Initialisation

Added the packages and files for the backend server

node_modules/graphql/jsutils/suggestionList.mjs

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+import { naturalCompare } from './naturalCompare.mjs';
+/**
+ * Given an invalid input string and a list of valid options, returns a filtered
+ * list of valid options sorted based on their similarity with the input.
+ */
+
+export function suggestionList(input, options) {
+  const optionsByDistance = Object.create(null);
+  const lexicalDistance = new LexicalDistance(input);
+  const threshold = Math.floor(input.length * 0.4) + 1;
+
+  for (const option of options) {
+    const distance = lexicalDistance.measure(option, threshold);
+
+    if (distance !== undefined) {
+      optionsByDistance[option] = distance;
+    }
+  }
+
+  return Object.keys(optionsByDistance).sort((a, b) => {
+    const distanceDiff = optionsByDistance[a] - optionsByDistance[b];
+    return distanceDiff !== 0 ? distanceDiff : naturalCompare(a, b);
+  });
+}
+/**
+ * Computes the lexical distance between strings A and B.
+ *
+ * The "distance" between two strings is given by counting the minimum number
+ * of edits needed to transform string A into string B. An edit can be an
+ * insertion, deletion, or substitution of a single character, or a swap of two
+ * adjacent characters.
+ *
+ * Includes a custom alteration from Damerau-Levenshtein to treat case changes
+ * as a single edit which helps identify mis-cased values with an edit distance
+ * of 1.
+ *
+ * This distance can be useful for detecting typos in input or sorting
+ */
+
+class LexicalDistance {
+  constructor(input) {
+    this._input = input;
+    this._inputLowerCase = input.toLowerCase();
+    this._inputArray = stringToArray(this._inputLowerCase);
+    this._rows = [
+      new Array(input.length + 1).fill(0),
+      new Array(input.length + 1).fill(0),
+      new Array(input.length + 1).fill(0),
+    ];
+  }
+
+  measure(option, threshold) {
+    if (this._input === option) {
+      return 0;
+    }
+
+    const optionLowerCase = option.toLowerCase(); // Any case change counts as a single edit
+
+    if (this._inputLowerCase === optionLowerCase) {
+      return 1;
+    }
+
+    let a = stringToArray(optionLowerCase);
+    let b = this._inputArray;
+
+    if (a.length < b.length) {
+      const tmp = a;
+      a = b;
+      b = tmp;
+    }
+
+    const aLength = a.length;
+    const bLength = b.length;
+
+    if (aLength - bLength > threshold) {
+      return undefined;
+    }
+
+    const rows = this._rows;
+
+    for (let j = 0; j <= bLength; j++) {
+      rows[0][j] = j;
+    }
+
+    for (let i = 1; i <= aLength; i++) {
+      const upRow = rows[(i - 1) % 3];
+      const currentRow = rows[i % 3];
+      let smallestCell = (currentRow[0] = i);
+
+      for (let j = 1; j <= bLength; j++) {
+        const cost = a[i - 1] === b[j - 1] ? 0 : 1;
+        let currentCell = Math.min(
+          upRow[j] + 1, // delete
+          currentRow[j - 1] + 1, // insert
+          upRow[j - 1] + cost, // substitute
+        );
+
+        if (i > 1 && j > 1 && a[i - 1] === b[j - 2] && a[i - 2] === b[j - 1]) {
+          // transposition
+          const doubleDiagonalCell = rows[(i - 2) % 3][j - 2];
+          currentCell = Math.min(currentCell, doubleDiagonalCell + 1);
+        }
+
+        if (currentCell < smallestCell) {
+          smallestCell = currentCell;
+        }
+
+        currentRow[j] = currentCell;
+      } // Early exit, since distance can't go smaller than smallest element of the previous row.
+
+      if (smallestCell > threshold) {
+        return undefined;
+      }
+    }
+
+    const distance = rows[aLength % 3][bLength];
+    return distance <= threshold ? distance : undefined;
+  }
+}
+
+function stringToArray(str) {
+  const strLength = str.length;
+  const array = new Array(strLength);
+
+  for (let i = 0; i < strLength; ++i) {
+    array[i] = str.charCodeAt(i);
+  }
+
+  return array;
+}