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148
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1 import collections, re
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2 from ppci.errors import CompilerException, SourceLocation
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3
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4 """
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5 Lexical analyzer part. Splits the input character stream into tokens.
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6 """
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7
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8 # Token is used in the lexical analyzer:
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9 Token = collections.namedtuple('Token', 'typ val loc')
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10
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11 keywords = ['and', 'or', 'not','true', 'false', \
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12 'else', 'if', 'while', 'return', \
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149
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13 'function', 'var', 'type', \
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148
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14 'import', 'package' ]
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15
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16 def tokenize(s):
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17 """
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18 Tokenizer, generates an iterator that
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19 returns tokens!
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20
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21 This GREAT example was taken from python re doc page!
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22 """
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23 tok_spec = [
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24 ('REAL', r'\d+\.\d+'),
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25 ('HEXNUMBER', r'0x[\da-fA-F]+'),
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26 ('NUMBER', r'\d+'),
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27 ('ID', r'[A-Za-z][A-Za-z\d_]*'),
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28 ('NEWLINE', r'\n'),
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29 ('SKIP', r'[ \t]'),
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30 ('COMMENTS', r'//.*'),
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31 ('LEESTEKEN', r'==|[\.,=:;\-+*\[\]/\(\)]|>=|<=|<>|>|<|{|}'),
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32 ('STRING', r"'.*?'")
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33 ]
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34 tok_re = '|'.join('(?P<%s>%s)' % pair for pair in tok_spec)
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35 gettok = re.compile(tok_re).match
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36 line = 1
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37 pos = line_start = 0
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38 mo = gettok(s)
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39 while mo is not None:
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40 typ = mo.lastgroup
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41 val = mo.group(typ)
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42 if typ == 'NEWLINE':
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43 line_start = pos
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44 line += 1
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45 elif typ == 'COMMENTS':
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46 pass
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47 elif typ == 'SKIP':
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48 pass
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49 else:
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50 if typ == 'ID':
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51 if val in keywords:
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52 typ = val
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53 elif typ == 'LEESTEKEN':
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54 typ = val
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55 elif typ == 'NUMBER':
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56 val = int(val)
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57 elif typ == 'HEXNUMBER':
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58 val = int(val[2:], 16)
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59 typ = 'NUMBER'
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60 elif typ == 'REAL':
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61 val = float(val)
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62 elif typ == 'STRING':
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63 val = val[1:-1]
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64 loc = SourceLocation(line, mo.start()-line_start)
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65 yield Token(typ, val, loc)
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66 pos = mo.end()
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67 mo = gettok(s, pos)
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68 if pos != len(s):
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69 col = pos - line_start
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70 pos = line
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71 raise CompilerException('Unexpected character {0}'.format(s[pos]), pos)
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72 yield Token('END', '', line)
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73
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