Remove whitespace generation (#5833)

* Remove whitespace generation and rely on default printing

Changes to printing:
* Add newline after last empty SwitchCase
* Add newlines around block comments if they are non-flow comments or contain newlines

* Fix a few more fixtures

packages/babel-generator/src/printer.js

@@ -1,10 +1,7 @@
-import find from "lodash/find";
-import findLast from "lodash/findLast";
 import isInteger from "lodash/isInteger";
 import repeat from "lodash/repeat";
 import Buffer from "./buffer";
 import * as n from "./node";
-import Whitespace from "./whitespace";
 import * as t from "babel-types";
 
 import * as generatorFunctions from "./generators";
@@ -32,17 +29,15 @@ export type Format = {
 };
 
 export default class Printer {
-  constructor(format, map, tokens) {
+  constructor(format, map) {
     this.format = format || {};
     this._buf = new Buffer(map);
-    this._whitespace = tokens.length > 0 ? new Whitespace(tokens) : null;
   }
 
   format: Format;
   inForStatementInitCounter: number = 0;
 
   _buf: Buffer;
-  _whitespace: Whitespace;
   _printStack: Array<Node> = [];
   _indent: number = 0;
   _insideAux: boolean = false;
@@ -498,43 +493,13 @@ export default class Printer {
     }
 
     let lines = 0;
-
-    if (node.start != null && !node._ignoreUserWhitespace && this._whitespace) {
-      // user node
-      if (leading) {
-        const comments = node.leadingComments;
-        const comment =
-          comments &&
-          find(
-            comments,
-            comment =>
-              !!comment.loc && this.format.shouldPrintComment(comment.value),
-          );
-
-        lines = this._whitespace.getNewlinesBefore(comment || node);
-      } else {
-        const comments = node.trailingComments;
-        const comment =
-          comments &&
-          findLast(
-            comments,
-            comment =>
-              !!comment.loc && this.format.shouldPrintComment(comment.value),
-          );
-
-        lines = this._whitespace.getNewlinesAfter(comment || node);
-      }
-    } else {
-      // generated node
+    // don't add newlines at the beginning of the file
+    if (this._buf.hasContent()) {
       if (!leading) lines++; // always include at least a single line after
       if (opts.addNewlines) lines += opts.addNewlines(leading, node) || 0;
 
-      let needs = n.needsWhitespaceAfter;
-      if (leading) needs = n.needsWhitespaceBefore;
+      const needs = leading ? n.needsWhitespaceBefore : n.needsWhitespaceAfter;
       if (needs(node, parent)) lines++;
-
-      // generated nodes can't add starting file whitespace
-      if (!this._buf.hasContent()) lines = 0;
     }
 
     this.newline(lines);
@@ -563,23 +528,17 @@ export default class Printer {
       this._printedCommentStarts[comment.start] = true;
     }
 
-    // whitespace before
-    this.newline(
-      this._whitespace ? this._whitespace.getNewlinesBefore(comment) : 0,
-    );
+    const isBlockComment = comment.type === "CommentBlock";
+
+    // Always add a newline before a block comment
+    this.newline(this._buf.hasContent() && isBlockComment ? 1 : 0);
 
     if (!this.endsWith("[") && !this.endsWith("{")) this.space();
 
-    let val =
-      comment.type === "CommentLine"
-        ? `//${comment.value}\n`
-        : `/*${comment.value}*/`;
+    let val = !isBlockComment ? `//${comment.value}\n` : `/*${comment.value}*/`;
 
     //
-    if (
-      comment.type === "CommentBlock" &&
-      this.format.indent.adjustMultilineComment
-    ) {
+    if (isBlockComment && this.format.indent.adjustMultilineComment) {
       const offset = comment.loc && comment.loc.start.column;
       if (offset) {
         const newlineRegex = new RegExp("\\n\\s{1," + offset + "}", "g");
@@ -600,12 +559,8 @@ export default class Printer {
       this._append(val);
     });
 
-    // whitespace after
-    this.newline(
-      (this._whitespace ? this._whitespace.getNewlinesAfter(comment) : 0) +
-        // Subtract one to account for the line force-added above.
-        (comment.type === "CommentLine" ? -1 : 0),
-    );
+    // Always add a newline after a block comment
+    this.newline(isBlockComment ? 1 : 0);
   }
 
   _printComments(comments?: Array<Object>) {