added While loop

Author: ppaska

index.html

@@ -30,9 +30,11 @@
     <h4>JSPython development console</h4>
     <div id="editor">
       sum = 0
-      
-      for item in [1,2,3]:
-        sum = sum + item
+      i = 0
+
+      while i<1000:
+        sum = sum + i
+        i = i + 1
 
       sum
 
@@ -94,7 +96,11 @@ <h4>JSPython development console</h4>
       try {
         const scope = {
           Math,
-          print: (p1, p2) => { return p1; },
+          dateTime: () => new Date(),
+          print: (p1, p2) => { 
+            console.log(p1);
+            return p1; 
+          },
           x: 10,
           o: {
             f1: (x, y) => { return { x, y }; },

src/common/ast-types.ts

@@ -9,7 +9,7 @@ export abstract class AstNode {
             | 'getSingleVar' | 'setSingleVar' | 'dotObjectAccess' | 'bracketObjectAccess'
             | 'funcCall' | 'funcDef' | 'arrowFuncDef'
             | 'createObject' | 'createArray'
-            | 'if' | 'for' | 'tryCatch'
+            | 'if' | 'for' | 'while'
             | 'return' | 'continue' | 'break'
     ) { }
 }
@@ -88,6 +88,12 @@ export class ForNode extends AstNode {
     }
 }
 
+export class WhileNode extends AstNode {
+    constructor(public condition: AstNode, public body: AstNode[]) {
+        super('while');
+    }
+}
+
 export class GetSingleVarNode extends AstNode {
     name: string;
     nullCoelsing: boolean | undefined = undefined;

src/evaluator/evaluator.ts

@@ -1,7 +1,7 @@
 import {
     ArrowFuncDefNode,
     AssignNode, AstBlock, AstNode, BinOpNode, BracketObjectAccessNode, ConstNode, CreateArrayNode,
-    CreateObjectNode, DotObjectAccessNode, ForNode, FunctionCallNode, FunctionDefNode, GetSingleVarNode, IfNode, OperationFuncs, Primitive, SetSingleVarNode
+    CreateObjectNode, DotObjectAccessNode, ForNode, FunctionCallNode, FunctionDefNode, GetSingleVarNode, IfNode, OperationFuncs, Primitive, SetSingleVarNode, WhileNode
 } from '../common';
 import { Scope } from './scope';
 
@@ -110,6 +110,16 @@ export class Evaluator {
             return;
         }
 
+        if (node.type === 'while') {
+            const forNode = node as WhileNode;
+            const newScope = scope;
+
+            while(this.evalNode(forNode.condition, newScope)){
+                this.evalBlock({ body: forNode.body } as AstBlock, newScope);
+            }
+
+            return;
+        }
 
         if (node.type === "const") {
             return (node as ConstNode).value;

src/interpreter.spec.ts

@@ -209,7 +209,7 @@ describe('Interpreter', () => {
 
 
   it('if condition', () => {
-    const script = (p: ) => `
+    const script = (p: number) => `
     x = 1
     if x == ${p}:
       x = 5
@@ -240,5 +240,18 @@ describe('Interpreter', () => {
     expect(e.evaluate(script)).toBe(6);
   });
 
+  it('simple while', () => {
+    const script = `
+    sum = 0
+    i = 0
+    
+    while i < 5:
+        sum = sum + i
+        i = i + 1
+
+    sum
+    `; 
+    expect(e.evaluate(script)).toBe(10);
+  });
 
 });

src/parser/parser.ts

@@ -2,7 +2,7 @@ import {
     BinOpNode, ConstNode, AstBlock, Token, ParserOptions, AstNode, Operators, AssignNode, TokenTypes,
     GetSingleVarNode, FunctionCallNode, getTokenType, getTokenValue, isTokenTypeLiteral, getStartLine,
     getStartColumn, getEndColumn, getEndLine, findOperators, splitTokens, DotObjectAccessNode, BracketObjectAccessNode,
-    findTokenValueIndex, FunctionDefNode, CreateObjectNode, ObjectPropertyInfo, CreateArrayNode, ArrowFuncDefNode, ExpressionOperators, IfNode, ForNode
+    findTokenValueIndex, FunctionDefNode, CreateObjectNode, ObjectPropertyInfo, CreateArrayNode, ArrowFuncDefNode, ExpressionOperators, IfNode, ForNode, WhileNode
 } from '../common';
 
 export class InstructionLine {
@@ -125,6 +125,19 @@ export class Parser {
 
                 ast.body.push(new ForNode(sourceArray, itemVarName, forBody))
 
+            } else if (getTokenValue(instruction.tokens[0]) === 'while') {
+
+                const endDefOfDef = findTokenValueIndex(instruction.tokens, v => v === ':');
+
+                if (endDefOfDef === -1) {
+                    throw (`Can't find : for [while]`)
+                }
+
+                const condition = this.createExpressionNode(instruction.tokens.slice(1, endDefOfDef))
+                const body = getBody(instruction.tokens, endDefOfDef + 1);
+
+                ast.body.push(new WhileNode(condition, body))
+
             } else if (assignTokens.length > 1) {
                 const target = this.createExpressionNode(assignTokens[0]);
                 const source = this.createExpressionNode(assignTokens[1]);