| [2] | 1 | """Generate ast module from specification
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| 2 |
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| 3 | This script generates the ast module from a simple specification,
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| 4 | which makes it easy to accomodate changes in the grammar. This
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| 5 | approach would be quite reasonable if the grammar changed often.
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| 6 | Instead, it is rather complex to generate the appropriate code. And
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| 7 | the Node interface has changed more often than the grammar.
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| 8 | """
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| 9 |
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| 10 | import fileinput
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| 11 | import re
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| 12 | import sys
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| 13 | from StringIO import StringIO
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| 14 |
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| 15 | SPEC = "ast.txt"
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| 16 | COMMA = ", "
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| 17 |
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| 18 | def load_boilerplate(file):
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| 19 | f = open(file)
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| 20 | buf = f.read()
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| 21 | f.close()
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| 22 | i = buf.find('### ''PROLOGUE')
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| 23 | j = buf.find('### ''EPILOGUE')
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| 24 | pro = buf[i+12:j].strip()
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| 25 | epi = buf[j+12:].strip()
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| 26 | return pro, epi
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| 27 |
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| 28 | def strip_default(arg):
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| 29 | """Return the argname from an 'arg = default' string"""
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| 30 | i = arg.find('=')
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| 31 | if i == -1:
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| 32 | return arg
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| 33 | t = arg[:i].strip()
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| 34 | return t
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| 35 |
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| 36 | P_NODE = 1
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| 37 | P_OTHER = 2
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| 38 | P_NESTED = 3
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| 39 | P_NONE = 4
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| 40 |
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| 41 | class NodeInfo:
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| 42 | """Each instance describes a specific AST node"""
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| 43 | def __init__(self, name, args):
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| 44 | self.name = name
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| 45 | self.args = args.strip()
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| 46 | self.argnames = self.get_argnames()
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| 47 | self.argprops = self.get_argprops()
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| 48 | self.nargs = len(self.argnames)
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| 49 | self.init = []
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| 50 |
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| 51 | def get_argnames(self):
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| 52 | if '(' in self.args:
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| 53 | i = self.args.find('(')
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| 54 | j = self.args.rfind(')')
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| 55 | args = self.args[i+1:j]
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| 56 | else:
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| 57 | args = self.args
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| 58 | return [strip_default(arg.strip())
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| 59 | for arg in args.split(',') if arg]
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| 60 |
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| 61 | def get_argprops(self):
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| 62 | """Each argument can have a property like '*' or '!'
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| 63 |
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| 64 | XXX This method modifies the argnames in place!
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| 65 | """
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| 66 | d = {}
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| 67 | hardest_arg = P_NODE
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| 68 | for i in range(len(self.argnames)):
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| 69 | arg = self.argnames[i]
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| 70 | if arg.endswith('*'):
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| 71 | arg = self.argnames[i] = arg[:-1]
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| 72 | d[arg] = P_OTHER
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| 73 | hardest_arg = max(hardest_arg, P_OTHER)
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| 74 | elif arg.endswith('!'):
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| 75 | arg = self.argnames[i] = arg[:-1]
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| 76 | d[arg] = P_NESTED
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| 77 | hardest_arg = max(hardest_arg, P_NESTED)
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| 78 | elif arg.endswith('&'):
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| 79 | arg = self.argnames[i] = arg[:-1]
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| 80 | d[arg] = P_NONE
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| 81 | hardest_arg = max(hardest_arg, P_NONE)
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| 82 | else:
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| 83 | d[arg] = P_NODE
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| 84 | self.hardest_arg = hardest_arg
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| 85 |
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| 86 | if hardest_arg > P_NODE:
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| 87 | self.args = self.args.replace('*', '')
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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 |
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| 91 | return d
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| 92 |
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| 93 | def gen_source(self):
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| 94 | buf = StringIO()
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| 95 | print >> buf, "class %s(Node):" % self.name
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| 96 | self._gen_init(buf)
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| 97 | print >> buf
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| 98 | self._gen_getChildren(buf)
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| 99 | print >> buf
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| 100 | self._gen_getChildNodes(buf)
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| 101 | print >> buf
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| 102 | self._gen_repr(buf)
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| 103 | buf.seek(0, 0)
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| 104 | return buf.read()
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| 105 |
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| 106 | def _gen_init(self, buf):
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| 107 | if self.args:
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| [391] | 108 | argtuple = '(' in self.args
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| 109 | args = self.args if not argtuple else ''.join(self.argnames)
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| 110 | print >> buf, " def __init__(self, %s, lineno=None):" % args
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| [2] | 111 | else:
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| 112 | print >> buf, " def __init__(self, lineno=None):"
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| 113 | if self.argnames:
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| [391] | 114 | if argtuple:
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| 115 | for idx, name in enumerate(self.argnames):
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| 116 | print >> buf, " self.%s = %s[%s]" % (name, args, idx)
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| 117 | else:
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| 118 | for name in self.argnames:
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| 119 | print >> buf, " self.%s = %s" % (name, name)
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| [2] | 120 | print >> buf, " self.lineno = lineno"
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| 121 | # Copy the lines in self.init, indented four spaces. The rstrip()
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| 122 | # business is to get rid of the four spaces if line happens to be
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| 123 | # empty, so that reindent.py is happy with the output.
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| 124 | for line in self.init:
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| 125 | print >> buf, (" " + line).rstrip()
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| 126 |
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| 127 | def _gen_getChildren(self, buf):
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| 128 | print >> buf, " def getChildren(self):"
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| 129 | if len(self.argnames) == 0:
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| 130 | print >> buf, " return ()"
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| 131 | else:
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| 132 | if self.hardest_arg < P_NESTED:
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| 133 | clist = COMMA.join(["self.%s" % c
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| 134 | for c in self.argnames])
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| 135 | if self.nargs == 1:
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| 136 | print >> buf, " return %s," % clist
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| 137 | else:
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| 138 | print >> buf, " return %s" % clist
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| 139 | else:
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| 140 | if len(self.argnames) == 1:
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| 141 | print >> buf, " return tuple(flatten(self.%s))" % self.argnames[0]
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| 142 | else:
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| 143 | print >> buf, " children = []"
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| 144 | template = " children.%s(%sself.%s%s)"
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| 145 | for name in self.argnames:
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| 146 | if self.argprops[name] == P_NESTED:
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| 147 | print >> buf, template % ("extend", "flatten(",
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| 148 | name, ")")
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| 149 | else:
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| 150 | print >> buf, template % ("append", "", name, "")
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| 151 | print >> buf, " return tuple(children)"
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| 152 |
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| 153 | def _gen_getChildNodes(self, buf):
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| 154 | print >> buf, " def getChildNodes(self):"
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| 155 | if len(self.argnames) == 0:
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| 156 | print >> buf, " return ()"
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| 157 | else:
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| 158 | if self.hardest_arg < P_NESTED:
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| 159 | clist = ["self.%s" % c
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| 160 | for c in self.argnames
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| 161 | if self.argprops[c] == P_NODE]
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| 162 | if len(clist) == 0:
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| 163 | print >> buf, " return ()"
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| 164 | elif len(clist) == 1:
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| 165 | print >> buf, " return %s," % clist[0]
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| 166 | else:
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| 167 | print >> buf, " return %s" % COMMA.join(clist)
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| 168 | else:
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| 169 | print >> buf, " nodelist = []"
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| 170 | template = " nodelist.%s(%sself.%s%s)"
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| 171 | for name in self.argnames:
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| 172 | if self.argprops[name] == P_NONE:
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| 173 | tmp = (" if self.%s is not None:\n"
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| 174 | " nodelist.append(self.%s)")
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| 175 | print >> buf, tmp % (name, name)
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| 176 | elif self.argprops[name] == P_NESTED:
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| 177 | print >> buf, template % ("extend", "flatten_nodes(",
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| 178 | name, ")")
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| 179 | elif self.argprops[name] == P_NODE:
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| 180 | print >> buf, template % ("append", "", name, "")
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| 181 | print >> buf, " return tuple(nodelist)"
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| 182 |
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| 183 | def _gen_repr(self, buf):
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| 184 | print >> buf, " def __repr__(self):"
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| 185 | if self.argnames:
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| 186 | fmt = COMMA.join(["%s"] * self.nargs)
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| 187 | if '(' in self.args:
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| 188 | fmt = '(%s)' % fmt
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| 189 | vals = ["repr(self.%s)" % name for name in self.argnames]
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| 190 | vals = COMMA.join(vals)
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| 191 | if self.nargs == 1:
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| 192 | vals = vals + ","
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| 193 | print >> buf, ' return "%s(%s)" %% (%s)' % \
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| 194 | (self.name, fmt, vals)
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| 195 | else:
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| 196 | print >> buf, ' return "%s()"' % self.name
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| 197 |
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| 198 | rx_init = re.compile('init\((.*)\):')
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| 199 |
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| 200 | def parse_spec(file):
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| 201 | classes = {}
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| 202 | cur = None
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| 203 | for line in fileinput.input(file):
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| 204 | if line.strip().startswith('#'):
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| 205 | continue
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| 206 | mo = rx_init.search(line)
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| 207 | if mo is None:
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| 208 | if cur is None:
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| 209 | # a normal entry
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| 210 | try:
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| 211 | name, args = line.split(':')
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| 212 | except ValueError:
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| 213 | continue
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| 214 | classes[name] = NodeInfo(name, args)
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| 215 | cur = None
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| 216 | else:
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| 217 | # some code for the __init__ method
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| 218 | cur.init.append(line)
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| 219 | else:
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| 220 | # some extra code for a Node's __init__ method
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| 221 | name = mo.group(1)
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| 222 | cur = classes[name]
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| 223 | return sorted(classes.values(), key=lambda n: n.name)
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| 224 |
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| 225 | def main():
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| 226 | prologue, epilogue = load_boilerplate(sys.argv[-1])
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| 227 | print prologue
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| 228 | print
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| 229 | classes = parse_spec(SPEC)
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| 230 | for info in classes:
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| 231 | print info.gen_source()
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| 232 | print epilogue
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| 233 |
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| 234 | if __name__ == "__main__":
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| 235 | main()
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| 236 | sys.exit(0)
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| 237 |
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| 238 | ### PROLOGUE
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| 239 | """Python abstract syntax node definitions
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| 240 |
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| 241 | This file is automatically generated by Tools/compiler/astgen.py
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| 242 | """
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| 243 | from consts import CO_VARARGS, CO_VARKEYWORDS
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| 244 |
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| 245 | def flatten(seq):
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| 246 | l = []
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| 247 | for elt in seq:
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| 248 | t = type(elt)
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| 249 | if t is tuple or t is list:
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| 250 | for elt2 in flatten(elt):
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| 251 | l.append(elt2)
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| 252 | else:
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| 253 | l.append(elt)
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| 254 | return l
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| 255 |
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| 256 | def flatten_nodes(seq):
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| 257 | return [n for n in flatten(seq) if isinstance(n, Node)]
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| 258 |
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| 259 | nodes = {}
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| 260 |
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| 261 | class Node:
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| 262 | """Abstract base class for ast nodes."""
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| 263 | def getChildren(self):
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| 264 | pass # implemented by subclasses
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| 265 | def __iter__(self):
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| 266 | for n in self.getChildren():
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| 267 | yield n
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| 268 | def asList(self): # for backwards compatibility
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| 269 | return self.getChildren()
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| 270 | def getChildNodes(self):
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| 271 | pass # implemented by subclasses
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| 272 |
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| 273 | class EmptyNode(Node):
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| 274 | pass
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| 275 |
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| 276 | class Expression(Node):
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| 277 | # Expression is an artificial node class to support "eval"
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| 278 | nodes["expression"] = "Expression"
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| 279 | def __init__(self, node):
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| 280 | self.node = node
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| 281 |
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| 282 | def getChildren(self):
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| 283 | return self.node,
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| 284 |
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| 285 | def getChildNodes(self):
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| 286 | return self.node,
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| 287 |
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| 288 | def __repr__(self):
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| 289 | return "Expression(%s)" % (repr(self.node))
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| 290 |
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| 291 | ### EPILOGUE
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| 292 | for name, obj in globals().items():
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| 293 | if isinstance(obj, type) and issubclass(obj, Node):
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| 294 | nodes[name.lower()] = obj
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