feat: lazy evaluation of and, or, &, | (#3101, #3090)

* If fn has rawArgs set, pass unevaluated args * Add shared helper function for evaluating truthiness * Add and & or transform functions for lazy evaluation * Add lazy evaluation of bitwise & and | operators * Add unit tests for lazy evaluation * Add lazy evaluation note to docs * Move documentation to Syntax page * Replace `testCondition()` with test evaluation of logical function itself * Use `isCollection()` to simplify bitwise transform functions * fix: do not copy scope in raw OperatorNode, test lazy operators scope * fix: linting issues --------- Co-authored-by: Brooks Smith <[email protected]>
josdejong · Dec 8, 2023 · 7e9ff61 · 7e9ff61
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diff --git a/docs/expressions/syntax.md b/docs/expressions/syntax.md
@@ -121,18 +121,25 @@ See section below                 | Implicit multiplication
 `to`, `in`                        | Unit conversion
 `<<`, `>>`, `>>>`                 | Bitwise left shift, bitwise right arithmetic shift, bitwise right logical shift
 `==`, `!=`, `<`, `>`, `<=`, `>=`  | Relational
-`&`                               | Bitwise and
+`&`                               | Bitwise and (lazily evaluated)
 <code>^&#124;</code>              | Bitwise xor
-<code>&#124;</code>               | Bitwise or
-`and`                             | Logical and
+<code>&#124;</code>               | Bitwise or (lazily evaluated)
+`and`                             | Logical and (lazily evaluated)
 `xor`                             | Logical xor
-`or`                              | Logical or
+`or`                              | Logical or (lazily evaluated)
 `?`, `:`                          | Conditional expression
 `=`                               | Assignment
 `,`                               | Parameter and column separator
 `;`                               | Row separator
 `\n`, `;`                         | Statement separators
 
+Lazy evaluation is used where logically possible for bitwise and logical
+operators. In the following example, the value of `x` will not even be 
+evaluated because it cannot effect the final result: 
+```js
+math.evaluate('false and x')        // false, no matter what x equals
+```
+
 
 ## Functions
 

diff --git a/src/expression/node/OperatorNode.js b/src/expression/node/OperatorNode.js
@@ -304,7 +304,14 @@ export const createOperatorNode = /* #__PURE__ */ factory(name, dependencies, ({
         return arg._compile(math, argNames)
       })
 
-      if (evalArgs.length === 1) {
+      if (typeof fn === 'function' && fn.rawArgs === true) {
+        // pass unevaluated parameters (nodes) to the function
+        // "raw" evaluation
+        const rawArgs = this.args
+        return function evalOperatorNode (scope, args, context) {
+          return fn(rawArgs, math, scope)
+        }
+      } else if (evalArgs.length === 1) {
         const evalArg0 = evalArgs[0]
         return function evalOperatorNode (scope, args, context) {
           return fn(evalArg0(scope, args, context))

diff --git a/src/expression/transform/and.transform.js b/src/expression/transform/and.transform.js
@@ -0,0 +1,23 @@
+import { createAnd } from '../../function/logical/and.js'
+import { factory } from '../../utils/factory.js'
+import { isCollection } from '../../utils/is.js'
+
+const name = 'and'
+const dependencies = ['typed', 'matrix', 'zeros', 'add', 'equalScalar', 'not', 'concat']
+
+export const createAndTransform = /* #__PURE__ */ factory(name, dependencies, ({ typed, matrix, equalScalar, zeros, not, concat }) => {
+  const and = createAnd({ typed, matrix, equalScalar, zeros, not, concat })
+
+  function andTransform (args, math, scope) {
+    const condition1 = args[0].compile().evaluate(scope)
+    if (!isCollection(condition1) && !and(condition1, true)) {
+      return false
+    }
+    const condition2 = args[1].compile().evaluate(scope)
+    return and(condition1, condition2)
+  }
+
+  andTransform.rawArgs = true
+
+  return andTransform
+}, { isTransformFunction: true })
diff --git a/src/expression/transform/bitAnd.transform.js b/src/expression/transform/bitAnd.transform.js
@@ -0,0 +1,28 @@
+import { createBitAnd } from '../../function/bitwise/bitAnd.js'
+import { factory } from '../../utils/factory.js'
+import { isCollection } from '../../utils/is.js'
+
+const name = 'bitAnd'
+const dependencies = ['typed', 'matrix', 'zeros', 'add', 'equalScalar', 'not', 'concat']
+
+export const createBitAndTransform = /* #__PURE__ */ factory(name, dependencies, ({ typed, matrix, equalScalar, zeros, not, concat }) => {
+  const bitAnd = createBitAnd({ typed, matrix, equalScalar, zeros, not, concat })
+
+  function bitAndTransform (args, math, scope) {
+    const condition1 = args[0].compile().evaluate(scope)
+    if (!isCollection(condition1)) {
+      if (isNaN(condition1)) {
+        return NaN
+      }
+      if (condition1 === 0 || condition1 === false) {
+        return 0
+      }
+    }
+    const condition2 = args[1].compile().evaluate(scope)
+    return bitAnd(condition1, condition2)
+  }
+
+  bitAndTransform.rawArgs = true
+
+  return bitAndTransform
+}, { isTransformFunction: true })
diff --git a/src/expression/transform/bitOr.transform.js b/src/expression/transform/bitOr.transform.js
@@ -0,0 +1,31 @@
+import { createBitOr } from '../../function/bitwise/bitOr.js'
+import { factory } from '../../utils/factory.js'
+import { isCollection } from '../../utils/is.js'
+
+const name = 'bitOr'
+const dependencies = ['typed', 'matrix', 'equalScalar', 'DenseMatrix', 'concat']
+
+export const createBitOrTransform = /* #__PURE__ */ factory(name, dependencies, ({ typed, matrix, equalScalar, DenseMatrix, concat }) => {
+  const bitOr = createBitOr({ typed, matrix, equalScalar, DenseMatrix, concat })
+
+  function bitOrTransform (args, math, scope) {
+    const condition1 = args[0].compile().evaluate(scope)
+    if (!isCollection(condition1)) {
+      if (isNaN(condition1)) {
+        return NaN
+      }
+      if (condition1 === (-1)) {
+        return -1
+      }
+      if (condition1 === true) {
+        return 1
+      }
+    }
+    const condition2 = args[1].compile().evaluate(scope)
+    return bitOr(condition1, condition2)
+  }
+
+  bitOrTransform.rawArgs = true
+
+  return bitOrTransform
+}, { isTransformFunction: true })
diff --git a/src/expression/transform/or.transform.js b/src/expression/transform/or.transform.js
@@ -0,0 +1,23 @@
+import { createOr } from '../../function/logical/or.js'
+import { factory } from '../../utils/factory.js'
+import { isCollection } from '../../utils/is.js'
+
+const name = 'or'
+const dependencies = ['typed', 'matrix', 'equalScalar', 'DenseMatrix', 'concat']
+
+export const createOrTransform = /* #__PURE__ */ factory(name, dependencies, ({ typed, matrix, equalScalar, DenseMatrix, concat }) => {
+  const or = createOr({ typed, matrix, equalScalar, DenseMatrix, concat })
+
+  function orTransform (args, math, scope) {
+    const condition1 = args[0].compile().evaluate(scope)
+    if (!isCollection(condition1) && or(condition1, false)) {
+      return true
+    }
+    const condition2 = args[1].compile().evaluate(scope)
+    return or(condition1, condition2)
+  }
+
+  orTransform.rawArgs = true
+
+  return orTransform
+}, { isTransformFunction: true })
diff --git a/src/factoriesAny.js b/src/factoriesAny.js
@@ -359,3 +359,7 @@ export { createQuantileSeqTransform } from './expression/transform/quantileSeq.t
 export { createCumSumTransform } from './expression/transform/cumsum.transform.js'
 export { createVarianceTransform } from './expression/transform/variance.transform.js'
 export { createPrintTransform } from './expression/transform/print.transform.js'
+export { createAndTransform } from './expression/transform/and.transform.js'
+export { createOrTransform } from './expression/transform/or.transform.js'
+export { createBitAndTransform } from './expression/transform/bitAnd.transform.js'
+export { createBitOrTransform } from './expression/transform/bitOr.transform.js'
diff --git a/test/unit-tests/expression/parse.test.js b/test/unit-tests/expression/parse.test.js
@@ -1465,6 +1465,16 @@ describe('parse', function () {
       assert.strictEqual(parseAndEval('true & false'), 0)
       assert.strictEqual(parseAndEval('false & true'), 0)
       assert.strictEqual(parseAndEval('false & false'), 0)
+
+      assert.strictEqual(parseAndEval('0 & undefined'), 0)
+      assert.strictEqual(parseAndEval('false & undefined'), 0)
+      assert.throws(function () { parseAndEval('true & undefined') }, TypeError)
+    })
+
+    it('should parse bitwise and & lazily', function () {
+      const scope = {}
+      parseAndEval('(a=false) & (b=true)', scope)
+      assert.deepStrictEqual(scope, { a: false })
     })
 
     it('should parse bitwise xor ^|', function () {
@@ -1483,6 +1493,16 @@ describe('parse', function () {
       assert.strictEqual(parseAndEval('true | false'), 1)
       assert.strictEqual(parseAndEval('false | true'), 1)
       assert.strictEqual(parseAndEval('false | false'), 0)
+
+      assert.strictEqual(parseAndEval('-1 | undefined'), -1)
+      assert.strictEqual(parseAndEval('true | undefined'), 1)
+      assert.throws(function () { parseAndEval('false | undefined') }, TypeError)
+    })
+
+    it('should parse bitwise or | lazily', function () {
+      const scope = {}
+      parseAndEval('(a=true) | (b=true)', scope)
+      assert.deepStrictEqual(scope, { a: true })
     })
 
     it('should parse bitwise left shift <<', function () {
@@ -1506,6 +1526,16 @@ describe('parse', function () {
       assert.strictEqual(parseAndEval('true and false'), false)
       assert.strictEqual(parseAndEval('false and true'), false)
       assert.strictEqual(parseAndEval('false and false'), false)
+
+      assert.strictEqual(parseAndEval('0 and undefined'), false)
+      assert.strictEqual(parseAndEval('false and undefined'), false)
+      assert.throws(function () { parseAndEval('true and undefined') }, TypeError)
+    })
+
+    it('should parse logical and lazily', function () {
+      const scope = {}
+      parseAndEval('(a=false) and (b=true)', scope)
+      assert.deepStrictEqual(scope, { a: false })
     })
 
     it('should parse logical xor', function () {
@@ -1524,6 +1554,16 @@ describe('parse', function () {
       assert.strictEqual(parseAndEval('true or false'), true)
       assert.strictEqual(parseAndEval('false or true'), true)
       assert.strictEqual(parseAndEval('false or false'), false)
+
+      assert.strictEqual(parseAndEval('2 or undefined'), true)
+      assert.strictEqual(parseAndEval('true or undefined'), true)
+      assert.throws(function () { parseAndEval('false or undefined') }, TypeError)
+    })
+
+    it('should parse logical or lazily', function () {
+      const scope = {}
+      parseAndEval('(a=true) or (b=true)', scope)
+      assert.deepStrictEqual(scope, { a: true })
     })
 
     it('should parse logical not', function () {