需求是:用文件的方式模擬select,insert 等操做 由於是模擬，不用數據庫模塊實現 用文件模擬數據庫，記錄形式是 id,name,dept,phoe,eroll_data記錄到磁盤 支持select ,insert 等標準形式的sql語法 用了兩個 模塊實現需求 sql_func.py 用來執行sql操做 mock_sql.py用來解析用戶的輸入 其中，在mock_sql.py裏面用了裝飾器parse_user_input用來解析用戶的輸入，經過這個裝飾器，獲得用戶不一樣的sql語句對應的表名，字段名，和限定條件（好比where 子句後面的條件），和insert 操做裏的values的內容 用了反射的方法去匹配不一樣的insert/delete/update/select的具體函數 具體到sql_func.py裏面實現的都是字符串解析，經過字符串解析獲取內容，寫入文件 sql_func裏面的 read_file()函數實現讀取文件，對應select功能 sql_func裏面的get_last_line實現讀取當前文件的最後一行的功能，這個是爲了給insert用的 ，inser實現id自增，須要判斷當前最後一行的id號 sql_func裏面的write_file()函數實現寫文件 文件名: sql_func.pypython
# coding:utf-8
import re
import os
def insert(action_name, dbname, fieldname, condition_limit, condition_values):
print "action:", action_name, dbname, fieldname, condition_limit
# insert into staff (name, dept, phone, eroll_date) values (li, DEV, 123456677, 20110101)
write_file(dbname, fieldname, condition_limit, condition_values)
def delete(action_name, dbname, fieldname, condition_limit, condition_values):
print "action:", action_name, dbname, fieldname, condition_limit
def update(action_name, dbname, fieldname, condition_limit, condition_values):
print "action:", action_name, dbname, fieldname, condition_limit
def select(action_name, dbname, fieldname, condition_limit, condition_values):
print "action:", action_name, dbname, fieldname, condition_limit
read_file(dbname, fieldname, condition_limit)
def read_file(fname, fieldname, condition_limit):
with open(fname, "r") as fd:
for line in fd:
if fieldname == "*" and condition_limit == "no":
print line.strip("\n")
elif fieldname == "*" and condition_limit != "no":
condition_item = condition_limit.strip(";").split()[0].strip('"')
condition_signal = condition_limit.strip(";").split()[1]
condition_value = condition_limit.strip(";").split()[2].strip('"')
if condition_item == "name" and condition_signal == "=":
if line.strip("\n").split(",")[1] == condition_value:
print line.strip("\n")
elif condition_item == "dept":
if line.strip("\n").split(",")[2] == condition_value:
print line.strip("\n")
elif condition_item == "eroll_date" and condition_signal == "like":
if line.strip("\n").split(",")[4].__contains__(condition_value):
print line.strip("\n")
def get_last_line(fname):
block_size = 1024
with open(fname, "r") as fd:
file_size = os.path.getsize(fname)
if file_size > block_size:
seek_point = (file_size // block_size)
fd.seek((seek_point - 1) * file_size)
else:
fd.seek(0, 0)
lines = fd.readlines()
if lines:
last_line = lines[-1].strip()
print last_line
return last_line
def write_file(fname, fieldname, condition_limit, condition_values):
with open(fname ,"a+") as fd:
last_line = get_last_line(fname)
cur_max_id = last_line.split(",")[0]
print cur_max_id
item = ",".join(condition_values.split(","))
record = re.sub(r'"| ', "", item.strip()).strip("(").strip(")")
record_id = int(cur_max_id) + 1
fd.writelines(str(record_id) + "," + record)
文件名: mock_sql.py正則表達式
# coding:utf-8
'''
sql_func是導入的另一個模塊，即位於同級目錄的sql_func.py
需求語法:
insert into tablename
delete from tablename
delete from tablename where clause
update tablename set filedname=value
update tablename set (fieldname1, fieldname2, fieldname3...) values (val1, val2, val3...)
select * from tablename where clasuse
select filedname from tablename where clause
'''
import re
import sql_func
def parse_user_rawinput(func):
# 拆分字符串得到表名的正則表達式
re_parse_dbname = r"' '+|from|update|into"
# 拆分字符串得到字段名的正則表達式
re_field_name = r"select|from|set|where|into|values|="
# 拆分字符串得到where條件的正則表達式
re_condition = r"where"
# 拆分是insert into插入記錄的狀況下的values的正則表達式
re_insert_values = r"values"
def wrapper_parse(user_input):
user_action_pointer, user_line, user_sql = func(user_input)
if user_action_pointer in ["select", "delete","insert", "update"]:
user_action_pointer, user_sql, user_line = func(user_input)
dbname = re.split(re_parse_dbname, user_line)[1].lstrip().split()[0].rstrip(";")
fieldname = re.sub(r"(^.* )\(", "", re.split(re_field_name, user_line)[1]).strip(" )")
if user_action_pointer in ["select", "delete", "update"]:
condition = re.split(re_condition, user_line)
if len(condition) == 1:
condition_limit = "no"
else:
condition_limit = condition[1]
elif user_action_pointer == "insert":
condition_limit = "no"
condition_values = re.split(re_insert_values, user_line)[1]
sql_action(user_action_pointer, dbname, fieldname, condition_limit, condition_values)
else:
print "invalid action"
return "invalid action"
exit(1)
return wrapper_parse
@parse_user_rawinput
def parse_user_input(user_input):
user_action_pointer = user_input["user_sql_list"][0]
user_sql = user_input["user_sql_list"]
user_line = user_input["user_line"]
return user_action_pointer, user_sql, user_line
def sql_action(action_name, dbname, fieldname, condition_limit, condition_values):
if action_name in ["select", "insert", "update", "delete"]:
if hasattr(sql_func, action_name):
func = getattr(sql_func, action_name)
result = func(action_name, dbname, fieldname, condition_limit, condition_values)
def input():
user_results = dict()
user_line = raw_input("input your sql:")
user_sql_list = user_line.rstrip(";").split()
user_results["user_line"] = user_line
user_results["user_sql_list"] = user_sql_list
return user_results
if __name__ == "__main__":
user_input = input()
parse_user_input(user_input)
1,zhang,DEV,13600010001,20100101 2,wang,DEV,1360020002,20110101 3,zhao,OPS,13600030005,20110201 4,qian,OPS,13600040006,20130203 5,sun,OPS,13600050007,20070709 6,li,OPS,13600060008,20150602 7,wu,OPS,13600070009,20160703sql