Mercurial > hg
annotate mercurial/parser.py @ 27015:341cb90ffd18
util: disable floating point stat times (issue4836)
Alternate fix for this issue which avoids putting extra function calls
and exception handling in the fast path.
For almost all purposes, integer timestamps are preferable to
Mercurial. It stores integer timestamps in the dirstate and would thus
like to avoid doing any float/int comparisons or conversions. We will
continue to have to deal with 1-second granularity on filesystems for
quite some time, so this won't significantly hinder our capabilities.
This has some impact on our file cache validation code in that it
lowers timestamp resolution. But as we still have to deal with
low-resolution filesystems, we're not relying on this anyway.
An alternate approach is to use stat[ST_MTIME], which is guaranteed to
be an integer. But since this support isn't already in our extension,
we can't depend on it being available without adding a hard Python->C
API dependency that's painful for people like yours truly who have
bisect regularly and people without compilers.
author | Matt Mackall <mpm@selenic.com> |
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date | Thu, 19 Nov 2015 13:21:24 -0600 |
parents | 87c9c562c37a |
children | 639e0f1e8ffa |
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11274 | 1 # parser.py - simple top-down operator precedence parser for mercurial |
2 # | |
3 # Copyright 2010 Matt Mackall <mpm@selenic.com> | |
4 # | |
5 # This software may be used and distributed according to the terms of the | |
6 # GNU General Public License version 2 or any later version. | |
7 | |
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8 # see http://effbot.org/zone/simple-top-down-parsing.htm and |
11274 | 9 # http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/ |
10 # for background | |
11 | |
12 # takes a tokenizer and elements | |
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13 # tokenizer is an iterator that returns (type, value, pos) tuples |
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14 # elements is a mapping of types to binding strength, primary, prefix, infix |
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15 # and suffix actions |
11274 | 16 # an action is a tree node name, a tree label, and an optional match |
17500 | 17 # __call__(program) parses program into a labeled tree |
11274 | 18 |
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19 from __future__ import absolute_import |
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20 |
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21 from .i18n import _ |
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22 from . import error |
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23 |
11274 | 24 class parser(object): |
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25 def __init__(self, elements, methods=None): |
11274 | 26 self._elements = elements |
27 self._methods = methods | |
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28 self.current = None |
11274 | 29 def _advance(self): |
30 'advance the tokenizer' | |
31 t = self.current | |
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32 self.current = next(self._iter, None) |
11274 | 33 return t |
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34 def _hasnewterm(self): |
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35 'True if next token may start new term' |
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36 return any(self._elements[self.current[0]][1:3]) |
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37 def _match(self, m): |
11274 | 38 'make sure the tokenizer matches an end condition' |
39 if self.current[0] != m: | |
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40 raise error.ParseError(_("unexpected token: %s") % self.current[0], |
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41 self.current[2]) |
11274 | 42 self._advance() |
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43 def _parseoperand(self, bind, m=None): |
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44 'gather right-hand-side operand until an end condition or binding met' |
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45 if m and self.current[0] == m: |
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46 expr = None |
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47 else: |
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48 expr = self._parse(bind) |
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49 if m: |
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50 self._match(m) |
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51 return expr |
11274 | 52 def _parse(self, bind=0): |
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53 token, value, pos = self._advance() |
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54 # handle prefix rules on current token, take as primary if unambiguous |
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55 primary, prefix = self._elements[token][1:3] |
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56 if primary and not (prefix and self._hasnewterm()): |
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57 expr = (primary, value) |
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58 elif prefix: |
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59 expr = (prefix[0], self._parseoperand(*prefix[1:])) |
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60 else: |
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61 raise error.ParseError(_("not a prefix: %s") % token, pos) |
11274 | 62 # gather tokens until we meet a lower binding strength |
63 while bind < self._elements[self.current[0]][0]: | |
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64 token, value, pos = self._advance() |
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65 # handle infix rules, take as suffix if unambiguous |
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66 infix, suffix = self._elements[token][3:] |
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67 if suffix and not (infix and self._hasnewterm()): |
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68 expr = (suffix[0], expr) |
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69 elif infix: |
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70 expr = (infix[0], expr, self._parseoperand(*infix[1:])) |
11274 | 71 else: |
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72 raise error.ParseError(_("not an infix: %s") % token, pos) |
11274 | 73 return expr |
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74 def parse(self, tokeniter): |
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75 'generate a parse tree from tokens' |
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76 self._iter = tokeniter |
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77 self._advance() |
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78 res = self._parse() |
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79 token, value, pos = self.current |
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80 return res, pos |
11274 | 81 def eval(self, tree): |
82 'recursively evaluate a parse tree using node methods' | |
83 if not isinstance(tree, tuple): | |
84 return tree | |
85 return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]]) | |
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86 def __call__(self, tokeniter): |
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87 'parse tokens into a parse tree and evaluate if methods given' |
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88 t = self.parse(tokeniter) |
11274 | 89 if self._methods: |
90 return self.eval(t) | |
91 return t | |
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92 |
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93 def buildargsdict(trees, funcname, keys, keyvaluenode, keynode): |
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94 """Build dict from list containing positional and keyword arguments |
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95 |
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96 Invalid keywords or too many positional arguments are rejected, but |
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97 missing arguments are just omitted. |
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98 """ |
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99 if len(trees) > len(keys): |
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100 raise error.ParseError(_("%(func)s takes at most %(nargs)d arguments") |
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101 % {'func': funcname, 'nargs': len(keys)}) |
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102 args = {} |
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103 # 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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107 args[k] = x |
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108 # remainder should be keyword arguments |
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109 for x in trees[len(args):]: |
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110 if x[0] != keyvaluenode or x[1][0] != keynode: |
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111 raise error.ParseError(_("%(func)s got an invalid argument") |
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112 % {'func': funcname}) |
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113 k = x[1][1] |
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114 if k not in keys: |
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115 raise error.ParseError(_("%(func)s got an unexpected keyword " |
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116 "argument '%(key)s'") |
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117 % {'func': funcname, 'key': k}) |
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118 if k in args: |
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119 raise error.ParseError(_("%(func)s got multiple values for keyword " |
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120 "argument '%(key)s'") |
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121 % {'func': funcname, 'key': k}) |
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122 args[k] = x[2] |
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123 return args |
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124 |
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125 def unescapestr(s): |
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126 try: |
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127 return s.decode("string_escape") |
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128 except ValueError as e: |
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129 # mangle Python's exception into our format |
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130 raise error.ParseError(str(e).lower()) |
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131 |
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132 def _prettyformat(tree, leafnodes, level, lines): |
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133 if not isinstance(tree, tuple) or tree[0] in leafnodes: |
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134 lines.append((level, str(tree))) |
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135 else: |
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136 lines.append((level, '(%s' % tree[0])) |
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137 for s in tree[1:]: |
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138 _prettyformat(s, leafnodes, level + 1, lines) |
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139 lines[-1:] = [(lines[-1][0], lines[-1][1] + ')')] |
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140 |
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141 def prettyformat(tree, leafnodes): |
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142 lines = [] |
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143 _prettyformat(tree, leafnodes, 0, lines) |
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144 output = '\n'.join((' ' * l + s) for l, s in lines) |
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145 return output |
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146 |
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147 def simplifyinfixops(tree, targetnodes): |
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148 """Flatten chained infix operations to reduce usage of Python stack |
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149 |
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150 >>> def f(tree): |
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151 ... print prettyformat(simplifyinfixops(tree, ('or',)), ('symbol',)) |
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152 >>> f(('or', |
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153 ... ('or', |
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154 ... ('symbol', '1'), |
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155 ... ('symbol', '2')), |
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156 ... ('symbol', '3'))) |
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157 (or |
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158 ('symbol', '1') |
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159 ('symbol', '2') |
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160 ('symbol', '3')) |
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161 >>> f(('func', |
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162 ... ('symbol', 'p1'), |
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163 ... ('or', |
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164 ... ('or', |
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165 ... ('func', |
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166 ... ('symbol', 'sort'), |
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167 ... ('list', |
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168 ... ('or', |
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169 ... ('or', |
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170 ... ('symbol', '1'), |
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171 ... ('symbol', '2')), |
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172 ... ('symbol', '3')), |
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173 ... ('negate', |
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174 ... ('symbol', 'rev')))), |
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175 ... ('and', |
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176 ... ('symbol', '4'), |
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177 ... ('group', |
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178 ... ('or', |
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179 ... ('or', |
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180 ... ('symbol', '5'), |
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181 ... ('symbol', '6')), |
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182 ... ('symbol', '7'))))), |
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183 ... ('symbol', '8')))) |
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184 (func |
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185 ('symbol', 'p1') |
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186 (or |
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187 (func |
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188 ('symbol', 'sort') |
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189 (list |
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190 (or |
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191 ('symbol', '1') |
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192 ('symbol', '2') |
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193 ('symbol', '3')) |
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194 (negate |
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195 ('symbol', 'rev')))) |
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196 (and |
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197 ('symbol', '4') |
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198 (group |
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199 (or |
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200 ('symbol', '5') |
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201 ('symbol', '6') |
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202 ('symbol', '7')))) |
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203 ('symbol', '8'))) |
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204 """ |
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205 if not isinstance(tree, tuple): |
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206 return tree |
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207 op = tree[0] |
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208 if op not in targetnodes: |
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209 return (op,) + tuple(simplifyinfixops(x, targetnodes) for x in tree[1:]) |
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210 |
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211 # walk down left nodes taking each right node. no recursion to left nodes |
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212 # because infix operators are left-associative, i.e. left tree is deep. |
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213 # e.g. '1 + 2 + 3' -> (+ (+ 1 2) 3) -> (+ 1 2 3) |
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214 simplified = [] |
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215 x = tree |
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216 while x[0] == op: |
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217 l, r = x[1:] |
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218 simplified.append(simplifyinfixops(r, targetnodes)) |
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219 x = l |
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220 simplified.append(simplifyinfixops(x, targetnodes)) |
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221 simplified.append(op) |
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222 return tuple(reversed(simplified)) |