将Python字符串解释为条件语句?
我正在用python处理一些json格式的日志文件。编写一些条件查询代码非常简单,例如将Python字符串解释为条件语句?,python,Python,我正在用python处理一些json格式的日志文件。编写一些条件查询代码非常简单,例如 line=[1,'runtime',{'elapsed':12.3,'jobname':'high38853'}] # read from json # split the record and see what jobs take over 30 seconds key,category,details=line if category == 'runtime' and details['elapsed
line=[1,'runtime',{'elapsed':12.3,'jobname':'high38853'}] # read from json
# split the record and see what jobs take over 30 seconds
key,category,details=line
if category == 'runtime' and details['elapsed'] > 30:
print details
是否有一种方法可以安全地将字符串解释为条件表达式的一部分,这样我就可以在命令行上接受条件并将其作为查询的一部分
search 'details["elapsed"] > 30'
所以在代码中我可以做这样的事情
if *something involving sys.argv[1]*:
print line
这并不是一个真正安全的方法。对于基本条件,可以解析特定格式的输入字符串。如果您的输入格式为“var>5”,您可以这样解析它:
var, op, num = argv[1].split()
var = getattr(sys.modules[__name__], var) # Get a reference to the data
num = int(num)
if op == ">":
r = var > num
elif op == "<":
r = var < num
...
if r:
<do stuff>
var,op,num=argv[1].split()
var=getattr(sys.modules[\uuuuu name\uuuu],var)#获取对数据的引用
num=int(num)
如果op==“>”:
r=var>num
elif op==“这应该是您想要的:
from __future__ import print_function
import ast
import operator
import sys
OPERATORS = {
'<': operator.lt,
'<=': operator.le,
'>': operator.gt,
'>=': operator.ge,
'==': operator.eq,
'!=': operator.ne,
# 'in' is using a lambda because of the opposite operator order
# 'in': (lambda item, container: operator.contains(container, item),
'in': (lambda item, container: item in container),
'contains': operator.contains,
}
def process_conditionals(conditional_strings, variables):
for conditional_string in conditional_strings:
# Everything after first and op is part of second
first, op, second = conditional_string.split(None, 2)
resolved_operands = []
for raw_operand in (first, second):
try:
resolved_operand = ast.literal_eval(raw_operand)
except ValueError: # If the operand is not a valid literal
ve = sys.exc_info()
try:
# Check if the operand is a known value
resolved_operand = variables[raw_operand]
except KeyError: # If the operand is not a known value
# Re-raise the ValueError
raise ve[1], None, ve[2]
resolved_operands.append(resolved_operand)
yield (op, tuple(resolved_operands))
def main(lines, *conditional_strings):
for line in lines:
key, category, details = line
variables = {
'key': key,
'category': category,
'elapsed': details['elapsed'],
'jobname': details['jobname'],
}
conditionals = process_conditionals(conditional_strings, variables)
try:
# You could check each conditional separately to determine
# which ones have errors.
condition = all(OPERATORS[op](*operands)
for op, operands in conditionals)
except TypeError:
print("A literal in one of your conditionals is the wrong type. "
"If you can't see it, try running each one separately.",
file=sys.stderr)
break
except ValueError:
print("An operand in one of your conditionals is neither a known "
"variable nor a valid literal. If you can't see it, try "
"running each one separately.", file=sys.stderr)
break
else:
if condition:
print(line)
if __name__ == '__main__':
lines = [
[1, 'runtime', {'elapsed': 12.3, 'jobname': 'high38853'}],
[2, 'runtime', {'elapsed': 45.6, 'jobname': 'high38854'}],
[3, 'runtime', {'elapsed': 78.9, 'jobname': 'high38855'}],
[4, 'runtime', {'elapsed': 14.7, 'jobname': 'high38856'}],
[5, 'runtime', {'elapsed': 25.8, 'jobname': 'high38857'}],
[6, 'runtime', {'elapsed': 36.9, 'jobname': 'high38858'}],
[7, 'runtime', {'elapsed': 75.3, 'jobname': 'high38859'}],
]
conditional_strings = sys.argv[1:]
main(lines, *conditional_strings)
from\uuuuu future\uuuuu导入打印功能
导入ast
进口经营者
导入系统
运算符={
“=”:operator.ge,
“=”:operator.eq,
“!=”:operator.ne,
#“in”使用lambda,因为运算符顺序相反
#'in':(lambda项,容器:operator.contains(容器,项),
'in':(lambda项目,容器:容器中的项目),
“包含”:运算符.contains,
}
def process_条件(条件字符串、变量):
对于条件字符串中的条件字符串:
#第一次和第二次之后的一切都是第二次的一部分
第一,op,second=条件字符串.split(无,2)
已解析的_操作数=[]
对于中的原始操作数(第一个,第二个):
尝试:
已解析的\u操作数=ast.literal\u eval(原始\u操作数)
ValueError除外:#如果操作数不是有效的文字
ve=sys.exc_info()
尝试:
#检查操作数是否为已知值
已解析操作数=变量[原始操作数]
KeyError除外:#如果操作数不是已知值
#重新提出错误
提高ve[1],无,ve[2]
解析的\u操作数。追加(解析的\u操作数)
产量(运算,元组(解析的_操作数))
def main(行,*条件_字符串):
对于行中的行:
关键字、类别、详细信息=行
变量={
“键”:键,
“类别”:类别,
“已用”:详细信息[“已用”],
“jobname”:详细信息[“jobname”],
}
条件=过程条件(条件字符串、变量)
尝试:
#您可以分别检查每个条件以确定
#哪些有错误。
条件=所有(运算符[op](*操作数)
对于op,条件中的操作数)
除类型错误外:
print(“某个条件语句中的文字类型错误。”
“如果看不到,请尝试分别运行每一个。”,
文件=sys.stderr)
打破
除值错误外:
print(“其中一个条件中的操作数既不是已知的”
变量或有效文本。如果看不到,请重试
“分别运行每一个。”,file=sys.stderr)
打破
其他:
如果条件:
打印(行)
如果uuuu name uuuuuu='\uuuuuuu main\uuuuuuu':
行=[
[1,'runtime',{'Appeased':12.3,'jobname':'high38853'}],
[2,'runtime',{'Appeased':45.6,'jobname':'high38854'}],
[3,'runtime',{'Appeased':78.9,'jobname':'high38855'}],
[4,'runtime',{'Appeased':14.7,'jobname':'high38856'}],
[5,'runtime',{'Appeased':25.8,'jobname':'high38857'}],
[6,'runtime',{'Appeased':36.9,'jobname':'high38858'}],
[7,'runtime',{'Appeased':75.3,'jobname':'high38859'}],
]
条件_strings=sys.argv[1:]
main(行,*条件字符串)
示例:
$。/SO_31999444.py“已用时间>30”
[2,'runtime',{'jobname':'high38854','appeased':45.6}]
[3,'runtime',{'jobname':'high38855','appeased':78.9}]
[6,'runtime',{'jobname':'high38858','appeased':36.9}]
[7,'runtime',{'jobname':'high38859','appeased':75.3}]
$./SO_31999444.py'经过时间>20''经过时间<50'
[2,'runtime',{'jobname':'high38854','appeased':45.6}]
[5,'runtime',{'jobname':'high38857','appeased':25.8}]
[6,'runtime',{'jobname':'high38858','appeased':36.9}]
$./SO_31999444.py'已用时间>20''已用时间<50''键>=5'
[5,'runtime',{'jobname':'high38857','appeased':25.8}]
[6,'runtime',{'jobname':'high38858','appeased':36.9}]
$./SO_31999444.py“'9'在jobname中”
[7,'runtime',{'jobname':'high38859','appeased':75.3}]
$./SO_31999444.py“jobname包含'9'”
[7,'runtime',{'jobname':'high38859','appeased':75.3}]
$./SO_31999444.py“jobname in['high38857','high38858']中的作业名”
[5,'runtime',{'jobname':'high38857','appeased':25.8}]
[6,'runtime',{'jobname':'high38858','appeased':36.9}]
$./SO_31999444.py“jobname中的9”
其中一个条件语句中的文字类型错误。如果看不到,请尝试分别运行每一个。
$./SO_31999444.py“notakey==‘某物’”
其中一个条件中的操作数既不是已知变量,也不是有效的文字。如果看不到,请尝试分别运行每个操作数。
$./SO_31999444.py“2==2”
[1,'runtime',{'jobname':'high38853','appeased':12.3}]
[2,'runtime',{'jobname':'high38854','appeased':45.6}]
[3,'runtime',{'jobname':'high38855','appeased':78.9}]
[4,'runtime',{'jobname':'high38856','appeased':14.7}]
[5,'runtime',{'jobname':'high38857','appeased':25.8}]
[6,'runtime',{'jobname':'high38858','appeased':36.9}]
[7,'runtime',{'jobname':'high38859','appeased':75.3}]
美元/苏31999444.py
[1,'runtime',{'jobname':'high38853','appeased':12.3}]
[2,'runtime',{'jobname':'high38854','appeased':45.6}]
[3,'runtime',{'jobname':'high38855','appeased':78.9}]
[4,'runtime',{'jobname':'high38856','appeased':14.7}]
[5,'运行时',{'