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1 | 1 | # parser.py - simple top-down operator precedence parser for mercurial |
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2 | 2 | # |
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3 | 3 | # Copyright 2010 Matt Mackall <mpm@selenic.com> |
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4 | 4 | # |
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5 | 5 | # This software may be used and distributed according to the terms of the |
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6 | 6 | # GNU General Public License version 2 or any later version. |
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7 | 7 | |
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8 | 8 | # see http://effbot.org/zone/simple-top-down-parsing.htm and |
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9 | 9 | # http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/ |
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10 | 10 | # for background |
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11 | 11 | |
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12 | 12 | # takes a tokenizer and elements |
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13 | 13 | # tokenizer is an iterator that returns (type, value, pos) tuples |
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14 | 14 | # elements is a mapping of types to binding strength, primary, prefix, infix |
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15 | 15 | # and suffix actions |
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16 | 16 | # an action is a tree node name, a tree label, and an optional match |
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17 | 17 | # __call__(program) parses program into a labeled tree |
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18 | 18 | |
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19 | 19 | from __future__ import absolute_import |
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20 | 20 | |
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21 | 21 | from .i18n import _ |
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22 | 22 | from . import error |
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23 | 23 | |
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24 | 24 | class parser(object): |
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25 | 25 | def __init__(self, elements, methods=None): |
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26 | 26 | self._elements = elements |
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27 | 27 | self._methods = methods |
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28 | 28 | self.current = None |
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29 | 29 | def _advance(self): |
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30 | 30 | 'advance the tokenizer' |
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31 | 31 | t = self.current |
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32 | 32 | self.current = next(self._iter, None) |
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33 | 33 | return t |
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34 | 34 | def _hasnewterm(self): |
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35 | 35 | 'True if next token may start new term' |
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36 | 36 | return any(self._elements[self.current[0]][1:3]) |
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37 | 37 | def _match(self, m): |
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38 | 38 | 'make sure the tokenizer matches an end condition' |
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39 | 39 | if self.current[0] != m: |
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40 | 40 | raise error.ParseError(_("unexpected token: %s") % self.current[0], |
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41 | 41 | self.current[2]) |
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42 | 42 | self._advance() |
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43 | 43 | def _parseoperand(self, bind, m=None): |
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44 | 44 | 'gather right-hand-side operand until an end condition or binding met' |
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45 | 45 | if m and self.current[0] == m: |
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46 | 46 | expr = None |
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47 | 47 | else: |
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48 | 48 | expr = self._parse(bind) |
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49 | 49 | if m: |
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50 | 50 | self._match(m) |
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51 | 51 | return expr |
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52 | 52 | def _parse(self, bind=0): |
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53 | 53 | token, value, pos = self._advance() |
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54 | 54 | # handle prefix rules on current token, take as primary if unambiguous |
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55 | 55 | primary, prefix = self._elements[token][1:3] |
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56 | 56 | if primary and not (prefix and self._hasnewterm()): |
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57 | 57 | expr = (primary, value) |
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58 | 58 | elif prefix: |
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59 | 59 | expr = (prefix[0], self._parseoperand(*prefix[1:])) |
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60 | 60 | else: |
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61 | 61 | raise error.ParseError(_("not a prefix: %s") % token, pos) |
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62 | 62 | # gather tokens until we meet a lower binding strength |
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63 | 63 | while bind < self._elements[self.current[0]][0]: |
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64 | 64 | token, value, pos = self._advance() |
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65 | 65 | # handle infix rules, take as suffix if unambiguous |
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66 | 66 | infix, suffix = self._elements[token][3:] |
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67 | 67 | if suffix and not (infix and self._hasnewterm()): |
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68 | 68 | expr = (suffix, expr) |
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69 | 69 | elif infix: |
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70 | 70 | expr = (infix[0], expr, self._parseoperand(*infix[1:])) |
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71 | 71 | else: |
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72 | 72 | raise error.ParseError(_("not an infix: %s") % token, pos) |
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73 | 73 | return expr |
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74 | 74 | def parse(self, tokeniter): |
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75 | 75 | 'generate a parse tree from tokens' |
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76 | 76 | self._iter = tokeniter |
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77 | 77 | self._advance() |
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78 | 78 | res = self._parse() |
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79 | 79 | token, value, pos = self.current |
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80 | 80 | return res, pos |
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81 | 81 | def eval(self, tree): |
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82 | 82 | 'recursively evaluate a parse tree using node methods' |
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83 | 83 | if not isinstance(tree, tuple): |
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84 | 84 | return tree |
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85 | 85 | return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]]) |
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86 | 86 | def __call__(self, tokeniter): |
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87 | 87 | 'parse tokens into a parse tree and evaluate if methods given' |
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88 | 88 | t = self.parse(tokeniter) |
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89 | 89 | if self._methods: |
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90 | 90 | return self.eval(t) |
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91 | 91 | return t |
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92 | 92 | |
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93 | 93 | def buildargsdict(trees, funcname, keys, keyvaluenode, keynode): |
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94 | 94 | """Build dict from list containing positional and keyword arguments |
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95 | 95 | |
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96 | 96 | Invalid keywords or too many positional arguments are rejected, but |
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97 | 97 | missing arguments are just omitted. |
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98 | 98 | """ |
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99 | kwstart = next((i for i, x in enumerate(trees) if x[0] == keyvaluenode), | |
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100 | len(trees)) | |
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99 | 101 | if len(trees) > len(keys): |
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100 | 102 | raise error.ParseError(_("%(func)s takes at most %(nargs)d arguments") |
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101 | 103 | % {'func': funcname, 'nargs': len(keys)}) |
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102 | 104 | args = {} |
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103 | 105 | # consume positional arguments |
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104 | for k, x in zip(keys, trees): | |
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105 | if x[0] == keyvaluenode: | |
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106 | break | |
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106 | for k, x in zip(keys, trees[:kwstart]): | |
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107 | 107 | args[k] = x |
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108 | assert len(args) == kwstart | |
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108 | 109 | # remainder should be keyword arguments |
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109 |
for x in trees[ |
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110 | for x in trees[kwstart:]: | |
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110 | 111 | if x[0] != keyvaluenode or x[1][0] != keynode: |
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111 | 112 | raise error.ParseError(_("%(func)s got an invalid argument") |
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112 | 113 | % {'func': funcname}) |
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113 | 114 | k = x[1][1] |
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114 | 115 | if k not in keys: |
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115 | 116 | raise error.ParseError(_("%(func)s got an unexpected keyword " |
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116 | 117 | "argument '%(key)s'") |
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117 | 118 | % {'func': funcname, 'key': k}) |
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118 | 119 | if k in args: |
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119 | 120 | raise error.ParseError(_("%(func)s got multiple values for keyword " |
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120 | 121 | "argument '%(key)s'") |
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121 | 122 | % {'func': funcname, 'key': k}) |
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122 | 123 | args[k] = x[2] |
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123 | 124 | return args |
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124 | 125 | |
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125 | 126 | def unescapestr(s): |
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126 | 127 | try: |
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127 | 128 | return s.decode("string_escape") |
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128 | 129 | except ValueError as e: |
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129 | 130 | # mangle Python's exception into our format |
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130 | 131 | raise error.ParseError(str(e).lower()) |
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131 | 132 | |
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132 | 133 | def _prettyformat(tree, leafnodes, level, lines): |
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133 | 134 | if not isinstance(tree, tuple) or tree[0] in leafnodes: |
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134 | 135 | lines.append((level, str(tree))) |
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135 | 136 | else: |
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136 | 137 | lines.append((level, '(%s' % tree[0])) |
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137 | 138 | for s in tree[1:]: |
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138 | 139 | _prettyformat(s, leafnodes, level + 1, lines) |
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139 | 140 | lines[-1:] = [(lines[-1][0], lines[-1][1] + ')')] |
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140 | 141 | |
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141 | 142 | def prettyformat(tree, leafnodes): |
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142 | 143 | lines = [] |
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143 | 144 | _prettyformat(tree, leafnodes, 0, lines) |
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144 | 145 | output = '\n'.join((' ' * l + s) for l, s in lines) |
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145 | 146 | return output |
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146 | 147 | |
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147 | 148 | def simplifyinfixops(tree, targetnodes): |
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148 | 149 | """Flatten chained infix operations to reduce usage of Python stack |
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149 | 150 | |
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150 | 151 | >>> def f(tree): |
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151 | 152 | ... print prettyformat(simplifyinfixops(tree, ('or',)), ('symbol',)) |
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152 | 153 | >>> f(('or', |
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153 | 154 | ... ('or', |
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154 | 155 | ... ('symbol', '1'), |
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155 | 156 | ... ('symbol', '2')), |
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156 | 157 | ... ('symbol', '3'))) |
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157 | 158 | (or |
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158 | 159 | ('symbol', '1') |
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159 | 160 | ('symbol', '2') |
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160 | 161 | ('symbol', '3')) |
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161 | 162 | >>> f(('func', |
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162 | 163 | ... ('symbol', 'p1'), |
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163 | 164 | ... ('or', |
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164 | 165 | ... ('or', |
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165 | 166 | ... ('func', |
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166 | 167 | ... ('symbol', 'sort'), |
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167 | 168 | ... ('list', |
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168 | 169 | ... ('or', |
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169 | 170 | ... ('or', |
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170 | 171 | ... ('symbol', '1'), |
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171 | 172 | ... ('symbol', '2')), |
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172 | 173 | ... ('symbol', '3')), |
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173 | 174 | ... ('negate', |
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174 | 175 | ... ('symbol', 'rev')))), |
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175 | 176 | ... ('and', |
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176 | 177 | ... ('symbol', '4'), |
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177 | 178 | ... ('group', |
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178 | 179 | ... ('or', |
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179 | 180 | ... ('or', |
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180 | 181 | ... ('symbol', '5'), |
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181 | 182 | ... ('symbol', '6')), |
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182 | 183 | ... ('symbol', '7'))))), |
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183 | 184 | ... ('symbol', '8')))) |
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184 | 185 | (func |
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185 | 186 | ('symbol', 'p1') |
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186 | 187 | (or |
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187 | 188 | (func |
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188 | 189 | ('symbol', 'sort') |
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189 | 190 | (list |
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190 | 191 | (or |
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191 | 192 | ('symbol', '1') |
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192 | 193 | ('symbol', '2') |
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193 | 194 | ('symbol', '3')) |
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194 | 195 | (negate |
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195 | 196 | ('symbol', 'rev')))) |
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196 | 197 | (and |
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197 | 198 | ('symbol', '4') |
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198 | 199 | (group |
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199 | 200 | (or |
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200 | 201 | ('symbol', '5') |
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201 | 202 | ('symbol', '6') |
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202 | 203 | ('symbol', '7')))) |
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203 | 204 | ('symbol', '8'))) |
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204 | 205 | """ |
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205 | 206 | if not isinstance(tree, tuple): |
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206 | 207 | return tree |
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207 | 208 | op = tree[0] |
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208 | 209 | if op not in targetnodes: |
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209 | 210 | return (op,) + tuple(simplifyinfixops(x, targetnodes) for x in tree[1:]) |
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210 | 211 | |
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211 | 212 | # walk down left nodes taking each right node. no recursion to left nodes |
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212 | 213 | # because infix operators are left-associative, i.e. left tree is deep. |
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213 | 214 | # e.g. '1 + 2 + 3' -> (+ (+ 1 2) 3) -> (+ 1 2 3) |
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214 | 215 | simplified = [] |
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215 | 216 | x = tree |
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216 | 217 | while x[0] == op: |
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217 | 218 | l, r = x[1:] |
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218 | 219 | simplified.append(simplifyinfixops(r, targetnodes)) |
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219 | 220 | x = l |
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220 | 221 | simplified.append(simplifyinfixops(x, targetnodes)) |
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221 | 222 | simplified.append(op) |
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222 | 223 | return tuple(reversed(simplified)) |
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223 | 224 | |
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224 | 225 | def parseerrordetail(inst): |
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225 | 226 | """Compose error message from specified ParseError object |
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226 | 227 | """ |
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227 | 228 | if len(inst.args) > 1: |
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228 | 229 | return _('at %s: %s') % (inst.args[1], inst.args[0]) |
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229 | 230 | else: |
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230 | 231 | return inst.args[0] |
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231 | 232 | |
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232 | 233 | class alias(object): |
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233 | 234 | """Parsed result of alias""" |
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234 | 235 | |
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235 | 236 | def __init__(self, name, args, err, replacement): |
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236 | 237 | self.name = name |
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237 | 238 | self.args = args |
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238 | 239 | self.error = err |
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239 | 240 | self.replacement = replacement |
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240 | 241 | # whether own `error` information is already shown or not. |
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241 | 242 | # this avoids showing same warning multiple times at each |
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242 | 243 | # `expandaliases`. |
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243 | 244 | self.warned = False |
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244 | 245 | |
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245 | 246 | class basealiasrules(object): |
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246 | 247 | """Parsing and expansion rule set of aliases |
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247 | 248 | |
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248 | 249 | This is a helper for fileset/revset/template aliases. A concrete rule set |
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249 | 250 | should be made by sub-classing this and implementing class/static methods. |
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250 | 251 | |
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251 | 252 | It supports alias expansion of symbol and function-call styles:: |
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252 | 253 | |
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253 | 254 | # decl = defn |
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254 | 255 | h = heads(default) |
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255 | 256 | b($1) = ancestors($1) - ancestors(default) |
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256 | 257 | """ |
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257 | 258 | # typically a config section, which will be included in error messages |
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258 | 259 | _section = None |
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259 | 260 | # tag of symbol node |
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260 | 261 | _symbolnode = 'symbol' |
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261 | 262 | |
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262 | 263 | def __new__(cls): |
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263 | 264 | raise TypeError("'%s' is not instantiatable" % cls.__name__) |
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264 | 265 | |
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265 | 266 | @staticmethod |
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266 | 267 | def _parse(spec): |
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267 | 268 | """Parse an alias name, arguments and definition""" |
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268 | 269 | raise NotImplementedError |
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269 | 270 | |
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270 | 271 | @staticmethod |
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271 | 272 | def _trygetfunc(tree): |
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272 | 273 | """Return (name, args) if tree is a function; otherwise None""" |
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273 | 274 | raise NotImplementedError |
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274 | 275 | |
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275 | 276 | @classmethod |
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276 | 277 | def _builddecl(cls, decl): |
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277 | 278 | """Parse an alias declaration into ``(name, args, errorstr)`` |
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278 | 279 | |
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279 | 280 | This function analyzes the parsed tree. The parsing rule is provided |
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280 | 281 | by ``_parse()``. |
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281 | 282 | |
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282 | 283 | - ``name``: of declared alias (may be ``decl`` itself at error) |
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283 | 284 | - ``args``: list of argument names (or None for symbol declaration) |
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284 | 285 | - ``errorstr``: detail about detected error (or None) |
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285 | 286 | |
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286 | 287 | >>> sym = lambda x: ('symbol', x) |
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287 | 288 | >>> symlist = lambda *xs: ('list',) + tuple(sym(x) for x in xs) |
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288 | 289 | >>> func = lambda n, a: ('func', sym(n), a) |
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289 | 290 | >>> parsemap = { |
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290 | 291 | ... 'foo': sym('foo'), |
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291 | 292 | ... '$foo': sym('$foo'), |
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292 | 293 | ... 'foo::bar': ('dagrange', sym('foo'), sym('bar')), |
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293 | 294 | ... 'foo()': func('foo', None), |
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294 | 295 | ... '$foo()': func('$foo', None), |
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295 | 296 | ... 'foo($1, $2)': func('foo', symlist('$1', '$2')), |
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296 | 297 | ... 'foo(bar_bar, baz.baz)': |
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297 | 298 | ... func('foo', symlist('bar_bar', 'baz.baz')), |
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298 | 299 | ... 'foo(bar($1, $2))': |
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299 | 300 | ... func('foo', func('bar', symlist('$1', '$2'))), |
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300 | 301 | ... 'foo($1, $2, nested($1, $2))': |
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301 | 302 | ... func('foo', (symlist('$1', '$2') + |
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302 | 303 | ... (func('nested', symlist('$1', '$2')),))), |
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303 | 304 | ... 'foo("bar")': func('foo', ('string', 'bar')), |
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304 | 305 | ... 'foo($1, $2': error.ParseError('unexpected token: end', 10), |
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305 | 306 | ... 'foo("bar': error.ParseError('unterminated string', 5), |
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306 | 307 | ... 'foo($1, $2, $1)': func('foo', symlist('$1', '$2', '$1')), |
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307 | 308 | ... } |
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308 | 309 | >>> def parse(expr): |
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309 | 310 | ... x = parsemap[expr] |
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310 | 311 | ... if isinstance(x, Exception): |
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311 | 312 | ... raise x |
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312 | 313 | ... return x |
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313 | 314 | >>> def trygetfunc(tree): |
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314 | 315 | ... if not tree or tree[0] != 'func' or tree[1][0] != 'symbol': |
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315 | 316 | ... return None |
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316 | 317 | ... if not tree[2]: |
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317 | 318 | ... return tree[1][1], [] |
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318 | 319 | ... if tree[2][0] == 'list': |
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319 | 320 | ... return tree[1][1], list(tree[2][1:]) |
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320 | 321 | ... return tree[1][1], [tree[2]] |
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321 | 322 | >>> class aliasrules(basealiasrules): |
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322 | 323 | ... _parse = staticmethod(parse) |
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323 | 324 | ... _trygetfunc = staticmethod(trygetfunc) |
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324 | 325 | >>> builddecl = aliasrules._builddecl |
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325 | 326 | >>> builddecl('foo') |
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326 | 327 | ('foo', None, None) |
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327 | 328 | >>> builddecl('$foo') |
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328 | 329 | ('$foo', None, "invalid symbol '$foo'") |
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329 | 330 | >>> builddecl('foo::bar') |
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330 | 331 | ('foo::bar', None, 'invalid format') |
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331 | 332 | >>> builddecl('foo()') |
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332 | 333 | ('foo', [], None) |
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333 | 334 | >>> builddecl('$foo()') |
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334 | 335 | ('$foo()', None, "invalid function '$foo'") |
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335 | 336 | >>> builddecl('foo($1, $2)') |
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336 | 337 | ('foo', ['$1', '$2'], None) |
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337 | 338 | >>> builddecl('foo(bar_bar, baz.baz)') |
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338 | 339 | ('foo', ['bar_bar', 'baz.baz'], None) |
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339 | 340 | >>> builddecl('foo($1, $2, nested($1, $2))') |
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340 | 341 | ('foo($1, $2, nested($1, $2))', None, 'invalid argument list') |
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341 | 342 | >>> builddecl('foo(bar($1, $2))') |
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342 | 343 | ('foo(bar($1, $2))', None, 'invalid argument list') |
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343 | 344 | >>> builddecl('foo("bar")') |
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344 | 345 | ('foo("bar")', None, 'invalid argument list') |
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345 | 346 | >>> builddecl('foo($1, $2') |
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346 | 347 | ('foo($1, $2', None, 'at 10: unexpected token: end') |
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347 | 348 | >>> builddecl('foo("bar') |
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348 | 349 | ('foo("bar', None, 'at 5: unterminated string') |
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349 | 350 | >>> builddecl('foo($1, $2, $1)') |
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350 | 351 | ('foo', None, 'argument names collide with each other') |
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351 | 352 | """ |
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352 | 353 | try: |
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353 | 354 | tree = cls._parse(decl) |
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354 | 355 | except error.ParseError as inst: |
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355 | 356 | return (decl, None, parseerrordetail(inst)) |
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356 | 357 | |
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357 | 358 | if tree[0] == cls._symbolnode: |
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358 | 359 | # "name = ...." style |
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359 | 360 | name = tree[1] |
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360 | 361 | if name.startswith('$'): |
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361 | 362 | return (decl, None, _("invalid symbol '%s'") % name) |
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362 | 363 | return (name, None, None) |
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363 | 364 | |
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364 | 365 | func = cls._trygetfunc(tree) |
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365 | 366 | if func: |
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366 | 367 | # "name(arg, ....) = ...." style |
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367 | 368 | name, args = func |
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368 | 369 | if name.startswith('$'): |
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369 | 370 | return (decl, None, _("invalid function '%s'") % name) |
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370 | 371 | if any(t[0] != cls._symbolnode for t in args): |
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371 | 372 | return (decl, None, _("invalid argument list")) |
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372 | 373 | if len(args) != len(set(args)): |
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373 | 374 | return (name, None, _("argument names collide with each other")) |
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374 | 375 | return (name, [t[1] for t in args], None) |
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375 | 376 | |
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376 | 377 | return (decl, None, _("invalid format")) |
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377 | 378 | |
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378 | 379 | @classmethod |
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379 | 380 | def _relabelargs(cls, tree, args): |
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380 | 381 | """Mark alias arguments as ``_aliasarg``""" |
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381 | 382 | if not isinstance(tree, tuple): |
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382 | 383 | return tree |
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383 | 384 | op = tree[0] |
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384 | 385 | if op != cls._symbolnode: |
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385 | 386 | return (op,) + tuple(cls._relabelargs(x, args) for x in tree[1:]) |
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386 | 387 | |
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387 | 388 | assert len(tree) == 2 |
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388 | 389 | sym = tree[1] |
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389 | 390 | if sym in args: |
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390 | 391 | op = '_aliasarg' |
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391 | 392 | elif sym.startswith('$'): |
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392 | 393 | raise error.ParseError(_("invalid symbol '%s'") % sym) |
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393 | 394 | return (op, sym) |
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394 | 395 | |
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395 | 396 | @classmethod |
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396 | 397 | def _builddefn(cls, defn, args): |
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397 | 398 | """Parse an alias definition into a tree and marks substitutions |
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398 | 399 | |
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399 | 400 | This function marks alias argument references as ``_aliasarg``. The |
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400 | 401 | parsing rule is provided by ``_parse()``. |
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401 | 402 | |
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402 | 403 | ``args`` is a list of alias argument names, or None if the alias |
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403 | 404 | is declared as a symbol. |
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404 | 405 | |
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405 | 406 | >>> parsemap = { |
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406 | 407 | ... '$1 or foo': ('or', ('symbol', '$1'), ('symbol', 'foo')), |
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407 | 408 | ... '$1 or $bar': ('or', ('symbol', '$1'), ('symbol', '$bar')), |
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408 | 409 | ... '$10 or baz': ('or', ('symbol', '$10'), ('symbol', 'baz')), |
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409 | 410 | ... '"$1" or "foo"': ('or', ('string', '$1'), ('string', 'foo')), |
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410 | 411 | ... } |
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411 | 412 | >>> class aliasrules(basealiasrules): |
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412 | 413 | ... _parse = staticmethod(parsemap.__getitem__) |
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413 | 414 | ... _trygetfunc = staticmethod(lambda x: None) |
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414 | 415 | >>> builddefn = aliasrules._builddefn |
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415 | 416 | >>> def pprint(tree): |
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416 | 417 | ... print prettyformat(tree, ('_aliasarg', 'string', 'symbol')) |
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417 | 418 | >>> args = ['$1', '$2', 'foo'] |
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418 | 419 | >>> pprint(builddefn('$1 or foo', args)) |
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419 | 420 | (or |
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420 | 421 | ('_aliasarg', '$1') |
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421 | 422 | ('_aliasarg', 'foo')) |
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422 | 423 | >>> try: |
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423 | 424 | ... builddefn('$1 or $bar', args) |
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424 | 425 | ... except error.ParseError as inst: |
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425 | 426 | ... print parseerrordetail(inst) |
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426 | 427 | invalid symbol '$bar' |
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427 | 428 | >>> args = ['$1', '$10', 'foo'] |
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428 | 429 | >>> pprint(builddefn('$10 or baz', args)) |
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429 | 430 | (or |
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430 | 431 | ('_aliasarg', '$10') |
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431 | 432 | ('symbol', 'baz')) |
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432 | 433 | >>> pprint(builddefn('"$1" or "foo"', args)) |
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433 | 434 | (or |
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434 | 435 | ('string', '$1') |
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435 | 436 | ('string', 'foo')) |
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436 | 437 | """ |
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437 | 438 | tree = cls._parse(defn) |
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438 | 439 | if args: |
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439 | 440 | args = set(args) |
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440 | 441 | else: |
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441 | 442 | args = set() |
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442 | 443 | return cls._relabelargs(tree, args) |
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443 | 444 | |
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444 | 445 | @classmethod |
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445 | 446 | def build(cls, decl, defn): |
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446 | 447 | """Parse an alias declaration and definition into an alias object""" |
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447 | 448 | repl = efmt = None |
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448 | 449 | name, args, err = cls._builddecl(decl) |
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449 | 450 | if err: |
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450 | 451 | efmt = _('bad declaration of %(section)s "%(name)s": %(error)s') |
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451 | 452 | else: |
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452 | 453 | try: |
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453 | 454 | repl = cls._builddefn(defn, args) |
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454 | 455 | except error.ParseError as inst: |
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455 | 456 | err = parseerrordetail(inst) |
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456 | 457 | efmt = _('bad definition of %(section)s "%(name)s": %(error)s') |
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457 | 458 | if err: |
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458 | 459 | err = efmt % {'section': cls._section, 'name': name, 'error': err} |
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459 | 460 | return alias(name, args, err, repl) |
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460 | 461 | |
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461 | 462 | @classmethod |
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462 | 463 | def buildmap(cls, items): |
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463 | 464 | """Parse a list of alias (name, replacement) pairs into a dict of |
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464 | 465 | alias objects""" |
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465 | 466 | aliases = {} |
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466 | 467 | for decl, defn in items: |
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467 | 468 | a = cls.build(decl, defn) |
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468 | 469 | aliases[a.name] = a |
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469 | 470 | return aliases |
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470 | 471 | |
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471 | 472 | @classmethod |
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472 | 473 | def _getalias(cls, aliases, tree): |
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473 | 474 | """If tree looks like an unexpanded alias, return (alias, pattern-args) |
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474 | 475 | pair. Return None otherwise. |
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475 | 476 | """ |
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476 | 477 | if not isinstance(tree, tuple): |
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477 | 478 | return None |
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478 | 479 | if tree[0] == cls._symbolnode: |
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479 | 480 | name = tree[1] |
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480 | 481 | a = aliases.get(name) |
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481 | 482 | if a and a.args is None: |
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482 | 483 | return a, None |
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483 | 484 | func = cls._trygetfunc(tree) |
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484 | 485 | if func: |
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485 | 486 | name, args = func |
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486 | 487 | a = aliases.get(name) |
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487 | 488 | if a and a.args is not None: |
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488 | 489 | return a, args |
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489 | 490 | return None |
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490 | 491 | |
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491 | 492 | @classmethod |
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492 | 493 | def _expandargs(cls, tree, args): |
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493 | 494 | """Replace _aliasarg instances with the substitution value of the |
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494 | 495 | same name in args, recursively. |
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495 | 496 | """ |
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496 | 497 | if not isinstance(tree, tuple): |
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497 | 498 | return tree |
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498 | 499 | if tree[0] == '_aliasarg': |
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499 | 500 | sym = tree[1] |
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500 | 501 | return args[sym] |
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501 | 502 | return tuple(cls._expandargs(t, args) for t in tree) |
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502 | 503 | |
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503 | 504 | @classmethod |
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504 | 505 | def _expand(cls, aliases, tree, expanding, cache): |
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505 | 506 | if not isinstance(tree, tuple): |
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506 | 507 | return tree |
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507 | 508 | r = cls._getalias(aliases, tree) |
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508 | 509 | if r is None: |
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509 | 510 | return tuple(cls._expand(aliases, t, expanding, cache) |
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510 | 511 | for t in tree) |
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511 | 512 | a, l = r |
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512 | 513 | if a.error: |
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513 | 514 | raise error.Abort(a.error) |
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514 | 515 | if a in expanding: |
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515 | 516 | raise error.ParseError(_('infinite expansion of %(section)s ' |
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516 | 517 | '"%(name)s" detected') |
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517 | 518 | % {'section': cls._section, 'name': a.name}) |
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518 | 519 | # get cacheable replacement tree by expanding aliases recursively |
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519 | 520 | expanding.append(a) |
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520 | 521 | if a.name not in cache: |
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521 | 522 | cache[a.name] = cls._expand(aliases, a.replacement, expanding, |
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522 | 523 | cache) |
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523 | 524 | result = cache[a.name] |
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524 | 525 | expanding.pop() |
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525 | 526 | if a.args is None: |
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526 | 527 | return result |
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527 | 528 | # substitute function arguments in replacement tree |
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528 | 529 | if len(l) != len(a.args): |
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529 | 530 | raise error.ParseError(_('invalid number of arguments: %d') |
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530 | 531 | % len(l)) |
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531 | 532 | l = [cls._expand(aliases, t, [], cache) for t in l] |
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532 | 533 | return cls._expandargs(result, dict(zip(a.args, l))) |
|
533 | 534 | |
|
534 | 535 | @classmethod |
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535 | 536 | def expand(cls, aliases, tree): |
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536 | 537 | """Expand aliases in tree, recursively. |
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537 | 538 | |
|
538 | 539 | 'aliases' is a dictionary mapping user defined aliases to alias objects. |
|
539 | 540 | """ |
|
540 | 541 | return cls._expand(aliases, tree, [], {}) |
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