109 lines
2.4 KiB
Python
109 lines
2.4 KiB
Python
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import sys
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import re
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# command description
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cmd_desc = """
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simple compiler example
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compiler.py filename
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"""
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if len(sys.argv) == 1:
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print(cmd_desc)
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if len(sys.argv) > 2:
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raise Exception("you input too more arguments.")
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#input_filename = sys.argv[1]
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#file_content = open(input_filename,'r')
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# test code
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# test = "1 + 2 * (23 / 12)"
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test = "1 + 2 * 3 * 4"
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# TOKEN
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INT = r'(?P<INT>\d+)'
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ADD = r'(?P<ADD>\+)'
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SUB = r'(?P<SUB>-)'
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MUL = r'(?P<MUL>\*)'
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DIV = r'(?P<DIV>/)'
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LPARE = r'(?P<LPARE>\()'
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RPARE = r'(?P<RPARE>\))'
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ASSIGN = r'(?P<ASSIGN>=)'
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L_INT = r'(?P<L_INT>int)' # let int
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IND = r'(?P<IND>[_a-zA-Z][_0-9a-zA-Z]+)' #indicator
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WSNL = r'(?P<WS>(\s|\n|\r)+)'# whitespace & newline
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token_pattern_list = [INT, ADD, SUB, MUL, DIV , LPARE, RPARE, ASSIGN, L_INT , IND, WSNL]
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token_pattern = re.compile("|".join(token_pattern_list))
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raw_token_result_list = []
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for match in re.finditer(token_pattern, test):
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raw_token_result_list.append((match.lastgroup, match.group(0)))
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# [(None, None)] 必加，以避免出錯
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token_result_list = [i for i in raw_token_result_list if i[0] != "WS"] + [(None, None)]
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print(token_result_list)
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"""
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expr = term {+ term }*
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term = factor {* factor}*
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factor = number
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"""
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class Parser:
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def __init__(self):
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self.token = None
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self.remained_token = None
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def parse(self, token_list):
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self.token = token_list[0]
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self.remained_token = token_list[1:]
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result = self.expr()
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print(result)
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return result
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def advance(self):
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self.token = self.remained_token[0]
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self.remained_token = self.remained_token[1:]
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def expr(self):
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result = self.term()
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while self.token[0] == "ADD":
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result_head = self.token[1]
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self.advance()
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rhs = self.term()
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result = [result_head, result, rhs]
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rhs = result
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return result
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def term(self):
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result = self.factor()
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while self.token[0] == "MUL":
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result_head = self.token[1]
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self.advance()
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rhs = self.factor()
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result = [result_head, result, rhs]
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rhs = result
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return result
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def factor(self):
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if self.token[0] != "INT":
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raise Exception("Expect Number, find %s" % self.token[1])
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else:
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result = int(self.token[1])
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self.advance()
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return result
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parser = Parser()
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parser.parse(token_result_list)
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'''
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'''
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