| 1 | "use strict";
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| 2 | Object.defineProperty(exports, "__esModule", { value: true });
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| 3 | const boundaries_1 = require("./boundaries");
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| 4 | // BreakTypes
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| 5 | // @type {BreakType}
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| 6 | const NotBreak = 0;
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| 7 | const BreakStart = 1;
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| 8 | const Break = 2;
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| 9 | const BreakLastRegional = 3;
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| 10 | const BreakPenultimateRegional = 4;
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| 11 | class GraphemerHelper {
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| 12 | /**
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| 13 | * Check if the the character at the position {pos} of the string is surrogate
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| 14 | * @param str {string}
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| 15 | * @param pos {number}
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| 16 | * @returns {boolean}
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| 17 | */
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| 18 | static isSurrogate(str, pos) {
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| 19 | return (0xd800 <= str.charCodeAt(pos) &&
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| 20 | str.charCodeAt(pos) <= 0xdbff &&
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| 21 | 0xdc00 <= str.charCodeAt(pos + 1) &&
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| 22 | str.charCodeAt(pos + 1) <= 0xdfff);
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| 23 | }
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| 24 | /**
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| 25 | * The String.prototype.codePointAt polyfill
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| 26 | * Private function, gets a Unicode code point from a JavaScript UTF-16 string
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| 27 | * handling surrogate pairs appropriately
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| 28 | * @param str {string}
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| 29 | * @param idx {number}
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| 30 | * @returns {number}
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| 31 | */
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| 32 | static codePointAt(str, idx) {
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| 33 | if (idx === undefined) {
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| 34 | idx = 0;
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| 35 | }
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| 36 | const code = str.charCodeAt(idx);
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| 37 | // if a high surrogate
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| 38 | if (0xd800 <= code && code <= 0xdbff && idx < str.length - 1) {
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| 39 | const hi = code;
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| 40 | const low = str.charCodeAt(idx + 1);
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| 41 | if (0xdc00 <= low && low <= 0xdfff) {
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| 42 | return (hi - 0xd800) * 0x400 + (low - 0xdc00) + 0x10000;
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| 43 | }
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| 44 | return hi;
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| 45 | }
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| 46 | // if a low surrogate
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| 47 | if (0xdc00 <= code && code <= 0xdfff && idx >= 1) {
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| 48 | const hi = str.charCodeAt(idx - 1);
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| 49 | const low = code;
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| 50 | if (0xd800 <= hi && hi <= 0xdbff) {
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| 51 | return (hi - 0xd800) * 0x400 + (low - 0xdc00) + 0x10000;
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| 52 | }
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| 53 | return low;
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| 54 | }
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| 55 | // just return the char if an unmatched surrogate half or a
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| 56 | // single-char codepoint
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| 57 | return code;
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| 58 | }
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| 59 | //
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| 60 | /**
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| 61 | * Private function, returns whether a break is allowed between the two given grapheme breaking classes
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| 62 | * Implemented the UAX #29 3.1.1 Grapheme Cluster Boundary Rules on extended grapheme clusters
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| 63 | * @param start {number}
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| 64 | * @param mid {Array<number>}
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| 65 | * @param end {number}
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| 66 | * @param startEmoji {number}
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| 67 | * @param midEmoji {Array<number>}
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| 68 | * @param endEmoji {number}
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| 69 | * @returns {number}
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| 70 | */
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| 71 | static shouldBreak(start, mid, end, startEmoji, midEmoji, endEmoji) {
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| 72 | const all = [start].concat(mid).concat([end]);
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| 73 | const allEmoji = [startEmoji].concat(midEmoji).concat([endEmoji]);
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| 74 | const previous = all[all.length - 2];
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| 75 | const next = end;
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| 76 | const nextEmoji = endEmoji;
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| 77 | // Lookahead terminator for:
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| 78 | // GB12. ^ (RI RI)* RI ? RI
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| 79 | // GB13. [^RI] (RI RI)* RI ? RI
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| 80 | const rIIndex = all.lastIndexOf(boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR);
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| 81 | if (rIIndex > 0 &&
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| 82 | all.slice(1, rIIndex).every(function (c) {
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| 83 | return c === boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR;
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| 84 | }) &&
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| 85 | [boundaries_1.CLUSTER_BREAK.PREPEND, boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR].indexOf(previous) === -1) {
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| 86 | if (all.filter(function (c) {
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| 87 | return c === boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR;
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| 88 | }).length %
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| 89 | 2 ===
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| 90 | 1) {
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| 91 | return BreakLastRegional;
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| 92 | }
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| 93 | else {
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| 94 | return BreakPenultimateRegional;
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| 95 | }
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| 96 | }
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| 97 | // GB3. CR × LF
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| 98 | if (previous === boundaries_1.CLUSTER_BREAK.CR && next === boundaries_1.CLUSTER_BREAK.LF) {
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| 99 | return NotBreak;
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| 100 | }
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| 101 | // GB4. (Control|CR|LF) ÷
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| 102 | else if (previous === boundaries_1.CLUSTER_BREAK.CONTROL ||
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| 103 | previous === boundaries_1.CLUSTER_BREAK.CR ||
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| 104 | previous === boundaries_1.CLUSTER_BREAK.LF) {
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| 105 | return BreakStart;
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| 106 | }
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| 107 | // GB5. ÷ (Control|CR|LF)
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| 108 | else if (next === boundaries_1.CLUSTER_BREAK.CONTROL ||
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| 109 | next === boundaries_1.CLUSTER_BREAK.CR ||
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| 110 | next === boundaries_1.CLUSTER_BREAK.LF) {
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| 111 | return BreakStart;
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| 112 | }
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| 113 | // GB6. L × (L|V|LV|LVT)
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| 114 | else if (previous === boundaries_1.CLUSTER_BREAK.L &&
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| 115 | (next === boundaries_1.CLUSTER_BREAK.L ||
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| 116 | next === boundaries_1.CLUSTER_BREAK.V ||
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| 117 | next === boundaries_1.CLUSTER_BREAK.LV ||
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| 118 | next === boundaries_1.CLUSTER_BREAK.LVT)) {
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| 119 | return NotBreak;
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| 120 | }
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| 121 | // GB7. (LV|V) × (V|T)
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| 122 | else if ((previous === boundaries_1.CLUSTER_BREAK.LV || previous === boundaries_1.CLUSTER_BREAK.V) &&
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| 123 | (next === boundaries_1.CLUSTER_BREAK.V || next === boundaries_1.CLUSTER_BREAK.T)) {
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| 124 | return NotBreak;
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| 125 | }
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| 126 | // GB8. (LVT|T) × (T)
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| 127 | else if ((previous === boundaries_1.CLUSTER_BREAK.LVT || previous === boundaries_1.CLUSTER_BREAK.T) &&
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| 128 | next === boundaries_1.CLUSTER_BREAK.T) {
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| 129 | return NotBreak;
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| 130 | }
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| 131 | // GB9. × (Extend|ZWJ)
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| 132 | else if (next === boundaries_1.CLUSTER_BREAK.EXTEND || next === boundaries_1.CLUSTER_BREAK.ZWJ) {
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| 133 | return NotBreak;
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| 134 | }
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| 135 | // GB9a. × SpacingMark
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| 136 | else if (next === boundaries_1.CLUSTER_BREAK.SPACINGMARK) {
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| 137 | return NotBreak;
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| 138 | }
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| 139 | // GB9b. Prepend ×
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| 140 | else if (previous === boundaries_1.CLUSTER_BREAK.PREPEND) {
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| 141 | return NotBreak;
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| 142 | }
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| 143 | // GB11. \p{Extended_Pictographic} Extend* ZWJ × \p{Extended_Pictographic}
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| 144 | const previousNonExtendIndex = allEmoji
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| 145 | .slice(0, -1)
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| 146 | .lastIndexOf(boundaries_1.EXTENDED_PICTOGRAPHIC);
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| 147 | if (previousNonExtendIndex !== -1 &&
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| 148 | allEmoji[previousNonExtendIndex] === boundaries_1.EXTENDED_PICTOGRAPHIC &&
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| 149 | all.slice(previousNonExtendIndex + 1, -2).every(function (c) {
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| 150 | return c === boundaries_1.CLUSTER_BREAK.EXTEND;
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| 151 | }) &&
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| 152 | previous === boundaries_1.CLUSTER_BREAK.ZWJ &&
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| 153 | nextEmoji === boundaries_1.EXTENDED_PICTOGRAPHIC) {
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| 154 | return NotBreak;
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| 155 | }
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| 156 | // GB12. ^ (RI RI)* RI × RI
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| 157 | // GB13. [^RI] (RI RI)* RI × RI
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| 158 | if (mid.indexOf(boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR) !== -1) {
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| 159 | return Break;
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| 160 | }
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| 161 | if (previous === boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR &&
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| 162 | next === boundaries_1.CLUSTER_BREAK.REGIONAL_INDICATOR) {
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| 163 | return NotBreak;
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| 164 | }
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| 165 | // GB999. Any ? Any
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| 166 | return BreakStart;
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| 167 | }
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| 168 | }
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| 169 | exports.default = GraphemerHelper;
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