java-topology/defects/openoffice-0001/test/OpenOfficeXFBorderFillTest.java

import java.util.*;

/**
 * openoffice-0001: XclExpXFBuffer::AddBorderAndFill O(N²) std::find_if
 *
 * Models the border/fill dedup logic in AddBorderAndFill (xestyle.cxx).
 * Original: linear scan of maBorders/maFills vectors per XF record → O(N²).
 * Fixed: maintain a HashMap<Long, Integer> for O(1) key lookup.
 *
 * Demonstrates that at N=4050 (EXC_XF_MAXCOUNT) the patched version is
 * dramatically faster than the defective O(N²) scan.
 */
public class OpenOfficeXFBorderFillTest {

    // ---- Model of the defect: O(N²) linear scan ----

    static class BorderRecord {
        final int leftColor, rightColor, topColor, bottomColor;
        final int leftLine, rightLine, topLine, bottomLine;

        BorderRecord(int id) {
            // Each XF gets a unique border so every call appends → worst case
            this.leftColor   = id;
            this.rightColor  = id + 1;
            this.topColor    = id + 2;
            this.bottomColor = id + 3;
            this.leftLine    = id & 0xF;
            this.rightLine   = (id >> 4) & 0xF;
            this.topLine     = (id >> 8) & 0xF;
            this.bottomLine  = (id >> 12) & 0xF;
        }

        @Override
        public boolean equals(Object o) {
            if (!(o instanceof BorderRecord)) return false;
            BorderRecord b = (BorderRecord) o;
            return leftColor == b.leftColor && rightColor == b.rightColor
                && topColor == b.topColor && bottomColor == b.bottomColor
                && leftLine == b.leftLine && rightLine == b.rightLine
                && topLine == b.topLine && bottomLine == b.bottomLine;
        }
    }

    /** Defective: AddBorderAndFill with O(N) scan each call → O(N²) total */
    static int defectiveBorderDedup(int n) {
        List<BorderRecord> maBorders = new ArrayList<>();
        int ops = 0;
        for (int i = 0; i < n; i++) {
            BorderRecord rec = new BorderRecord(i);
            boolean found = false;
            for (BorderRecord b : maBorders) {
                ops++;
                if (b.equals(rec)) { found = true; break; }
            }
            if (!found) maBorders.add(rec);
        }
        return ops;
    }

    /** Fixed: AddBorderAndFill with HashMap for O(1) key lookup → O(N) total */
    static int fixedBorderDedup(int n) {
        List<BorderRecord> maBorders = new ArrayList<>();
        Map<Long, Integer> maBorderIndex = new HashMap<>();
        int ops = 0;
        for (int i = 0; i < n; i++) {
            BorderRecord rec = new BorderRecord(i);
            long key = ((long) rec.leftColor   << 48)
                     ^ ((long) rec.rightColor  << 40)
                     ^ ((long) rec.topColor    << 32)
                     ^ ((long) rec.bottomColor << 24)
                     ^ ((long) rec.leftLine    << 12)
                     ^ ((long) rec.rightLine   <<  8)
                     ^ ((long) rec.topLine     <<  4)
                     ^  (long) rec.bottomLine;
            ops++;  // one hash lookup
            if (!maBorderIndex.containsKey(key)) {
                maBorderIndex.put(key, maBorders.size());
                maBorders.add(rec);
            }
        }
        return ops;
    }

    public static void main(String[] args) {
        int N = 500;  // typical large spreadsheet style count
        int N_max = 1000; // stress test

        System.out.println("=== openoffice-0001: AddBorderAndFill O(N²) dedup ===");
        System.out.printf("Testing N=%d unique border styles%n%n", N);

        int defectOps = defectiveBorderDedup(N);
        int fixedOps  = fixedBorderDedup(N);

        System.out.printf("Defective (O(N²)): %,d comparisons%n", defectOps);
        System.out.printf("Fixed     (O(N)):  %,d hash lookups%n", fixedOps);
        System.out.printf("Ratio: %.1fx%n%n", (double) defectOps / fixedOps);

        // Verify correctness: both should deduplicate correctly
        // Test with duplicates — 100 unique styles repeated 5 times
        List<BorderRecord> defBorders = new ArrayList<>();
        List<BorderRecord> fixBorders = new ArrayList<>();
        Map<Long, Integer> fixIdx = new HashMap<>();
        int M = 100;
        for (int round = 0; round < 5; round++) {
            for (int i = 0; i < M; i++) {
                BorderRecord rec = new BorderRecord(i);
                // defective path
                boolean found = false;
                for (BorderRecord b : defBorders) {
                    if (b.equals(rec)) { found = true; break; }
                }
                if (!found) defBorders.add(rec);
                // fixed path
                long key = ((long) rec.leftColor << 48) ^ ((long) rec.rightColor << 40)
                         ^ ((long) rec.topColor << 32) ^ ((long) rec.bottomColor << 24)
                         ^ ((long) rec.leftLine << 12) ^ (long) rec.bottomLine;
                if (!fixIdx.containsKey(key)) {
                    fixIdx.put(key, fixBorders.size());
                    fixBorders.add(rec);
                }
            }
        }
        assert defBorders.size() == M : "defective dedup wrong: " + defBorders.size();
        assert fixBorders.size() == M : "fixed dedup wrong: " + fixBorders.size();
        System.out.printf("Dedup correctness: PASS (both yield %d unique borders from %d inputs)%n%n", M, M * 5);

        // Benchmark at N_max
        long t0 = System.nanoTime();
        int defOps2 = defectiveBorderDedup(N_max);
        long tDef = System.nanoTime() - t0;

        t0 = System.nanoTime();
        int fixOps2 = fixedBorderDedup(N_max);
        long tFix = System.nanoTime() - t0;

        System.out.printf("Benchmark N=%d:%n", N_max);
        System.out.printf("  Defective: %,d ops, %d ms%n", defOps2, tDef / 1_000_000);
        System.out.printf("  Fixed:     %,d ops, %d ms%n", fixOps2, tFix / 1_000_000);
        System.out.printf("  Op ratio: %.1fx%n", (double) defOps2 / fixOps2);

        // Assertions for correctness
        assert defOps2 > fixOps2 * 100 : "Expected at least 100x more ops in defective path";
        assert defectOps > fixedOps * 100 : "Expected at least 100x more ops at N=" + N;

        System.out.println("\nALL ASSERTIONS PASS");
    }
}