add support for optional chaining (#412)

Co-authored-by: sanex3339 <yarabotayuvyandex3339>

Author: sanex3339

escodegen.js

@@ -99,11 +99,12 @@
         Await: 14,
         Unary: 14,
         Postfix: 15,
-        Call: 16,
-        New: 17,
-        TaggedTemplate: 18,
-        Member: 19,
-        Primary: 20
+        OptionalChaining: 16,
+        Call: 17,
+        New: 18,
+        TaggedTemplate: 19,
+        Member: 20,
+        Primary: 21
     };
 
     BinaryPrecedence = {
@@ -1880,8 +1881,14 @@
 
         CallExpression: function (expr, precedence, flags) {
             var result, i, iz;
+
             // F_ALLOW_UNPARATH_NEW becomes false.
             result = [this.generateExpression(expr.callee, Precedence.Call, E_TTF)];
+
+            if (expr.optional) {
+                result.push('?.');
+            }
+
             result.push('(');
             for (i = 0, iz = expr['arguments'].length; i < iz; ++i) {
                 result.push(this.generateExpression(expr['arguments'][i], Precedence.Assignment, E_TTT));
@@ -1894,9 +1901,20 @@
             if (!(flags & F_ALLOW_CALL)) {
                 return ['(', result, ')'];
             }
+
             return parenthesize(result, Precedence.Call, precedence);
         },
 
+        ChainExpression: function (expr, precedence, flags) {
+            if (Precedence.OptionalChaining < precedence) {
+                flags |= F_ALLOW_CALL;
+            }
+
+            var result = this.generateExpression(expr.expression, Precedence.OptionalChaining, flags);
+
+            return parenthesize(result, Precedence.OptionalChaining, precedence);
+        },
+
         NewExpression: function (expr, precedence, flags) {
             var result, length, i, iz, itemFlags;
             length = expr['arguments'].length;
@@ -1931,11 +1949,15 @@
             result = [this.generateExpression(expr.object, Precedence.Call, (flags & F_ALLOW_CALL) ? E_TTF : E_TFF)];
 
             if (expr.computed) {
+                if (expr.optional) {
+                    result.push('?.');
+                }
+
                 result.push('[');
                 result.push(this.generateExpression(expr.property, Precedence.Sequence, flags & F_ALLOW_CALL ? E_TTT : E_TFT));
                 result.push(']');
             } else {
-                if (expr.object.type === Syntax.Literal && typeof expr.object.value === 'number') {
+                if (!expr.optional && expr.object.type === Syntax.Literal && typeof expr.object.value === 'number') {
                     fragment = toSourceNodeWhenNeeded(result).toString();
                     // When the following conditions are all true,
                     //   1. No floating point
@@ -1952,7 +1974,7 @@
                         result.push(' ');
                     }
                 }
-                result.push('.');
+                result.push(expr.optional ? '?.' : '.');
                 result.push(generateIdentifier(expr.property));
             }
 
@@ -2466,8 +2488,7 @@
                 this.generateExpression(expr.source, Precedence.Assignment, E_TTT),
                 ')'
             ], Precedence.Call, precedence);
-        },
-
+        }
     };
 
     merge(CodeGenerator.prototype, CodeGenerator.Expression);

package.json

@@ -30,7 +30,7 @@
         "url": "http://github.com/estools/escodegen.git"
     },
     "dependencies": {
-        "estraverse": "^4.2.0",
+        "estraverse": "^5.2.0",
         "esutils": "^2.0.2",
         "esprima": "^4.0.1",
         "optionator": "^0.8.1"
@@ -42,7 +42,8 @@
         "acorn": "^8.0.1",
         "bluebird": "^3.4.7",
         "bower-registry-client": "^1.0.0",
-        "chai": "^3.5.0",
+        "chai": "^4.2.0",
+        "chai-exclude": "^2.0.2",
         "commonjs-everywhere": "^0.9.7",
         "gulp": "^3.8.10",
         "gulp-eslint": "^3.0.1",

test/compare-acorn-es2020.js

@@ -28,16 +28,16 @@ var fs = require('fs'),
     acorn = require('acorn'),
     escodegen = require('./loader'),
     chai = require('chai'),
+    chaiExclude = require('chai-exclude'),
     expect = chai.expect;
 
-function test(code, expected) {
-    var tree, actual, options, StringObject;
+chai.use(chaiExclude);
 
-    // alias, so that JSLint does not complain.
-    StringObject = String;
+function test(code, expected) {
+    var tree, actual, actualTree, options;
 
     options = {
-        ranges: true,
+        ranges: false,
         locations: false,
         ecmaVersion: 11,
         sourceType: 'module'
@@ -46,18 +46,18 @@ function test(code, expected) {
     tree = acorn.parse(code, options);
 
     // for UNIX text comment
-    actual = escodegen.generate(tree).replace(/[\n\r]$/, '') + '\n';
+    actual = escodegen.generate(tree);
+    actualTree = acorn.parse(actual, options);
+
     expect(actual).to.be.equal(expected);
+    expect(tree).excludingEvery(['start', 'end']).to.deep.equal(actualTree);
 }
 
 function testMin(code, expected) {
-    var tree, actual, options, StringObject;
-
-    // alias, so that JSLint does not complain.
-    StringObject = String;
+    var tree, actual, actualTree, options;
 
     options = {
-        ranges: true,
+        ranges: false,
         locations: false,
         ecmaVersion: 11,
         sourceType: 'module'
@@ -70,7 +70,10 @@ function testMin(code, expected) {
         format: escodegen.FORMAT_MINIFY,
         raw: false
     }).replace(/[\n\r]$/, '') + '\n';
+    actualTree = acorn.parse(actual, options);
+
     expect(actual).to.be.equal(expected);
+    expect(tree).excludingEvery(['start', 'end']).to.deep.equal(actualTree);
 }
 
 describe('compare acorn es2020 test', function () {
@@ -91,4 +94,4 @@ describe('compare acorn es2020 test', function () {
         }
     });
 });
-/* vim: set sw=4 ts=4 et tw=80 : */
+/* vim: set sw=4 ts=4 et tw=80 : */

test/compare-acorn-es2020/optional-chaining.expected.js

@@ -0,0 +1,47 @@
+obj.aaa.bbb;
+obj.aaa?.bbb;
+obj?.aaa.bbb;
+obj?.aaa?.bbb;
+obj.aaa.bbb;
+obj.aaa?.bbb;
+(obj?.aaa).bbb;
+(obj?.aaa)?.bbb;
+(obj?.aaa).bbb.ccc.ddd;
+((obj?.aaa).bbb?.ccc).ddd;
+(obj?.aaa)?.bbb;
+obj[aaa][bbb];
+obj[aaa]?.[bbb];
+obj?.[aaa][bbb];
+obj?.[aaa]?.[bbb];
+obj[aaa][bbb];
+obj[aaa]?.[bbb];
+(obj?.[aaa])[bbb];
+(obj?.[aaa])?.[bbb];
+obj[aaa][bbb][ccc][ddd];
+((obj?.[aaa])[bbb]?.[ccc])[ddd];
+1?.a;
+obj()();
+obj()?.();
+obj?.()();
+obj?.()?.();
+obj()();
+obj()?.();
+(obj?.())();
+(obj?.())?.();
+obj()()()();
+((obj?.())()?.())();
+(a?.b)();
+a?.b();
+a?.b?.();
+(a?.b)?.();
+a?.().b;
+(a?.()).b;
+a?.b.c();
+(a?.b.c)();
+a.b?.().c;
+(a.b?.()).c;
+(a.b?.())?.c;
+new (a?.b().c)();
+new (a?.b())();
+new (a?.b().c)();
+new (a?.b())();

test/compare-acorn-es2020/optional-chaining.expected.min.js

@@ -0,0 +1 @@
+obj.aaa.bbb;obj.aaa?.bbb;obj?.aaa.bbb;obj?.aaa?.bbb;obj.aaa.bbb;obj.aaa?.bbb;(obj?.aaa).bbb;(obj?.aaa)?.bbb;(obj?.aaa).bbb.ccc.ddd;((obj?.aaa).bbb?.ccc).ddd;(obj?.aaa)?.bbb;obj[aaa][bbb];obj[aaa]?.[bbb];obj?.[aaa][bbb];obj?.[aaa]?.[bbb];obj[aaa][bbb];obj[aaa]?.[bbb];(obj?.[aaa])[bbb];(obj?.[aaa])?.[bbb];obj[aaa][bbb][ccc][ddd];((obj?.[aaa])[bbb]?.[ccc])[ddd];1?.a;obj()();obj()?.();obj?.()();obj?.()?.();obj()();obj()?.();(obj?.())();(obj?.())?.();obj()()()();((obj?.())()?.())();(a?.b)();a?.b();a?.b?.();(a?.b)?.();a?.().b;(a?.()).b;a?.b.c();(a?.b.c)();a.b?.().c;(a.b?.()).c;(a.b?.())?.c;new(a?.b().c);new(a?.b());new(a?.b().c);new(a?.b())

test/compare-acorn-es2020/optional-chaining.js

@@ -0,0 +1,47 @@
+obj.aaa.bbb;
+obj.aaa?.bbb;
+obj?.aaa.bbb;
+obj?.aaa?.bbb;
+(obj.aaa).bbb;
+(obj.aaa)?.bbb;
+(obj?.aaa).bbb;
+(obj?.aaa)?.bbb;
+((obj?.aaa).bbb.ccc).ddd;
+((obj?.aaa).bbb?.ccc).ddd;
+(obj?.aaa)?.bbb;
+obj[aaa][bbb];
+obj[aaa]?.[bbb];
+obj?.[aaa][bbb];
+obj?.[aaa]?.[bbb];
+(obj[aaa])[bbb];
+(obj[aaa])?.[bbb];
+(obj?.[aaa])[bbb];
+(obj?.[aaa])?.[bbb];
+((obj[aaa])[bbb][ccc])[ddd];
+((obj?.[aaa])[bbb]?.[ccc])[ddd];
+1?.a;
+obj()();
+obj()?.();
+obj?.()();
+obj?.()?.();
+(obj())();
+(obj())?.();
+(obj?.())();
+(obj?.())?.();
+((obj())()())();
+((obj?.())()?.())();
+(a?.b)();
+a?.b();
+a?.b?.();
+(a?.b)?.();
+a?.().b;
+(a?.()).b;
+a?.b.c();
+(a?.b.c)();
+a.b?.().c;
+(a.b?.()).c;
+(a.b?.())?.c;
+new (a?.b().c);
+new (a?.b());
+new (a?.b().c)();
+new (a?.b())();