optimize formatting

changelog.md

@@ -40,6 +40,7 @@ This version is not yet released. If you are reading this on the website, then t
   - This should not affect any language semantics
 - Improve pattern matching error messages
 - Optimize the "root" pattern `ⁿ%:1`
+- Optimize format strings applied to strings or boxed strings
 - Add an `-e`/`--experimental` flag to the `uiua eval` command to enable experimental features
 ### Website
 - Add a new pad setting to show line values to the right of the code

src/algorithm/mod.rs

@@ -12,13 +12,13 @@ use std::{
     option,
 };
 
-use ecow::EcoVec;
+use ecow::{EcoString, EcoVec};
 use tinyvec::TinyVec;
 
 use crate::{
-    Array, ArrayCmp, ArrayValue, Boxed, CodeSpan, Complex, ExactDoubleIterator, Inputs, Ops,
-    PersistentMeta, Shape, SigNode, Signature, Span, Uiua, UiuaError, UiuaErrorKind, UiuaResult,
-    Value,
+    cowslice::ecovec_extend_cowslice, Array, ArrayCmp, ArrayValue, Boxed, CodeSpan, Complex,
+    ExactDoubleIterator, Inputs, Ops, PersistentMeta, Shape, SigNode, Signature, Span, Uiua,
+    UiuaError, UiuaErrorKind, UiuaResult, Value,
 };
 
 mod dyadic;
@@ -606,6 +606,33 @@ pub fn try_(ops: Ops, env: &mut Uiua) -> UiuaResult {
     Ok(())
 }
 
+pub fn format(parts: &[EcoString], env: &mut Uiua) -> UiuaResult {
+    fn format_val(chars: &mut EcoVec<char>, val: Value) {
+        match val {
+            Value::Char(arr) if arr.rank() <= 1 => {
+                if chars.is_empty() {
+                    *chars = arr.data.into();
+                } else {
+                    ecovec_extend_cowslice(chars, arr.data);
+                }
+            }
+            Value::Box(arr) if arr.rank() == 0 => format_val(chars, arr.into_scalar().unwrap().0),
+            val => chars.extend(val.format().chars()),
+        }
+    }
+
+    let mut chars = EcoVec::new();
+    for (i, part) in parts.iter().enumerate() {
+        if i > 0 {
+            let value = env.pop(("format argument", i))?;
+            format_val(&mut chars, value);
+        }
+        chars.extend(part.chars());
+    }
+    env.push(chars);
+    Ok(())
+}
+
 #[repr(transparent)]
 #[derive(Debug)]
 struct ArrayCmpSlice<'a, T>(&'a [T]);

src/cowslice.rs

@@ -269,6 +269,10 @@ pub(crate) fn extend_repeat_slice<T: Clone>(vec: &mut EcoVec<T>, slice: &[T], co
     }
 }
 
+pub(crate) fn ecovec_extend_cowslice<T: Clone>(vec: &mut EcoVec<T>, cowslice: CowSlice<T>) {
+    unsafe { vec.extend_from_trusted(cowslice) }
+}
+
 /// Exact sized repeating iterator
 pub(crate) struct Repeat<'a, T> {
     elem: &'a T,

src/run.rs

@@ -565,20 +565,7 @@ at {}",
             } => self.with_span(span, |env| {
                 algorithm::switch(branches, sig, under_cond, env)
             }),
-            Node::Format(parts, span) => {
-                let parts = parts.clone();
-                self.with_span(span, |env| {
-                    let mut s = String::new();
-                    for (i, part) in parts.into_iter().enumerate() {
-                        if i > 0 {
-                            s.push_str(&env.pop(("format argument", i))?.format());
-                        }
-                        s.push_str(&part);
-                    }
-                    env.push(s);
-                    Ok(())
-                })
-            }
+            Node::Format(parts, span) => self.with_span(span, |env| algorithm::format(&parts, env)),
             Node::MatchFormatPattern(parts, span) => {
                 self.with_span(span, |env| match_format_pattern(parts, env))
             }