| 1 | """
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| 2 | format_strings.py
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| 3 |
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| 4 | Parse a printf format string so we can compile it to function calls.
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| 5 | """
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| 6 | from __future__ import print_function
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| 7 |
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| 8 | import re
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| 9 |
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| 10 | from typing import List
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| 11 |
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| 12 |
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| 13 | def DecodeMyPyString(s):
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| 14 | # type: (str) -> str
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| 15 | """Workaround for MyPy's weird escaping.
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| 16 |
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| 17 | Used below and in cppgen_pass.py.
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| 18 | """
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| 19 | byte_string = bytes(s, 'utf-8')
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| 20 |
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| 21 | # In Python 3
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| 22 | # >>> b'\\t'.decode('unicode_escape')
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| 23 | # '\t'
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| 24 |
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| 25 | raw_string = byte_string.decode('unicode_escape')
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| 26 | return raw_string
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| 27 |
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| 28 |
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| 29 | class _Part:
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| 30 | pass
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| 31 |
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| 32 |
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| 33 | class LiteralPart(_Part):
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| 34 |
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| 35 | def __init__(self, s: str):
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| 36 | self.s = s
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| 37 | self.strlen = len(s)
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| 38 |
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| 39 | def __repr__(self) -> str:
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| 40 | return '(Literal %r)' % (self.s)
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| 41 |
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| 42 |
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| 43 | class SubstPart(_Part):
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| 44 |
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| 45 | def __init__(self, width: str, char_code: str, arg_num: int) -> None:
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| 46 | self.width = width
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| 47 | self.char_code = char_code
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| 48 | self.arg_num = arg_num
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| 49 |
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| 50 | def __repr__(self) -> str:
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| 51 | return '(Subst %r %s %d)' % (self.width, self.char_code, self.arg_num)
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| 52 |
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| 53 |
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| 54 | PAT = re.compile(
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| 55 | '''
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| 56 | ([^%]*)
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| 57 | (?:
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| 58 | %-?([0-9]*)(.) # optional number, and then character code
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| 59 | )?
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| 60 | ''', re.VERBOSE)
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| 61 |
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| 62 |
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| 63 | def Parse(fmt: str) -> List[_Part]:
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| 64 |
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| 65 | arg_num = 0
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| 66 | parts: List[_Part] = []
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| 67 | for m in PAT.finditer(fmt):
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| 68 | lit = m.group(1)
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| 69 | width = m.group(2)
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| 70 | char_code = m.group(3)
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| 71 |
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| 72 | if lit:
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| 73 | parts.append(LiteralPart(lit))
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| 74 | if char_code:
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| 75 | if char_code == '%':
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| 76 | part: _Part = LiteralPart('%')
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| 77 | elif char_code in 'rsdo':
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| 78 | part = SubstPart(width, char_code, arg_num)
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| 79 | arg_num += 1
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| 80 | else:
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| 81 | raise AssertionError("mycpp expects a format specifier in [rsdo%%], got '%s' instead" % char_code)
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| 82 | parts.append(part)
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| 83 |
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| 84 | #print('end =', m.end(0))
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| 85 |
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| 86 | return parts
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| 87 |
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| 88 |
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| 89 | # Note: This would be a lot easier in Oil!
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| 90 | # TODO: Should there be a char type?
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| 91 | """
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| 92 | enum format_part {
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| 93 | case Literal(s BigStr)
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| 94 | case Subst(char_code BigStr, arg_num Int)
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| 95 | }
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| 96 |
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| 97 | let PAT = ///
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| 98 | < ~['%']* : lit > # anything except %
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| 99 | < '%' dot : subst > # % and then any char
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| 100 | ///
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| 101 |
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| 102 | func Parse(fmt BigStr) {
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| 103 | var arg_num = 0
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| 104 | let parts = []
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| 105 |
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| 106 | for (m in find(fmt, PAT)) {
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| 107 | if (m.lit) {
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| 108 | do parts.append(format_part.Literal(m.lit))
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| 109 | }
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| 110 | if (m.subst) {
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| 111 | if (char_code == '%') {
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| 112 | part = format_part.Literal('%')
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| 113 | } else {
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| 114 | part = format_part.Subst(char_code, arg_num)
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| 115 | }
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| 116 | do parts.append(part)
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| 117 | set arg_num += 1
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| 118 | }
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| 119 | }
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| 120 | return parts
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| 121 | }
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| 122 | """
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