Split all of the separators into functions.

packages/babel-generator/src/generators/expressions.js

@@ -91,6 +91,10 @@ export function Decorator(node: Object) {
   this.newline();
 }
 
+function commaSeparatorNewline() {
+  this.push(",\n");
+}
+
 export function CallExpression(node: Object) {
   this.print(node.callee, node);
   if (node.loc) this.printAuxAfterComment();
@@ -101,7 +105,7 @@ export function CallExpression(node: Object) {
 
   let separator;
   if (isPrettyCall) {
-    separator = ",\n";
+    separator = commaSeparatorNewline;
     this.newline();
     this.indent();
   }

packages/babel-generator/src/generators/flow.js

@@ -127,8 +127,12 @@ export function InterfaceDeclaration(node: Object) {
   this._interfaceish(node);
 }
 
+function andSeparator() {
+  this.push(" & ");
+}
+
 export function IntersectionTypeAnnotation(node: Object) {
-  this.printJoin(node.types, node, { separator: " & " });
+  this.printJoin(node.types, node, { separator: andSeparator });
 }
 
 export function MixedTypeAnnotation() {
@@ -277,8 +281,12 @@ export function QualifiedTypeIdentifier(node: Object) {
   this.print(node.id, node);
 }
 
+function orSeparator() {
+  this.push(" | ");
+}
+
 export function UnionTypeAnnotation(node: Object) {
-  this.printJoin(node.types, node, { separator: " | " });
+  this.printJoin(node.types, node, { separator: orSeparator });
 }
 
 export function TypeCastExpression(node: Object) {

packages/babel-generator/src/generators/jsx.js

@@ -52,12 +52,16 @@ export function JSXElement(node: Object) {
   this.print(node.closingElement, node);
 }
 
+function spaceSeparator() {
+  this.push(" ");
+}
+
 export function JSXOpeningElement(node: Object) {
   this.push("<");
   this.print(node.name, node);
   if (node.attributes.length > 0) {
     this.push(" ");
-    this.printJoin(node.attributes, node, { separator: " " });
+    this.printJoin(node.attributes, node, { separator: spaceSeparator });
   }
   this.push(node.selfClosing ? " />" : ">");
 }

packages/babel-generator/src/generators/statements.js

@@ -1,4 +1,3 @@
-import repeat from "lodash/repeat";
 import * as t from "babel-types";
 
 const NON_ALPHABETIC_UNARY_OPERATORS = t.UPDATE_OPERATORS.concat(t.NUMBER_UNARY_OPERATORS).concat(["!"]);
@@ -205,6 +204,16 @@ export function DebuggerStatement() {
   this.semicolon();
 }
 
+function variableDeclarationIdent() {
+  // "let " or "var " indentation.
+  this.push(",\n    ");
+}
+
+function constDeclarationIdent() {
+  // "const " indentation.
+  this.push(",\n      ");
+}
+
 export function VariableDeclaration(node: Object, parent: Object) {
   this.push(node.kind + " ");
 
@@ -231,14 +240,14 @@ export function VariableDeclaration(node: Object, parent: Object) {
   //       bar = "foo";
   //
 
-  let sep;
+  let separator;
   if (!this.format.compact && !this.format.concise && hasInits && !this.format.retainLines) {
-    sep = `,\n${repeat(" ", node.kind.length + 1)}`;
+    separator = node.kind === "const" ? constDeclarationIdent : variableDeclarationIdent;
   }
 
   //
 
-  this.printList(node.declarations, node, { separator: sep });
+  this.printList(node.declarations, node, { separator });
 
   if (t.isFor(parent)) {
     // don't give semicolons to these nodes since they'll be inserted in the parent generator

packages/babel-generator/src/printer.js

@@ -125,7 +125,7 @@ export default class Printer extends Buffer {
         }
 
         if (opts.separator && i < len - 1) {
-          this.push(opts.separator);
+          opts.separator.call(this);
         }
       }
     };
@@ -187,8 +187,7 @@ export default class Printer extends Buffer {
 
   printList(items, parent, opts = {}) {
     if (opts.separator == null) {
-      opts.separator = ",";
+      opts.separator = commaSeparator;
-      if (!this.format.compact) opts.separator += " ";
     }
 
     return this.printJoin(items, parent, opts);
@@ -316,6 +315,11 @@ export default class Printer extends Buffer {
   }
 }
 
+function commaSeparator() {
+  this.push(",");
+  this.space();
+}
+
 for (let generator of [
   require("./generators/template-literals"),
   require("./generators/expressions"),