lsp: Fix completions when editing existing item

Many completion snippets insert more than just the name. For example,
the object completer inserts the braces and places your cursor inside
them automatically, to save some typing. However, if you're changing the
class of an existing object, this isn't what you want. Changed so that
if the next token is '{', only the name is inserted.

Made similar changes to the property and signal completers.

blueprintcompiler/completions_utils.py

@@ -19,10 +19,21 @@
 
 
 import typing as T
+from dataclasses import dataclass
 
+from .ast_utils import AstNode
 from .lsp_utils import Completion
 from .tokenizer import Token, TokenType
 
+
+@dataclass
+class CompletionContext:
+    client_supports_completion_choice: bool
+    ast_node: AstNode
+    match_variables: T.List[str]
+    next_token: Token
+
+
 new_statement_patterns = [
     [(TokenType.PUNCTUATION, "{")],
     [(TokenType.PUNCTUATION, "}")],
@@ -32,8 +43,8 @@ new_statement_patterns = [
 
 
 def completer(applies_in: T.List, matches: T.List = [], applies_in_subclass=None):
-    def decorator(func):
-        def inner(prev_tokens: T.List[Token], ast_node, lsp):
+    def decorator(func: T.Callable[[CompletionContext], T.Generator[Completion]]):
+        def inner(prev_tokens: T.List[Token], next_token: Token, ast_node, lsp):
             # For completers that apply in ObjectContent nodes, we can further
             # check that the object is the right class
             if applies_in_subclass is not None:
@@ -66,7 +77,13 @@ def completer(applies_in: T.List, matches: T.List = [], applies_in_subclass=None
             if not any_match:
                 return
 
-            yield from func(lsp, ast_node, match_variables)
+            context = CompletionContext(
+                client_supports_completion_choice=lsp.client_supports_completion_choice,
+                ast_node=ast_node,
+                match_variables=match_variables,
+                next_token=next_token,
+            )
+            yield from func(context)
 
         for c in applies_in:
             c.completers.append(inner)