89 lines
2.3 KiB
Python
89 lines
2.3 KiB
Python
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# SPDX-License-Identifier: AGPL-3.0-or-later
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"""Calculate mathematical expressions using ack#eval
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"""
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import ast
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import operator
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from flask_babel import gettext
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from searx import settings
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name = "Basic Calculator"
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description = gettext("Calculate mathematical expressions via the search bar")
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default_on = False
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preference_section = 'general'
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plugin_id = 'calculator'
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operators = {
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ast.Add: operator.add,
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ast.Sub: operator.sub,
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ast.Mult: operator.mul,
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ast.Div: operator.truediv,
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ast.Pow: operator.pow,
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ast.BitXor: operator.xor,
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ast.USub: operator.neg,
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}
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def _eval_expr(expr):
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"""
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>>> _eval_expr('2^6')
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4
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>>> _eval_expr('2**6')
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64
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>>> _eval_expr('1 + 2*3**(4^5) / (6 + -7)')
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-5.0
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"""
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return _eval(ast.parse(expr, mode='eval').body)
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def _eval(node):
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if isinstance(node, ast.Constant) and isinstance(node.value, int):
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return node.value
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if isinstance(node, ast.BinOp):
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return operators[type(node.op)](_eval(node.left), _eval(node.right))
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if isinstance(node, ast.UnaryOp):
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return operators[type(node.op)](_eval(node.operand))
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raise TypeError(node)
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def post_search(_request, search):
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# don't run on public instances due to possible attack surfaces
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if settings['server']['public_instance']:
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return True
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# only show the result of the expression on the first page
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if search.search_query.pageno > 1:
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return True
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query = search.search_query.query
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# in order to avoid DoS attacks with long expressions, ignore long expressions
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if len(query) > 100:
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return True
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# replace commonly used math operators with their proper Python operator
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query = query.replace("x", "*").replace(":", "/")
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# only numbers and math operators are accepted
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if any(str.isalpha(c) for c in query):
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return True
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# in python, powers are calculated via **
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query_py_formatted = query.replace("^", "**")
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try:
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result = str(_eval_expr(query_py_formatted))
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if result != query:
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search.result_container.answers['calculate'] = {'answer': f"{query} = {result}"}
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except (TypeError, SyntaxError, ArithmeticError):
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pass
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return True
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def is_allowed():
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return not settings['server']['public_instance']
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