42 lines
1.2 KiB
Plaintext
42 lines
1.2 KiB
Plaintext
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/**
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* Apply Arabic required ligatures feature to a range of tokens
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*/
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import { ContextParams } from '../../tokenizer';
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import applySubstitution from '../applySubstitution';
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/**
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* Update context params
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* @param {any} tokens a list of tokens
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* @param {number} index current item index
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*/
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function getContextParams(tokens, index) {
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const context = tokens.map(token => token.activeState.value);
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return new ContextParams(context, index || 0);
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}
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/**
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* Apply Arabic required ligatures to a context range
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* @param {ContextRange} range a range of tokens
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*/
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function arabicRequiredLigatures(range) {
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const script = 'arab';
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let tokens = this.tokenizer.getRangeTokens(range);
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let contextParams = getContextParams(tokens);
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contextParams.context.forEach((glyphIndex, index) => {
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contextParams.setCurrentIndex(index);
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let substitutions = this.query.lookupFeature({
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tag: 'rlig', script, contextParams
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});
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if (substitutions.length) {
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substitutions.forEach(
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action => applySubstitution(action, tokens, index)
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);
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contextParams = getContextParams(tokens);
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}
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});
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}
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export default arabicRequiredLigatures;
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export { arabicRequiredLigatures };
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