Code Matching pipeline

The aim of this tutorial is to show how to use the MatchCode.io API to perform code matching on an archive of files.

Note

This tutorial assumes that you have a working installation of PurlDB. If you don’t, please refer to the Installation page.

Throughout this tutorial, we will use pkg:npm/deep-equal@1.0.1 and a modified copy of index.js from it.

BPF.cpp

var pSlice = Array.prototype.slice;
var objectKeys = require('./lib/keys.js');
var isArguments = require('./lib/is_arguments.js');

var deepEqual = module.exports = function (actual, expected, opts) {
    if (!opts) opts = {};
    // 7.1. All identical values are equivalent, as determined by ===.
    if (actual === expected) {
        return true;

    } else if (actual instanceof Date && expected instanceof Date) {
        return actual.getTime() === expected.getTime();

    // 7.3. Other pairs that do not both pass typeof value == 'object',
    // equivalence is determined by ==.
    } else if (!actual || !expected || typeof actual != 'object' && typeof expected != 'object') {
        return opts.strict ? actual === expected : actual == expected;

    // 7.4. For all other Object pairs, including Array objects, equivalence is
    // determined by having the same number of owned properties (as verified
    // with Object.prototype.hasOwnProperty.call), the same set of keys
    // (although not necessarily the same order), equivalent values for every
    // corresponding key, and an identical 'prototype' property. Note: this
    // accounts for both named and indexed properties on Arrays.
    } else {
        return objEquiv(actual, expected, opts);
    }
}

function isBuffer (x) {
    if (!x || typeof x !== 'object' || typeof x.length !== 'number') return false;
    if (typeof x.copy !== 'function' || typeof x.slice !== 'function') {
        return false;
    }
    if (x.length > 0 && typeof x[0] !== 'number') return false;
    return true;
}

function objEquiv(a, b, opts) {
    var i, key;
    if (isUndefinedOrNull(a) || isUndefinedOrNull(b))
        return false;
    // an identical 'prototype' property.
    if (a.prototype !== b.prototype) return false;
    //~~~I've managed to break Object.keys through screwy arguments passing.
    //   Converting to array solves the problem.
    if (isArguments(a)) {
        if (!isArguments(b)) {
            return false;
        }
        a = pSlice.call(a);
        b = pSlice.call(b);
        return deepEqual(a, b, opts);
    }
    if (isBuffer(a)) {
        if (!isBuffer(b)) {
            return false;
        }
        if (a.length !== b.length) return false;
        for (i = 0; i < a.length; i++) {
            if (a[i] !== b[i]) return false;
        }
        return true;
    }
    try {
        var ka = objectKeys(a),
            kb = objectKeys(b);
    } catch (e) {//happens when one is a string literal and the other isn't
        return false;
    }
    // having the same number of owned properties (keys incorporates
    // hasOwnProperty)
    if (ka.length != kb.length)
        return false;
    //the same set of keys (although not necessarily the same order),
    ka.sort();
    kb.sort();
    //~~~cheap key test
    for (i = ka.length - 1; i >= 0; i--) {
        if (ka[i] != kb[i])
        return false;
    }
    //equivalent values for every corresponding key, and
    //~~~possibly expensive deep test
    for (i = ka.length - 1; i >= 0; i--) {
        key = ka[i];
        if (!deepEqual(a[key], b[key], opts)) return false;
    }
    return typeof a === typeof b;
}

Instructions

• First, index the package pkg:npm/deep-equal@1.0.1:

  /api/collect/?purl=pkg:npm/deep-equal@1.0.1
  

• Scan index.js from pkg:npm/deep-equal@1.0.1 with ScanCode toolkit:

  scancode --info index.js --json index.js-results.json
  

• Visit /api/matching/ and POST a new matching request.

Note

Whether you follow this tutorial and previous instructions using cURL or Python script, the final results should be the same.

api_url="http://localhost/api/matching/"
content_type="Content-Type: application/json"
upload_file="upload_file=@/path/to/index.js-results.json"
curl -X POST "$api_url" -H "$content_type" -F "$upload_file"

• When the match has completed, the results can be seen at /api/matching/<uuid>/results