Feat: Add Support for NaN and Infinity

Author: kavishsathia

Diff for: src/tracer/__tests__/tracer_debug.ts

@@ -109,9 +109,10 @@ function h(f, x) {
 })
 
 
+// TODO: Check for -Infinity
 test('general', () => {
   const code = `
-  3 % 0;
+  -NaN;
   `
   const program = parse(code, { ecmaVersion: 10 })!
   const steps = getSteps(convert(program), { stepLimit: 200 })

Diff for: src/tracer/generator.ts

@@ -51,7 +51,15 @@ const nodeConverters: { [Key: string]: (node: any) => StepperBaseNode } = {
   Program: (node: es.Program) => StepperProgram.create(node),
   VariableDeclaration: (node: es.VariableDeclaration) => StepperVariableDeclaration.create(node),
   VariableDeclarator: (node: es.VariableDeclarator) => StepperVariableDeclarator.create(node),
-  Identifier: (node: es.Identifier) => StepperIdentifier.create(node),
+  Identifier: (node: es.Identifier) => {
+    if (node.name === 'NaN') {
+      return new StepperLiteral(NaN, 'NaN');
+    } else if (node.name === 'Infinity') {
+      return new StepperLiteral(Infinity, 'Infinity');
+    } else {
+      return StepperIdentifier.create(node);
+    }
+  },
   BlockStatement: (node: es.BlockStatement) => StepperBlockStatement.create(node),
   IfStatement: (node: es.IfStatement) => StepperIfStatement.create(node)
 }

Diff for: src/tracer/nodes/Expression/BinaryExpression.ts

@@ -59,14 +59,6 @@ export class StepperBinaryExpression implements BinaryExpression, StepperBaseNod
       }
       return ret
     } else if (left_type === 'number' && right_type === 'number') {
-      if (this.operator === '/' && this.right.value === 0) {
-        throw new Error('Division by zero');
-      }
-
-      if (this.operator === '%' && this.right.value === 0) {
-        throw new Error('Modulo by zero');
-      }
-
       const ret =
         ['*', '+', '/', '-', '===', '!==', '<', '>', '<=', '>=', '%'].includes(this.operator as string)
       if (ret) {
@@ -120,7 +112,7 @@ export class StepperBinaryExpression implements BinaryExpression, StepperBaseNod
         ? left! >= right!
         : left! > right!
 
-    let ret = new StepperLiteral(value)
+    let ret = new StepperLiteral(value, value !== null ? value.toString() : "null")
     redex.postRedex = [ret]
     return ret
   }

Diff for: src/tracer/nodes/Expression/UnaryExpression.ts

@@ -95,7 +95,7 @@ export class StepperUnaryExpression implements UnaryExpression, StepperBaseNode
       redex.postRedex = [ret]
       return ret
     } else if (this.operator === '-') {
-      const ret = new StepperLiteral(-(operand as number))
+      const ret = new StepperLiteral(-(operand as number), (-(operand as number)).toString())
       redex.postRedex = [ret]
       return ret
     }