Initial import with skill sheet working

node_modules/prettier-linter-helpers/index.js

@@ -0,0 +1,145 @@
+const diff = require('fast-diff');
+
+const LINE_ENDING_RE = /\r\n|[\r\n\u2028\u2029]/;
+
+/**
+ * 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 containing { 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: generateDifferences.REPLACE,
+        insertText: aheadInsertText,
+        deleteText: aheadDeleteText,
+      });
+    } else if (!aheadDeleteText && aheadInsertText) {
+      differences.push({
+        offset,
+        operation: generateDifferences.INSERT,
+        insertText: aheadInsertText,
+      });
+    } else if (aheadDeleteText && !aheadInsertText) {
+      differences.push({
+        offset,
+        operation: generateDifferences.DELETE,
+        deleteText: aheadDeleteText,
+      });
+    }
+    offset += aheadDeleteText.length;
+  }
+}
+
+generateDifferences.INSERT = 'insert';
+generateDifferences.DELETE = 'delete';
+generateDifferences.REPLACE = 'replace';
+
+module.exports = {
+  showInvisibles,
+  generateDifferences,
+};