From 7ef304d90151985ea9b1aa5569fba99c42350040 Mon Sep 17 00:00:00 2001
From: Kamila Szewczyk <kspalaiologos@gmail.com>
Date: Sat, 12 Nov 2022 23:43:59 +0100
Subject: [PATCH] spaceship operator. 10'000 lines of code!

---
 .../kamilalisp/runtime/FunctionRegistry.java  |  4 +-
 .../kamilalisp/runtime/math/cmp/Neq.java      |  2 +-
 .../runtime/math/cmp/Spaceship.java           | 45 +++++++++++++++++++
 3 files changed, 49 insertions(+), 2 deletions(-)
 create mode 100644 src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Spaceship.java

diff --git a/src/main/java/palaiologos/kamilalisp/runtime/FunctionRegistry.java b/src/main/java/palaiologos/kamilalisp/runtime/FunctionRegistry.java
index bea592e31..4e43a43b5 100644
--- a/src/main/java/palaiologos/kamilalisp/runtime/FunctionRegistry.java
+++ b/src/main/java/palaiologos/kamilalisp/runtime/FunctionRegistry.java
@@ -41,7 +41,7 @@ public class FunctionRegistry {
             "n-prod", "Π", "unique-mask", "unique", "intersection", "union", "bernoulli", "regex-matches?",
             "date:from", "date:time-from", "date:add", "date:difference", "date:hours",
             "date:minutes", "date:seconds", "date:nanoseconds", "date:years", "date:months",
-            "date:days", "date:to-list", "time:day-of-week", "⍣"
+            "date:days", "date:to-list", "time:day-of-week", "⍣", "<=>", "⇔"
     );
 
     public static void registerDefault(Environment env) {
@@ -207,6 +207,8 @@ public static void registerDefault(Environment env) {
         env.set("*", new Atom(new Star()));
         env.set("/", new Atom(new Slash()));
         env.set("mod", new Atom(new Mod()));
+        env.set("<=>", new Atom(new Spaceship()));
+        env.set("⇔", new Atom(new Spaceship()));
 
         env.set("regex:matches?", new Atom(new RegexMatches()));
 
diff --git a/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Neq.java b/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Neq.java
index 59d9a9af7..01a61f7c9 100644
--- a/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Neq.java
+++ b/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Neq.java
@@ -7,7 +7,7 @@
 import java.util.List;
 
 public class Neq extends PrimitiveFunction implements Lambda {
-    private static final String name = "!=";
+    private static final String name = "/=";
 
     @Override
     protected String name() {
diff --git a/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Spaceship.java b/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Spaceship.java
new file mode 100644
index 000000000..55ae7460a
--- /dev/null
+++ b/src/main/java/palaiologos/kamilalisp/runtime/math/cmp/Spaceship.java
@@ -0,0 +1,45 @@
+package palaiologos.kamilalisp.runtime.math.cmp;
+
+import com.google.common.collect.Streams;
+import palaiologos.kamilalisp.atom.*;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.List;
+
+public class Spaceship extends PrimitiveFunction implements Lambda {
+    private static final String name = "<=>";
+
+    @Override
+    protected String name() {
+        return name;
+    }
+
+    private static Atom cmp2(Environment e, Atom a, Atom b) {
+        if (a.getType() == Type.REAL && b.getType() == Type.REAL) {
+            return new Atom(BigInteger.valueOf(a.getReal().compareTo(b.getReal())));
+        } else if (a.getType() == Type.REAL && b.getType() == Type.INTEGER) {
+            return new Atom(BigInteger.valueOf(a.getReal().compareTo(new BigDecimal(b.getInteger()))));
+        } else if (a.getType() == Type.INTEGER && b.getType() == Type.REAL) {
+            return new Atom(BigInteger.valueOf(new BigDecimal(a.getInteger()).compareTo(b.getReal())));
+        } else if (a.getType() == Type.INTEGER && b.getType() == Type.INTEGER) {
+            return new Atom(BigInteger.valueOf(a.getInteger().compareTo(b.getInteger())));
+        } else if (a.getType() == Type.STRING && b.getType() == Type.STRING) {
+            return new Atom(BigInteger.valueOf(a.getString().compareTo(b.getString())));
+        } else if (a.getType() == Type.LIST && (b.getType() == Type.REAL || b.getType() == Type.INTEGER || b.getType() == Type.STRING)) {
+            return new Atom(a.getList().stream().map(x -> cmp2(e, x, b)).toList());
+        } else if ((a.getType() == Type.REAL || a.getType() == Type.INTEGER || a.getType() == Type.STRING) && b.getType() == Type.LIST) {
+            return new Atom(b.getList().stream().map(x -> cmp2(e, a, x)).toList());
+        } else if (a.getType() == Type.LIST && b.getType() == Type.LIST) {
+            return new Atom(Streams.zip(a.getList().stream(), b.getList().stream(), (x, y) -> cmp2(e, x, y)).toList());
+        } else {
+            throw new UnsupportedOperationException(name + " not defined for: " + a.getType() + " and " + b.getType());
+        }
+    }
+
+    @Override
+    public Atom apply(Environment env, List<Atom> args) {
+        assertArity(args, 2);
+        return cmp2(env, args.get(0), args.get(1));
+    }
+}