HTML.format specifiers (#1566)

Add support for formatting parameters in HTML.format().

html_escape parameters after formatting, not before.

Co-authored-by: Tapple Fulmer <mfulmer@cisco.com>

Author: tapple

prompt_toolkit/formatted_text/html.py

@@ -1,4 +1,5 @@
 import xml.dom.minidom as minidom
+from string import Formatter
 from typing import Any, List, Tuple, Union
 
 from .base import FormattedText, StyleAndTextTuples
@@ -107,11 +108,7 @@ def format(self, *args: object, **kwargs: object) -> "HTML":
         Like `str.format`, but make sure that the arguments are properly
         escaped.
         """
-        # Escape all the arguments.
-        escaped_args = [html_escape(a) for a in args]
-        escaped_kwargs = {k: html_escape(v) for k, v in kwargs.items()}
-
-        return HTML(self.value.format(*escaped_args, **escaped_kwargs))
+        return HTML(FORMATTER.vformat(self.value, args, kwargs))
 
     def __mod__(self, value: Union[object, Tuple[object, ...]]) -> "HTML":
         """
@@ -124,6 +121,11 @@ def __mod__(self, value: Union[object, Tuple[object, ...]]) -> "HTML":
         return HTML(self.value % value)
 
 
+class HTMLFormatter(Formatter):
+    def format_field(self, value: object, format_spec: str) -> str:
+        return html_escape(format(value, format_spec))
+
+
 def html_escape(text: object) -> str:
     # The string interpolation functions also take integers and other types.
     # Convert to string first.
@@ -136,3 +138,6 @@ def html_escape(text: object) -> str:
         .replace(">", ">")
         .replace('"', """)
     )
+
+
+FORMATTER = HTMLFormatter()

tests/test_formatted_text.py

@@ -141,6 +141,9 @@ def test_html_interpolation():
     value = HTML("<b>{a}</b><u>{b}</u>").format(a="hello", b="world")
     assert to_formatted_text(value) == [("class:b", "hello"), ("class:u", "world")]
 
+    value = HTML("<b>{:02d}</b><u>{:.3f}</u>").format(3, 3.14159)
+    assert to_formatted_text(value) == [("class:b", "03"), ("class:u", "3.142")]
+
 
 def test_merge_formatted_text():
     html1 = HTML("<u>hello</u>")