Expose isPreviousLineEmpty to plugins (#4747). (#4748)

docs/plugins.md

@@ -218,6 +218,7 @@ makeString(rawContent: string, enclosingQuote: string, unescapeUnnecessarEscapes
 getNextNonSpaceNonCommentCharacterIndex(text: string, node: object, options: object): number;
 isNextLineEmptyAfterIndex(text: string, index: number): boolean;
 isNextLineEmpty(text: string, node: object, options: object): boolean;
+isPreviousLineEmpty(text: string, node: object, options: object): boolean;
 mapDoc(doc: object, callback: function): void;
 ```
 

src/common/util-shared.js

@@ -7,6 +7,10 @@ function isNextLineEmpty(text, node, options) {
   return util.isNextLineEmpty(text, node, options.locEnd);
 }
 
+function isPreviousLineEmpty(text, node, options) {
+  return util.isPreviousLineEmpty(text, node, options.locStart);
+}
+
 function getNextNonSpaceNonCommentCharacterIndex(text, node, options) {
   return util.getNextNonSpaceNonCommentCharacterIndex(
     text,
@@ -18,6 +22,7 @@ function getNextNonSpaceNonCommentCharacterIndex(text, node, options) {
 module.exports = {
   isNextLineEmpty,
   isNextLineEmptyAfterIndex: util.isNextLineEmptyAfterIndex,
+  isPreviousLineEmpty,
   getNextNonSpaceNonCommentCharacterIndex,
   mapDoc, // TODO: remove in 2.0, we already exposed it in docUtils
   makeString: util.makeString,

tests_integration/__tests__/util-shared.js

@@ -5,6 +5,7 @@ const sharedUtil = require("../../src/common/util-shared");
 test("shared util has correct structure", () => {
   expect(typeof sharedUtil.isNextLineEmpty).toEqual("function");
   expect(typeof sharedUtil.isNextLineEmptyAfterIndex).toEqual("function");
+  expect(typeof sharedUtil.isPreviousLineEmpty).toEqual("function");
   expect(typeof sharedUtil.getNextNonSpaceNonCommentCharacterIndex).toEqual(
     "function"
   );