Improve line length enforcement for breakables

fixtures/large/rspec_mocks_proxy_expected.rb

@@ -393,7 +393,9 @@ def initialize(source_space, *args)
       # That's what this method (together with `original_unbound_method_handle_from_ancestor_for`)
       # does.
       def original_method_handle_for(message)
-        unbound_method = superclass_proxy && superclass_proxy.original_unbound_method_handle_from_ancestor_for(message.to_sym)
+        unbound_method = superclass_proxy && superclass_proxy.original_unbound_method_handle_from_ancestor_for(
+          message.to_sym
+        )
 
         return super unless unbound_method
         unbound_method.bind(object)

fixtures/small/breakables_over_line_length_actual.rb

@@ -0,0 +1,7 @@
+# Nested breakables over the max line length
+# (Sung to the tune of "Carol of the Bells")
+[ReallyLongThing, ReallyLongThing, ReallyLongThing, ReallyLongThing, [ReallyLongThing, ReallyLongThing, ReallyLongThing, ReallyLongThing, ReallyLongThing, ReallyLongThing, ReallyLongThing], ReallyLongThing, ReallyLongThing]
+
+if Opus::Foo::Bar::Baz::ReallyLongName::Example::ExampleExampleExampleExampleExampleExampleExampleExample.calls_a_thing(a, b)
+    puts ""
+end

fixtures/small/breakables_over_line_length_expected.rb

@@ -0,0 +1,26 @@
+# Nested breakables over the max line length
+# (Sung to the tune of "Carol of the Bells")
+[
+  ReallyLongThing,
+  ReallyLongThing,
+  ReallyLongThing,
+  ReallyLongThing,
+  [
+    ReallyLongThing,
+    ReallyLongThing,
+    ReallyLongThing,
+    ReallyLongThing,
+    ReallyLongThing,
+    ReallyLongThing,
+    ReallyLongThing
+  ],
+  ReallyLongThing,
+  ReallyLongThing
+]
+
+if Opus::Foo::Bar::Baz::ReallyLongName::Example::ExampleExampleExampleExampleExampleExampleExampleExample.calls_a_thing(
+    a,
+    b
+  )
+  puts("")
+end

librubyfmt/src/delimiters.rs

@@ -91,4 +91,8 @@ impl BreakableDelims {
             contents: self.multi_line.close.clone(),
         }
     }
+
+    pub fn single_line_len(&self) -> usize {
+        self.single_line.open.len() + self.single_line.close.len()
+    }
 }

librubyfmt/src/intermediary.rs

@@ -90,6 +90,17 @@ impl Intermediary {
         self.tokens
     }
 
+    pub fn current_line_length(&self) -> usize {
+        if self.tokens.is_empty() {
+            return 0;
+        }
+
+        let line_start_index = self.index_of_last_hard_newline + 1;
+        let tokens_on_current_line = &self.tokens[line_start_index..];
+
+        tokens_on_current_line.iter().map(|t| t.len()).sum()
+    }
+
     pub fn push(&mut self, lt: ConcreteLineToken) {
         self.debug_assert_newlines();
         let mut do_push = true;

librubyfmt/src/line_tokens.rs

@@ -98,6 +98,34 @@ impl ConcreteLineToken {
         }
     }
 
+    /// The length of the token's string representation
+    pub fn len(&self) -> usize {
+        use ConcreteLineToken::*;
+        // The alternative to this match condition would be to clone and render
+        // each individual string token, which would increase the allocations of rubyfmt
+        // by an order of magnitude
+        match self {
+            AfterCallChain => 0, // purely semantic token, doesn't render
+            Indent { depth } => *depth as usize,
+            Keyword { keyword: contents }
+            | Op { op: contents }
+            | DirectPart { part: contents }
+            | LTStringContent { content: contents }
+            | Comment { contents }
+            | Delim { contents }
+            | ConditionalKeyword { contents }
+            | HeredocClose { symbol: contents }
+            | ModKeyword { contents } => contents.len(),
+            HardNewLine | Comma | Space | Dot | OpenSquareBracket | CloseSquareBracket
+            | OpenCurlyBracket | CloseCurlyBracket | OpenParen | CloseParen | SingleSlash => 1,
+            DoKeyword | CommaSpace | LonelyOperator | ColonColon | DoubleQuote => 2,
+            DefKeyword | Ellipsis | End => 3, // "def"/"..."/"end"
+            ClassKeyword => 5,                // "class"
+            ModuleKeyword => 6,               // "module"
+            DataEnd => 7,                     // "__END__"
+        }
+    }
+
     fn is_block_closing_token(&self) -> bool {
         match self {
             Self::End => true,

librubyfmt/src/render_queue_writer.rs

@@ -115,7 +115,7 @@ impl RenderQueueWriter {
     }
 
     fn format_breakable_entry(accum: &mut Intermediary, be: BreakableEntry) {
-        let length = be.single_line_string_length();
+        let length = accum.current_line_length() + be.single_line_string_length();
 
         if (length > MAX_LINE_LENGTH || be.is_multiline())
             && be.entry_formatting_context() != FormattingContext::StringEmbexpr

librubyfmt/src/render_targets.rs

@@ -136,7 +136,8 @@ impl AbstractTokenTarget for BreakableEntry {
             .iter()
             .map(|tok| tok.clone().into_single_line())
             .map(|tok| tok.into_ruby().len())
-            .sum()
+            .sum::<usize>()
+            + self.delims.single_line_len()
     }
 
     fn push_line_number(&mut self, number: LineNumber) {