column_dic = {"id": 0, "name": 1, "age": 2, "phone": 3, "job": 4}
def get_show_list(col_condition): # "select age,name"
"""
獲取要展示的列名
:param col_condition: 用戶輸入的select條件
:return: 列名組成的列表
"""
col_info_list = col_condition.strip().split("select") # ["", "age,name"]
col_info_list = [col_info_item for col_info_item in col_info_list if col_info_item.strip()] # ["age,name"]
if col_info_list:
col_info = col_info_list[0].strip() # "age,name"
if "*" in col_info:
return column_dic.keys()
elif col_info:
ret = col_info.split(",") # [" age ","name"]
return [item.strip() for item in ret] # ["age","name"]
else:
print(col_info)
def filter_handler(operate, con): # ">" , "age>22"
selected_list = []
col, val = con.split(operate)
col = col.strip()
val = val.strip()
judge = "int(line_list[column_dic[col]]) %s int(val)" % operate if operate == "<" or operate == ">" \
else "line_list[column_dic[col]] %s val" % operate
f = open("student", encoding="utf-8")
for line in f:
line_list = line.strip().split(",")
if eval(judge):
selected_list.append(line_list)
f.close()
return selected_list
def get_selected_line(con): # con = "age>22"
"""
獲取要查找的行，並將每一行作為列表項存儲到selected_list
:param con:
:return:
"""
if ">" in con:
selected_list = filter_handler(">", con)
elif "<" in con:
selected_list = filter_handler("<", con)
elif "=" in con:
selected_list = filter_handler("==", con.replace("=", '=='))
elif "like" in con:
selected_list = filter_handler("in", con)
return selected_list
def show(selected_list, show_list):
for selected_item in selected_list:
for col in show_list:
print(selected_item[column_dic[col]], end=" ")
print()
condition = input(">>>") # "select age,name where age>22"
ret = condition.split('where') # ["select age,name", "age>22"]
con = ret[1].strip() # "age>22"
show_list = get_show_list(ret[0]) # ["name", "age"]
selected_list = get_selected_line(con)
show(selected_list, show_list)
