27 def _advance(self): |
27 def _advance(self): |
28 'advance the tokenizer' |
28 'advance the tokenizer' |
29 t = self.current |
29 t = self.current |
30 self.current = next(self._iter, None) |
30 self.current = next(self._iter, None) |
31 return t |
31 return t |
32 def _match(self, m, pos): |
32 def _match(self, m): |
33 'make sure the tokenizer matches an end condition' |
33 'make sure the tokenizer matches an end condition' |
34 if self.current[0] != m: |
34 if self.current[0] != m: |
35 raise error.ParseError(_("unexpected token: %s") % self.current[0], |
35 raise error.ParseError(_("unexpected token: %s") % self.current[0], |
36 self.current[2]) |
36 self.current[2]) |
37 self._advance() |
37 self._advance() |
43 raise error.ParseError(_("not a prefix: %s") % token, pos) |
43 raise error.ParseError(_("not a prefix: %s") % token, pos) |
44 if len(prefix) == 1: |
44 if len(prefix) == 1: |
45 expr = (prefix[0], value) |
45 expr = (prefix[0], value) |
46 else: |
46 else: |
47 if len(prefix) > 2 and prefix[2] == self.current[0]: |
47 if len(prefix) > 2 and prefix[2] == self.current[0]: |
48 self._match(prefix[2], pos) |
48 self._match(prefix[2]) |
49 expr = (prefix[0], None) |
49 expr = (prefix[0], None) |
50 else: |
50 else: |
51 expr = (prefix[0], self._parse(prefix[1])) |
51 expr = (prefix[0], self._parse(prefix[1])) |
52 if len(prefix) > 2: |
52 if len(prefix) > 2: |
53 self._match(prefix[2], pos) |
53 self._match(prefix[2]) |
54 # gather tokens until we meet a lower binding strength |
54 # gather tokens until we meet a lower binding strength |
55 while bind < self._elements[self.current[0]][0]: |
55 while bind < self._elements[self.current[0]][0]: |
56 token, value, pos = self._advance() |
56 token, value, pos = self._advance() |
57 infix, suffix = self._elements[token][2:] |
57 infix, suffix = self._elements[token][2:] |
58 # check for suffix - next token isn't a valid prefix |
58 # check for suffix - next token isn't a valid prefix |
61 else: |
61 else: |
62 # handle infix rules |
62 # handle infix rules |
63 if not infix: |
63 if not infix: |
64 raise error.ParseError(_("not an infix: %s") % token, pos) |
64 raise error.ParseError(_("not an infix: %s") % token, pos) |
65 if len(infix) == 3 and infix[2] == self.current[0]: |
65 if len(infix) == 3 and infix[2] == self.current[0]: |
66 self._match(infix[2], pos) |
66 self._match(infix[2]) |
67 expr = (infix[0], expr, (None)) |
67 expr = (infix[0], expr, (None)) |
68 else: |
68 else: |
69 expr = (infix[0], expr, self._parse(infix[1])) |
69 expr = (infix[0], expr, self._parse(infix[1])) |
70 if len(infix) == 3: |
70 if len(infix) == 3: |
71 self._match(infix[2], pos) |
71 self._match(infix[2]) |
72 return expr |
72 return expr |
73 def parse(self, tokeniter): |
73 def parse(self, tokeniter): |
74 'generate a parse tree from tokens' |
74 'generate a parse tree from tokens' |
75 self._iter = tokeniter |
75 self._iter = tokeniter |
76 self._advance() |
76 self._advance() |