✨ Add support for \middle

latex2mathml/commands.py

@@ -21,6 +21,7 @@
 DPRIME = r"\dprime"
 
 LEFT = r"\left"
+MIDDLE = r"\middle"
 RIGHT = r"\right"
 
 ABOVE = r"\above"
@@ -412,6 +413,7 @@ def font_factory(default: Optional[str], replacement: Dict[str, Optional[str]])
     **MSTYLE_SIZES,
     **{limit: ("mo", {}) for limit in LIMIT},
     LEFT: ("mo", OrderedDict([("stretchy", "true"), ("fence", "true"), ("form", "prefix")])),
+    MIDDLE: ("mo", OrderedDict([("stretchy", "true"), ("fence", "true"), ("lspace", "0.05em"), ("rspace", "0.05em")])),
     RIGHT: ("mo", OrderedDict([("stretchy", "true"), ("fence", "true"), ("form", "postfix")])),
     # styles
     COLOR: ("mstyle", {}),

latex2mathml/converter.py

@@ -261,7 +261,9 @@ def _convert_command(node: Node, parent: Element, font: Optional[Dict[str, Optio
         element.text = "mod"
         SubElement(parent, "mspace", width="0.333em")
     elif node.text is not None:
-        if command == commands.HBOX:
+        if command == commands.MIDDLE:
+            element.text = "&#x{};".format(convert_symbol(node.text))
+        elif command == commands.HBOX:
             mtext: Optional[Element] = element
             for text, mode in separate_by_mode(node.text):
                 if mode == Mode.TEXT:

latex2mathml/walker.py

@@ -43,7 +43,7 @@ def _walk(tokens: Iterator[str], terminator: str = None, limit: int = 0) -> List
                 delimiter = next(tokens)
             group.append(Node(token=token, delimiter=delimiter))
             break
-        elif token == commands.RIGHT != terminator:
+        elif (token == commands.RIGHT != terminator) or (token == commands.MIDDLE and terminator != commands.RIGHT):
             raise ExtraLeftOrMissingRightError
         elif token == commands.LEFT:
             delimiter = next(tokens)
@@ -132,6 +132,7 @@ def _walk(tokens: Iterator[str], terminator: str = None, limit: int = 0) -> List
             commands.FBOX,
             commands.HBOX,
             commands.MBOX,
+            commands.MIDDLE,
             commands.TEXT,
             commands.TEXTBF,
             commands.TEXTIT,

tests/test_converter.py

@@ -3792,6 +3792,28 @@
             ),
             id="pmod",
         ),
+        pytest.param(
+            r"\left\{\middle|\right\}",
+            {
+                "mrow": MultiDict(
+                    [
+                        ("mo", {"@stretchy": "true", "@fence": "true", "@form": "prefix", "$": "{"}),
+                        (
+                            "mo",
+                            {
+                                "@stretchy": "true",
+                                "@fence": "true",
+                                "@lspace": "0.05em",
+                                "@rspace": "0.05em",
+                                "$": "|",
+                            },
+                        ),
+                        ("mo", {"@stretchy": "true", "@fence": "true", "@form": "postfix", "$": "}"}),
+                    ]
+                )
+            },
+            id="middle",
+        ),
     ],
 )
 def test_converter(latex: str, json: MultiDict) -> None:

tests/test_walker.py

@@ -1681,6 +1681,7 @@ def test_walk(latex: str, expected: list) -> None:
     [
         pytest.param(r"\right)", ExtraLeftOrMissingRightError, id=r"missing-\left"),
         pytest.param(r"\left(x", ExtraLeftOrMissingRightError, id=r"missing-\right"),
+        pytest.param(r"\middle|", ExtraLeftOrMissingRightError, id=r"missing-\left"),
         pytest.param(r"{ \over 2}", NumeratorNotFoundError, id="fraction-without-numerator"),
         pytest.param(r"{1 \over }", DenominatorNotFoundError, id="fraction-without-denominator"),
         pytest.param(r"1_", MissingSuperScriptOrSubscriptError, id="missing-subscript"),