#39 skipping last commas in JSON

Author: ppaska

package.json

@@ -1,6 +1,6 @@
 {
   "name": "jspython-interpreter",
-  "version": "2.1.14",
+  "version": "2.1.15",
   "description": "JSPython is a javascript implementation of Python language that runs within web browser or NodeJS environment",
   "keywords": [
     "python",

src/interpreter.spec.ts

@@ -132,6 +132,12 @@ describe('Interpreter', () => {
     expect(e.eval("x = {['m'+1]: 1+2*3}\nx.m1")).toBe(7);
   });
 
+  it('json ignore last comma', () => {
+    expect(JSON.stringify(e.eval('[{a:1,}, {a:2},]'))).toBe(JSON.stringify([{ a: 1, }, { a: 2 },]));
+  });
+
+  [{ a: 1 }, { a: 2 }];
+
   it('json with dynamic key', () => {
     expect(e.eval("p = 'prop'\nx = {[p + '_'+1]: 1+2*3}\nx.prop_1")).toBe(7);
     expect(e.eval("p = {x:'prop'}\nx = {[p.x + '_'+1]: 1+2*3}\nx.prop_1")).toBe(7);
@@ -296,7 +302,6 @@ describe('Interpreter', () => {
     expect(e.eval(script, {}, ['times', 2, 3])).toBe(6);
   });
 
-
   it('long comments issue', () => {
     const script = `
     async def f2():
@@ -988,7 +993,7 @@ describe('Interpreter', () => {
     `;
     expect(await interpreter.evalAsync(script)).toBe(11);
     expect(interpreter.eval(script)).toBe(11);
-  });  
+  });
 
   //
 });

src/interpreter.ts

@@ -221,7 +221,7 @@ export class Interpreter {
     return scripts.indexOf(`def ${funcName}`) > -1;
   }
 
-  private assignImportContext(
+  assignImportContext(
     ast: AstBlock,
     context: Record<string, unknown>
   ): Record<string, unknown> {

src/interpreter.v1.spec.ts

@@ -1384,13 +1384,13 @@ describe('Interpreter', () => {
   it('JSON parsing last comma error', async () => {
     let x = '';
     try {
-      await e.evaluate(`[[12, 42],`);
+      await e.evaluate(`[[12, 42],]`);
       x = 'NO ERROR';
     } catch (error) {
       x = 'ERROR';
     }
 
-    expect(x).toBe('ERROR');
+    expect(x).toBe('NO ERROR');
 
     x = '';
     try {
@@ -1401,7 +1401,7 @@ describe('Interpreter', () => {
     } catch (error) {
       x = 'ERROR';
     }
-    expect(x).toBe('ERROR');
+    expect(x).toBe('NO ERROR');
 
     x = '';
     try {

src/parser/parser.ts

@@ -204,22 +204,24 @@ export class Parser {
           instructions.length > i + 1 &&
           getTokenValue(instructions[i + 1].tokens[0]) === 'elif'
         ) {
-
           const elifInstruction = instructions[++i];
 
           const endOfElif = findTokenValueIndex(elifInstruction.tokens, v => v === ':');
 
           const conditionTokens = elifInstruction.tokens.slice(1, endDefOfDef);
 
-          const elifConditionNode = findIndexes(conditionTokens, OperationTypes.Logical, logicOpIndexes)
+          const elifConditionNode = findIndexes(
+            conditionTokens,
+            OperationTypes.Logical,
+            logicOpIndexes
+          )
             ? this.groupLogicalOperations(logicOpIndexes, conditionTokens)
             : this.createExpressionNode(conditionTokens);
-  
-          const elifBody = getBody(elifInstruction.tokens, endOfElif+1);
+
+          const elifBody = getBody(elifInstruction.tokens, endOfElif + 1);
           elifNodes.push(
             new ElifNode(elifConditionNode, elifBody, getTokenLoc(elifInstruction.tokens[0]))
           );
-          
         }
 
         // else
@@ -690,6 +692,9 @@ export class Parser {
       const keyValueTokens = splitTokens(tokens.splice(1, tokens.length - 2), ',');
       const props = [] as ObjectPropertyInfo[];
       for (let i = 0; i < keyValueTokens.length; i++) {
+        if (!keyValueTokens[i].length) {
+          continue;
+        }
         const keyValue = splitTokens(keyValueTokens[i], ':');
         if (keyValue.length === 1) {
           const pInfo = {
@@ -731,9 +736,9 @@ export class Parser {
 
     // create Array Node
     if (getTokenValue(tokens[0]) === '[' && getTokenValue(tokens[tokens.length - 1]) === ']') {
-      const items = splitTokens(tokens.splice(1, tokens.length - 2), ',').map(tkns =>
-        this.createExpressionNode(tkns)
-      );
+      const items = splitTokens(tokens.splice(1, tokens.length - 2), ',')
+        .filter(tkns => tkns?.length)
+        .map(tkns => this.createExpressionNode(tkns));
 
       return new CreateArrayNode(items, getTokenLoc(tokens[0]));
     }