Fix parsing of strings with two slashes (#27)

Also, add more tests around strings

Author: bioball

grammar.js

@@ -59,6 +59,7 @@ module.exports = grammar({
   name: 'pkl',
 
   externals: $ => [
+    $._sl_string_chars,
     $._sl1_string_chars,
     $._sl2_string_chars,
     $._sl3_string_chars,
@@ -553,7 +554,7 @@ module.exports = grammar({
       ),
     ),
 
-    slStringLiteralPart: $ => token.immediate(/[^"\\\n\r]+/),
+    slStringLiteralPart: $ => $._sl_string_chars,
 
     slStringLiteralPart1: $ => $._sl1_string_chars,
 

src/grammar.json

@@ -2443,11 +2443,8 @@
       ]
     },
     "slStringLiteralPart": {
-      "type": "IMMEDIATE_TOKEN",
-      "content": {
-        "type": "PATTERN",
-        "value": "[^\"\\\\\\n\\r]+"
-      }
+      "type": "SYMBOL",
+      "name": "_sl_string_chars"
     },
     "slStringLiteralPart1": {
       "type": "SYMBOL",
@@ -3281,8 +3278,12 @@
               "name": "identifier"
             },
             {
-              "type": "STRING",
-              "value": "\n"
+              "type": "FIELD",
+              "name": "err",
+              "content": {
+                "type": "STRING",
+                "value": "\n"
+              }
             }
           ]
         }
@@ -4220,6 +4221,10 @@
   ],
   "precedences": [],
   "externals": [
+    {
+      "type": "SYMBOL",
+      "name": "_sl_string_chars"
+    },
     {
       "type": "SYMBOL",
       "name": "_sl1_string_chars"

src/node-types.json

@@ -4049,6 +4049,16 @@
     "type": "propertyCallExpr",
     "named": true,
     "fields": {
+      "err": {
+        "multiple": false,
+        "required": false,
+        "types": [
+          {
+            "type": "\n",
+            "named": false
+          }
+        ]
+      },
       "receiver": {
         "multiple": false,
         "required": true,