fix: build null validity predicates without dynamic code generation

src/builder/valid.ts

@@ -16,12 +16,11 @@
 // under the License.
 
 import { DataType } from '../type.js';
-import { valueToString } from '../util/pretty.js';
 
 /**
- * Dynamically compile the null values into an `isValid()` function whose
- * implementation is a switch statement. Microbenchmarks in v8 indicate
- * this approach is 25% faster than using an ES6 Map.
+ * Creates a validity predicate without compiling strings as JavaScript.
+ * A single null sentinel uses a direct comparison; multiple sentinels use a
+ * snapshot Set, including NaN and treating positive and negative zero equally.
  *
  * @example
  * console.log(createIsValidFunction([null, 'N/A', NaN]));
@@ -45,30 +44,12 @@ export function createIsValidFunction<T extends DataType = any, TNull = any>(nul
         return function isValid(value: any) { return true; };
     }
 
-    let fnBody = '';
-    const noNaNs = nullValues.filter((x) => x === x);
-
-    if (noNaNs.length > 0) {
-        fnBody = `
-    switch (x) {${noNaNs.map((x) => `
-        case ${valueToCase(x)}:`).join('')}
-            return false;
-    }`;
-    }
-
-    // NaN doesn't equal anything including itself, so it doesn't work as a
-    // switch case. Instead we must explicitly check for NaN before the switch.
-    if (nullValues.length !== noNaNs.length) {
-        fnBody = `if (x !== x) return false;\n${fnBody}`;
-    }
-
-    return new Function(`x`, `${fnBody}\nreturn true;`) as (value: T['TValue'] | TNull) => boolean;
-}
-
-/** @ignore */
-function valueToCase(x: any) {
-    if (typeof x !== 'bigint') {
-        return valueToString(x);
+    if (nullValues.length === 1) {
+        const nullValue = nullValues[0];
+        return nullValue !== nullValue
+            ? function isValid(value: T['TValue'] | TNull) { return value === value; }
+            : function isValid(value: T['TValue'] | TNull) { return value !== nullValue; };
     }
-    return `${valueToString(x)}n`;
+    const invalidValues = new Set<T['TValue'] | TNull>(nullValues);
+    return function isValid(value: T['TValue'] | TNull) { return !invalidValues.has(value); };
 }

test/unit/builders/valid-tests.ts

@@ -0,0 +1,62 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+import { createIsValidFunction } from 'apache-arrow/builder/valid';
+
+describe('Null sentinel validity predicates', () => {
+    test('empty sentinel lists accept every value, including NaN', () => {
+        for (const nullValues of [undefined, []]) {
+            const isValid = createIsValidFunction(nullValues);
+            expect([null, undefined, Number.NaN, 0, ''].every(value => isValid(value))).toBe(true);
+        }
+    });
+
+    test.each([null, undefined, Number.NaN, 0, false, '', 'quoted "text"\nwith\\slashes', 42n])(
+        'matches a single sentinel without coercion: %p', nullValue => {
+            const isValid = createIsValidFunction([nullValue]);
+            expect(isValid(nullValue)).toBe(false);
+            expect(isValid(Symbol('different'))).toBe(true);
+        }
+    );
+
+    test('multiple sentinels preserve NaN, zero and primitive type distinctions', () => {
+        const isValid = createIsValidFunction([null, undefined, Number.NaN, -0, 42n, '42', false]);
+        expect([null, undefined, Number.NaN, 0, -0, 42n, '42', false].map(value => isValid(value))).toEqual(new Array(8).fill(false));
+        expect([42, true, '', 'NaN', 1n].every(value => isValid(value))).toBe(true);
+    });
+
+    test('snapshots sentinel lists, including duplicate entries', () => {
+        const nullValues = ['missing', 'missing'];
+        const isValid = createIsValidFunction(nullValues);
+        nullValues.splice(0, 2, 'changed');
+        expect(isValid('missing')).toBe(false);
+        expect(isValid('changed')).toBe(true);
+    });
+
+    test('does not require the Function constructor permitted by unsafe-eval', () => {
+        const originalFunction = globalThis.Function;
+        let results: boolean[];
+        try {
+            globalThis.Function = (() => { throw new Error('Dynamic compilation blocked'); }) as unknown as FunctionConstructor;
+            const isValid = createIsValidFunction([null, 'quoted "text"\nwith\\slashes', Number.NaN]);
+            results = [null, Number.NaN, 'valid'].map(value => isValid(value));
+        } finally {
+            globalThis.Function = originalFunction;
+        }
+        expect(results!).toEqual([false, false, true]);
+    });
+});