Add TreeSitterLanguageMode.tokenForPosition

spec/tree-sitter-language-mode-spec.js

@@ -1360,6 +1360,14 @@ describe('TreeSitterLanguageMode', () => {
         'source.js',
         'property.name'
       ])
+
+      // Drive-by test for .tokenForPosition()
+      const token = editor.tokenForBufferPosition([0, 'foo({b'.length])
+      expect(token.value).toBe('bar')
+      expect(token.scopes).toEqual([
+        'source.js',
+        'property.name'
+      ])
     })
 
     it('includes nodes in injected syntax trees', async () => {

src/tree-sitter-language-mode.js

@@ -3,6 +3,7 @@ const {Point, Range, spliceArray} = require('text-buffer')
 const {Patch} = require('superstring')
 const {Emitter} = require('event-kit')
 const ScopeDescriptor = require('./scope-descriptor')
+const Token = require('./token')
 const TokenizedLine = require('./tokenized-line')
 const TextMateLanguageMode = require('./text-mate-language-mode')
 const {matcherForSelector} = require('./selectors')
@@ -435,6 +436,12 @@ class TreeSitterLanguageMode {
     return new ScopeDescriptor({scopes})
   }
 
+  tokenForPosition (point) {
+    const node = this.getSyntaxNodeAtPosition(point)
+    const scopes = this.scopeDescriptorForPosition(point).getScopesArray()
+    return new Token({value: node.text, scopes})
+  }
+
   getGrammar () {
     return this.grammar
   }