Keep small prefix inlined in call chain (#550)

* Add test case

* Ensure small prefix is kept inlined

* Update changelog

* Update snapshots

Author: JohnnyMorganz

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed unnecessary break on `else` in an if-expression when the expression contains a comment ([#520](https://github.com/JohnnyMorganz/StyLua/issues/520))
 - Take into account the extra line created when hanging at equals token in an assignment. This should prevent unnecessary hanging ([#542](https://github.com/JohnnyMorganz/StyLua/issues/542))
 - Fixed comments added to a newly created trailing comment not being formatted ([#547](https://github.com/JohnnyMorganz/StyLua/issues/547))
+- Fixed call chain with a small prefix not being kept inlined causing unstable formatting ([#514](https://github.com/JohnnyMorganz/StyLua/issues/514))
 
 ## [0.14.2] - 2022-07-27
 

src/formatters/functions.rs

@@ -906,6 +906,13 @@ pub fn format_function_body(
         .with_end_token(end_token)
 }
 
+fn should_inline_prefix(ctx: &Context, prefix: &Prefix) -> bool {
+    let prefix = strip_trivia(prefix).to_string();
+
+    prefix.as_str().chars().next().unwrap().is_uppercase()
+        || prefix.len() <= ctx.config().indent_width
+}
+
 /// Formats a FunctionCall node
 pub fn format_function_call(
     ctx: &Context,
@@ -977,14 +984,7 @@ pub fn format_function_call(
 
             // If the prefix starts with an uppercase character, or is smaller than the indent width
             // we can inline the first call. BUT, inlining overall should still be under the column width
-            keep_first_call_inlined = (strip_leading_trivia(function_call.prefix())
-                .to_string()
-                .as_str()
-                .chars()
-                .next()
-                .unwrap()
-                .is_uppercase()
-                || function_call.prefix().to_string().len() <= ctx.config().indent_width)
+            keep_first_call_inlined = should_inline_prefix(ctx, function_call.prefix())
                 && !shape
                     .take_last_line(&strip_leading_trivia(&formatted_prefix))
                     .test_over_budget(&formatted_suffixes.into_iter().next().unwrap());

src/formatters/trivia.rs

@@ -410,6 +410,18 @@ define_update_leading_trivia!(Prefix, |this, leading| {
     }
 });
 
+define_update_trailing_trivia!(Prefix, |this, trailing| {
+    match this {
+        Prefix::Name(token_reference) => {
+            Prefix::Name(token_reference.update_trailing_trivia(trailing))
+        }
+        Prefix::Expression(expression) => {
+            Prefix::Expression(expression.update_trailing_trivia(trailing))
+        }
+        other => panic!("unknown node {:?}", other),
+    }
+});
+
 impl<T> UpdateLeadingTrivia for Punctuated<T>
 where
     T: UpdateLeadingTrivia + Clone,

tests/inputs/hang-call-chain-small-prefix.lua

@@ -0,0 +1,21 @@
+-- https://github.com/JohnnyMorganz/StyLua/issues/514
+local function escape(str)
+	return (str:gsub("\\", "\\\\"):gsub("(%c)%f[0-9]", longControlCharEscapesssssssssssssssssssss):gsub("%c", shortControlCharEscapes))
+end
+
+do
+	function dec(data)
+		data = string.gsub(data, '[^' .. chars .. '=]', '')
+		return (data:gsub('.', function(x)
+			if (x == '=') then return '' end
+			local r, f = '', (chars:find(x) - 1)
+			for i=6,1,-1 do r=r..(f%2^i-f%2^(i-1)>0 and '1' or '0') end
+			return r;
+		end):gsub('%d%d%d?%d?%d?%d?%d?%d?', function(x)
+			if (#x ~= 8) then return '' end
+			local c=0
+			for i=1,8 do c=c+(x:sub(i,i)=='1' and 2^(8-i) or 0) end
+			return string.char(c)
+		end))
+	end
+end

tests/snapshots/tests__standard@hang-call-chain-small-prefix.lua.snap

@@ -0,0 +1,40 @@
+---
+source: tests/tests.rs
+expression: format(&contents)
+---
+-- https://github.com/JohnnyMorganz/StyLua/issues/514
+local function escape(str)
+	return (
+		str:gsub("\\", "\\\\")
+			:gsub("(%c)%f[0-9]", longControlCharEscapesssssssssssssssssssss)
+			:gsub("%c", shortControlCharEscapes)
+	)
+end
+
+do
+	function dec(data)
+		data = string.gsub(data, "[^" .. chars .. "=]", "")
+		return (
+			data:gsub(".", function(x)
+				if x == "=" then
+					return ""
+				end
+				local r, f = "", (chars:find(x) - 1)
+				for i = 6, 1, -1 do
+					r = r .. (f % 2 ^ i - f % 2 ^ (i - 1) > 0 and "1" or "0")
+				end
+				return r
+			end):gsub("%d%d%d?%d?%d?%d?%d?%d?", function(x)
+				if #x ~= 8 then
+					return ""
+				end
+				local c = 0
+				for i = 1, 8 do
+					c = c + (x:sub(i, i) == "1" and 2 ^ (8 - i) or 0)
+				end
+				return string.char(c)
+			end)
+		)
+	end
+end
+

tests/snapshots/tests__standard@hang-call-chains-static.lua.snap

@@ -1,12 +1,9 @@
 ---
 source: tests/tests.rs
-assertion_line: 12
 expression: format(&contents)
-
 ---
 -- https://github.com/JohnnyMorganz/StyLua/issues/368
-foo
-	.bar("-------------------------------------------------------------------------------------------------------------")
+foo.bar("-------------------------------------------------------------------------------------------------------------")
 	.returns()
 foo.bar("--------------------------------------------------------------------------------------------------")
 	.returns()

tests/snapshots/tests__standard@hang-call-chains.lua.snap

@@ -1,8 +1,6 @@
 ---
 source: tests/tests.rs
-assertion_line: 12
 expression: format(&contents)
-
 ---
 Promise.new()
 	:andThen(callThis)
@@ -29,8 +27,7 @@ local f = this:andThen(callThis):andThen({
 	true,
 }).X.Y.Z
 
-this
-	:andThen(callThis)
+this:andThen(callThis)
 	:andThen({
 		true,
 	}).X.Y.Z