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/*
* Copyright (c) 2016-2023 Martin Donath <martin.donath@squidfunk.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
import { split } from "../_"
import {
Extract,
extract
} from "../extract"
/* ----------------------------------------------------------------------------
* Functions
* ------------------------------------------------------------------------- */
/**
* Split a string or set of strings into tokens
*
* This tokenizer supersedes the default tokenizer that is provided by Lunr.js,
* as it is aware of HTML tags and allows for multi-character splitting.
*
* It takes the given inputs, splits each of them into markup and text sections,
* tokenizes and segments (if necessary) each of them, and then indexes them in
* a table by using a compact bit representation. Bitwise techniques are used
* to write and read from the table during indexing and querying.
*
* @see https://bit.ly/3W3Xw4J - Search: better, faster, smaller
*
* @param input - Input value(s)
*
* @returns Tokens
*/
export function tokenize(
input?: string | string[]
): lunr.Token[] {
const tokens: lunr.Token[] = []
if (typeof input === "undefined")
return tokens
/* Tokenize strings one after another */
const inputs = Array.isArray(input) ? input : [input]
for (let i = 0; i < inputs.length; i++) {
const table = lunr.tokenizer.table
const total = table.length
/* Split string into sections and tokenize content blocks */
extract(inputs[i], (block, type, start, end) => {
table[block += total] ||= []
switch (type) {
/* Handle markup */
case Extract.TAG_OPEN:
case Extract.TAG_CLOSE:
table[block].push(
start << 12 |
end - start << 2 |
type
)
break
/* Handle text content */
case Extract.TEXT:
const section = inputs[i].slice(start, end)
split(section, lunr.tokenizer.separator, (index, until) => {
/**
* Apply segmenter after tokenization. Note that the segmenter will
* also split words at word boundaries, which is not what we want,
* so we need to check if we can somehow mitigate this behavior.
*/
if (typeof lunr.segmenter !== "undefined") {
const subsection = section.slice(index, until)
if (/^[MHIK]$/.test(lunr.segmenter.ctype_(subsection))) {
const segments = lunr.segmenter.segment(subsection)
for (let s = 0, l = 0; s < segments.length; s++) {
/* Add block to section */
table[block] ||= []
table[block].push(
start + index + l << 12 |
segments[s].length << 2 |
type
)
/* Add token with position */
tokens.push(new lunr.Token(
segments[s].toLowerCase(), {
position: block << 20 | table[block].length - 1
}
))
/* Keep track of length */
l += segments[s].length
}
return
}
}
/* Add block to section */
table[block].push(
start + index << 12 |
until - index << 2 |
type
)
/* Add token with position */
tokens.push(new lunr.Token(
section.slice(index, until).toLowerCase(), {
position: block << 20 | table[block].length - 1
}
))
})
}
})
}
/* Return tokens */
return tokens
}
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