1 | #!/usr/bin/env python2
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2 | """Generate ast module from specification
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3 |
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4 | This script generates the ast module from a simple specification,
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5 | which makes it easy to accommodate changes in the grammar. This
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6 | approach would be quite reasonable if the grammar changed often.
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7 | Instead, it is rather complex to generate the appropriate code. And
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8 | the Node interface has changed more often than the grammar.
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9 | """
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10 | from __future__ import print_function
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11 |
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12 | import fileinput
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13 | import re
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14 | import sys
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15 | import cStringIO
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16 |
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17 | COMMA = ", "
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18 |
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19 | def load_boilerplate(file):
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20 | f = open(file)
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21 | buf = f.read()
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22 | f.close()
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23 | i = buf.find('### ''PROLOGUE')
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24 | j = buf.find('### ''EPILOGUE')
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25 | pro = buf[i+12:j].strip()
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26 | epi = buf[j+12:].strip()
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27 | return pro, epi
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28 |
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29 | def strip_default(arg):
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30 | """Return the argname from an 'arg = default' string"""
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31 | i = arg.find('=')
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32 | if i == -1:
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33 | return arg
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34 | t = arg[:i].strip()
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35 | return t
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36 |
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37 | P_NODE = 1 # It's another node.
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38 | P_OTHER = 2 # * means it's a Python value like string, int, tuple, etc.
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39 | P_NESTED = 3 # ! means this is a list of more nodes.
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40 | P_NONE = 4 # & means it's a node or None.
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41 |
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42 | class NodeInfo(object):
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43 | """Each instance describes a specific AST node"""
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44 | def __init__(self, name, args):
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45 | self.name = name
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46 | self.args = args.strip()
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47 | self.argnames = self.get_argnames()
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48 | self.argprops = self.get_argprops()
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49 | self.nargs = len(self.argnames)
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50 | self.init = []
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51 |
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52 | def get_argnames(self):
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53 | if '(' in self.args:
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54 | i = self.args.find('(')
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55 | j = self.args.rfind(')')
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56 | args = self.args[i+1:j]
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57 | else:
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58 | args = self.args
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59 | return [strip_default(arg.strip())
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60 | for arg in args.split(',') if arg]
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61 |
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62 | def get_argprops(self):
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63 | """Each argument can have a property like '*' or '!'
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64 |
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65 | XXX This method modifies the argnames in place!
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66 | """
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67 | d = {}
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68 | hardest_arg = P_NODE
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69 | for i in range(len(self.argnames)):
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70 | arg = self.argnames[i]
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71 | if arg.endswith('*'):
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72 | arg = self.argnames[i] = arg[:-1]
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73 | d[arg] = P_OTHER
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74 | hardest_arg = max(hardest_arg, P_OTHER)
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75 | elif arg.endswith('!'):
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76 | arg = self.argnames[i] = arg[:-1]
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77 | d[arg] = P_NESTED
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78 | hardest_arg = max(hardest_arg, P_NESTED)
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79 | elif arg.endswith('&'):
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80 | arg = self.argnames[i] = arg[:-1]
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81 | d[arg] = P_NONE
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82 | hardest_arg = max(hardest_arg, P_NONE)
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83 | else:
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84 | d[arg] = P_NODE
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85 | self.hardest_arg = hardest_arg
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86 |
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87 | if hardest_arg > P_NODE:
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88 | self.args = self.args.replace('*', '')
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89 | self.args = self.args.replace('!', '')
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90 | self.args = self.args.replace('&', '')
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91 |
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92 | return d
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93 |
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94 | def gen_source(self):
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95 | print("class %s(Node):" % self.name)
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96 | print(" ARGNAMES = %r" % self.argnames)
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97 | self._gen_init(sys.stdout)
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98 | print()
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99 | self._gen_getChildren(sys.stdout)
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100 | print()
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101 | self._gen_getChildNodes(sys.stdout)
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102 | print()
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103 |
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104 | def _gen_init(self, buf):
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105 | if self.args:
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106 | argtuple = '(' in self.args
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107 | args = self.args if not argtuple else ''.join(self.argnames)
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108 | print(" def __init__(self, %s, lineno=None):" % args, file=buf)
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109 | else:
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110 | print(" def __init__(self, lineno=None):", file=buf)
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111 | if self.argnames:
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112 | if argtuple:
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113 | for idx, name in enumerate(self.argnames):
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114 | print(" self.%s = %s[%s]" % (name, args, idx), file=buf)
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115 | else:
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116 | for name in self.argnames:
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117 | print(" self.%s = %s" % (name, name), file=buf)
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118 | print(" self.lineno = lineno", file=buf)
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119 | # Copy the lines in self.init, indented four spaces. The rstrip()
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120 | # business is to get rid of the four spaces if line happens to be
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121 | # empty, so that reindent.py is happy with the output.
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122 | for line in self.init:
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123 | print((" " + line).rstrip(), file=buf)
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124 |
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125 | def _gen_getChildren(self, buf):
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126 | print(" def getChildren(self):", file=buf)
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127 | if len(self.argnames) == 0:
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128 | print(" return ()", file=buf)
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129 | else:
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130 | if self.hardest_arg < P_NESTED:
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131 | clist = COMMA.join(["self.%s" % c
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132 | for c in self.argnames])
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133 | if self.nargs == 1:
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134 | print(" return %s," % clist, file=buf)
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135 | else:
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136 | print(" return %s" % clist, file=buf)
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137 | else:
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138 | if len(self.argnames) == 1:
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139 | print(" return tuple(flatten(self.%s))" % self.argnames[0], file=buf)
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140 | else:
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141 | print(" children = []", file=buf)
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142 | template = " children.%s(%sself.%s%s)"
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143 | for name in self.argnames:
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144 | if self.argprops[name] == P_NESTED:
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145 | print(template % ("extend", "flatten(",
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146 | name, ")"), file=buf)
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147 | else:
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148 | print(template % ("append", "", name, ""), file=buf)
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149 | print(" return tuple(children)", file=buf)
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150 |
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151 | def _gen_getChildNodes(self, buf):
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152 | print(" def getChildNodes(self):", file=buf)
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153 | if len(self.argnames) == 0:
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154 | print(" return ()", file=buf)
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155 | else:
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156 | if self.hardest_arg < P_NESTED:
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157 | clist = ["self.%s" % c
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158 | for c in self.argnames
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159 | if self.argprops[c] == P_NODE]
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160 | if len(clist) == 0:
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161 | print(" return ()", file=buf)
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162 | elif len(clist) == 1:
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163 | print(" return %s," % clist[0], file=buf)
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164 | else:
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165 | print(" return %s" % COMMA.join(clist), file=buf)
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166 | else:
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167 | print(" nodelist = []", file=buf)
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168 | template = " nodelist.%s(%sself.%s%s)"
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169 | for name in self.argnames:
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170 | if self.argprops[name] == P_NONE:
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171 | tmp = (" if self.%s is not None:\n"
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172 | " nodelist.append(self.%s)")
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173 | print(tmp % (name, name), file=buf)
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174 | elif self.argprops[name] == P_NESTED:
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175 | print(template % ("extend", "flatten_nodes(",
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176 | name, ")"), file=buf)
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177 | elif self.argprops[name] == P_NODE:
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178 | print(template % ("append", "", name, ""), file=buf)
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179 | print(" return tuple(nodelist)", file=buf)
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180 |
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181 |
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182 | rx_init = re.compile('init\((.*)\):')
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183 |
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184 | def parse_spec(file):
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185 | classes = {}
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186 | cur = None
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187 | for line in fileinput.input(file):
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188 | if line.strip().startswith('#'):
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189 | continue
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190 | mo = rx_init.search(line)
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191 | if mo is None:
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192 | if cur is None:
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193 | # a normal entry
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194 | try:
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195 | name, args = line.split(':')
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196 | except ValueError:
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197 | continue
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198 | classes[name] = NodeInfo(name, args)
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199 | cur = None
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200 | else:
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201 | # some code for the __init__ method
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202 | cur.init.append(line)
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203 | else:
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204 | # some extra code for a Node's __init__ method
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205 | name = mo.group(1)
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206 | cur = classes[name]
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207 | return sorted(classes.values(), key=lambda n: n.name)
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208 |
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209 | def main():
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210 | prologue, epilogue = load_boilerplate(sys.argv[0])
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211 | print('from __future__ import print_function')
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212 | print('import cStringIO')
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213 | print(prologue)
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214 | print()
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215 | classes = parse_spec(sys.argv[1])
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216 | for info in classes:
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217 | info.gen_source()
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218 | print(epilogue)
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219 |
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220 | if __name__ == "__main__":
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221 | main()
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222 | sys.exit(0)
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223 |
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224 | ### PROLOGUE
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225 | """Python abstract syntax node definitions
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226 |
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227 | This file is automatically generated by Tools/compiler/astgen.py
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228 | """
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229 | from .consts import CO_VARARGS, CO_VARKEYWORDS
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230 |
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231 | # NOTE: Similar to pyassem.flatten().
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232 | def flatten(seq):
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233 | l = []
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234 | for elt in seq:
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235 | if isinstance(elt, (tuple, list)):
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236 | l.extend(flatten(elt))
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237 | else:
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238 | l.append(elt)
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239 | return l
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240 |
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241 | def flatten_nodes(seq):
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242 | return [n for n in flatten(seq) if isinstance(n, Node)]
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243 |
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244 | nodes = {}
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245 |
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246 |
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247 | # NOTE: after_equals is a hack to make the output prettier. You could copy
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248 | # _TrySingleLine in asdl/format.py. That took a long time to get right!
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249 | def _PrettyPrint(val, f, indent=0, after_equals=False):
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250 | indent_str = ' ' * indent
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251 |
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252 | if isinstance(val, Node):
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253 | val.PrettyPrint(f, indent=indent, after_equals=after_equals)
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254 |
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255 | elif isinstance(val, list):
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256 | if not after_equals:
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257 | print('%s' % indent_str, end='', file=f)
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258 | print('[', file=f) # No indent here
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259 | for item in val:
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260 | _PrettyPrint(item, f, indent=indent+2)
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261 | # Not indented as much
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262 | print('%s]' % indent_str, file=f)
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263 |
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264 | elif isinstance(val, tuple):
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265 | if not after_equals:
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266 | print('%s' % indent_str, end='', file=f)
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267 | print('(', file=f)
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268 | for item in val:
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269 | _PrettyPrint(item, f, indent=indent+2)
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270 | print('%s)' % indent_str, file=f)
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271 |
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272 | else:
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273 | if not after_equals:
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274 | print('%s' % indent_str, end='', file=f)
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275 | # String or int?
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276 | print('%r' % val, file=f)
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277 |
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278 |
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279 | class Node(object):
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280 | """Abstract base class for ast nodes."""
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281 |
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282 | ARGNAMES = []
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283 |
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284 | def getChildren(self):
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285 | pass # implemented by subclasses
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286 |
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287 | def __iter__(self):
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288 | for n in self.getChildren():
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289 | yield n
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290 |
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291 | def asList(self): # for backwards compatibility
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292 | return self.getChildren()
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293 |
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294 | def getChildNodes(self):
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295 | pass # implemented by subclasses
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296 |
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297 | def __repr__(self):
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298 | f = cStringIO.StringIO()
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299 | self.PrettyPrint(f)
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300 | return f.getvalue()
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301 |
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302 | def PrettyPrint(self, f, indent=0, after_equals=False):
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303 | indent_str = ' ' * indent
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304 |
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305 | if not after_equals:
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306 | print('%s' % indent_str, end='', file=f)
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307 | print('%s(' % self.__class__.__name__, file=f)
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308 | for name in self.ARGNAMES:
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309 | # Print the field name
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310 | print('%s %s = ' % (indent_str, name), end='', file=f)
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311 |
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312 | # Print the value
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313 | val = getattr(self, name)
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314 |
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315 | _PrettyPrint(val, f, indent=indent+2, after_equals=True)
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316 |
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317 | print('%s) # %s' % (indent_str, self.__class__.__name__), file=f)
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318 |
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319 |
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320 | class EmptyNode(Node):
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321 | pass
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322 |
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323 | class Expression(Node):
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324 | # Expression is an artificial node class to support "eval"
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325 | nodes["expression"] = "Expression"
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326 | def __init__(self, node):
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327 | self.node = node
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328 |
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329 | def getChildren(self):
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330 | return self.node,
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331 |
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332 | def getChildNodes(self):
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333 | return self.node,
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334 |
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335 | def __repr__(self):
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336 | return "Expression(%s)" % (repr(self.node))
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337 |
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338 | ### EPILOGUE
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339 | for name, obj in globals().items():
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340 | if isinstance(obj, type) and issubclass(obj, Node):
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341 | nodes[name.lower()] = obj
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