don't replace percent when it is not the first non-whitespace character

mako/lexer.py

@@ -247,6 +247,8 @@ def parse(self):
                 continue
             if self.match_python_block():
                 continue
+            if self.match_percent():
+                continue
             if self.match_text():
                 continue
 
@@ -352,18 +354,37 @@ def match_end(self):
         else:
             return True
 
+    def match_percent(self):
+        match = self.match(r"([^%]*?)%(%+)", re.S)
+        if match:
+            text = match.group(1)
+            if text:
+                self.append_node(parsetree.Text, text)
+                for char in text[::-1]:  # Look back, check wheither '%'
+                    #  is the first non-whitespace character in a line
+                    if char == "\n":
+                        break
+                    elif char in ("\t", " "):
+                        continue
+                    else:
+                        self.append_node(parsetree.Text, "%")
+                        break
+                self.append_node(parsetree.Text, match.group(2))
+            else:
+                self.append_node(parsetree.Text, "%")
+            return True
+        else:
+            return False
+
     def match_text(self):
         match = self.match(
             r"""
                 (.*?)         # anything, followed by:
                 (
-                 (?<=\n)(?=[ \t]*(?=%(?!%)|\#\#))  # an eval or line-based
+                 (?<=\n)(?=[ \t]*(?=%|\#\#))  # an eval or line-based
                                             # comment, preceded by a
                                             # consumed newline and whitespace
                  |
-                 (?<!%)(?=%%+) # consume the first percent sign
-                               # out of a group of percent signs
-                 |
                  (?=\${)      # an expression
                  |
                  (?=</?[%&])  # a substitution or block or call start or end

test/test_lexer.py

@@ -200,9 +200,11 @@ def test_percent_escape(self):
             TemplateNode(
                 {},
                 [
-                    Text("""\n\n""", (1, 1)),
-                    Text("""% some whatever.\n\n    """, (3, 2)),
-                    Text("% more some whatever\n", (5, 6)),
+                    Text("\n\n", (1, 1)),
+                    Text("%", (1, 1)),
+                    Text(" some whatever.\n\n    ", (3, 3)),
+                    Text("%", (3, 3)),
+                    Text(" more some whatever\n", (5, 7)),
                     ControlLine("if", "if foo:", False, (6, 1)),
                     ControlLine("if", "endif", True, (7, 1)),
                     Text("        ", (8, 1)),
@@ -222,11 +224,12 @@ def test_percent_escape2(self):
             TemplateNode(
                 {},
                 [
-                    Text("% do something\n", (1, 2)),
-                    Text(
-                        "%% do something\nif <some condition>:\n    ", (2, 2)
-                    ),
-                    Text("%%% do something\n        ", (4, 6)),
+                    Text("%", (1, 1)),
+                    Text(" do something\n", (1, 3)),
+                    Text("%%", (1, 3)),
+                    Text(" do something\nif <some condition>:\n    ", (2, 4)),
+                    Text("%%%", (2, 4)),
+                    Text(" do something\n        ", (4, 9)),
                 ],
             ),
         )
@@ -246,14 +249,63 @@ def test_percent_escape_with_control_block(self):
                     Text("\n", (1, 1)),
                     ControlLine("for", "for i in [1, 2, 3]:", False, (2, 1)),
                     Text("    ", (3, 1)),
-                    Text("% do something ", (3, 6)),
+                    Text("%", (3, 1)),
+                    Text(" do something ", (3, 7)),
                     Expression("i", [], (3, 21)),
                     Text("\n", (3, 25)),
                     ControlLine("for", "endfor", True, (4, 1)),
                 ],
             ),
         )
 
+    def test_inline_percent(self):
+        template = """
+%% foo
+bar %% baz
+"""
+        node = Lexer(template).parse()
+        self._compare(
+            node,
+            TemplateNode(
+                {},
+                [
+                    Text("\n", (1, 1)),
+                    Text("%", (1, 1)),
+                    Text(" foo\nbar ", (2, 3)),
+                    Text("%", (2, 3)),
+                    Text("%", (2, 3)),
+                    Text(" baz\n", (3, 7)),
+                ],
+            ),
+        )
+
+        def test_inline_percent_with_control_block(self):
+            template = """
+% for i in [1, 2, 3]:
+%% foo
+bar %% baz
+% endfor
+"""
+            node = Lexer(template).parse()
+            self._compare(
+                node,
+                TemplateNode(
+                    {},
+                    [
+                        Text("\n", (1, 1)),
+                        ControlLine(
+                            "for", "for i in [1, 2, 3]:", False, (2, 1)
+                        ),
+                        Text("%", (3, 1)),
+                        Text(" foo\nbar ", (3, 3)),
+                        Text("%", (3, 3)),
+                        Text("%", (3, 3)),
+                        Text(" baz\n", (4, 7)),
+                        ControlLine("for", "endfor", True, (5, 1)),
+                    ],
+                ),
+            )
+
     def test_old_multiline_comment(self):
         template = """#*"""
         node = Lexer(template).parse()

test/test_template.py

@@ -1699,3 +1699,21 @@ def test_percent_escape2(self):
             "    % do something 2",
             "    % do something 3",
         ]
+
+    def test_inline_percent(self):
+        t = Template(
+            """
+% for i in [1, 2, 3]:
+%% foo
+bar %% baz
+% endfor
+"""
+        )
+        assert result_raw_lines(t.render()) == [
+            "% foo",
+            "bar %% baz",
+            "% foo",
+            "bar %% baz",
+            "% foo",
+            "bar %% baz",
+        ]