Add GREATEST and LEAST functions (#399)

src/functions/index.ts

@@ -2,11 +2,13 @@ import { stringFunctions } from './string';
 import { dateFunctions } from './date';
 import { systemFunctions } from './system';
 import { sequenceFunctions } from './sequence-fns';
+import { numberFunctions } from './numbers';
 
 
 export const allFunctions = [
     ...stringFunctions
     , ... dateFunctions
     , ... systemFunctions
     , ... sequenceFunctions
+    , ... numberFunctions
 ]

src/functions/numbers.ts

@@ -0,0 +1,18 @@
+import { DataType, FunctionDefinition } from "../interfaces";
+
+export const numberFunctions: FunctionDefinition[] = [
+    {
+        name: 'greatest',
+        args: [DataType.integer],
+        argsVariadic: DataType.integer,
+        returns: DataType.integer,
+        implementation: (...args: number[]) => Math.max(...args),
+    },
+    {
+        name: 'least',
+        args: [DataType.integer],
+        argsVariadic: DataType.integer,
+        returns: DataType.integer,
+        implementation: (...args: number[]) => Math.min(...args),
+    },
+]

src/tests/function-calls.spec.ts

@@ -35,6 +35,26 @@ describe('Functions', () => {
             .to.deep.equal([{ concat: 'text-123-end' }]);
     });
 
+    it('GREATEST 2 arguments', () => {
+        expect(many(`select GREATEST(0, -1);`))
+            .to.deep.equal([{ greatest: 0 }]);
+    });
+
+    it('GREATEST 4 arguments', () => {
+        expect(many(`select GREATEST(3, 8, 10, 4);`))
+            .to.deep.equal([{ greatest: 10 }]);
+    });
+
+    it('LEAST 2 arguments', () => {
+        expect(many(`select LEAST(0, -1);`))
+            .to.deep.equal([{ least: -1 }]);
+    });
+
+    it('LEAST 4 arguments', () => {
+        expect(many(`select LEAST(3, 8, 1, 4);`))
+            .to.deep.equal([{ least: 1 }]);
+    });
+
     it('can declare & call function', () => {
         db.registerLanguage('mylang', ({ code, args, returns }) => {
             expect(code).to.equal('some code');