chore: format array and index expressions (noir-lang#3223)

tooling/nargo_fmt/src/config.rs

@@ -42,8 +42,11 @@ macro_rules! config {
 }
 
 config! {
+    max_width: usize, 100, "Maximum width of each line";
     tab_spaces: usize, 4, "Number of spaces per tab";
     remove_nested_parens: bool, true, "Remove nested parens";
+    short_array_element_width_threshold: usize, 10, "Width threshold for an array element to be considered short";
+    array_width: usize, 60, "Maximum width of an array literal before falling back to vertical formatting";
 }
 
 impl Config {

tooling/nargo_fmt/src/utils.rs

@@ -31,11 +31,21 @@ pub(crate) fn comments(source: &str) -> impl Iterator<Item = String> + '_ {
 #[derive(Debug)]
 pub(crate) struct Expr {
     pub(crate) leading: String,
-    pub(crate) expr: String,
+    pub(crate) value: String,
     pub(crate) trailing: String,
     pub(crate) different_line: bool,
 }
 
+impl Expr {
+    pub(crate) fn total_width(&self) -> usize {
+        comment_len(&self.leading) + self.value.chars().count() + comment_len(&self.trailing)
+    }
+
+    pub(crate) fn is_multiline(&self) -> bool {
+        self.leading.contains('\n') || self.trailing.contains('\n')
+    }
+}
+
 pub(crate) struct Exprs<'me> {
     pub(crate) visitor: &'me FmtVisitor<'me>,
     pub(crate) elements: std::iter::Peekable<std::vec::IntoIter<Expression>>,
@@ -71,17 +81,17 @@ impl Iterator for Exprs<'_> {
         let is_last = self.elements.peek().is_none();
         let next_start = self.elements.peek().map_or(self.end_position, |expr| expr.span.start());
 
-        let (leading, newlines) = self.leading(start, end);
+        let (leading, different_line) = self.leading(start, end);
         let expr = self.visitor.format_expr(element);
         let trailing = self.trailing(element_span.end(), next_start, is_last);
 
-        Expr { leading, expr, trailing, different_line: newlines }.into()
+        Expr { leading, value: expr, trailing, different_line }.into()
     }
 }
 
 impl<'me> Exprs<'me> {
     pub(crate) fn leading(&mut self, start: u32, end: u32) -> (String, bool) {
-        let mut newlines = false;
+        let mut different_line = false;
 
         let leading = slice!(self.visitor, start, end);
         let leading_trimmed = slice!(self.visitor, start, end).trim();
@@ -94,13 +104,13 @@ impl<'me> Exprs<'me> {
             let comment_end = leading_trimmed.rfind(|c| c == '/').unwrap();
 
             if leading[comment_end..].contains('\n') {
-                newlines = true;
+                different_line = true;
             }
         } else if starts_with_single_line_comment || starts_with_block_comment {
-            newlines = true;
+            different_line = true;
         };
 
-        (leading_trimmed.to_string(), newlines)
+        (leading_trimmed.to_string(), different_line)
     }
 
     pub(crate) fn trailing(&mut self, start: u32, end: u32, is_last: bool) -> String {
@@ -177,3 +187,17 @@ pub(crate) fn find_comment_end(slice: &str, is_last: bool) -> usize {
         0
     }
 }
+
+fn comment_len(comment: &str) -> usize {
+    match comment {
+        "" => 0,
+        _ => {
+            let len = comment.trim().len();
+            if len > 0 {
+                len + 6
+            } else {
+                len
+            }
+        }
+    }
+}

tooling/nargo_fmt/src/visitor.rs

@@ -33,6 +33,13 @@ impl<'me> FmtVisitor<'me> {
         }
     }
 
+    fn shape(&self) -> Shape {
+        Shape {
+            width: self.config.max_width.saturating_sub(self.indent.width()),
+            indent: self.indent,
+        }
+    }
+
     pub(crate) fn fork(&self) -> Self {
         Self {
             buffer: String::new(),
@@ -151,12 +158,16 @@ impl<'me> FmtVisitor<'me> {
     }
 }
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
 struct Indent {
     block_indent: usize,
 }
 
 impl Indent {
+    fn width(&self) -> usize {
+        self.block_indent
+    }
+
     fn block_indent(&mut self, config: &Config) {
         self.block_indent += config.tab_spaces;
     }
@@ -174,3 +185,9 @@ impl Indent {
         " ".repeat(self.block_indent)
     }
 }
+
+#[derive(Clone, Copy, Debug)]
+struct Shape {
+    width: usize,
+    indent: Indent,
+}