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1 # -----------------------------------------------------------------------------
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2 # yacc_error5.py
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3 #
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4 # Lineno and position tracking with error tokens
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5 # -----------------------------------------------------------------------------
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6 import sys
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7
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8 if ".." not in sys.path: sys.path.insert(0,"..")
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9 import ply.yacc as yacc
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10
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11 from calclex import tokens
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12
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13 # Parsing rules
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14 precedence = (
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15 ('left','PLUS','MINUS'),
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16 ('left','TIMES','DIVIDE'),
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17 ('right','UMINUS'),
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18 )
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19
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20 # dictionary of names
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21 names = { }
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22
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23 def p_statement_assign(t):
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24 'statement : NAME EQUALS expression'
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25 names[t[1]] = t[3]
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26
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27 def p_statement_assign_error(t):
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28 'statement : NAME EQUALS error'
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29 line_start, line_end = t.linespan(3)
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30 pos_start, pos_end = t.lexspan(3)
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31 print("Assignment Error at %d:%d to %d:%d" % (line_start,pos_start,line_end,pos_end))
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32
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33 def p_statement_expr(t):
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34 'statement : expression'
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35 print(t[1])
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36
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37 def p_expression_binop(t):
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38 '''expression : expression PLUS expression
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39 | expression MINUS expression
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40 | expression TIMES expression
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41 | expression DIVIDE expression'''
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42 if t[2] == '+' : t[0] = t[1] + t[3]
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43 elif t[2] == '-': t[0] = t[1] - t[3]
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44 elif t[2] == '*': t[0] = t[1] * t[3]
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45 elif t[2] == '/': t[0] = t[1] / t[3]
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46
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47 def p_expression_uminus(t):
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48 'expression : MINUS expression %prec UMINUS'
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49 t[0] = -t[2]
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50
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51 def p_expression_group(t):
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52 'expression : LPAREN expression RPAREN'
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53 line_start, line_end = t.linespan(2)
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54 pos_start, pos_end = t.lexspan(2)
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55 print("Group at %d:%d to %d:%d" % (line_start,pos_start, line_end, pos_end))
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56 t[0] = t[2]
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57
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58 def p_expression_group_error(t):
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59 'expression : LPAREN error RPAREN'
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60 line_start, line_end = t.linespan(2)
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61 pos_start, pos_end = t.lexspan(2)
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62 print("Syntax error at %d:%d to %d:%d" % (line_start,pos_start, line_end, pos_end))
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63 t[0] = 0
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64
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65 def p_expression_number(t):
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66 'expression : NUMBER'
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67 t[0] = t[1]
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68
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69 def p_expression_name(t):
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70 'expression : NAME'
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71 try:
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72 t[0] = names[t[1]]
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73 except LookupError:
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74 print("Undefined name '%s'" % t[1])
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75 t[0] = 0
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76
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77 def p_error(t):
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78 print("Syntax error at '%s'" % t.value)
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79
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80 parser = yacc.yacc()
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81 import calclex
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82 calclex.lexer.lineno=1
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83 parser.parse("""
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84 a = 3 +
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85 (4*5) +
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86 (a b c) +
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87 + 6 + 7
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88 """, tracking=True)
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89
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90
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91
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92
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93
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94
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