task 5

README.md

@@ -1,6 +1,5 @@
 # PPJ
 
-This repository exists to archive PJATK tasks for the PPJ curriculum.
+This branch contains the solution for the **5th task**.
 
-Each task can be found under its **corresponding branch**: `task/n`.  
+[Go back to main](/femsci/ppj/src/branch/nya)
-Example: `task/2`.

dev/meowmeow/Kitku.java

@@ -0,0 +1,31 @@
+/*
+ * TASK 5
+ * archived at https://git.femboy.science/femsci/ppj/src/branch/task/5
+ * by femsci
+ */
+
+package dev.meowmeow;
+
+public class Kitku {
+
+    public static void main(String[] args) {
+        // let's play with silly datestamps and serialization
+        // 2127 + 10
+
+        LimitedDate from = new LimitedDate(3, 2, 2000),
+                to = new LimitedDate(29, 11, 2127);
+
+        System.out.printf("**Original**\n%s -> %s\n\n", from, to);
+        
+        // for more explicitness let's stress test the system by redundant serde ops
+        int spanRaw = new LimitedDateSpan(from, to).rawSpan();
+
+        LimitedDateSpan theActualSpanAbstraction = new LimitedDateSpan(spanRaw);
+
+        // here we perform the another batch of deserialization operations :3
+        LimitedDate fromde = theActualSpanAbstraction.dateFrom(),
+                tode = theActualSpanAbstraction.dateTo();
+        
+        System.out.printf("**Reconstructed**\n%s -> %s\n", fromde, tode);
+    }
+}

dev/meowmeow/LimitedDate.java

@@ -0,0 +1,51 @@
+/*
+ * TASK 5
+ * archived at https://git.femboy.science/femsci/ppj/src/branch/task/5
+ * by femsci
+ */
+
+package dev.meowmeow;
+
+public class LimitedDate {
+    public LimitedDate(int day, int month, int year) {
+        if (year < 2000 || year > 2127) {
+            throw new IllegalArgumentException("year must be within [2000..2127]");
+        }
+
+        if (month < 1 || month > 12) {
+            throw new IllegalArgumentException("month must be within [1..12]");
+        }
+
+        if (day < 1 || day > 31) {
+            throw new IllegalArgumentException("day must be within [1..31]");
+        }
+        this.day = day;
+        this.month = month;
+        this.year = year;
+    }
+
+    private final int day, month, year;
+
+    @Override
+    public String toString() {
+        return String.format("%02d.%02d.%04d", day, month, year);
+    }
+
+    /*
+     * the structure (sadly java does not support unsigned integers):
+     * | octet 1 .| octet 2. |
+     * | 01234567 | 89abcdef |
+     * | Yyyyyyym | mmmddddd |
+     */
+    public short toSillyDatestamp() {
+        int yr = year - 2000;
+        return (short) ((yr << 9) | (month << 5) | (day));
+    }
+
+    public static LimitedDate fromSillyDatestamp(short datestamp) {
+        int day = datestamp & 0x1f;
+        int month = (datestamp >> 5) & 0xf;
+        int year = (datestamp >> 9) & 0x7f;
+        return new LimitedDate(day, month, year + 2000);
+    }
+}

dev/meowmeow/LimitedDateSpan.java

@@ -0,0 +1,44 @@
+/*
+ * TASK 5
+ * archived at https://git.femboy.science/femsci/ppj/src/branch/task/5
+ * by femsci
+ */
+
+package dev.meowmeow;
+
+public class LimitedDateSpan {
+    
+    // we still don't account for the transitions and abominable human-made
+    // exceptions
+    public LimitedDateSpan(LimitedDate from, LimitedDate to) {
+        this(from.toSillyDatestamp(), to.toSillyDatestamp());
+    }
+
+    LimitedDateSpan(short rawFrom, short rawTo) {
+        this((rawFrom << 16) | Short.toUnsignedInt(rawTo));
+    }
+
+    LimitedDateSpan(int raw) {
+        this.serializedData = raw;
+    }
+
+    // let's pretend that we need some weird optimization scheme, despite GC being
+    // finally smart enough
+
+    private final int serializedData;
+
+    public LimitedDate dateFrom() {
+        return LimitedDate.fromSillyDatestamp((short) ((serializedData >> 16) & 0xffff));
+    }
+
+    public LimitedDate dateTo() {
+        return LimitedDate.fromSillyDatestamp((short) (serializedData & 0xffff));
+    }
+
+    int rawSpan() {
+        return serializedData;
+    }
+
+    // span calc methods etc...
+    // years(), days()...
+}