Breaking: Extract showInvisibles and generateDifferences

Move these two functions into a helper module 'prettier-linter-helpers'.
If you used those functions then plese reference that package directly.

Fixes #101

Author: BPScott

eslint-plugin-prettier.js

@@ -9,17 +9,16 @@
 //  Requirements
 // ------------------------------------------------------------------------------
 
-const diff = require('fast-diff');
+const {
+  showInvisibles,
+  generateDifferences
+} = require('prettier-linter-helpers');
 
 // ------------------------------------------------------------------------------
 //  Constants
 // ------------------------------------------------------------------------------
 
-const LINE_ENDING_RE = /\r\n|[\r\n\u2028\u2029]/;
-
-const OPERATION_INSERT = 'insert';
-const OPERATION_DELETE = 'delete';
-const OPERATION_REPLACE = 'replace';
+const { INSERT, DELETE, REPLACE } = generateDifferences;
 
 // ------------------------------------------------------------------------------
 //  Privates
@@ -28,142 +27,6 @@ const OPERATION_REPLACE = 'replace';
 // Lazily-loaded Prettier.
 let prettier;
 
-// ------------------------------------------------------------------------------
-//  Helpers
-// ------------------------------------------------------------------------------
-
-/**
- * Converts invisible characters to a commonly recognizable visible form.
- * @param {string} str - The string with invisibles to convert.
- * @returns {string} The converted string.
- */
-function showInvisibles(str) {
-  let ret = '';
-  for (let i = 0; i < str.length; i++) {
-    switch (str[i]) {
-      case ' ':
-        ret += '·'; // Middle Dot, \u00B7
-        break;
-      case '\n':
-        ret += '⏎'; // Return Symbol, \u23ce
-        break;
-      case '\t':
-        ret += '↹'; // Left Arrow To Bar Over Right Arrow To Bar, \u21b9
-        break;
-      case '\r':
-        ret += '␍'; // Carriage Return Symbol, \u240D
-        break;
-      default:
-        ret += str[i];
-        break;
-    }
-  }
-  return ret;
-}
-
-/**
- * Generate results for differences between source code and formatted version.
- * @param {string} source - The original source.
- * @param {string} prettierSource - The Prettier formatted source.
- * @returns {Array} - An array contains { operation, offset, insertText, deleteText }
- */
-function generateDifferences(source, prettierSource) {
-  // fast-diff returns the differences between two texts as a series of
-  // INSERT, DELETE or EQUAL operations. The results occur only in these
-  // sequences:
-  //           /-> INSERT -> EQUAL
-  //    EQUAL |           /-> EQUAL
-  //           \-> DELETE |
-  //                      \-> INSERT -> EQUAL
-  // Instead of reporting issues at each INSERT or DELETE, certain sequences
-  // are batched together and are reported as a friendlier "replace" operation:
-  // - A DELETE immediately followed by an INSERT.
-  // - Any number of INSERTs and DELETEs where the joining EQUAL of one's end
-  // and another's beginning does not have line endings (i.e. issues that occur
-  // on contiguous lines).
-
-  const results = diff(source, prettierSource);
-  const differences = [];
-
-  const batch = [];
-  let offset = 0; // NOTE: INSERT never advances the offset.
-  while (results.length) {
-    const result = results.shift();
-    const op = result[0];
-    const text = result[1];
-    switch (op) {
-      case diff.INSERT:
-      case diff.DELETE:
-        batch.push(result);
-        break;
-      case diff.EQUAL:
-        if (results.length) {
-          if (batch.length) {
-            if (LINE_ENDING_RE.test(text)) {
-              flush();
-              offset += text.length;
-            } else {
-              batch.push(result);
-            }
-          } else {
-            offset += text.length;
-          }
-        }
-        break;
-      default:
-        throw new Error(`Unexpected fast-diff operation "${op}"`);
-    }
-    if (batch.length && !results.length) {
-      flush();
-    }
-  }
-
-  return differences;
-
-  function flush() {
-    let aheadDeleteText = '';
-    let aheadInsertText = '';
-    while (batch.length) {
-      const next = batch.shift();
-      const op = next[0];
-      const text = next[1];
-      switch (op) {
-        case diff.INSERT:
-          aheadInsertText += text;
-          break;
-        case diff.DELETE:
-          aheadDeleteText += text;
-          break;
-        case diff.EQUAL:
-          aheadDeleteText += text;
-          aheadInsertText += text;
-          break;
-      }
-    }
-    if (aheadDeleteText && aheadInsertText) {
-      differences.push({
-        offset,
-        operation: OPERATION_REPLACE,
-        insertText: aheadInsertText,
-        deleteText: aheadDeleteText
-      });
-    } else if (!aheadDeleteText && aheadInsertText) {
-      differences.push({
-        offset,
-        operation: OPERATION_INSERT,
-        insertText: aheadInsertText
-      });
-    } else if (aheadDeleteText && !aheadInsertText) {
-      differences.push({
-        offset,
-        operation: OPERATION_DELETE,
-        deleteText: aheadDeleteText
-      });
-    }
-    offset += aheadDeleteText.length;
-  }
-}
-
 // ------------------------------------------------------------------------------
 //  Rule Definition
 // ------------------------------------------------------------------------------
@@ -242,8 +105,6 @@ function reportReplace(context, offset, deleteText, insertText) {
 // ------------------------------------------------------------------------------
 
 module.exports = {
-  showInvisibles,
-  generateDifferences,
   configs: {
     recommended: {
       extends: ['prettier'],
@@ -354,21 +215,21 @@ module.exports = {
 
               differences.forEach(difference => {
                 switch (difference.operation) {
-                  case OPERATION_INSERT:
+                  case INSERT:
                     reportInsert(
                       context,
                       difference.offset,
                       difference.insertText
                     );
                     break;
-                  case OPERATION_DELETE:
+                  case DELETE:
                     reportDelete(
                       context,
                       difference.offset,
                       difference.deleteText
                     );
                     break;
-                  case OPERATION_REPLACE:
+                  case REPLACE:
                     reportReplace(
                       context,
                       difference.offset,

package.json

@@ -28,7 +28,7 @@
   },
   "homepage": "https://github.com/prettier/eslint-plugin-prettier#readme",
   "dependencies": {
-    "fast-diff": "^1.1.2"
+    "prettier-linter-helpers": "^1.0.0"
   },
   "peerDependencies": {
     "prettier": ">= 1.13.0"

test/prettier.js

@@ -14,7 +14,6 @@
 
 const fs = require('fs');
 const path = require('path');
-const assert = require('assert');
 
 const eslintPluginPrettier = require('..');
 
@@ -104,42 +103,6 @@ vueRuleTester.run('prettier', rule, {
   ]
 });
 
-describe('showInvisibles', () => {
-  it('shows invisibles', () => {
-    assert.strictEqual(
-      eslintPluginPrettier.showInvisibles('1 2\n3\t4\r5'),
-      '1·2⏎3↹4␍5'
-    );
-  });
-});
-
-describe('generateDifferences', () => {
-  it('operation: insert', () => {
-    const differences = eslintPluginPrettier.generateDifferences(
-      'abc',
-      'abcdef'
-    );
-    assert.deepStrictEqual(differences, [
-      { operation: 'insert', offset: 3, insertText: 'def' }
-    ]);
-  });
-  it('operation: delete', () => {
-    const differences = eslintPluginPrettier.generateDifferences(
-      'abcdef',
-      'abc'
-    );
-    assert.deepStrictEqual(differences, [
-      { operation: 'delete', offset: 3, deleteText: 'def' }
-    ]);
-  });
-  it('operation: replace', () => {
-    const differences = eslintPluginPrettier.generateDifferences('abc', 'def');
-    assert.deepStrictEqual(differences, [
-      { operation: 'replace', offset: 0, deleteText: 'abc', insertText: 'def' }
-    ]);
-  });
-});
-
 // ------------------------------------------------------------------------------
 //  Helpers
 // ------------------------------------------------------------------------------

yarn.lock

@@ -671,6 +671,12 @@ prelude-ls@~1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
 
+prettier-linter-helpers@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/prettier-linter-helpers/-/prettier-linter-helpers-1.0.0.tgz#d23d41fe1375646de2d0104d3454a3008802cf7b"
+  dependencies:
+    fast-diff "^1.1.2"
+
 prettier@^1.13.0:
   version "1.14.3"
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.14.3.tgz#90238dd4c0684b7edce5f83b0fb7328e48bd0895"