter(self) -> impl Iterator<Item = (DictKey, V)> {
-        self.nums
-            .into_iter()
-            .map(|(k, v)| (DictKey::Num(k), v))
-            .chain(self.strs.into_iter().map(|(k, v)| (DictKey::Str(k), v)))
-    }
-
     /// Move into an owned iterator over all values in the dictionary.
     pub fn into_values(self) -> impl Iterator<Item = V> {
         self.nums
@@ -164,17 +155,6 @@ impl<V> Dict<V> {
     }
 }
 
-impl<'a, K, V> Index<K> for Dict<V>
-where
-    K: Into<RefKey<'a>>,
-{
-    type Output = V;
-
-    fn index(&self, index: K) -> &Self::Output {
-        self.get(index).expect("key not in dict")
-    }
-}
-
 impl<V> Default for Dict<V> {
     fn default() -> Self {
         Self::new()
@@ -189,6 +169,68 @@ impl<V: PartialEq> PartialEq for Dict<V> {
     }
 }
 
+impl<V> IntoIterator for Dict<V> {
+    type Item = (DictKey, V);
+    type IntoIter = std::iter::Chain<
+        std::iter::Map<
+            std::collections::btree_map::IntoIter<u64, V>,
+            fn((u64, V)) -> (DictKey, V),
+        >,
+        std::iter::Map<
+            std::collections::btree_map::IntoIter<String, V>,
+            fn((String, V)) -> (DictKey, V),
+        >,
+    >;
+
+    fn into_iter(self) -> Self::IntoIter {
+        let nums = self.nums.into_iter().map((|(k, v)| (DictKey::Num(k), v)) as _);
+        let strs = self.strs.into_iter().map((|(k, v)| (DictKey::Str(k), v)) as _);
+        nums.chain(strs)
+    }
+}
+
+impl<'a, V> IntoIterator for &'a Dict<V> {
+    type Item = (RefKey<'a>, &'a V);
+    type IntoIter = std::iter::Chain<
+        std::iter::Map<
+            std::collections::btree_map::Iter<'a, u64, V>,
+            fn((&'a u64, &'a V)) -> (RefKey<'a>, &'a V),
+        >,
+        std::iter::Map<
+            std::collections::btree_map::Iter<'a, String, V>,
+            fn((&'a String, &'a V)) -> (RefKey<'a>, &'a V),
+        >,
+    >;
+
+    fn into_iter(self) -> Self::IntoIter {
+        let strs = self.strs().map((|(k, v): (&'a String, _)| (RefKey::Str(k), v)) as _);
+        let nums = self.nums().map((|(k, v): (&u64, _)| (RefKey::Num(*k), v)) as _);
+        nums.chain(strs)
+    }
+}
+
+impl<V> Extend<(DictKey, V)> for Dict<V> {
+    fn extend<T>(&mut self, iter: T)
+    where
+        T: IntoIterator<Item = (DictKey, V)>,
+    {
+        for (key, value) in iter.into_iter() {
+            self.insert(key, value);
+        }
+    }
+}
+
+impl<'a, K, V> Index<K> for Dict<V>
+where
+    K: Into<RefKey<'a>>,
+{
+    type Output = V;
+
+    fn index(&self, index: K) -> &Self::Output {
+        self.get(index).expect("key not in dict")
+    }
+}
+
 impl<V: Debug> Debug for Dict<V> {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         if self.is_empty() {
diff --git a/src/eval/value.rs b/src/eval/value.rs
index 51bc55ab..85ac2367 100644
--- a/src/eval/value.rs
+++ b/src/eval/value.rs
@@ -17,6 +17,8 @@ use crate::{DynFuture, Feedback, Pass};
 /// A computational value.
 #[derive(Clone, PartialEq)]
 pub enum Value {
+    /// The result of invalid operations.
+    Error,
     /// An identifier: `ident`.
     Ident(Ident),
     /// A boolean: `true, false`.
@@ -54,6 +56,7 @@ impl Value {
     /// The natural-language name of this value for use in error messages.
     pub fn name(&self) -> &'static str {
         match self {
+            Self::Error => "error",
             Self::Ident(_) => "identifier",
             Self::Bool(_) => "bool",
             Self::Int(_) => "integer",
@@ -111,6 +114,7 @@ impl Spanned<Value> {
 impl Debug for Value {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match self {
+            Self::Error => f.pad("<error>"),
             Self::Ident(i) => i.fmt(f),
             Self::Bool(b) => b.fmt(f),
             Self::Int(i) => i.fmt(f),
diff --git a/src/geom.rs b/src/geom.rs
index 05143f22..0a65a090 100644
--- a/src/geom.rs
+++ b/src/geom.rs
@@ -299,6 +299,14 @@ impl DivAssign<f64> for Linear {
     }
 }
 
+impl Neg for Linear {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self { rel: -self.rel, abs: -self.abs }
+    }
+}
+
 impl Debug for Linear {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         write!(f, "{}x + {}", self.rel, self.abs)
diff --git a/src/parse/tokens.rs b/src/parse/tokens.rs
index 0f6fb378..fbfb71e6 100644
--- a/src/parse/tokens.rs
+++ b/src/parse/tokens.rs
@@ -245,9 +245,9 @@ impl<'s> Tokens<'s> {
         self.s.eat_until(|c| {
             let end = match c {
                 c if c.is_whitespace() => true,
-                '[' | ']' | '*' | '/' => true,
+                '[' | ']' | '{' | '}' | '*' | '/' | '#' => true,
                 '_' | '`' | '~' | '\\' if body => true,
-                '(' | ')' | '{' | '}' | ':' | ',' | '=' | '"' | '#' if header => true,
+                '(' | ')' | ':' | ',' | '=' | '"' if header => true,
                 '+' | '-' if header && !last_was_e => true,
                 _ => false,
             };
@@ -360,19 +360,21 @@ mod tests {
 
     #[test]
     fn tokenize_body_tokens() {
-        t!(Body, "_*"            => Underscore, Star);
-        t!(Body, "***"           => Star, Star, Star);
+        t!(Body, "a_*"           => T("a"), Underscore, Star);
+        t!(Body, "a***"          => T("a"), Star, Star, Star);
         t!(Body, "[func]*bold*"  => L, T("func"), R, Star, T("bold"), Star);
         t!(Body, "hi_you_ there" => T("hi"), Underscore, T("you"), Underscore, S(0), T("there"));
         t!(Body, "# hi"          => Hashtag, S(0), T("hi"));
-        t!(Body, "#()"           => Hashtag, T("()"));
+        t!(Body, "ab# hi"        => T("ab"), Hashtag, S(0), T("hi"));
+        t!(Body, "#{}"           => Hashtag, LB, RB);
+        t!(Body, "{text}"        => LB, Text("text"), RB);
         t!(Header, "_`"          => Invalid("_`"));
     }
 
     #[test]
     fn test_tokenize_raw() {
         // Basics.
-        t!(Body, "`raw`"    => Raw("raw", 1, true));
+        t!(Body, "a`raw`"   => T("a"), Raw("raw", 1, true));
         t!(Body, "`[func]`" => Raw("[func]", 1, true));
         t!(Body, "`]"       => Raw("]", 1, false));
         t!(Body, r"`\`` "   => Raw(r"\", 1, true), Raw(" ", 1, false));
diff --git a/src/syntax/ast/expr.rs b/src/syntax/ast/expr.rs
index c07c6216..4f067145 100644
--- a/src/syntax/ast/expr.rs
+++ b/src/syntax/ast/expr.rs
@@ -3,7 +3,7 @@
 use crate::eval::Value;
 use crate::layout::LayoutContext;
 use crate::syntax::{Decoration, Ident, Lit, LitDict, SpanWith, Spanned};
-use crate::Feedback;
+use crate::{DynFuture, Feedback};
 
 /// An expression.
 #[derive(Debug, Clone, PartialEq)]
@@ -20,13 +20,19 @@ pub enum Expr {
 
 impl Expr {
     /// Evaluate the expression to a value.
-    pub async fn eval(&self, ctx: &LayoutContext<'_>, f: &mut Feedback) -> Value {
-        match self {
-            Self::Lit(lit) => lit.eval(ctx, f).await,
-            Self::Unary(unary) => unary.eval(ctx, f).await,
-            Self::Binary(binary) => binary.eval(ctx, f).await,
-            Self::Call(call) => call.eval(ctx, f).await,
-        }
+    pub fn eval<'a>(
+        &'a self,
+        ctx: &'a LayoutContext<'a>,
+        f: &'a mut Feedback,
+    ) -> DynFuture<'a, Value> {
+        Box::pin(async move {
+            match self {
+                Self::Lit(lit) => lit.eval(ctx, f).await,
+                Self::Unary(unary) => unary.eval(ctx, f).await,
+                Self::Binary(binary) => binary.eval(ctx, f).await,
+                Self::Call(call) => call.eval(ctx, f).await,
+            }
+        })
     }
 }
 
@@ -41,9 +47,27 @@ pub struct ExprUnary {
 
 impl ExprUnary {
     /// Evaluate the expression to a value.
-    pub async fn eval(&self, _: &LayoutContext<'_>, _: &mut Feedback) -> Value {
+    pub async fn eval(&self, ctx: &LayoutContext<'_>, f: &mut Feedback) -> Value {
+        use Value::*;
+
+        let value = self.expr.v.eval(ctx, f).await;
+        if value == Error {
+            return Error;
+        }
+
+        let span = self.op.span.join(self.expr.span);
         match self.op.v {
-            UnOp::Neg => todo!("eval neg"),
+            UnOp::Neg => match value {
+                Int(x) => Int(-x),
+                Float(x) => Float(-x),
+                Length(x) => Length(-x),
+                Relative(x) => Relative(-x),
+                Linear(x) => Linear(-x),
+                v => {
+                    error!(@f, span, "cannot negate {}", v.name());
+                    Value::Error
+                }
+            },
         }
     }
 }
@@ -68,16 +92,138 @@ pub struct ExprBinary {
 
 impl ExprBinary {
     /// Evaluate the expression to a value.
-    pub async fn eval(&self, _: &LayoutContext<'_>, _: &mut Feedback) -> Value {
+    pub async fn eval(&self, ctx: &LayoutContext<'_>, f: &mut Feedback) -> Value {
+        use crate::geom::Linear as Lin;
+        use Value::*;
+
+        let lhs = self.lhs.v.eval(ctx, f).await;
+        let rhs = self.rhs.v.eval(ctx, f).await;
+
+        if lhs == Error || rhs == Error {
+            return Error;
+        }
+
+        let span = self.lhs.span.join(self.rhs.span);
         match self.op.v {
-            BinOp::Add => todo!("eval add"),
-            BinOp::Sub => todo!("eval sub"),
-            BinOp::Mul => todo!("eval mul"),
-            BinOp::Div => todo!("eval div"),
+            BinOp::Add => match (lhs, rhs) {
+                // Numbers to themselves.
+                (Int(a), Int(b)) => Int(a + b),
+                (Int(i), Float(f)) | (Float(f), Int(i)) => Float(i as f64 + f),
+                (Float(a), Float(b)) => Float(a + b),
+
+                // Lengths, relatives and linears to themselves.
+                (Length(a), Length(b)) => Length(a + b),
+                (Length(a), Relative(b)) => Linear(Lin::abs(a) + Lin::rel(b)),
+                (Length(a), Linear(b)) => Linear(Lin::abs(a) + b),
+
+                (Relative(a), Length(b)) => Linear(Lin::rel(a) + Lin::abs(b)),
+                (Relative(a), Relative(b)) => Relative(a + b),
+                (Relative(a), Linear(b)) => Linear(Lin::rel(a) + b),
+
+                (Linear(a), Length(b)) => Linear(a + Lin::abs(b)),
+                (Linear(a), Relative(b)) => Linear(a + Lin::rel(b)),
+                (Linear(a), Linear(b)) => Linear(a + b),
+
+                // Complex data types to themselves.
+                (Str(a), Str(b)) => Str(a + &b),
+                (Dict(a), Dict(b)) => Dict(concat(a, b)),
+                (Tree(a), Tree(b)) => Tree(concat(a, b)),
+                (Commands(a), Commands(b)) => Commands(concat(a, b)),
+
+                (a, b) => {
+                    error!(@f, span, "cannot add {} and {}", a.name(), b.name());
+                    Value::Error
+                }
+            },
+
+            BinOp::Sub => match (lhs, rhs) {
+                // Numbers from themselves.
+                (Int(a), Int(b)) => Int(a - b),
+                (Int(a), Float(b)) => Float(a as f64 - b),
+                (Float(a), Int(b)) => Float(a - b as f64),
+                (Float(a), Float(b)) => Float(a - b),
+
+                // Lengths, relatives and linears from themselves.
+                (Length(a), Length(b)) => Length(a - b),
+                (Length(a), Relative(b)) => Linear(Lin::abs(a) - Lin::rel(b)),
+                (Length(a), Linear(b)) => Linear(Lin::abs(a) - b),
+                (Relative(a), Length(b)) => Linear(Lin::rel(a) - Lin::abs(b)),
+                (Relative(a), Relative(b)) => Relative(a - b),
+                (Relative(a), Linear(b)) => Linear(Lin::rel(a) - b),
+                (Linear(a), Length(b)) => Linear(a - Lin::abs(b)),
+                (Linear(a), Relative(b)) => Linear(a - Lin::rel(b)),
+                (Linear(a), Linear(b)) => Linear(a - b),
+
+                (a, b) => {
+                    error!(@f, span, "cannot subtract {1} from {0}", a.name(), b.name());
+                    Value::Error
+                }
+            },
+
+            BinOp::Mul => match (lhs, rhs) {
+                // Numbers with themselves.
+                (Int(a), Int(b)) => Int(a * b),
+                (Int(a), Float(b)) => Float(a as f64 * b),
+                (Float(a), Int(b)) => Float(a * b as f64),
+                (Float(a), Float(b)) => Float(a * b),
+
+                // Lengths, relatives and linears with numbers.
+                (Length(a), Int(b)) => Length(a * b as f64),
+                (Length(a), Float(b)) => Length(a * b),
+                (Int(a), Length(b)) => Length(a as f64 * b),
+                (Float(a), Length(b)) => Length(a * b),
+                (Relative(a), Int(b)) => Relative(a * b as f64),
+                (Relative(a), Float(b)) => Relative(a * b),
+                (Int(a), Relative(b)) => Relative(a as f64 * b),
+                (Float(a), Relative(b)) => Relative(a * b),
+                (Linear(a), Int(b)) => Linear(a * b as f64),
+                (Linear(a), Float(b)) => Linear(a * b),
+                (Int(a), Linear(b)) => Linear(a as f64 * b),
+                (Float(a), Linear(b)) => Linear(a * b),
+
+                // Integers with strings.
+                (Int(a), Str(b)) => Str(b.repeat(a.max(0) as usize)),
+                (Str(a), Int(b)) => Str(a.repeat(b.max(0) as usize)),
+
+                (a, b) => {
+                    error!(@f, span, "cannot multiply {} with {}", a.name(), b.name());
+                    Value::Error
+                }
+            },
+
+            BinOp::Div => match (lhs, rhs) {
+                // Numbers by themselves.
+                (Int(a), Int(b)) => Float(a as f64 / b as f64),
+                (Int(a), Float(b)) => Float(a as f64 / b),
+                (Float(a), Int(b)) => Float(a / b as f64),
+                (Float(a), Float(b)) => Float(a / b),
+
+                // Lengths by numbers.
+                (Length(a), Int(b)) => Length(a / b as f64),
+                (Length(a), Float(b)) => Length(a / b),
+                (Relative(a), Int(b)) => Relative(a / b as f64),
+                (Relative(a), Float(b)) => Relative(a / b),
+                (Linear(a), Int(b)) => Linear(a / b as f64),
+                (Linear(a), Float(b)) => Linear(a / b),
+
+                (a, b) => {
+                    error!(@f, span, "cannot divide {} by {}", a.name(), b.name());
+                    Value::Error
+                }
+            },
         }
     }
 }
 
+/// Concatenate two collections.
+fn concat<T, A>(mut a: T, b: T) -> T
+where
+    T: Extend<A> + IntoIterator<Item = A>,
+{
+    a.extend(b);
+    a
+}
+
 /// A binary operator.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum BinOp {
diff --git a/src/syntax/ast/lit.rs b/src/syntax/ast/lit.rs
index ba7e7e4f..c08dc8cd 100644
--- a/src/syntax/ast/lit.rs
+++ b/src/syntax/ast/lit.rs
@@ -39,11 +39,7 @@ pub enum Lit {
 
 impl Lit {
     /// Evaluate the dictionary literal to a dictionary value.
-    pub async fn eval<'a>(
-        &'a self,
-        ctx: &'a LayoutContext<'a>,
-        f: &'a mut Feedback,
-    ) -> Value {
+    pub async fn eval(&self, ctx: &LayoutContext<'_>, f: &mut Feedback) -> Value {
         match *self {
             Lit::Ident(ref i) => Value::Ident(i.clone()),
             Lit::Bool(b) => Value::Bool(b),