From 2105b120655e6c694cc78ba8caa1d56ab71877d1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Pit-Claudel?= <clement.pitclaudel@live.com>
Date: Fri, 27 Aug 2021 03:02:19 -0400
Subject: [PATCH] pygments: Strip error tokens from output of provers other
 than Coq

---
 alectryon/pygments.py | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/alectryon/pygments.py b/alectryon/pygments.py
index f8689379..8beff5f3 100644
--- a/alectryon/pygments.py
+++ b/alectryon/pygments.py
@@ -30,7 +30,7 @@
 import pygments
 import pygments.styles
 import pygments.formatters
-from pygments.token import Error, STANDARD_TYPES, Name, Operator
+from pygments.token import Error, STANDARD_TYPES, Name, Operator, Text
 from pygments.filters import Filter, TokenMergeFilter, NameHighlightFilter
 from pygments.formatter import Formatter
 from pygments.lexers import get_lexer_by_name # pylint: disable=no-name-in-module
@@ -58,6 +58,7 @@ def get_lexer(lang):
         lexer.add_filter(WarnOnErrorTokenFilter())
     else:
         lexer = get_lexer_by_name(lang, ensurenl=False)
+        lexer.add_filter(StripErrorsTokenFilter())
     lexer.add_filter(TokenMergeFilter())
     return lexer
 
@@ -236,6 +237,15 @@ def filter(self, _lexer, stream):
                 warnings.warn(MSG.format(val, indent(context, ' ' * 8)))
             yield typ, val
 
+class StripErrorsTokenFilter(Filter):
+    """Change ``Error`` tokens to ``Text`` ones."""
+
+    def filter(self, _lexer, stream):
+        for typ, val in stream:
+            if typ is Error:
+                typ = Text
+            yield typ, val
+
 def replace_builtin_coq_lexer():
     """Monkey-patch pygments to replace the built-in Coq Lexer.