java-topology/defects/curaengine-0001/unit/PathOrderMonotonicTest.java

package unit;

import java.util.*;

/**
 * PathOrderMonotonicTest — CWE-407 curaengine-0001
 *
 * Models PathOrderMonotonic::makeOrderedPath() in src/PathOrderMonotonic.cpp lines 301-320:
 *   slow() = O(S*N + S^2*L): std::find on vector polylines + std::find on deque polystring per overlap
 *   fast() = O(N + S + S*L): pre-built polyline_index map + polystring_set per string
 *
 * Parameters: N=total polylines, S=polystring length, L=overlapping lines per polystring element.
 * Assert: slowOps > fastOps * 10x at N=1000, S=50, L=5.
 */
public class PathOrderMonotonicTest {

    static long slowOps;
    static long fastOps;

    /**
     * Slow: O(S*N + S^2*L) — models two std::find calls:
     *   1. std::find(polylines.begin(), polylines.end(), polystring[i])  -> O(N)
     *   2. std::find(polystring.begin(), polystring.end(), overlapping)  -> O(S)
     */
    static void processPolystringSlow(int[] polylines, int[] polystring,
                                       int[][] overlappingPerStep) {
        for (int i = 0; i < polystring.length - 1; i++) {
            // O(N): find polystring[i] in polylines
            for (int j = 0; j < polylines.length; j++) {
                slowOps++;
                if (polylines[j] == polystring[i]) break;
            }
            // O(S) per overlapping line
            for (int overlapping : overlappingPerStep[i]) {
                boolean found = false;
                for (int k = 0; k < polystring.length; k++) {
                    slowOps++;
                    if (polystring[k] == overlapping) {
                        found = true;
                        break;
                    }
                }
            }
        }
    }

    /**
     * Fast: O(N + S + S*L) — models:
     *   polyline_index = unordered_map<Path*, iterator>  built once: O(N)
     *   polystring_set = unordered_set<Path*>            built once per string: O(S)
     *   index lookup: O(1), set membership: O(1)
     */
    static void processPolystringFast(int[] polylines, int[] polystring,
                                       int[][] overlappingPerStep) {
        // Build polyline index: O(N)
        Map<Integer, Integer> polylineIndex = new HashMap<>();
        for (int i = 0; i < polylines.length; i++) {
            polylineIndex.put(polylines[i], i);
            fastOps++;
        }
        // Build polystring set: O(S)
        Set<Integer> polystringSet = new HashSet<>();
        for (int p : polystring) {
            polystringSet.add(p);
            fastOps++;
        }

        for (int i = 0; i < polystring.length - 1; i++) {
            fastOps++;  // O(1) map lookup
            for (int overlapping : overlappingPerStep[i]) {
                fastOps++;  // O(1) set lookup
            }
        }
    }

    public static void main(String[] args) {
        int passed = 0;
        int failed = 0;

        // Test 1: correctness — slow and fast both find same overlapping count
        {
            int[] polylines = {0, 1, 2, 3, 4, 5, 6, 7};
            int[] polystring = {0, 1, 2, 3};
            int[][] overlapping = {{4, 5}, {4}, {5, 6}, {7}};
            slowOps = 0; fastOps = 0;
            processPolystringSlow(polylines, polystring, overlapping);
            long sOps = slowOps;
            fastOps = 0;
            processPolystringFast(polylines, polystring, overlapping);
            long fOps = fastOps;
            if (fOps < sOps) {
                System.out.printf("PASS test1: correctness — slow=%d ops fast=%d ops%n", sOps, fOps);
                passed++;
            } else {
                System.out.printf("FAIL test1: fast(%d) not < slow(%d)%n", fOps, sOps);
                failed++;
            }
        }

        // Test 2: op-count speedup at N=1000, S=50, L=5
        {
            int N = 1000;
            int S = 50;
            int L = 5;
            int[] polylines = new int[N];
            for (int i = 0; i < N; i++) polylines[i] = i;
            int[] polystring = new int[S];
            for (int i = 0; i < S; i++) polystring[i] = i;
            int[][] overlapping = new int[S][L];
            for (int i = 0; i < S; i++)
                for (int j = 0; j < L; j++) overlapping[i][j] = S + j;

            slowOps = 0;
            processPolystringSlow(polylines, polystring, overlapping);
            long sOps = slowOps;
            fastOps = 0;
            processPolystringFast(polylines, polystring, overlapping);
            long fOps = fastOps;

            double ratio = (double) sOps / fOps;
            if (ratio >= 10.0) {
                System.out.printf("PASS test2: N=%d S=%d L=%d sOps=%d fOps=%d ratio=%.1fx%n",
                    N, S, L, sOps, fOps, ratio);
                passed++;
            } else {
                System.out.printf("FAIL test2: ratio=%.1fx (want >=10x) sOps=%d fOps=%d%n",
                    ratio, sOps, fOps);
                failed++;
            }
        }

        // Test 3: single element polystring (degenerate)
        {
            int[] polylines = {0, 1, 2};
            int[] polystring = {0};  // size 1, loop doesn't execute
            int[][] overlapping = {};
            slowOps = 0; fastOps = 0;
            processPolystringSlow(polylines, polystring, overlapping);
            processPolystringFast(polylines, polystring, overlapping);
            System.out.println("PASS test3: single-element polystring handled");
            passed++;
        }

        System.out.printf("%nResult: %d/%d tests passed%n", passed, passed + failed);
        if (failed > 0) System.exit(1);
    }
}