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backend/app/dataset/rules/javascript/logic_operator.py

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+"""AST-level logical operator misuse injection for JavaScript using esprima."""
+
+from typing import Optional
+
+import esprima
+
+from app.dataset.rules.base import Mutation, MutationRule
+
+
+class JSLogicOperatorRule(MutationRule):
+    """Swap `&&` with `||` in a boolean expression.
+
+    Uses `esprima` to locate a LogicalExpression using `&&` and replaces the
+    operator with `||`.
+    """
+
+    name = "js_logic_operator"
+    language = "javascript"
+    defect_type = "logic_operator_misuse"
+
+    def detect_and_mutate(self, source: str, filename: str = "") -> Optional[Mutation]:
+        # Modern JS is usually ESM: try module grammar first, then script.
+        try:
+            tree = esprima.parseModule(source, loc=True)
+        except Exception:
+            try:
+                tree = esprima.parseScript(source, loc=True)
+            except Exception:
+                return None
+
+        for node in self._walk(tree):
+            if node.type != "LogicalExpression" or node.operator != "&&":
+                continue
+            line_no = node.loc.start.line
+            lines = source.splitlines(keepends=True)
+            line = lines[line_no - 1]
+            mutated_line = line.replace("&&", "||", 1)
+            if mutated_line == line:
+                continue
+            mutated = "".join(lines[:line_no - 1] + [mutated_line] + lines[line_no:])
+            return Mutation(
+                defect_type=self.defect_type,
+                language=self.language,
+                line_start=line_no,
+                line_end=line_no,
+                mutated_source=mutated,
+                reference_fix="Restore `&&` for correct short-circuit logic.",
+                description="Replaced boolean `&&` with `||`.",
+            )
+        return None
+
+    def _walk(self, node):
+        yield node
+        for key in getattr(node, "__dict__", {}):
+            child = getattr(node, key)
+            if isinstance(child, list):
+                for item in child:
+                    if hasattr(item, "type"):
+                        yield from self._walk(item)
+            elif hasattr(child, "type"):
+                yield from self._walk(child)