🐛 Fix prime combined with subscripts or superscripts

latex2mathml/walker.py

@@ -67,7 +67,11 @@ def _walk(tokens: Iterator[str], terminator: Optional[str] = None, limit: int =
 
             if token == previous.token == commands.SUBSCRIPT:
                 raise DoubleSubscriptsError
-            if token == previous.token == commands.SUPERSCRIPT:
+            if (token == previous.token == commands.SUPERSCRIPT) and (
+                previous.children is not None
+                and len(previous.children) >= 2
+                and previous.children[1].token != commands.PRIME
+            ):
                 raise DoubleSuperscriptsError
 
             modifier = None
@@ -92,6 +96,22 @@ def _walk(tokens: Iterator[str], terminator: Optional[str] = None, limit: int =
             ):
                 children = tuple(_walk(tokens, terminator=terminator, limit=1))
                 node = Node(token=commands.SUBSUP, children=(*previous.children, *children), modifier=previous.modifier)
+            elif (
+                token == commands.SUPERSCRIPT
+                and previous.token == commands.SUPERSCRIPT
+                and previous.children is not None
+                and previous.children[1].token == commands.PRIME
+            ):
+                children = tuple(_walk(tokens, terminator=terminator, limit=1))
+
+                node = Node(
+                    token=commands.SUPERSCRIPT,
+                    children=(
+                        previous.children[0],
+                        Node(token=commands.BRACES, children=(previous.children[1], *children)),
+                    ),
+                    modifier=previous.modifier,
+                )
             else:
                 try:
                     children = tuple(_walk(tokens, terminator=terminator, limit=1))
@@ -106,13 +126,27 @@ def _walk(tokens: Iterator[str], terminator: Optional[str] = None, limit: int =
             except IndexError:
                 previous = Node(token="")  # left operand can be empty if not present
 
+            if (
+                previous.token == commands.SUPERSCRIPT
+                and previous.children is not None
+                and len(previous.children) >= 2
+                and previous.children[1].token != commands.PRIME
+            ):
+                raise DoubleSuperscriptsError
+
             if (
                 previous.token == commands.SUPERSCRIPT
                 and previous.children is not None
                 and len(previous.children) >= 2
                 and previous.children[1].token == commands.PRIME
             ):
                 node = Node(token=commands.SUPERSCRIPT, children=(previous.children[0], Node(token=commands.DPRIME)))
+            elif previous.token == commands.SUBSCRIPT and previous.children is not None:
+                node = Node(
+                    token=commands.SUBSUP,
+                    children=(*previous.children, Node(token=commands.PRIME)),
+                    modifier=previous.modifier,
+                )
             else:
                 node = Node(token=commands.SUPERSCRIPT, children=(previous, Node(token=commands.PRIME)))
         elif token in commands.COMMANDS_WITH_TWO_PARAMETERS:

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "latex2mathml"
-version = "3.75.4"
+version = "3.75.5"
 repository = "https://github.com/roniemartinez/latex2mathml"
 description = "Pure Python library for LaTeX to MathML conversion"
 authors = ["Ronie Martinez <[email protected]>"]

tests/test_walker.py

@@ -1697,6 +1697,32 @@
             ],
             id="not",
         ),
+        pytest.param(
+            "x_1'",
+            [
+                Node(
+                    token="_^",
+                    children=(Node(token="x"), Node(token="1"), Node(token="\\prime")),
+                ),
+            ],
+            id="issue-392-subscript",
+        ),
+        pytest.param(
+            "x'^2",
+            [
+                Node(
+                    token="^",
+                    children=(
+                        Node(token="x"),
+                        Node(
+                            token="{}",
+                            children=(Node(token="\\prime"), Node(token="2")),
+                        ),
+                    ),
+                )
+            ],
+            id="issue-392-superscript",
+        ),
     ],
 )
 def test_walk(latex: str, expected: list) -> None:
@@ -1722,6 +1748,7 @@ def test_walk(latex: str, expected: list) -> None:
         pytest.param(r"\skew{X}\hat b", InvalidWidthError, id="invalid-width-not-number"),
         pytest.param(r"\limits^{\pi}", LimitsMustFollowMathOperatorError, id="limits-must-follow-math-operator-blank"),
         pytest.param(r"5\limits^{\pi}", LimitsMustFollowMathOperatorError, id="limits-must-follow-math-operator"),
+        pytest.param(r"x^2'", DoubleSuperscriptsError, id="issue-392"),
     ],
 )
 def test_error(latex: str, exception: Union[Tuple[Any, ...], Any]) -> None: