string-differ/dist/operations/backtrack.js

A Javascript library to compare and transform strings.

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.getOperations = void 0;
const helpers_1 = require("./helpers");
function createOperations(type, helper, { a, b, store }) {
    const retainOp = (index) => helper.addOperation("retain", index);
    const insertOp = (index) => type === "Char"
        ? helper.addOperation("insert", b[index])
        : helper.addOperation("insert", index);
    const deleteOp = (index) => helper.addOperation("delete", index);
    let x = a.length, y = b.length;
    for (let d = store.getSize() - 1; d > 0; d--) {
        const k = x - y;
        const prevK = d === -k ||
            (d !== k &&
                (store.get(d - 1, k + 1) ?? -1) > (store.get(d - 1, k - 1) ?? -1)) // prefer the move with larger x value
            ? k + 1
            : k - 1;
        const prevX = store.get(d - 1, prevK) ?? -1;
        const prevY = prevX - prevK;
        // backtrack diagonal moves
        while (x > prevX && y > prevY) {
            x = x - 1;
            y = y - 1;
            retainOp(x);
        }
        if (x > prevX) {
            deleteOp(x - 1);
        }
        else {
            insertOp(y - 1);
        }
        x = prevX;
        y = prevY;
    }
    while (x !== 0 || y !== 0) {
        retainOp(--x);
        y -= 1;
    }
    return helper.getOperations();
}
const getOperations = (type, context) => {
    switch (type) {
        case "Range": {
            return createOperations("Range", (0, helpers_1.RangeOperationsHelper)(context.b), context);
        }
        case "Char": {
            return createOperations("Char", (0, helpers_1.CharOperationsHelper)(), context);
        }
        default: {
            throw new Error("Unsupported operation type!");
        }
    }
};
exports.getOperations = getOperations;
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