Fix performance issue with ProgressBar formatters

Signed-off-by: Alessandro Salvatori <[email protected]>

src/prompt_toolkit/shortcuts/progress_bar/formatters.py

@@ -130,15 +130,15 @@ class Percentage(Formatter):
     Display the progress as a percentage.
     """
 
-    template = "<percentage>{percentage:>5}%</percentage>"
+    template = HTML("<percentage>{percentage:>5}%</percentage>")
 
     def format(
         self,
         progress_bar: ProgressBar,
         progress: ProgressBarCounter[object],
         width: int,
     ) -> AnyFormattedText:
-        return HTML(self.template).format(percentage=round(progress.percentage, 1))
+        return self.template.format(percentage=round(progress.percentage, 1))
 
     def get_width(self, progress_bar: ProgressBar) -> AnyDimension:
         return D.exact(6)
@@ -149,7 +149,7 @@ class Bar(Formatter):
     Display the progress bar itself.
     """
 
-    template = "<bar>{start}<bar-a>{bar_a}</bar-a><bar-b>{bar_b}</bar-b><bar-c>{bar_c}</bar-c>{end}</bar>"
+    template = HTML("<bar>{start}<bar-a>{bar_a}</bar-a><bar-b>{bar_b}</bar-b><bar-c>{bar_c}</bar-c>{end}</bar>")
 
     def __init__(
         self,
@@ -202,7 +202,7 @@ def format(
         bar_b = sym_b
         bar_c = sym_c * (width - pb_a)
 
-        return HTML(self.template).format(
+        return self.template.format(
             start=self.start, end=self.end, bar_a=bar_a, bar_b=bar_b, bar_c=bar_c
         )
 
@@ -215,15 +215,15 @@ class Progress(Formatter):
     Display the progress as text.  E.g. "8/20"
     """
 
-    template = "<current>{current:>3}</current>/<total>{total:>3}</total>"
+    template = HTML("<current>{current:>3}</current>/<total>{total:>3}</total>")
 
     def format(
         self,
         progress_bar: ProgressBar,
         progress: ProgressBarCounter[object],
         width: int,
     ) -> AnyFormattedText:
-        return HTML(self.template).format(
+        return self.template.format(
             current=progress.items_completed, total=progress.total or "?"
         )
 
@@ -250,14 +250,16 @@ class TimeElapsed(Formatter):
     Display the elapsed time.
     """
 
+    template = HTML("<time-elapsed>{time_elapsed}</time-elapsed>")
+
     def format(
         self,
         progress_bar: ProgressBar,
         progress: ProgressBarCounter[object],
         width: int,
     ) -> AnyFormattedText:
         text = _format_timedelta(progress.time_elapsed).rjust(width)
-        return HTML("<time-elapsed>{time_elapsed}</time-elapsed>").format(
+        return self.template.format(
             time_elapsed=text
         )
 
@@ -275,7 +277,7 @@ class TimeLeft(Formatter):
     Display the time left.
     """
 
-    template = "<time-left>{time_left}</time-left>"
+    template = HTML("<time-left>{time_left}</time-left>")
     unknown = "?:??:??"
 
     def format(
@@ -290,7 +292,7 @@ def format(
         else:
             formatted_time_left = self.unknown
 
-        return HTML(self.template).format(time_left=formatted_time_left.rjust(width))
+        return self.template.format(time_left=formatted_time_left.rjust(width))
 
     def get_width(self, progress_bar: ProgressBar) -> AnyDimension:
         all_values = [
@@ -307,7 +309,7 @@ class IterationsPerSecond(Formatter):
     Display the iterations per second.
     """
 
-    template = (
+    template = HTML(
         "<iterations-per-second>{iterations_per_second:.2f}</iterations-per-second>"
     )
 
@@ -318,7 +320,7 @@ def format(
         width: int,
     ) -> AnyFormattedText:
         value = progress.items_completed / progress.time_elapsed.total_seconds()
-        return HTML(self.template.format(iterations_per_second=value))
+        return self.template.format(iterations_per_second=value)
 
     def get_width(self, progress_bar: ProgressBar) -> AnyDimension:
         all_values = [
@@ -335,6 +337,7 @@ class SpinningWheel(Formatter):
     Display a spinning wheel.
     """
 
+    template = HTML("<spinning-wheel>{0}</spinning-wheel>")
     characters = r"/-\|"
 
     def format(
@@ -344,7 +347,7 @@ def format(
         width: int,
     ) -> AnyFormattedText:
         index = int(time.time() * 3) % len(self.characters)
-        return HTML("<spinning-wheel>{0}</spinning-wheel>").format(
+        return self.template.format(
             self.characters[index]
         )