263 lines
6.0 KiB
Python
263 lines
6.0 KiB
Python
"""Chinese search language: includes routine to split words."""
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from __future__ import annotations
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import os
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import re
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from typing import TYPE_CHECKING, Dict, List
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import snowballstemmer
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from sphinx.search import SearchLanguage
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try:
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import jieba
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JIEBA = True
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except ImportError:
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JIEBA = False
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english_stopwords = set("""
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a and are as at
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be but by
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for
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if in into is it
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near no not
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of on or
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such
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that the their then there these they this to
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was will with
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""".split())
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js_porter_stemmer = """
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/**
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* Porter Stemmer
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*/
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var Stemmer = function() {
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var step2list = {
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ational: 'ate',
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tional: 'tion',
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enci: 'ence',
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anci: 'ance',
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izer: 'ize',
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bli: 'ble',
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alli: 'al',
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entli: 'ent',
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eli: 'e',
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ousli: 'ous',
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ization: 'ize',
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ation: 'ate',
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ator: 'ate',
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alism: 'al',
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iveness: 'ive',
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fulness: 'ful',
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ousness: 'ous',
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aliti: 'al',
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iviti: 'ive',
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biliti: 'ble',
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logi: 'log'
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};
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var step3list = {
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icate: 'ic',
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ative: '',
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alize: 'al',
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iciti: 'ic',
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ical: 'ic',
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ful: '',
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ness: ''
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};
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var c = "[^aeiou]"; // consonant
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var v = "[aeiouy]"; // vowel
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var C = c + "[^aeiouy]*"; // consonant sequence
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var V = v + "[aeiou]*"; // vowel sequence
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var mgr0 = "^(" + C + ")?" + V + C; // [C]VC... is m>0
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var meq1 = "^(" + C + ")?" + V + C + "(" + V + ")?$"; // [C]VC[V] is m=1
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var mgr1 = "^(" + C + ")?" + V + C + V + C; // [C]VCVC... is m>1
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var s_v = "^(" + C + ")?" + v; // vowel in stem
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this.stemWord = function (w) {
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var stem;
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var suffix;
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var firstch;
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var origword = w;
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if (w.length < 3)
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return w;
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var re;
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var re2;
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var re3;
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var re4;
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firstch = w.substr(0,1);
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if (firstch == "y")
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w = firstch.toUpperCase() + w.substr(1);
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// Step 1a
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re = /^(.+?)(ss|i)es$/;
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re2 = /^(.+?)([^s])s$/;
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if (re.test(w))
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w = w.replace(re,"$1$2");
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else if (re2.test(w))
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w = w.replace(re2,"$1$2");
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// Step 1b
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re = /^(.+?)eed$/;
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re2 = /^(.+?)(ed|ing)$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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re = new RegExp(mgr0);
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if (re.test(fp[1])) {
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re = /.$/;
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w = w.replace(re,"");
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}
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}
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else if (re2.test(w)) {
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var fp = re2.exec(w);
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stem = fp[1];
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re2 = new RegExp(s_v);
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if (re2.test(stem)) {
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w = stem;
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re2 = /(at|bl|iz)$/;
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re3 = new RegExp("([^aeiouylsz])\\\\1$");
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re4 = new RegExp("^" + C + v + "[^aeiouwxy]$");
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if (re2.test(w))
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w = w + "e";
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else if (re3.test(w)) {
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re = /.$/;
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w = w.replace(re,"");
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}
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else if (re4.test(w))
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w = w + "e";
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}
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}
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// Step 1c
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re = /^(.+?)y$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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stem = fp[1];
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re = new RegExp(s_v);
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if (re.test(stem))
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w = stem + "i";
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}
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// Step 2
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re = /^(.+?)(ational|tional|enci|anci|izer|bli|alli|entli|eli|ousli|\
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ization|ation|ator|alism|iveness|fulness|ousness|aliti|iviti|biliti|logi)$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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stem = fp[1];
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suffix = fp[2];
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re = new RegExp(mgr0);
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if (re.test(stem))
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w = stem + step2list[suffix];
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}
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// Step 3
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re = /^(.+?)(icate|ative|alize|iciti|ical|ful|ness)$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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stem = fp[1];
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suffix = fp[2];
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re = new RegExp(mgr0);
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if (re.test(stem))
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w = stem + step3list[suffix];
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}
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// Step 4
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re = /^(.+?)(al|ance|ence|er|ic|able|ible|ant|ement|ment|ent|ou|ism|ate|\
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iti|ous|ive|ize)$/;
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re2 = /^(.+?)(s|t)(ion)$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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stem = fp[1];
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re = new RegExp(mgr1);
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if (re.test(stem))
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w = stem;
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}
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else if (re2.test(w)) {
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var fp = re2.exec(w);
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stem = fp[1] + fp[2];
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re2 = new RegExp(mgr1);
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if (re2.test(stem))
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w = stem;
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}
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// Step 5
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re = /^(.+?)e$/;
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if (re.test(w)) {
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var fp = re.exec(w);
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stem = fp[1];
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re = new RegExp(mgr1);
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re2 = new RegExp(meq1);
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re3 = new RegExp("^" + C + v + "[^aeiouwxy]$");
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if (re.test(stem) || (re2.test(stem) && !(re3.test(stem))))
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w = stem;
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}
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re = /ll$/;
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re2 = new RegExp(mgr1);
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if (re.test(w) && re2.test(w)) {
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re = /.$/;
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w = w.replace(re,"");
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}
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// and turn initial Y back to y
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if (firstch == "y")
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w = firstch.toLowerCase() + w.substr(1);
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return w;
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}
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}
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"""
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class SearchChinese(SearchLanguage):
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"""
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Chinese search implementation
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"""
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lang = 'zh'
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language_name = 'Chinese'
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js_stemmer_code = js_porter_stemmer
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stopwords = english_stopwords
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latin1_letters = re.compile(r'[a-zA-Z0-9_]+')
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latin_terms: list[str] = []
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def init(self, options: dict) -> None:
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if JIEBA:
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dict_path = options.get('dict')
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if dict_path and os.path.isfile(dict_path):
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jieba.load_userdict(dict_path)
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self.stemmer = snowballstemmer.stemmer('english')
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def split(self, input: str) -> list[str]:
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chinese: list[str] = []
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if JIEBA:
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chinese = list(jieba.cut_for_search(input))
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latin1 = \
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[term.strip() for term in self.latin1_letters.findall(input)]
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self.latin_terms.extend(latin1)
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return chinese + latin1
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def word_filter(self, stemmed_word: str) -> bool:
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return len(stemmed_word) > 1
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def stem(self, word: str) -> str:
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# Don't stem Latin words that are long enough to be relevant for search
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# if not stemmed, but would be too short after being stemmed
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# avoids some issues with acronyms
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should_not_be_stemmed = (
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word in self.latin_terms and
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len(word) >= 3 and
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len(self.stemmer.stemWord(word.lower())) < 3
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)
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if should_not_be_stemmed:
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return word.lower()
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return self.stemmer.stemWord(word.lower())
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