Fix: Don't treat the tab trigger as part of $TM_SELECTED_TEXT

Author: savetheclocktower

lib/snippet-expansion.js

@@ -1,7 +1,7 @@
 const {CompositeDisposable, Range, Point} = require('atom')
 
 module.exports = class SnippetExpansion {
-  constructor (snippet, editor, cursor, snippets) {
+  constructor (snippet, editor, cursor, snippets, {method} = {}) {
     this.settingTabStop = false
     this.isIgnoringBufferChanges = false
     this.onUndoOrRedo = this.onUndoOrRedo.bind(this)
@@ -12,6 +12,11 @@ module.exports = class SnippetExpansion {
     this.subscriptions = new CompositeDisposable
     this.selections = [this.cursor.selection]
 
+    // Method refers to how the snippet was invoked; known values are `prefix`
+    // or `command`. If neither is present, then snippet was inserted
+    // programmatically.
+    this.method = method
+
     // Holds the `Insertion` instance corresponding to each tab stop marker. We
     // don't use the tab stop's own numbering here; we renumber them
     // consecutively starting at 0 in the order in which they should be
@@ -191,7 +196,8 @@ module.exports = class SnippetExpansion {
     let params = {
       editor: this.editor,
       cursor: this.cursor,
-      selectionRange: this.cursor.selection.getBufferRange()
+      selectionRange: this.cursor.selection.getBufferRange(),
+      method: this.method
     }
 
     for (const variable of this.snippet.variables) {

lib/snippets.js

@@ -760,6 +760,7 @@ module.exports = {
     }
   },
 
+  // Expands a snippet invoked via command.
   expandSnippet (editor, snippet) {
     this.getStore(editor).observeHistory({
       undo: event => { this.onUndoOrRedo(editor, event, true) },
@@ -771,11 +772,13 @@ module.exports = {
     editor.transact(() => {
       const cursors = editor.getCursors()
       for (const cursor of cursors) {
-        this.insert(snippet, editor, cursor)
+        this.insert(snippet, editor, cursor, {method: 'command'})
       }
     })
   },
 
+  // Expands a snippet defined via tab trigger _if_ such a snippet can be found
+  // for the current prefix and scope.
   expandSnippetsUnderCursors (editor) {
     const snippet = this.snippetToExpandUnderCursor(editor)
     if (!snippet) { return false }
@@ -789,10 +792,12 @@ module.exports = {
     editor.transact(() => {
       const cursors = editor.getCursors()
       for (const cursor of cursors) {
+        // Select the prefix text so that it gets consumed when the snippet
+        // expands.
         const cursorPosition = cursor.getBufferPosition()
         const startPoint = cursorPosition.translate([0, -snippet.prefix.length], [0, 0])
         cursor.selection.setBufferRange([startPoint, cursorPosition])
-        this.insert(snippet, editor, cursor)
+        this.insert(snippet, editor, cursor, {method: 'prefix'})
       }
     })
     return true
@@ -884,14 +889,14 @@ module.exports = {
     this.getStore(editor).makeCheckpoint()
   },
 
-  insert (snippet, editor, cursor) {
+  insert (snippet, editor, cursor, {method = null} = {}) {
     if (editor == null) { editor = atom.workspace.getActiveTextEditor() }
     if (cursor == null) { cursor = editor.getLastCursor() }
     if (typeof snippet === 'string') {
       const bodyTree = this.getBodyParser().parse(snippet)
       snippet = new Snippet({id: this.snippetIdCounter++, name: '__anonymous', prefix: '', bodyTree, bodyText: snippet})
     }
-    return new SnippetExpansion(snippet, editor, cursor, this)
+    return new SnippetExpansion(snippet, editor, cursor, this, {method})
   },
 
   getUnparsedSnippets () {

lib/variable.js

@@ -24,7 +24,14 @@ function makeDateResolver (dateParams) {
 const RESOLVERS = {
   // All the TM_-prefixed variables are part of the LSP specification for
   // snippets.
-  'TM_SELECTED_TEXT' ({editor, selectionRange}) {
+  'TM_SELECTED_TEXT' ({editor, selectionRange, method}) {
+    // When a snippet is inserted via tab trigger, the trigger is
+    // programmatically selected prior to snippet expansion so that it is
+    // consumed when the snippet body is inserted. The trigger _should not_ be
+    // treated as selected text. There is no way for $TM_SELECTED_TEXT to
+    // contain anything when a snippet is invoked via tab trigger.
+    if (method === 'prefix') return ''
+
     if (!selectionRange || selectionRange.isEmpty()) return ''
     return editor.getTextInBufferRange(selectionRange)
   },

spec/snippets-spec.js

@@ -1534,7 +1534,8 @@ foo\
           ".source.js": {
             "Uses TM_SELECTED_TEXT": {
               body: 'lorem ipsum $TM_SELECTED_TEXT dolor sit amet',
-              command: 'test-command-tm-selected-text'
+              command: 'test-command-tm-selected-text',
+              prefix: 'tmSelectedText'
             },
             "Uses CLIPBOARD": {
               body: 'lorem ipsum $CLIPBOARD dolor sit amet',
@@ -1599,6 +1600,13 @@ foo\
       expect(editor.getText()).toBe('lorem ipsum (selected text) dolor sit amet');
     });
 
+    it("does not consider the tab trigger to be part of $TM_SELECTED_TEXT when a snippet is invoked via tab trigger", () => {
+      editor.insertText('tmSelectedText');
+      simulateTabKeyEvent();
+
+      expect(editor.getText()).toBe('lorem ipsum  dolor sit amet');
+    });
+
     it("interpolates line number variables correctly", () => {
       editor.insertText('ln');
       simulateTabKeyEvent();