force-render multi-line tokens on one line, except raw content

README.md

@@ -36,7 +36,8 @@ Need more examples?
 1. Every **Declaration** starts on a new line
 1. Every **Declaration** ends with a semicolon (;)
 1. An empty line is placed after a **Block**, unless it’s the last in the surrounding **Block**
-1. Unknown syntax is rendered as-is
+1. Multiline tokens like **Selectors, Values, etc.** are rendered on a single line
+1. Unknown syntax is rendered as-is, with multi-line formatting kept intact
 
 ## Acknowledgements
 

index.js

@@ -15,10 +15,26 @@ function indent(size) {
  * @returns A portion of the CSS
  */
 function substr(node, css) {
-	if (node.loc) {
-		return css.substring(node.loc.start.offset, node.loc.end.offset)
+	if (node.loc === null) return ''
+	let str = css.substring(node.loc.start.offset, node.loc.end.offset)
+
+	// Single-line node, most common case
+	if (node.loc.start.line === node.loc.end.line) {
+		return str
 	}
-	return ''
+
+	// Multi-line nodes, not common
+	return str.split('\n').map(part => part.trim()).join(' ')
+}
+
+/**
+ * @param {import('css-tree').CssNode} node
+ * @param {string} css
+ * @returns A portion of the CSS
+ */
+function substr_raw(node, css) {
+	if (node.loc === null) return ''
+	return css.substring(node.loc.start.offset, node.loc.end.offset)
 }
 
 /**
@@ -178,7 +194,7 @@ function print_declaration(node, indent_level, css) {
  * @returns {string} A formatted unknown CSS string
  */
 function print_unknown(node, indent_level, css) {
-	return indent(indent_level) + substr(node, css).trim()
+	return indent(indent_level) + substr_raw(node, css).trim()
 }
 
 /**

test.js

@@ -428,4 +428,28 @@ test('empty input', () => {
 	assert.equal(actual, expected)
 })
 
+test('formats multiline tokens on a single line', () => {
+	let actual = format(`
+a {
+  background: linear-gradient(
+    red,
+  10% blue,
+20% green,100% yellow);
+}
+
+a.b
+ .c .d
+   .e .f {
+color: green }
+	`)
+	let expected = `a {
+	background: linear-gradient( red, 10% blue, 20% green,100% yellow);
+}
+
+a.b .c .d .e .f {
+	color: green;
+}`
+	assert.equal(actual, expected)
+})
+
 test.run();