Optional chaining

[LivingInSyn]

Hi All,

This PR is a port of the following PR from the main esprima project:

jquery/esprima#2048

I've hit a bit of a wall when running unit tests getting the added optional parameter to get serialized when toDict is called. Any help you can provide to fix that and get this merged would be great!

[LivingInSyn]

An example is:

test/fixtures/declaration/function/migrated_0006.js

The expected output has this in the output:

esprima-python/test/fixtures/declaration/function/migrated_0006.tree.json

Line 70 in 2e108bf

"optional": false,

Where the actual just doesn't have optional as a member of the CallExpression object:

"expression": {
              "arguments": [],
              "callee": {
                "loc": {
                  "end": {
                    "column": 25,
                    "line": 1
                  },
                  "start": {
                    "column": 20,
                    "line": 1
                  }
                },
                "name": "sayHi",
                "range": [
                  20,
                  25
                ],
                "type": "Identifier"
              },
              "loc": {
                "end": {
                  "column": 27,
                  "line": 1
                },
                "start": {
                  "column": 20,
                  "line": 1
                }
              },
              "optional": false,
              "range": [
                20,
                27
              ],
              "type": "CallExpression"
            }
            

[LivingInSyn]

Update: I was using the pip installed version while running tests

Removed unsupported tests. I plan on pulling in the following PRs in the near future:

jquery/esprima#1190
jquery/esprima#2032
jquery/esprima#2039

Only two problems left to fix

[LivingInSyn]

@Kronuz : spent a bit more time but I'm not sure how to where the last errors are coming from. On test/fixtures/expression/primary/literal/regular-expression/u-flag-surrogate-pair.js I get

"init": {
            "loc": {
              "end": {
                "column": 41, 
                "line": 1
              }, 
              "start": {
                "column": 8, 
                "line": 1
              }
            }, 
            "range": [
              8, 
              41
            ], 
            "raw": "/[\\uD834\\uDF06-\\uD834\\uDF08a-z]/u", 
            "regex": {
              "flags": "u", 
              "pattern": "[\\uD834\\uDF06-\\uD834\\uDF08a-z]"
            }, 
            "type": "Literal", 
            "value": {}
          }

I'm not sure where "value": {} is coming from given the changes made for this feature.

Any help you can provide would be appreciated

[djn3m0]

Any idea when this is going to be done and merged?

[LivingInSyn]

@djn3m0 I dropped this work since I changed positions, sorry. IIRC we changed from esprima-python to using https://github.com/eslint/espree directly