Add table expressions with arg-parsing functions 🪔

2 files changed, 221 insertions, 19 deletions

diff --git a/src/syntax/expr.rs b/src/syntax/expr.rs
index f5ca55ab..98c67392 100644
--- a/src/syntax/expr.rs
+++ b/src/syntax/expr.rs
@@ -10,8 +10,9 @@ use fontdock::{FontStyle, FontWeight, FontWidth};
 use crate::layout::{Dir, SpecAlign};
 use crate::length::{Length, ScaleLength};
 use crate::paper::Paper;
+use crate::table::{BorrowedKey, Table};
 use crate::Feedback;
-use super::span::{SpanVec, Spanned};
+use super::span::{Span, SpanVec, Spanned};
 use super::tokens::is_identifier;
 use super::tree::SyntaxTree;
 
@@ -398,6 +399,120 @@ impl Debug for Object {
     }
 }
 
+/// A table expression.
+///
+/// # Example
+/// ```typst
+/// (false, 12cm, greeting="hi")
+/// ```
+pub type TableExpr = Table<TableExprEntry>;
+
+/// An entry in a table expression.
+///
+/// Contains the key's span and the value.
+pub struct TableExprEntry {
+    pub key: Span,
+    pub val: Spanned<Expr>,
+}
+
+impl TableExpr {
+    /// Retrieve and remove the matching value with the lowest number key,
+    /// skipping and ignoring all non-matching entries with lower keys.
+    pub fn take<T: TryFromExpr>(&mut self) -> Option<T> {
+        for (&key, entry) in self.nums() {
+            let expr = entry.val.as_ref();
+            if let Some(val) = T::try_from_expr(expr, &mut Feedback::new()) {
+                self.remove(key);
+                return Some(val);
+            }
+        }
+        None
+    }
+
+    /// Retrieve and remove the matching value with the lowest number key,
+    /// removing and generating errors for all non-matching entries with lower
+    /// keys.
+    pub fn expect<T: TryFromExpr>(&mut self, f: &mut Feedback) -> Option<T> {
+        while let Some((num, _)) = self.first() {
+            let entry = self.remove(num).unwrap();
+            if let Some(val) = T::try_from_expr(entry.val.as_ref(), f) {
+                return Some(val);
+            }
+        }
+        None
+    }
+
+    /// Retrieve and remove a matching value associated with the given key if
+    /// there is any.
+    ///
+    /// Generates an error if the key exists but the value does not match.
+    pub fn take_with_key<'a, T, K>(&mut self, key: K, f: &mut Feedback) -> Option<T>
+    where
+        T: TryFromExpr,
+        K: Into<BorrowedKey<'a>>,
+    {
+        self.remove(key).and_then(|entry| {
+            let expr = entry.val.as_ref();
+            T::try_from_expr(expr, f)
+        })
+    }
+
+    /// Retrieve and remove all matching pairs with number keys, skipping and
+    /// ignoring non-matching entries.
+    ///
+    /// The pairs are returned in order of increasing keys.
+    pub fn take_all_num<'a, T>(&'a mut self) -> impl Iterator<Item = (u64, T)> + 'a
+    where
+        T: TryFromExpr,
+    {
+        let mut skip = 0;
+        std::iter::from_fn(move || {
+            for (&key, entry) in self.nums().skip(skip) {
+                let expr = entry.val.as_ref();
+                if let Some(val) = T::try_from_expr(expr, &mut Feedback::new()) {
+                    self.remove(key);
+                    return Some((key, val));
+                }
+                skip += 1;
+            }
+
+            None
+        })
+    }
+
+    /// Retrieve and remove all matching pairs with string keys, skipping and
+    /// ignoring non-matching entries.
+    ///
+    /// The pairs are returned in order of increasing keys.
+    pub fn take_all_str<'a, T>(&'a mut self) -> impl Iterator<Item = (String, T)> + 'a
+    where
+        T: TryFromExpr,
+    {
+        let mut skip = 0;
+        std::iter::from_fn(move || {
+            for (key, entry) in self.strs().skip(skip) {
+                let expr = entry.val.as_ref();
+                if let Some(val) = T::try_from_expr(expr, &mut Feedback::new()) {
+                    let key = key.clone();
+                    self.remove(&key);
+                    return Some((key, val));
+                }
+                skip += 1;
+            }
+
+            None
+        })
+    }
+
+    /// Generated `"unexpected argument"` errors for all remaining entries.
+    pub fn unexpected(&self, f: &mut Feedback) {
+        for entry in self.values() {
+            let span = Span::merge(entry.key, entry.val.span);
+            error!(@f, span, "unexpected argument");
+        }
+    }
+}
+
 /// A trait for converting expressions into specific types.
 pub trait TryFromExpr: Sized {
     // This trait takes references because we don't want to move the expression
@@ -581,3 +696,64 @@ impl TryFromExpr for FontWidth {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn entry(expr: Expr) -> TableExprEntry {
+        TableExprEntry {
+            key: Span::ZERO,
+            val: Spanned::zero(expr),
+        }
+    }
+
+    #[test]
+    fn test_table_take_removes_correct_entry() {
+        let mut table = TableExpr::new();
+        table.insert(1, entry(Expr::Bool(false)));
+        table.insert(2, entry(Expr::Str("hi".to_string())));
+        assert_eq!(table.take::<String>(), Some("hi".to_string()));
+        assert_eq!(table.len(), 1);
+        assert_eq!(table.take::<bool>(), Some(false));
+        assert!(table.is_empty());
+    }
+
+    #[test]
+    fn test_table_expect_errors_about_previous_entries() {
+        let mut f = Feedback::new();
+        let mut table = TableExpr::new();
+        table.insert(1, entry(Expr::Bool(false)));
+        table.insert(3, entry(Expr::Str("hi".to_string())));
+        table.insert(5, entry(Expr::Bool(true)));
+        assert_eq!(table.expect::<String>(&mut f), Some("hi".to_string()));
+        assert_eq!(f.diagnostics, [error!(Span::ZERO, "expected string, found bool")]);
+        assert_eq!(table.len(), 1);
+    }
+
+    #[test]
+    fn test_table_take_with_key_removes_the_entry() {
+        let mut f = Feedback::new();
+        let mut table = TableExpr::new();
+        table.insert(1, entry(Expr::Bool(false)));
+        table.insert("hi", entry(Expr::Bool(true)));
+        assert_eq!(table.take_with_key::<bool, _>(1, &mut f), Some(false));
+        assert_eq!(table.take_with_key::<f64, _>("hi", &mut f), None);
+        assert_eq!(f.diagnostics, [error!(Span::ZERO, "expected number, found bool")]);
+        assert!(table.is_empty());
+    }
+
+    #[test]
+    fn test_table_take_all_removes_the_correct_entries() {
+        let mut table = TableExpr::new();
+        table.insert(1, entry(Expr::Bool(false)));
+        table.insert(3, entry(Expr::Number(0.0)));
+        table.insert(7, entry(Expr::Bool(true)));
+        assert_eq!(
+            table.take_all_num::<bool>().collect::<Vec<_>>(),
+            [(1, false), (7, true)],
+        );
+        assert_eq!(table.len(), 1);
+        assert_eq!(table[3].val.v, Expr::Number(0.0));
+    }
+}
diff --git a/src/table.rs b/src/table.rs
index f88a0ac7..2b49d451 100644
--- a/src/table.rs
+++ b/src/table.rs
@@ -15,7 +15,7 @@ use std::ops::Index;
 #[derive(Default, Clone, PartialEq)]
 pub struct Table<V> {
     nums: BTreeMap<u64, V>,
-    strings: BTreeMap<String, V>,
+    strs: BTreeMap<String, V>,
     lowest_free: u64,
 }
 
@@ -24,14 +24,19 @@ impl<V> Table<V> {
     pub fn new() -> Self {
         Self {
             nums: BTreeMap::new(),
-            strings: BTreeMap::new(),
+            strs: BTreeMap::new(),
             lowest_free: 0,
         }
     }
 
     /// The total number of entries in the table.
     pub fn len(&self) -> usize {
-        self.nums.len() + self.strings.len()
+        self.nums.len() + self.strs.len()
+    }
+
+    /// Whether the table contains no entries.
+    pub fn is_empty(&self) -> bool {
+        self.len() == 0
     }
 
     /// The first number key-value pair (with lowest number).
@@ -50,8 +55,8 @@ impl<V> Table<V> {
         K: Into<BorrowedKey<'a>>,
     {
         match key.into() {
-            BorrowedKey::Number(num) => self.nums.get(&num),
-            BorrowedKey::Str(string) => self.strings.get(string),
+            BorrowedKey::Num(num) => self.nums.get(&num),
+            BorrowedKey::Str(string) => self.strs.get(string),
         }
     }
 
@@ -61,8 +66,8 @@ impl<V> Table<V> {
         K: Into<BorrowedKey<'a>>,
     {
         match key.into() {
-            BorrowedKey::Number(num) => self.nums.get_mut(&num),
-            BorrowedKey::Str(string) => self.strings.get_mut(string),
+            BorrowedKey::Num(num) => self.nums.get_mut(&num),
+            BorrowedKey::Str(string) => self.strs.get_mut(string),
         }
     }
 
@@ -72,14 +77,14 @@ impl<V> Table<V> {
         K: Into<OwnedKey>,
     {
         match key.into() {
-            OwnedKey::Number(num) => {
+            OwnedKey::Num(num) => {
                 self.nums.insert(num, value);
                 if self.lowest_free == num {
                     self.lowest_free += 1;
                 }
             }
             OwnedKey::Str(string) => {
-                self.strings.insert(string, value);
+                self.strs.insert(string, value);
             }
         }
     }
@@ -90,11 +95,11 @@ impl<V> Table<V> {
         K: Into<BorrowedKey<'a>>,
     {
         match key.into() {
-            BorrowedKey::Number(num) => {
+            BorrowedKey::Num(num) => {
                 self.lowest_free = self.lowest_free.min(num);
                 self.nums.remove(&num)
             }
-            BorrowedKey::Str(string) => self.strings.remove(string),
+            BorrowedKey::Str(string) => self.strs.remove(string),
         }
     }
 
@@ -109,6 +114,21 @@ impl<V> Table<V> {
         self.nums.insert(self.lowest_free, value);
         self.lowest_free += 1;
     }
+
+    /// Iterate over the number key-value pairs.
+    pub fn nums(&self) -> std::collections::btree_map::Iter<u64, V> {
+        self.nums.iter()
+    }
+
+    /// Iterate over the string key-value pairs.
+    pub fn strs(&self) -> std::collections::btree_map::Iter<String, V> {
+        self.strs.iter()
+    }
+
+    /// Iterate over all values in the table.
+    pub fn values(&self) -> impl Iterator<Item = &V> {
+        self.nums().map(|(_, v)| v).chain(self.strs().map(|(_, v)| v))
+    }
 }
 
 impl<'a, K, V> Index<K> for Table<V>
@@ -125,13 +145,13 @@ where
 impl<V: Debug> Debug for Table<V> {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         f.write_str("(")?;
-        if f.alternate() && (!self.nums.is_empty() || !self.strings.is_empty()) {
+        if f.alternate() && (!self.nums.is_empty() || !self.strs.is_empty()) {
             f.write_str("\n")?;
         }
 
         let len = self.len();
-        let nums = self.nums.iter().map(|(k, v)| (k as &dyn Debug, v));
-        let strings = self.strings.iter().map(|(k, v)| (k as &dyn Debug, v));
+        let nums = self.nums().map(|(k, v)| (k as &dyn Debug, v));
+        let strings = self.strs().map(|(k, v)| (k as &dyn Debug, v));
         let pairs = nums.chain(strings);
 
         for (i, (key, value)) in pairs.enumerate() {
@@ -159,13 +179,13 @@ impl<V: Debug> Debug for Table<V> {
 /// The owned variant of a table key.
 #[derive(Debug, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub enum OwnedKey {
-    Number(u64),
+    Num(u64),
     Str(String),
 }
 
 impl From<u64> for OwnedKey {
     fn from(num: u64) -> Self {
-        Self::Number(num)
+        Self::Num(num)
     }
 }
 
@@ -184,13 +204,19 @@ impl From<&str> for OwnedKey {
 /// The borrowed variant of a table key.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub enum BorrowedKey<'a> {
-    Number(u64),
+    Num(u64),
     Str(&'a str),
 }
 
 impl From<u64> for BorrowedKey<'static> {
     fn from(num: u64) -> Self {
-        Self::Number(num)
+        Self::Num(num)
+    }
+}
+
+impl<'a> From<&'a String> for BorrowedKey<'a> {
+    fn from(string: &'a String) -> Self {
+        Self::Str(&string)
     }
 }