Split up `model` module

1 files changed, 189 insertions, 0 deletions

diff --git a/src/eval/symbol.rs b/src/eval/symbol.rs
new file mode 100644
index 00000000..73c41067
--- /dev/null
+++ b/src/eval/symbol.rs
@@ -0,0 +1,189 @@
+use std::cmp::Reverse;
+use std::collections::BTreeSet;
+use std::fmt::{self, Debug, Display, Formatter, Write};
+
+use ecow::{EcoString, EcoVec};
+
+use crate::diag::StrResult;
+
+#[doc(inline)]
+pub use typst_macros::symbols;
+
+/// A symbol.
+#[derive(Clone, Eq, PartialEq, Hash)]
+pub struct Symbol {
+    repr: Repr,
+    modifiers: EcoString,
+}
+
+/// A collection of symbols.
+#[derive(Clone, Eq, PartialEq, Hash)]
+enum Repr {
+    Single(char),
+    Static(&'static [(&'static str, char)]),
+    Runtime(EcoVec<(EcoString, char)>),
+}
+
+impl Symbol {
+    /// Create a new symbol from a single character.
+    pub const fn new(c: char) -> Self {
+        Self { repr: Repr::Single(c), modifiers: EcoString::new() }
+    }
+
+    /// Create a symbol with a static variant list.
+    #[track_caller]
+    pub const fn list(list: &'static [(&'static str, char)]) -> Self {
+        debug_assert!(!list.is_empty());
+        Self {
+            repr: Repr::Static(list),
+            modifiers: EcoString::new(),
+        }
+    }
+
+    /// Create a symbol with a runtime variant list.
+    #[track_caller]
+    pub fn runtime(list: EcoVec<(EcoString, char)>) -> Self {
+        debug_assert!(!list.is_empty());
+        Self {
+            repr: Repr::Runtime(list),
+            modifiers: EcoString::new(),
+        }
+    }
+
+    /// Get the symbol's text.
+    pub fn get(&self) -> char {
+        match self.repr {
+            Repr::Single(c) => c,
+            _ => find(self.variants(), &self.modifiers).unwrap(),
+        }
+    }
+
+    /// Apply a modifier to the symbol.
+    pub fn modified(mut self, modifier: &str) -> StrResult<Self> {
+        if !self.modifiers.is_empty() {
+            self.modifiers.push('.');
+        }
+        self.modifiers.push_str(modifier);
+        if find(self.variants(), &self.modifiers).is_none() {
+            Err("unknown modifier")?
+        }
+        Ok(self)
+    }
+
+    /// The characters that are covered by this symbol.
+    pub fn variants(&self) -> impl Iterator<Item = (&str, char)> {
+        match &self.repr {
+            Repr::Single(c) => Variants::Single(Some(*c).into_iter()),
+            Repr::Static(list) => Variants::Static(list.iter()),
+            Repr::Runtime(list) => Variants::Runtime(list.iter()),
+        }
+    }
+
+    /// Possible modifiers.
+    pub fn modifiers(&self) -> impl Iterator<Item = &str> + '_ {
+        let mut set = BTreeSet::new();
+        for modifier in self.variants().flat_map(|(name, _)| name.split('.')) {
+            if !modifier.is_empty() && !contained(&self.modifiers, modifier) {
+                set.insert(modifier);
+            }
+        }
+        set.into_iter()
+    }
+}
+
+impl Debug for Symbol {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.write_char(self.get())
+    }
+}
+
+impl Display for Symbol {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.write_char(self.get())
+    }
+}
+
+/// Iterator over variants.
+enum Variants<'a> {
+    Single(std::option::IntoIter<char>),
+    Static(std::slice::Iter<'static, (&'static str, char)>),
+    Runtime(std::slice::Iter<'a, (EcoString, char)>),
+}
+
+impl<'a> Iterator for Variants<'a> {
+    type Item = (&'a str, char);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            Self::Single(iter) => Some(("", iter.next()?)),
+            Self::Static(list) => list.next().copied(),
+            Self::Runtime(list) => list.next().map(|(s, c)| (s.as_str(), *c)),
+        }
+    }
+}
+
+/// Find the best symbol from the list.
+fn find<'a>(
+    variants: impl Iterator<Item = (&'a str, char)>,
+    modifiers: &str,
+) -> Option<char> {
+    let mut best = None;
+    let mut best_score = None;
+
+    // Find the best table entry with this name.
+    'outer: for candidate in variants {
+        for modifier in parts(modifiers) {
+            if !contained(candidate.0, modifier) {
+                continue 'outer;
+            }
+        }
+
+        let mut matching = 0;
+        let mut total = 0;
+        for modifier in parts(candidate.0) {
+            if contained(modifiers, modifier) {
+                matching += 1;
+            }
+            total += 1;
+        }
+
+        let score = (matching, Reverse(total));
+        if best_score.map_or(true, |b| score > b) {
+            best = Some(candidate.1);
+            best_score = Some(score);
+        }
+    }
+
+    best
+}
+
+/// Split a modifier list into its parts.
+fn parts(modifiers: &str) -> impl Iterator<Item = &str> {
+    modifiers.split('.').filter(|s| !s.is_empty())
+}
+
+/// Whether the modifier string contains the modifier `m`.
+fn contained(modifiers: &str, m: &str) -> bool {
+    parts(modifiers).any(|part| part == m)
+}
+
+/// Normalize an accent to a combining one.
+pub fn combining_accent(c: char) -> Option<char> {
+    Some(match c {
+        '\u{0300}' | '`' => '\u{0300}',
+        '\u{0301}' | '´' => '\u{0301}',
+        '\u{0302}' | '^' | 'ˆ' => '\u{0302}',
+        '\u{0303}' | '~' | '∼' | '˜' => '\u{0303}',
+        '\u{0304}' | '¯' => '\u{0304}',
+        '\u{0305}' | '-' | '‾' | '−' => '\u{0305}',
+        '\u{0306}' | '˘' => '\u{0306}',
+        '\u{0307}' | '.' | '˙' | '⋅' => '\u{0307}',
+        '\u{0308}' | '¨' => '\u{0308}',
+        '\u{030a}' | '∘' | '○' => '\u{030a}',
+        '\u{030b}' | '˝' => '\u{030b}',
+        '\u{030c}' | 'ˇ' => '\u{030c}',
+        '\u{20d6}' | '←' => '\u{20d6}',
+        '\u{20d7}' | '→' | '⟶' => '\u{20d7}',
+        _ => return None,
+    })
+}