used _match_subject_stack as suggested

src/latexify/codegen/function_codegen.py

@@ -25,6 +25,7 @@ def __init__(
         use_math_symbols: bool = False,
         use_signature: bool = True,
         use_set_symbols: bool = False,
+        _match_subject_stack: list[str] = [],
     ) -> None:
         """Initializer.
 
@@ -34,6 +35,7 @@ def __init__(
             use_signature: Whether to add the function signature before the expression
                 or not.
             use_set_symbols: Whether to use set symbols or not.
+            _match_subject_stack: a stack of subject names that are used in match
         """
         self._expression_codegen = expression_codegen.ExpressionCodegen(
             use_math_symbols=use_math_symbols, use_set_symbols=use_set_symbols
@@ -42,6 +44,7 @@ def __init__(
             use_math_symbols=use_math_symbols
         )
         self._use_signature = use_signature
+        self._match_subject_stack = _match_subject_stack
 
     def generic_visit(self, node: ast.AST) -> str:
         raise exceptions.LatexifyNotSupportedError(
@@ -141,6 +144,9 @@ def visit_If(self, node: ast.If) -> str:
 
     def visit_Match(self, node: ast.Match) -> str:
         """Visit a Match node."""
+        subject_latex = self._expression_codegen.visit(node.subject)
+        self._match_subject_stack.append(subject_latex)
+
         if not (
             len(node.cases) >= 2
             and isinstance(node.cases[-1].pattern, ast.MatchAs)
@@ -162,8 +168,6 @@ def visit_Match(self, node: ast.Match) -> str:
             if i < len(node.cases) - 1:
                 body_latex = self.visit(case.body[0])
                 cond_latex = self.visit(case.pattern)
-                # if case.guard is not None:
-                #     cond_latex = self._expression_codegen.visit(case.guard)
 
                 case_latexes.append(body_latex + r", & \mathrm{if} \ " + cond_latex)
             else:
@@ -177,21 +181,14 @@ def visit_Match(self, node: ast.Match) -> str:
             + r" \end{array} \right."
         )
 
-        latex_final = latex.replace("subject_name", subject_latex)
-        return latex_final
+        self._match_subject_stack.pop()
+        return latex
 
     def visit_MatchValue(self, node: ast.MatchValue) -> str:
         """Visit a MatchValue node."""
         latex = self._expression_codegen.visit(node.value)
-        return "subject_name = " + latex
+        return self._match_subject_stack[-1] + " = " + latex
 
     def visit_MatchOr(self, node: ast.MatchOr) -> str:
         """Visit a MatchOr node."""
-        # case_latexes = []
-        # for i, pattern in enumerate(node.patterns):
-        #     if i == 0:
-        #         case_latexes.append(self.visit(pattern))
-        #     else:
-        #         case_latexes.append(r" \lor " + self.visit(pattern))
-        # return "".join(case_latexes)
         return r" \lor ".join(self.visit(p) for p in node.patterns)