Call validation directly so its synchronous

We are calling the internals of the vscode library but its the only
way to keep it synchronous.

Fixes #20

.npmignore

@@ -1,3 +1,4 @@
 .npmignore
 .travis.yml
 test
+.vscode

lib/index.js

@@ -10,45 +10,113 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-var jsonService = require("vscode-json-languageservice")
+var jsonService = require("vscode-json-languageservice");
 
 var jsonServiceHandle = jsonService.getLanguageService({});
 jsonServiceHandle.configure({
     "validate": true,
     "allowComments": false
-})
+});
 
 //------------------------------------------------------------------------------
 // Plugin Definition
 //------------------------------------------------------------------------------
 
+var ErrorCode = {
+    Undefined: 0,
+    EnumValueMismatch: 1,
+    UnexpectedEndOfComment: 0x101,
+    UnexpectedEndOfString: 0x102,
+    UnexpectedEndOfNumber: 0x103,
+    InvalidUnicode: 0x104,
+    InvalidEscapeCharacter: 0x105,
+    InvalidCharacter: 0x106,
+    PropertyExpected: 0x201,
+    CommaExpected: 0x202,
+    ColonExpected: 0x203,
+    ValueExpected: 0x204,
+    CommaOrCloseBacketExpected: 0x205,
+    CommaOrCloseBraceExpected: 0x206,
+    TrailingComma: 0x207,
+    DuplicateKey: 0x208,
+    CommentNotPermitted: 0x209,
+    SchemaResolveError: 0x300
+};
+
+var fileContents = {};
+var fileDocuments = {};
+
+function toDiagnosticSeverity(severityLevel) {
+    switch (severityLevel) {
+    case "error": return 1;
+    case "warning": return 2;
+    case "ignore": return 0;
+    }
+    return 0;
+}
+
+function makeDiagnostic(c, message, severity, errorCode) {
+    return {
+        range: c,
+        message: message,
+        severity: severity,
+        code: errorCode
+    };
+}
+
+var getDiagnostics = function(textDocument, jsonDocument) {
+    var diagnostics = [];
+    var added  = {};
+    var addProblem = function(problem) {
+        // remove duplicated messages
+        var signature = problem.range.start.line + " " + problem.range.start.character + " " + problem.message;
+        if (!added[signature]) {
+            added[signature] = true;
+            diagnostics.push(problem);
+        }
+    };
+    var trailingCommaSeverity = 1; // ERROR
+    var commentSeverity = 1; // ERROR 
 
-let fileContents = {};
-let fileDocuments = {}
+    jsonDocument.syntaxErrors.forEach(function(p) {
+        if (p.code === ErrorCode.TrailingComma) {
+            if (typeof commentSeverity !== "number") {
+                return;
+            }
+            p.severity = trailingCommaSeverity;
+        }
+        addProblem(p);
+    });
+
+    if (typeof commentSeverity === "number") {
+        var message = "InvalidCommentToken: Comments are not permitted in JSON.";
+        jsonDocument.comments.forEach(function(c) {
+            addProblem(makeDiagnostic(c, message, commentSeverity, ErrorCode.CommentNotPermitted));
+        });
+    }
+    return diagnostics;
+};
 
 // import processors
 module.exports.processors = {
     // add your processors here
     ".json": {
         preprocess: function(text, fileName) {
-            let textDocument = jsonService.TextDocument.create(fileName, "json", 1, text)
-            let parsed = jsonServiceHandle.parseJSONDocument(textDocument)
-            let responsePromise = jsonServiceHandle.doValidation(textDocument, parsed)
-            responsePromise.then(response => {
-                fileContents[fileName] = response;
-                fileDocuments[fileName] = textDocument
-            });
+            var textDocument = jsonService.TextDocument.create(fileName, "json", 1, text);
+            var parsed = jsonServiceHandle.parseJSONDocument(textDocument);
+            fileContents[fileName] = getDiagnostics(textDocument, parsed);
+            fileDocuments[fileName] = textDocument;
             return [text];
         },
         postprocess: function(messages, fileName) {
-            let errors = fileContents[fileName]
+            var errors = fileContents[fileName];
             if (errors === undefined) {
-                return []
+                return [];
             }
-            let textDocument = fileDocuments[fileName]
+            var textDocument = fileDocuments[fileName];
             delete fileContents[fileName];
-            delete fileDocuments[fileName]
-            return errors.map((error) => {
+            delete fileDocuments[fileName];
+            var formattedErrors = errors.map(function(error) {
                 return {
                     ruleId: error.code,
                     severity: (error.severity == 1) ? 2 : 1,
@@ -58,8 +126,9 @@ module.exports.processors = {
                     endLine: error.range.end.line + 1,
                     endColumn: error.range.end.character + 1,
                     source: textDocument.getText(error.range)
-                }
-            })
+                };
+            });
+            return formattedErrors;
         }
     }
 };

package.json

@@ -1,6 +1,6 @@
 {
   "name": "eslint-plugin-json",
-  "version": "1.2.1",
+  "version": "1.3.1",
   "description": "Lint JSON files",
   "keywords": [
     "eslint",