minisearch
Version:
Tiny but powerful full-text search engine for browser and Node
556 lines (550 loc) • 21.7 kB
JavaScript
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
typeof define === 'function' && define.amd ? define(factory) :
(global = typeof globalThis !== 'undefined' ? globalThis : global || self, global.MiniSearch = factory());
})(this, (function () { 'use strict';
/** @ignore */
const ENTRIES = 'ENTRIES';
/** @ignore */
const KEYS = 'KEYS';
/** @ignore */
const VALUES = 'VALUES';
/** @ignore */
const LEAF = '';
/**
* @private
*/
class TreeIterator {
constructor(set, type) {
const node = set._tree;
const keys = Array.from(node.keys());
this.set = set;
this._type = type;
this._path = keys.length > 0 ? [{ node, keys }] : [];
}
next() {
const value = this.dive();
this.backtrack();
return value;
}
dive() {
if (this._path.length === 0) {
return { done: true, value: undefined };
}
const { node, keys } = last$1(this._path);
if (last$1(keys) === LEAF) {
return { done: false, value: this.result() };
}
const child = node.get(last$1(keys));
this._path.push({ node: child, keys: Array.from(child.keys()) });
return this.dive();
}
backtrack() {
if (this._path.length === 0) {
return;
}
const keys = last$1(this._path).keys;
keys.pop();
if (keys.length > 0) {
return;
}
this._path.pop();
this.backtrack();
}
key() {
return this.set._prefix + this._path
.map(({ keys }) => last$1(keys))
.filter(key => key !== LEAF)
.join('');
}
value() {
return last$1(this._path).node.get(LEAF);
}
result() {
switch (this._type) {
case VALUES: return this.value();
case KEYS: return this.key();
default: return [this.key(), this.value()];
}
}
[Symbol.iterator]() {
return this;
}
}
const last$1 = (array) => {
return array[array.length - 1];
};
/* eslint-disable no-labels */
/**
* @ignore
*/
const fuzzySearch = (node, query, maxDistance) => {
const results = new Map();
if (query === undefined)
return results;
// Number of columns in the Levenshtein matrix.
const n = query.length + 1;
// Matching terms can never be longer than N + maxDistance.
const m = n + maxDistance;
// Fill first matrix row and column with numbers: 0 1 2 3 ...
const matrix = new Uint8Array(m * n).fill(maxDistance + 1);
for (let j = 0; j < n; ++j)
matrix[j] = j;
for (let i = 1; i < m; ++i)
matrix[i * n] = i;
recurse(node, query, maxDistance, results, matrix, 1, n, '');
return results;
};
// Modified version of http://stevehanov.ca/blog/?id=114
// This builds a Levenshtein matrix for a given query and continuously updates
// it for nodes in the radix tree that fall within the given maximum edit
// distance. Keeping the same matrix around is beneficial especially for larger
// edit distances.
//
// k a t e <-- query
// 0 1 2 3 4
// c 1 1 2 3 4
// a 2 2 1 2 3
// t 3 3 2 1 [2] <-- edit distance
// ^
// ^ term in radix tree, rows are added and removed as needed
const recurse = (node, query, maxDistance, results, matrix, m, n, prefix) => {
const offset = m * n;
key: for (const key of node.keys()) {
if (key === LEAF) {
// We've reached a leaf node. Check if the edit distance acceptable and
// store the result if it is.
const distance = matrix[offset - 1];
if (distance <= maxDistance) {
results.set(prefix, [node.get(key), distance]);
}
}
else {
// Iterate over all characters in the key. Update the Levenshtein matrix
// and check if the minimum distance in the last row is still within the
// maximum edit distance. If it is, we can recurse over all child nodes.
let i = m;
for (let pos = 0; pos < key.length; ++pos, ++i) {
const char = key[pos];
const thisRowOffset = n * i;
const prevRowOffset = thisRowOffset - n;
// Set the first column based on the previous row, and initialize the
// minimum distance in the current row.
let minDistance = matrix[thisRowOffset];
const jmin = Math.max(0, i - maxDistance - 1);
const jmax = Math.min(n - 1, i + maxDistance);
// Iterate over remaining columns (characters in the query).
for (let j = jmin; j < jmax; ++j) {
const different = char !== query[j];
// It might make sense to only read the matrix positions used for
// deletion/insertion if the characters are different. But we want to
// avoid conditional reads for performance reasons.
const rpl = matrix[prevRowOffset + j] + +different;
const del = matrix[prevRowOffset + j + 1] + 1;
const ins = matrix[thisRowOffset + j] + 1;
const dist = matrix[thisRowOffset + j + 1] = Math.min(rpl, del, ins);
if (dist < minDistance)
minDistance = dist;
}
// Because distance will never decrease, we can stop. There will be no
// matching child nodes.
if (minDistance > maxDistance) {
continue key;
}
}
recurse(node.get(key), query, maxDistance, results, matrix, i, n, prefix + key);
}
}
};
/* eslint-disable no-labels */
/**
* A class implementing the same interface as a standard JavaScript
* [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map)
* with string keys, but adding support for efficiently searching entries with
* prefix or fuzzy search. This class is used internally by {@link MiniSearch}
* as the inverted index data structure. The implementation is a radix tree
* (compressed prefix tree).
*
* Since this class can be of general utility beyond _MiniSearch_, it is
* exported by the `minisearch` package and can be imported (or required) as
* `minisearch/SearchableMap`.
*
* @typeParam T The type of the values stored in the map.
*/
class SearchableMap {
/**
* The constructor is normally called without arguments, creating an empty
* map. In order to create a {@link SearchableMap} from an iterable or from an
* object, check {@link SearchableMap.from} and {@link
* SearchableMap.fromObject}.
*
* The constructor arguments are for internal use, when creating derived
* mutable views of a map at a prefix.
*/
constructor(tree = new Map(), prefix = '') {
this._size = undefined;
this._tree = tree;
this._prefix = prefix;
}
/**
* Creates and returns a mutable view of this {@link SearchableMap},
* containing only entries that share the given prefix.
*
* ### Usage:
*
* ```javascript
* let map = new SearchableMap()
* map.set("unicorn", 1)
* map.set("universe", 2)
* map.set("university", 3)
* map.set("unique", 4)
* map.set("hello", 5)
*
* let uni = map.atPrefix("uni")
* uni.get("unique") // => 4
* uni.get("unicorn") // => 1
* uni.get("hello") // => undefined
*
* let univer = map.atPrefix("univer")
* univer.get("unique") // => undefined
* univer.get("universe") // => 2
* univer.get("university") // => 3
* ```
*
* @param prefix The prefix
* @return A {@link SearchableMap} representing a mutable view of the original
* Map at the given prefix
*/
atPrefix(prefix) {
if (!prefix.startsWith(this._prefix)) {
throw new Error('Mismatched prefix');
}
const [node, path] = trackDown(this._tree, prefix.slice(this._prefix.length));
if (node === undefined) {
const [parentNode, key] = last(path);
for (const k of parentNode.keys()) {
if (k !== LEAF && k.startsWith(key)) {
const node = new Map();
node.set(k.slice(key.length), parentNode.get(k));
return new SearchableMap(node, prefix);
}
}
}
return new SearchableMap(node, prefix);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/clear
*/
clear() {
this._size = undefined;
this._tree.clear();
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/delete
* @param key Key to delete
*/
delete(key) {
this._size = undefined;
return remove(this._tree, key);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/entries
* @return An iterator iterating through `[key, value]` entries.
*/
entries() {
return new TreeIterator(this, ENTRIES);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/forEach
* @param fn Iteration function
*/
forEach(fn) {
for (const [key, value] of this) {
fn(key, value, this);
}
}
/**
* Returns a Map of all the entries that have a key within the given edit
* distance from the search key. The keys of the returned Map are the matching
* keys, while the values are two-element arrays where the first element is
* the value associated to the key, and the second is the edit distance of the
* key to the search key.
*
* ### Usage:
*
* ```javascript
* let map = new SearchableMap()
* map.set('hello', 'world')
* map.set('hell', 'yeah')
* map.set('ciao', 'mondo')
*
* // Get all entries that match the key 'hallo' with a maximum edit distance of 2
* map.fuzzyGet('hallo', 2)
* // => Map(2) { 'hello' => ['world', 1], 'hell' => ['yeah', 2] }
*
* // In the example, the "hello" key has value "world" and edit distance of 1
* // (change "e" to "a"), the key "hell" has value "yeah" and edit distance of 2
* // (change "e" to "a", delete "o")
* ```
*
* @param key The search key
* @param maxEditDistance The maximum edit distance (Levenshtein)
* @return A Map of the matching keys to their value and edit distance
*/
fuzzyGet(key, maxEditDistance) {
return fuzzySearch(this._tree, key, maxEditDistance);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/get
* @param key Key to get
* @return Value associated to the key, or `undefined` if the key is not
* found.
*/
get(key) {
const node = lookup(this._tree, key);
return node !== undefined ? node.get(LEAF) : undefined;
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/has
* @param key Key
* @return True if the key is in the map, false otherwise
*/
has(key) {
const node = lookup(this._tree, key);
return node !== undefined && node.has(LEAF);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/keys
* @return An `Iterable` iterating through keys
*/
keys() {
return new TreeIterator(this, KEYS);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/set
* @param key Key to set
* @param value Value to associate to the key
* @return The {@link SearchableMap} itself, to allow chaining
*/
set(key, value) {
if (typeof key !== 'string') {
throw new Error('key must be a string');
}
this._size = undefined;
const node = createPath(this._tree, key);
node.set(LEAF, value);
return this;
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/size
*/
get size() {
if (this._size) {
return this._size;
}
/** @ignore */
this._size = 0;
const iter = this.entries();
while (!iter.next().done)
this._size += 1;
return this._size;
}
/**
* Updates the value at the given key using the provided function. The function
* is called with the current value at the key, and its return value is used as
* the new value to be set.
*
* ### Example:
*
* ```javascript
* // Increment the current value by one
* searchableMap.update('somekey', (currentValue) => currentValue == null ? 0 : currentValue + 1)
* ```
*
* If the value at the given key is or will be an object, it might not require
* re-assignment. In that case it is better to use `fetch()`, because it is
* faster.
*
* @param key The key to update
* @param fn The function used to compute the new value from the current one
* @return The {@link SearchableMap} itself, to allow chaining
*/
update(key, fn) {
if (typeof key !== 'string') {
throw new Error('key must be a string');
}
this._size = undefined;
const node = createPath(this._tree, key);
node.set(LEAF, fn(node.get(LEAF)));
return this;
}
/**
* Fetches the value of the given key. If the value does not exist, calls the
* given function to create a new value, which is inserted at the given key
* and subsequently returned.
*
* ### Example:
*
* ```javascript
* const map = searchableMap.fetch('somekey', () => new Map())
* map.set('foo', 'bar')
* ```
*
* @param key The key to update
* @param initial A function that creates a new value if the key does not exist
* @return The existing or new value at the given key
*/
fetch(key, initial) {
if (typeof key !== 'string') {
throw new Error('key must be a string');
}
this._size = undefined;
const node = createPath(this._tree, key);
let value = node.get(LEAF);
if (value === undefined) {
node.set(LEAF, value = initial());
}
return value;
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/values
* @return An `Iterable` iterating through values.
*/
values() {
return new TreeIterator(this, VALUES);
}
/**
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map/@@iterator
*/
[Symbol.iterator]() {
return this.entries();
}
/**
* Creates a {@link SearchableMap} from an `Iterable` of entries
*
* @param entries Entries to be inserted in the {@link SearchableMap}
* @return A new {@link SearchableMap} with the given entries
*/
static from(entries) {
const tree = new SearchableMap();
for (const [key, value] of entries) {
tree.set(key, value);
}
return tree;
}
/**
* Creates a {@link SearchableMap} from the iterable properties of a JavaScript object
*
* @param object Object of entries for the {@link SearchableMap}
* @return A new {@link SearchableMap} with the given entries
*/
static fromObject(object) {
return SearchableMap.from(Object.entries(object));
}
}
const trackDown = (tree, key, path = []) => {
if (key.length === 0 || tree == null) {
return [tree, path];
}
for (const k of tree.keys()) {
if (k !== LEAF && key.startsWith(k)) {
path.push([tree, k]); // performance: update in place
return trackDown(tree.get(k), key.slice(k.length), path);
}
}
path.push([tree, key]); // performance: update in place
return trackDown(undefined, '', path);
};
const lookup = (tree, key) => {
if (key.length === 0 || tree == null) {
return tree;
}
for (const k of tree.keys()) {
if (k !== LEAF && key.startsWith(k)) {
return lookup(tree.get(k), key.slice(k.length));
}
}
};
// Create a path in the radix tree for the given key, and returns the deepest
// node. This function is in the hot path for indexing. It avoids unnecessary
// string operations and recursion for performance.
const createPath = (node, key) => {
const keyLength = key.length;
outer: for (let pos = 0; node && pos < keyLength;) {
for (const k of node.keys()) {
// Check whether this key is a candidate: the first characters must match.
if (k !== LEAF && key[pos] === k[0]) {
const len = Math.min(keyLength - pos, k.length);
// Advance offset to the point where key and k no longer match.
let offset = 1;
while (offset < len && key[pos + offset] === k[offset])
++offset;
const child = node.get(k);
if (offset === k.length) {
// The existing key is shorter than the key we need to create.
node = child;
}
else {
// Partial match: we need to insert an intermediate node to contain
// both the existing subtree and the new node.
const intermediate = new Map();
intermediate.set(k.slice(offset), child);
node.set(key.slice(pos, pos + offset), intermediate);
node.delete(k);
node = intermediate;
}
pos += offset;
continue outer;
}
}
// Create a final child node to contain the final suffix of the key.
const child = new Map();
node.set(key.slice(pos), child);
return child;
}
return node;
};
const remove = (tree, key) => {
const [node, path] = trackDown(tree, key);
if (node === undefined) {
return;
}
node.delete(LEAF);
if (node.size === 0) {
cleanup(path);
}
else if (node.size === 1) {
const [key, value] = node.entries().next().value;
merge(path, key, value);
}
};
const cleanup = (path) => {
if (path.length === 0) {
return;
}
const [node, key] = last(path);
node.delete(key);
if (node.size === 0) {
cleanup(path.slice(0, -1));
}
else if (node.size === 1) {
const [key, value] = node.entries().next().value;
if (key !== LEAF) {
merge(path.slice(0, -1), key, value);
}
}
};
const merge = (path, key, value) => {
if (path.length === 0) {
return;
}
const [node, nodeKey] = last(path);
node.set(nodeKey + key, value);
node.delete(nodeKey);
};
const last = (array) => {
return array[array.length - 1];
};
return SearchableMap;
}));
//# sourceMappingURL=SearchableMap.js.map