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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 5564 | serge | 1 | """Source List Parser |
| 2 | |||
| 3 | The syntax of a source list file is a very small subset of GNU Make. These |
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| 4 | features are supported |
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| 5 | |||
| 6 | operators: =, +=, := |
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| 7 | line continuation |
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| 8 | non-nested variable expansion |
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| 9 | comment |
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| 10 | |||
| 11 | The goal is to allow Makefile's and SConscript's to share source listing. |
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| 12 | """ |
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| 13 | |||
| 14 | class SourceListParser(object): |
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| 15 | def __init__(self): |
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| 16 | self.symbol_table = {} |
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| 17 | self._reset() |
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| 18 | |||
| 19 | def _reset(self, filename=None): |
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| 20 | self.filename = filename |
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| 21 | |||
| 22 | self.line_no = 1 |
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| 23 | self.line_cont = '' |
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| 24 | |||
| 25 | def _error(self, msg): |
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| 26 | raise RuntimeError('%s:%d: %s' % (self.filename, self.line_no, msg)) |
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| 27 | |||
| 28 | def _next_dereference(self, val, cur): |
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| 29 | """Locate the next $(...) in value.""" |
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| 30 | deref_pos = val.find('$', cur) |
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| 31 | if deref_pos < 0: |
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| 32 | return (-1, -1) |
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| 33 | elif val[deref_pos + 1] != '(': |
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| 34 | self._error('non-variable dereference') |
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| 35 | |||
| 36 | deref_end = val.find(')', deref_pos + 2) |
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| 37 | if deref_end < 0: |
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| 38 | self._error('unterminated variable dereference') |
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| 39 | |||
| 40 | return (deref_pos, deref_end + 1) |
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| 41 | |||
| 42 | def _expand_value(self, val): |
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| 43 | """Perform variable expansion.""" |
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| 44 | expanded = '' |
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| 45 | cur = 0 |
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| 46 | while True: |
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| 47 | deref_pos, deref_end = self._next_dereference(val, cur) |
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| 48 | if deref_pos < 0: |
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| 49 | expanded += val[cur:] |
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| 50 | break |
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| 51 | |||
| 52 | sym = val[(deref_pos + 2):(deref_end - 1)] |
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| 53 | expanded += val[cur:deref_pos] + self.symbol_table[sym] |
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| 54 | cur = deref_end |
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| 55 | |||
| 56 | return expanded |
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| 57 | |||
| 58 | def _parse_definition(self, line): |
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| 59 | """Parse a variable definition line.""" |
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| 60 | op_pos = line.find('=') |
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| 61 | op_end = op_pos + 1 |
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| 62 | if op_pos < 0: |
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| 63 | self._error('not a variable definition') |
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| 64 | |||
| 65 | if op_pos > 0: |
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| 66 | if line[op_pos - 1] in [':', '+', '?']: |
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| 67 | op_pos -= 1 |
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| 68 | else: |
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| 69 | self._error('only =, :=, and += are supported') |
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| 70 | |||
| 71 | # set op, sym, and val |
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| 72 | op = line[op_pos:op_end] |
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| 73 | sym = line[:op_pos].strip() |
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| 74 | val = self._expand_value(line[op_end:].lstrip()) |
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| 75 | |||
| 76 | if op in ('=', ':='): |
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| 77 | self.symbol_table[sym] = val |
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| 78 | elif op == '+=': |
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| 79 | self.symbol_table[sym] += ' ' + val |
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| 80 | elif op == '?=': |
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| 81 | if sym not in self.symbol_table: |
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| 82 | self.symbol_table[sym] = val |
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| 83 | |||
| 84 | def _parse_line(self, line): |
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| 85 | """Parse a source list line.""" |
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| 86 | # more lines to come |
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| 87 | if line and line[-1] == '\\': |
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| 88 | # spaces around "\\\n" are replaced by a single space |
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| 89 | if self.line_cont: |
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| 90 | self.line_cont += line[:-1].strip() + ' ' |
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| 91 | else: |
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| 92 | self.line_cont = line[:-1].rstrip() + ' ' |
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| 93 | return 0 |
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| 94 | |||
| 95 | # combine with previous lines |
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| 96 | if self.line_cont: |
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| 97 | line = self.line_cont + line.lstrip() |
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| 98 | self.line_cont = '' |
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| 99 | |||
| 100 | if line: |
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| 101 | begins_with_tab = (line[0] == '\t') |
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| 102 | |||
| 103 | line = line.lstrip() |
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| 104 | if line[0] != '#': |
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| 105 | if begins_with_tab: |
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| 106 | self._error('recipe line not supported') |
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| 107 | else: |
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| 108 | self._parse_definition(line) |
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| 109 | |||
| 110 | return 1 |
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| 111 | |||
| 112 | def parse(self, filename): |
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| 113 | """Parse a source list file.""" |
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| 114 | if self.filename != filename: |
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| 115 | fp = open(filename) |
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| 116 | lines = fp.read().splitlines() |
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| 117 | fp.close() |
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| 118 | |||
| 119 | try: |
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| 120 | self._reset(filename) |
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| 121 | for line in lines: |
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| 122 | self.line_no += self._parse_line(line) |
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| 123 | except: |
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| 124 | self._reset() |
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| 125 | raise |
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| 126 | |||
| 127 | return self.symbol_table |
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| 128 | |||
| 129 | def add_symbol(self, name, value): |
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| 130 | self.symbol_table[name] = value |