feat(palette): add fuzzy_match with subsequence matching and scoring

src/command_palette.py

@@ -5,42 +5,99 @@ from typing import Optional, Callable, List, Dict, Any
 
 @dataclass
 class Command:
-    id: str
-    title: str
-    category: str
-    shortcut: Optional[str] = None
-    description: str = ""
-    enabled_when: Optional[str] = None
-    action: Optional[Callable] = None
+ id: str
+ title: str
+ category: str
+ shortcut: Optional[str] = None
+ description: str = ""
+ enabled_when: Optional[str] = None
+ action: Optional[Callable] = None
 
 
 @dataclass
 class ScoredCommand:
-    command: Command
-    score: float
+ command: Command
+ score: float
 
 
 class CommandRegistry:
-    def __init__(self) -> None:
-        self._commands: Dict[str, Command] = {}
+ def __init__(self) -> None:
+  self._commands: Dict[str, Command] = {}
 
-    def register(self, command_or_callable: Any) -> Any:
-        if isinstance(command_or_callable, Command):
-            cmd = command_or_callable
-        else:
-            cmd = Command(
-                id=command_or_callable.__name__,
-                title=command_or_callable.__name__.replace("_", " ").title(),
-                category="uncategorized",
-                action=command_or_callable,
-            )
-        if cmd.id in self._commands:
-            raise ValueError(f"Command {cmd.id} already registered")
-        self._commands[cmd.id] = cmd
-        return command_or_callable
+ def register(self, command_or_callable: Any) -> Any:
+  if isinstance(command_or_callable, Command):
+   cmd = command_or_callable
+  else:
+   cmd = Command(
+    id=command_or_callable.__name__,
+    title=command_or_callable.__name__.replace("_", " ").title(),
+    category="uncategorized",
+    action=command_or_callable,
+   )
+  if cmd.id in self._commands:
+   raise ValueError(f"Command {cmd.id} already registered")
+  self._commands[cmd.id] = cmd
+  return command_or_callable
 
-    def all(self) -> List[Command]:
-        return list(self._commands.values())
+ def all(self) -> List[Command]:
+  return list(self._commands.values())
 
-    def get(self, command_id: str) -> Optional[Command]:
-        return self._commands.get(command_id)
+ def get(self, command_id: str) -> Optional[Command]:
+  return self._commands.get(command_id)
+
+
+def fuzzy_match(query: str, candidates: List[Command], top_n: int = 20) -> List[ScoredCommand]:
+ query_lower = query.lower()
+ scored: List[ScoredCommand] = []
+ for cmd in candidates:
+  title_lower = cmd.title.lower()
+  if not _is_subsequence(query_lower, title_lower):
+   continue
+  score = _compute_score(query_lower, title_lower)
+  scored.append(ScoredCommand(command=cmd, score=score))
+ scored.sort(key=lambda r: r.score, reverse=True)
+ return scored[:top_n]
+
+
+def _is_subsequence(query: str, target: str) -> bool:
+ qi = 0
+ for ch in target:
+  if qi < len(query) and ch == query[qi]:
+   qi += 1
+ return qi == len(query)
+
+
+def _compute_score(query: str, target: str) -> float:
+ score = 0.0
+ if target.startswith(query):
+  score += 1.0
+ elif _starts_at_word_boundary(query, target):
+  score += 0.5
+ if _is_contiguous(query, target):
+  score += 0.3
+ gaps = _count_gaps(query, target)
+ score -= 0.1 * gaps
+ return score
+
+
+def _starts_at_word_boundary(query: str, target: str) -> bool:
+ if not target.startswith(query):
+  return False
+ return len(query) == 0 or not query[0].isalnum() or len(target) == len(query) or not target[len(query)].isalnum()
+
+
+def _is_contiguous(query: str, target: str) -> bool:
+ return query in target
+
+
+def _count_gaps(query: str, target: str) -> int:
+ qi = 0
+ gaps = 0
+ last_match = -1
+ for ti, ch in enumerate(target):
+  if qi < len(query) and ch == query[qi]:
+   if last_match >= 0 and ti - last_match > 1:
+    gaps += ti - last_match - 1
+   last_match = ti
+   qi += 1
+ return gaps

tests/test_command_palette.py

@@ -0,0 +1,45 @@
+from src.command_palette import Command, ScoredCommand, fuzzy_match
+
+
+def _cmd(id: str, title: str) -> Command:
+ return Command(id=id, title=title, category="test")
+
+
+def test_fuzzy_match_prefix_ranks_first():
+ candidates = [
+  _cmd("find", "Find in Selection"),
+  _cmd("fold", "Fold All"),
+  _cmd("config", "Configure Settings"),
+ ]
+ results = fuzzy_match("fin", candidates, top_n=10)
+ assert len(results) > 0
+ assert results[0].command.id == "find"
+ assert results[0].score > 0.5
+
+
+def test_fuzzy_match_subsequence_match():
+ candidates = [_cmd("x", "Find")]
+ results = fuzzy_match("fd", candidates, top_n=10)
+ assert len(results) == 1
+ assert results[0].command.id == "x"
+
+
+def test_fuzzy_match_no_match_returns_empty():
+ candidates = [_cmd("x", "foo bar")]
+ results = fuzzy_match("xyz", candidates, top_n=10)
+ assert results == []
+
+
+def test_fuzzy_match_top_n_limits_results():
+ candidates = [_cmd(f"cmd_{i}", f"Command {i}") for i in range(50)]
+ results = fuzzy_match("cmd", candidates, top_n=10)
+ assert len(results) == 10
+
+
+def test_fuzzy_match_score_higher_for_exact_prefix():
+ candidates = [
+  _cmd("a", "find"),
+  _cmd("b", "Configure Find Settings"),
+ ]
+ results = fuzzy_match("fin", candidates, top_n=10)
+ assert results[0].command.id == "a"