1 | const supported_languages = [
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2 | "danish",
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3 | "dutch",
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4 | "english",
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5 | "french",
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6 | "galician",
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7 | "german",
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8 | "italian",
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9 | "polish",
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10 | "portuguese",
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11 | "romanian",
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12 | "russian",
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13 | "spanish",
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14 | "swedish",
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15 | "persian",
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16 | "arabic"
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17 | ];
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18 | const stopwords = require("./stopwords/stopwords");
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19 |
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20 | function extract(
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21 | str,
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22 | options = {
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23 | remove_digits: true,
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24 | return_changed_case: true,
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25 | }
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26 | ) {
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27 | if (!str) {
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28 | return [];
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29 | }
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30 |
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31 | const return_changed_case = options.return_changed_case;
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32 | const return_chained_words = options.return_chained_words;
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33 | const remove_digits = options.remove_digits;
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34 | const _language = options.language || "english";
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35 | const _remove_duplicates = options.remove_duplicates || false;
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36 | const return_max_ngrams = options.return_max_ngrams;
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37 |
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38 | if (supported_languages.indexOf(_language) < 0) {
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39 | throw new Error(
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40 | "Language must be one of [" + supported_languages.join(",") + "]"
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41 | );
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42 | }
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43 |
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44 |
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45 | const text = str.replace(/(<([^>]+)>)/gi, "").trim();
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46 | if (!text) {
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47 | return [];
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48 | } else {
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49 | const words = text.split(/\s/);
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50 | const unchanged_words = [];
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51 | const low_words = [];
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52 |
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53 | for (let x = 0; x < words.length; x++) {
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54 | let w = words[x].match(/https?:\/\/.*[\r\n]*/g)
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55 | ? words[x]
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56 | : words[x].replace(/\.|,|;|!|\?|\(|\)|:|"|^'|'$|“|”|‘|’/g, "");
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57 |
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58 |
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59 | if (w.length === 1) {
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60 | w = w.replace(/_|@|&|#/g, "");
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61 | }
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62 |
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63 | const digits_match = w.match(/\d/g);
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64 | if (remove_digits && digits_match && digits_match.length === w.length) {
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65 | w = "";
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66 | }
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67 | if (w.length > 0) {
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68 | low_words.push(w.toLowerCase());
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69 | unchanged_words.push(w);
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70 | }
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71 | }
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72 | let results = [];
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73 | const _stopwords =
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74 | options.stopwords || getStopwords({ language: _language });
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75 | let _last_result_word_index = 0;
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76 | let _start_result_word_index = 0;
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77 | let _unbroken_word_chain = false;
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78 | for (let y = 0; y < low_words.length; y++) {
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79 | if (_stopwords.indexOf(low_words[y]) < 0) {
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80 | if (_last_result_word_index !== y - 1) {
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81 | _start_result_word_index = y;
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82 | _unbroken_word_chain = false;
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83 | } else {
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84 | _unbroken_word_chain = true;
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85 | }
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86 | const result_word =
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87 | return_changed_case &&
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88 | !unchanged_words[y].match(/https?:\/\/.*[\r\n]*/g)
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89 | ? low_words[y]
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90 | : unchanged_words[y];
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91 |
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92 | if (
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93 | return_max_ngrams &&
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94 | _unbroken_word_chain &&
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95 | !return_chained_words &&
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96 | return_max_ngrams > y - _start_result_word_index &&
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97 | _last_result_word_index === y - 1
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98 | ) {
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99 | const change_pos = results.length - 1 < 0 ? 0 : results.length - 1;
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100 | results[change_pos] = results[change_pos]
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101 | ? results[change_pos] + " " + result_word
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102 | : result_word;
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103 | } else if (return_chained_words && _last_result_word_index === y - 1) {
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104 | const change_pos = results.length - 1 < 0 ? 0 : results.length - 1;
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105 | results[change_pos] = results[change_pos]
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106 | ? results[change_pos] + " " + result_word
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107 | : result_word;
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108 | } else {
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109 | results.push(result_word);
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110 | }
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111 |
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112 | _last_result_word_index = y;
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113 | } else {
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114 | _unbroken_word_chain = false;
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115 | }
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116 | }
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117 |
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118 | if (_remove_duplicates) {
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119 | results = results.filter((v, i, a) => a.indexOf(v) === i);;
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120 | }
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121 |
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122 | return results;
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123 | }
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124 | }
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125 |
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126 | function getStopwords(options) {
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127 | options = options || {};
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128 |
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129 | const _language = options.language || "english";
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130 | if (supported_languages.indexOf(_language) < 0) {
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131 | throw new Error(
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132 | "Language must be one of [" + supported_languages.join(",") + "]"
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133 | );
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134 | }
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135 |
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136 | return stopwords[_language];
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137 | }
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138 |
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139 | module.exports = {
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140 | getStopwords,
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141 | extract,
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142 | }
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