Python 中的安全表达式解析器 [英] Safe expression parser in Python
问题描述
如何让用户以安全的方式执行数学表达式?我需要写一个完整的解析器吗?
How can I allow users to execute mathematical expressions in a safe way? Do I need to write a full parser?
是否有类似 ast.literal_eval() 的东西,但是对于表达?
Is there something like ast.literal_eval(), but for expressions?
推荐答案
Pyparsing 示例页面列出了几个表达式解析器:
The Pyparsing examples page lists several expression parsers:
http://pyparsing.wikispaces.com/file/view/fourFn.py - 使用 pyparsing 的传统算术中缀符号解析器/评估器实现(尽管它的名字,它实际上执行 5 函数算术,加上几个触发函数)
http://pyparsing.wikispaces.com/file/view/fourFn.py - A conventional arithmetic infix notation parser/evaluator implementation using pyparsing (despite its name, this actually does 5-function arithmetic, plus several trig functions)
http://pyparsing.wikispaces.com/file/view/simpleBool.py - 布尔中缀符号解析器/求值器,使用 pyparsing 辅助方法 operatorPrecedence
,简化了中缀运算符符号的定义
http://pyparsing.wikispaces.com/file/view/simpleBool.py - A boolean infix notation parser/evaluator, using a pyparsing helper method operatorPrecedence
, which simplifies the definition of infix operator notations
http://pyparsing.wikispaces.com/file/view/simpleArith.py http://pyparsing.wikispaces.com/file/view/eval_arith.py -一对使用 operatorPrecedence
重铸fourFn.py 的示例.第一个只是解析并返回一个解析树,第二个添加了评估逻辑.
http://pyparsing.wikispaces.com/file/view/simpleArith.py http://pyparsing.wikispaces.com/file/view/eval_arith.py -
A pair of examples recasting fourFn.py using operatorPrecedence
. The first just parses and returns a parse tree, the second adds evaluation logic.
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