refactor: Remove Math.nextUp call in QueryConstants (deephaven#5747)

Math.nextUp is not presently usable in GWT, so this patch lets the JS API share QueryConstants and ensures that the MIN_FINITE values are correct, without actually initializing them via a call to Math.nextUp. Partial deephaven#188 Co-authored-by: Ryan Caudy <rcaudy@gmail.com>
rcaudy · Jul 11, 2024 · 2e835ce · 2e835ce
1 parent b1feeeb
commit 2e835ce
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Showing 3 changed files with 49 additions and 2 deletions.
diff --git a/engine/query-constants/build.gradle b/engine/query-constants/build.gradle
@@ -2,3 +2,7 @@ plugins {
     id 'java-library'
     id 'io.deephaven.project.register'
 }
+
+dependencies {
+    testImplementation libs.junit4
+}
diff --git a/engine/query-constants/src/main/java/io/deephaven/util/QueryConstants.java b/engine/query-constants/src/main/java/io/deephaven/util/QueryConstants.java
@@ -187,7 +187,13 @@ private QueryConstants() {}
     /**
      * Minimum finite value of type float.
      */
-    public static final float MIN_FINITE_FLOAT = Math.nextUp(-Float.MAX_VALUE);
+    /*
+     * Implemented as a constant so that it can be translated correctly to JS without needing a proper {@code
+     * Math.nextUp()} or {@code Math.nextAfter()} implementation that works in JavaScript. Value is generated by running
+     * {@code Float.toHexString(Math.nextUp(-Float.MAX_VALUE))} in jshell, and tests validate that this matches the
+     * expected expression.
+     */
+    public static final float MIN_FINITE_FLOAT = -0x1.fffffcp127f;
 
     /**
      * Maximum finite value of type float.
@@ -241,7 +247,13 @@ private QueryConstants() {}
     /**
      * Minimum finite value of type double.
      */
-    public static final double MIN_FINITE_DOUBLE = Math.nextUp(-Double.MAX_VALUE);
+    /*
+     * Implemented as a constant so that it can be translated correctly to JS without needing a proper {@code
+     * Math.nextUp()} or {@code Math.nextAfter()} implementation that works in JavaScript. Value is generated by running
+     * {@code Double.toHexString(Math.nextUp(-Double.MAX_VALUE))} in jshell, and tests validate that this matches the
+     * expected expression.
+     */
+    public static final double MIN_FINITE_DOUBLE = -0x1.ffffffffffffep1023;
 
     /**
      * Maximum finite value of type double.

diff --git a/engine/query-constants/src/test/java/io/deephaven/util/QueryConstantsTest.java b/engine/query-constants/src/test/java/io/deephaven/util/QueryConstantsTest.java
@@ -0,0 +1,31 @@
+//
+// Copyright (c) 2016-2024 Deephaven Data Labs and Patent Pending
+//
+package io.deephaven.util;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class QueryConstantsTest {
+
+    @Test
+    public void testMinFiniteFloat() {
+        final float calculated = Math.nextUp(-Float.MAX_VALUE);
+        // noinspection SimplifiableAssertion
+        assertTrue(calculated == QueryConstants.MIN_FINITE_FLOAT);
+        assertEquals(
+                Float.floatToIntBits(calculated),
+                Float.floatToIntBits(QueryConstants.MIN_FINITE_FLOAT));
+    }
+
+    @Test
+    public void testMinFiniteDouble() {
+        final double calculated = Math.nextUp(-Double.MAX_VALUE);
+        // noinspection SimplifiableAssertion
+        assertTrue(calculated == QueryConstants.MIN_FINITE_DOUBLE);
+        assertEquals(
+                Double.doubleToLongBits(calculated),
+                Double.doubleToLongBits(QueryConstants.MIN_FINITE_DOUBLE));
+    }
+}