font-ligatures/dist/walk.js

Find ligature replacements for any system font

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
function walkTree(tree, sequence, startIndex, index) {
    const glyphId = sequence[index];
    let subtree = tree[glyphId];
    if (!subtree) {
        return undefined;
    }
    let lookup = subtree.lookup;
    if (subtree.reverse) {
        const reverseLookup = walkReverse(subtree.reverse, sequence, startIndex);
        if ((!lookup && reverseLookup) ||
            (reverseLookup && lookup && (lookup.index > reverseLookup.index ||
                (lookup.index === reverseLookup.index && lookup.subIndex > reverseLookup.subIndex)))) {
            lookup = reverseLookup;
        }
    }
    if (++index >= sequence.length || !subtree.forward) {
        return lookup;
    }
    const forwardLookup = walkTree(subtree.forward, sequence, startIndex, index);
    if ((!lookup && forwardLookup) ||
        (forwardLookup && lookup && (lookup.index > forwardLookup.index ||
            (lookup.index === forwardLookup.index && lookup.subIndex > forwardLookup.subIndex)))) {
        lookup = forwardLookup;
    }
    return lookup;
}
exports.default = walkTree;
function walkReverse(tree, sequence, index) {
    let subtree = tree[sequence[--index]];
    let lookup = subtree && subtree.lookup;
    while (subtree) {
        if ((!lookup && subtree.lookup) ||
            (subtree.lookup && lookup && lookup.index > subtree.lookup.index)) {
            lookup = subtree.lookup;
        }
        if (--index < 0 || !subtree.reverse) {
            break;
        }
        subtree = subtree.reverse[sequence[index]];
    }
    return lookup;
}
//# sourceMappingURL=walk.js.map