| 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 |
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| 7 |
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| 8 | class AsdlVisitor:
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| 9 | """Base class for visitors.
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| 10 |
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| 11 | TODO:
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| 12 | - It might be useful to separate this into VisitChildren() / generic_visit()
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| 13 | like Python's ast.NodeVisitor does.
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| 14 | - Also remove self.f and self.Emit. Those can go in self.output?
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| 15 | - Move to common location, since gen_python uses it as well.
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| 16 | """
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| 17 |
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| 18 | def __init__(self, f):
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| 19 | self.f = f
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| 20 | self.current_depth = 0 # the current number of indent levels
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| 21 |
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| 22 | def Indent(self):
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| 23 | self.current_depth += 1
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| 24 |
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| 25 | def Dedent(self):
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| 26 | self.current_depth -= 1
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| 27 |
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| 28 | def Emit(self, s, depth=-1, reflow=True):
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| 29 | if depth == -1:
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| 30 | depth = self.current_depth
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| 31 | for line in FormatLines(s, depth, reflow=reflow):
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| 32 | self.f.write(line)
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| 33 |
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| 34 | def VisitModule(self, mod):
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| 35 | for dfn in mod.dfns:
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| 36 | if isinstance(dfn, ast.SubTypeDecl):
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| 37 | self.VisitSubType(dfn)
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| 38 | else:
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| 39 | self.VisitType(dfn)
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| 40 | self.EmitFooter()
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| 41 |
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| 42 | def VisitSubType(self, subtype):
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| 43 | pass
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| 44 |
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| 45 | def VisitType(self, typ, depth=0):
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| 46 | if isinstance(typ.value, ast.SimpleSum):
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| 47 | self.VisitSimpleSum(typ.value, typ.name, depth)
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| 48 |
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| 49 | elif isinstance(typ.value, ast.Sum):
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| 50 | self.VisitCompoundSum(typ.value, typ.name, depth)
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| 51 |
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| 52 | elif isinstance(typ.value, ast.Product):
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| 53 | self.VisitProduct(typ.value, typ.name, depth)
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| 54 |
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| 55 | else:
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| 56 | raise AssertionError(typ)
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| 57 |
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| 58 | # Optionally overridden.
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| 59 | def VisitSimpleSum(self, value, name, depth):
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| 60 | pass
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| 61 |
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| 62 | def VisitCompoundSum(self, value, name, depth):
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| 63 | pass
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| 64 |
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| 65 | def VisitProduct(self, value, name, depth):
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| 66 | pass
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| 67 |
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| 68 | def EmitFooter(self):
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| 69 | pass
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| 70 |
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| 71 |
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| 72 | TABSIZE = 2
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| 73 | MAX_COL = 80
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| 74 |
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| 75 | # Copied from asdl_c.py
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| 76 |
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| 77 |
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| 78 | def _ReflowLines(s, depth):
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| 79 | """Reflow the line s indented depth tabs.
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| 80 |
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| 81 | Return a sequence of lines where no line extends beyond MAX_COL when
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| 82 | properly indented. The first line is properly indented based
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| 83 | exclusively on depth * TABSIZE. All following lines -- these are
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| 84 | the reflowed lines generated by this function -- start at the same
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| 85 | column as the first character beyond the opening { in the first
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| 86 | line.
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| 87 | """
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| 88 | size = MAX_COL - depth * TABSIZE
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| 89 | if len(s) < size:
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| 90 | return [s]
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| 91 |
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| 92 | lines = []
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| 93 | cur = s
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| 94 | padding = ""
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| 95 | while len(cur) > size:
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| 96 | i = cur.rfind(' ', 0, size)
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| 97 | if i == -1:
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| 98 | if 0:
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| 99 | print(
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| 100 | "Warning: No space to reflow line (size=%d, depth=%d, cur=%r): %r"
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| 101 | % (size, depth, cur, s),
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| 102 | file=sys.stderr)
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| 103 | lines.append(padding + cur)
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| 104 | break
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| 105 |
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| 106 | lines.append(padding + cur[:i])
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| 107 | if len(lines) == 1:
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| 108 | # find new size based on brace
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| 109 | j = cur.find('{', 0, i)
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| 110 | if j >= 0:
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| 111 | j += 2 # account for the brace and the space after it
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| 112 | size -= j
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| 113 | padding = " " * j
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| 114 | else:
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| 115 | j = cur.find('(', 0, i)
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| 116 | if j >= 0:
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| 117 | j += 1 # account for the paren (no space after it)
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| 118 | size -= j
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| 119 | padding = " " * j
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| 120 | cur = cur[i + 1:]
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| 121 | else:
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| 122 | lines.append(padding + cur)
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| 123 | return lines
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| 124 |
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| 125 |
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| 126 | def FormatLines(s, depth, reflow=True):
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| 127 | """Make the generated code readable.
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| 128 |
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| 129 | Args:
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| 130 | depth: controls indentation
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| 131 | reflow: line wrapping.
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| 132 | """
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| 133 | if reflow:
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| 134 | lines = _ReflowLines(s, depth)
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| 135 | else:
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| 136 | lines = [s]
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| 137 |
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| 138 | result = []
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| 139 | for line in lines:
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| 140 | line = (" " * TABSIZE * depth) + line + "\n"
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| 141 | result.append(line)
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| 142 | return result
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