@nodesecure/js-x-ray/dist/utils/patterns.js

JavaScript AST XRay analysis

// Import Third-party Dependencies
import FrequencySet from "frequency-set";
// Import Internal Dependencies
import { toValue } from "../estree/index.js";
/**
 * @description get the common string prefix (at the start) pattern
 * @example
 * commonStringPrefix("boo", "foo"); // null
 * commonStringPrefix("bromance", "brother"); // "bro"
 */
export function commonStringPrefix(leftAnyValue, rightAnyValue) {
    const leftStr = toValue(leftAnyValue);
    const rightStr = toValue(rightAnyValue);
    // The length of leftStr cannot be greater than that rightStr
    const minLen = leftStr.length > rightStr.length ? rightStr.length : leftStr.length;
    let commonStr = "";
    for (let id = 0; id < minLen; id++) {
        if (leftStr.charAt(id) !== rightStr.charAt(id)) {
            break;
        }
        commonStr += leftStr.charAt(id);
    }
    return commonStr === "" ? null : commonStr;
}
function reverseString(string) {
    return string.split("").reverse().join("");
}
/**
 * @description get the common string suffixes (at the end) pattern
 * @param {!string} leftStr
 * @param {!string} rightStr
 * @returns {string | null}
 *
 * @example
 * commonStringSuffix("boo", "foo"); // oo
 * commonStringSuffix("bromance", "brother"); // null
 */
export function commonStringSuffix(leftStr, rightStr) {
    const commonPrefix = commonStringPrefix(reverseString(leftStr), reverseString(rightStr));
    return commonPrefix === null ? null : reverseString(commonPrefix);
}
export function commonHexadecimalPrefix(identifiersArray) {
    if (!Array.isArray(identifiersArray)) {
        throw new TypeError("identifiersArray must be an Array");
    }
    const prefix = new FrequencySet();
    mainLoop: for (const value of identifiersArray.slice().sort()) {
        for (const [cp, count] of prefix) {
            const commonStr = commonStringPrefix(value, cp);
            if (commonStr === null) {
                continue;
            }
            if (commonStr === cp || commonStr.startsWith(cp)) {
                prefix.add(cp);
            }
            else if (cp.startsWith(commonStr)) {
                prefix.delete(cp);
                prefix.add(commonStr, count + 1);
            }
            continue mainLoop;
        }
        prefix.add(value);
    }
    // We remove one-time occurences (because they are normal variables)
    let oneTimeOccurence = 0;
    for (const [key, value] of prefix.entries()) {
        if (value === 1) {
            prefix.delete(key);
            oneTimeOccurence++;
        }
    }
    return {
        oneTimeOccurence,
        prefix: Object.fromEntries(prefix)
    };
}
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