| 1 | """visitor.py."""
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| 2 | from __future__ import print_function
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| 3 |
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| 4 | import sys
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| 5 | from asdl import ast
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| 6 | from typing import List, IO
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| 7 |
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| 8 |
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| 9 | class AsdlVisitor:
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| 10 | """Tree walker base class.
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| 11 |
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| 12 | This is NOT a visitor, since it doesn't have accept(self) and double
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| 13 | dispatch.
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| 14 |
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| 15 | VisitModule uses the "template method pattern"
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| 16 | https://en.wikipedia.org/wiki/Template_method_pattern
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| 17 | """
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| 18 |
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| 19 | def __init__(self, f):
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| 20 | # type: (IO[bytes]) -> None
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| 21 | self.f = f
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| 22 | self.current_depth = 0 # the current number of indent levels
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| 23 |
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| 24 | def Indent(self):
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| 25 | # type: () -> None
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| 26 | self.current_depth += 1
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| 27 |
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| 28 | def Dedent(self):
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| 29 | # type: () -> None
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| 30 | self.current_depth -= 1
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| 31 |
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| 32 | def Emit(self, s, depth=-1, reflow=True):
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| 33 | # type: (str, int, bool) -> None
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| 34 | if depth == -1:
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| 35 | depth = self.current_depth
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| 36 | for line in FormatLines(s, depth, reflow=reflow):
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| 37 | self.f.write(line)
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| 38 |
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| 39 | def VisitModule(self, mod, depth=0):
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| 40 | # type: (ast.Module, int) -> None
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| 41 | """
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| 42 | Template method
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| 43 | """
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| 44 | self.EmitHeader(mod)
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| 45 |
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| 46 | for dfn in mod.dfns:
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| 47 | if isinstance(dfn, ast.SubTypeDecl):
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| 48 | self.VisitSubType(dfn)
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| 49 |
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| 50 | elif isinstance(dfn, ast.TypeDecl):
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| 51 | typ = dfn
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| 52 | if isinstance(typ.value, ast.SimpleSum):
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| 53 | self.VisitSimpleSum(typ.value, typ.name, depth)
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| 54 |
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| 55 | elif isinstance(typ.value, ast.Sum):
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| 56 | self.VisitCompoundSum(typ.value, typ.name, depth)
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| 57 |
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| 58 | elif isinstance(typ.value, ast.Product):
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| 59 | self.VisitProduct(typ.value, typ.name, depth)
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| 60 |
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| 61 | else:
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| 62 | raise AssertionError(typ)
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| 63 |
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| 64 | else:
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| 65 | raise AssertionError(dfn)
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| 66 |
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| 67 | self.EmitFooter()
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| 68 |
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| 69 | def VisitSubType(self, subtype):
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| 70 | # type: (ast.SubTypeDecl) -> None
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| 71 | pass
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| 72 |
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| 73 | # Optionally overridden.
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| 74 | def VisitSimpleSum(self, value, name, depth):
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| 75 | # type: (ast.SimpleSum, str, int) -> None
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| 76 | pass
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| 77 |
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| 78 | def VisitCompoundSum(self, value, name, depth):
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| 79 | # type: (ast.Sum, str, int) -> None
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| 80 | pass
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| 81 |
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| 82 | def VisitProduct(self, value, name, depth):
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| 83 | # type: (ast.Product, str, int) -> None
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| 84 | pass
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| 85 |
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| 86 | def EmitHeader(self, schema_ast):
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| 87 | # type: (ast.Module) -> None
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| 88 | pass
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| 89 |
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| 90 | def EmitFooter(self):
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| 91 | # type: () -> None
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| 92 | pass
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| 93 |
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| 94 |
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| 95 | TABSIZE = 2
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| 96 | MAX_COL = 80
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| 97 |
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| 98 | # Copied from asdl_c.py
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| 99 |
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| 100 |
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| 101 | def _ReflowLines(s, depth):
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| 102 | # type: (str, int) -> List[str]
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| 103 | """Reflow the line s indented depth tabs.
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| 104 |
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| 105 | Return a sequence of lines where no line extends beyond MAX_COL when
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| 106 | properly indented. The first line is properly indented based
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| 107 | exclusively on depth * TABSIZE. All following lines -- these are
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| 108 | the reflowed lines generated by this function -- start at the same
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| 109 | column as the first character beyond the opening { in the first
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| 110 | line.
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| 111 | """
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| 112 | size = MAX_COL - depth * TABSIZE
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| 113 | if len(s) < size:
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| 114 | return [s]
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| 115 |
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| 116 | lines = []
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| 117 | cur = s
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| 118 | padding = ""
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| 119 | while len(cur) > size:
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| 120 | i = cur.rfind(' ', 0, size)
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| 121 | if i == -1:
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| 122 | if 0:
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| 123 | print(
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| 124 | "Warning: No space to reflow line (size=%d, depth=%d, cur=%r): %r"
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| 125 | % (size, depth, cur, s),
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| 126 | file=sys.stderr)
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| 127 | lines.append(padding + cur)
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| 128 | break
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| 129 |
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| 130 | lines.append(padding + cur[:i])
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| 131 | if len(lines) == 1:
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| 132 | # find new size based on brace
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| 133 | j = cur.find('{', 0, i)
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| 134 | if j >= 0:
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| 135 | j += 2 # account for the brace and the space after it
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| 136 | size -= j
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| 137 | padding = " " * j
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| 138 | else:
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| 139 | j = cur.find('(', 0, i)
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| 140 | if j >= 0:
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| 141 | j += 1 # account for the paren (no space after it)
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| 142 | size -= j
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| 143 | padding = " " * j
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| 144 | cur = cur[i + 1:]
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| 145 | else:
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| 146 | lines.append(padding + cur)
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| 147 | return lines
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| 148 |
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| 149 |
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| 150 | def FormatLines(s, depth, reflow=True):
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| 151 | # type: (str, int, bool) -> List[str]
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| 152 | """Make the generated code readable.
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| 153 |
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| 154 | Args:
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| 155 | depth: controls indentation
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| 156 | reflow: line wrapping.
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| 157 | """
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| 158 | if reflow:
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| 159 | lines = _ReflowLines(s, depth)
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| 160 | else:
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| 161 | lines = [s]
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| 162 |
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| 163 | result = []
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| 164 | for line in lines:
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| 165 | line = (" " * TABSIZE * depth) + line + "\n"
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| 166 | result.append(line)
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| 167 | return result
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| 168 |
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| 169 |
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| 170 | """
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| 171 | For */*_gen.py, and asdl/gen_*.py
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| 172 |
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| 173 | from asdl.util import Write
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| 174 |
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| 175 | def f():
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| 176 | # constant string with leading stuff stripped off
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| 177 | Write(f, '''
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| 178 | hello
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| 179 | there
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| 180 | |''')
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| 181 |
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| 182 | # - option to reflow
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| 183 | # - option to add MORE depth, in addition to stripping whitespace
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| 184 | # - I wonder if YSH template strings could use something like that
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| 185 | Write(f, '''
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| 186 | a = {a}
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| 187 | b = {b}
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| 188 | |''', locals(), reflow=True, depth=2)
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| 189 |
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| 190 | with Printer(locals()) as p:
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| 191 | p.Write('''
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| 192 | a = {a}
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| 193 | b = {b}
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| 194 | |''')
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| 195 | """
|