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import {cache} from '../decorators';
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import {range} from '../utils';
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export default class AATLookupTable {
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constructor(table) {
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this.table = table;
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}
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lookup(glyph) {
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switch (this.table.version) {
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case 0: // simple array format
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return this.table.values.getItem(glyph);
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case 2: // segment format
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case 4: {
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let min = 0;
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let max = this.table.binarySearchHeader.nUnits - 1;
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while (min <= max) {
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var mid = (min + max) >> 1;
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var seg = this.table.segments[mid];
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// special end of search value
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if (seg.firstGlyph === 0xffff) {
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return null;
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}
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if (glyph < seg.firstGlyph) {
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max = mid - 1;
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} else if (glyph > seg.lastGlyph) {
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min = mid + 1;
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} else {
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if (this.table.version === 2) {
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return seg.value;
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} else {
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return seg.values[glyph - seg.firstGlyph];
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}
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}
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}
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return null;
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}
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case 6: { // lookup single
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let min = 0;
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let max = this.table.binarySearchHeader.nUnits - 1;
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while (min <= max) {
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var mid = (min + max) >> 1;
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var seg = this.table.segments[mid];
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// special end of search value
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if (seg.glyph === 0xffff) {
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return null;
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}
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if (glyph < seg.glyph) {
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max = mid - 1;
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} else if (glyph > seg.glyph) {
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min = mid + 1;
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} else {
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return seg.value;
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}
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}
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return null;
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}
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case 8: // lookup trimmed
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return this.table.values[glyph - this.table.firstGlyph];
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default:
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throw new Error(`Unknown lookup table format: ${this.table.version}`);
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}
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}
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@cache
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glyphsForValue(classValue) {
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let res = [];
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switch (this.table.version) {
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case 2: // segment format
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case 4: {
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for (let segment of this.table.segments) {
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if ((this.table.version === 2 && segment.value === classValue)) {
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res.push(...range(segment.firstGlyph, segment.lastGlyph + 1));
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} else {
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for (let index = 0; index < segment.values.length; index++) {
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if (segment.values[index] === classValue) {
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res.push(segment.firstGlyph + index);
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}
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}
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}
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}
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break;
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}
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case 6: { // lookup single
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for (let segment of this.table.segments) {
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if (segment.value === classValue) {
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res.push(segment.glyph);
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}
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}
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break;
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}
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case 8: { // lookup trimmed
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for (let i = 0; i < this.table.values.length; i++) {
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if (this.table.values[i] === classValue) {
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res.push(this.table.firstGlyph + i);
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}
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}
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break;
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}
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default:
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throw new Error(`Unknown lookup table format: ${this.table.version}`);
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}
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return res;
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}
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}
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