1 """Provide advanced parsing abilities for ParenMatch and other extensions.
2
3 HyperParser uses PyParser. PyParser mostly gives information on the
4 proper indentation of code. HyperParser gives additional information on
5 the structure of code.
6 """
7 from keyword import iskeyword
8 import string
9
10 from idlelib import pyparse
11
12 # all ASCII chars that may be in an identifier
13 _ASCII_ID_CHARS = frozenset(string.ascii_letters + string.digits + "_")
14 # all ASCII chars that may be the first char of an identifier
15 _ASCII_ID_FIRST_CHARS = frozenset(string.ascii_letters + "_")
16
17 # lookup table for whether 7-bit ASCII chars are valid in a Python identifier
18 _IS_ASCII_ID_CHAR = [(chr(x) in _ASCII_ID_CHARS) for x in range(128)]
19 # lookup table for whether 7-bit ASCII chars are valid as the first
20 # char in a Python identifier
21 _IS_ASCII_ID_FIRST_CHAR = \
22 [(chr(x) in _ASCII_ID_FIRST_CHARS) for x in range(128)]
23
24
25 class ESC[4;38;5;81mHyperParser:
26 def __init__(self, editwin, index):
27 "To initialize, analyze the surroundings of the given index."
28
29 self.editwin = editwin
30 self.text = text = editwin.text
31
32 parser = pyparse.Parser(editwin.indentwidth, editwin.tabwidth)
33
34 def index2line(index):
35 return int(float(index))
36 lno = index2line(text.index(index))
37
38 if not editwin.prompt_last_line:
39 for context in editwin.num_context_lines:
40 startat = max(lno - context, 1)
41 startatindex = repr(startat) + ".0"
42 stopatindex = "%d.end" % lno
43 # We add the newline because PyParse requires a newline
44 # at end. We add a space so that index won't be at end
45 # of line, so that its status will be the same as the
46 # char before it, if should.
47 parser.set_code(text.get(startatindex, stopatindex)+' \n')
48 bod = parser.find_good_parse_start(
49 editwin._build_char_in_string_func(startatindex))
50 if bod is not None or startat == 1:
51 break
52 parser.set_lo(bod or 0)
53 else:
54 r = text.tag_prevrange("console", index)
55 if r:
56 startatindex = r[1]
57 else:
58 startatindex = "1.0"
59 stopatindex = "%d.end" % lno
60 # We add the newline because PyParse requires it. We add a
61 # space so that index won't be at end of line, so that its
62 # status will be the same as the char before it, if should.
63 parser.set_code(text.get(startatindex, stopatindex)+' \n')
64 parser.set_lo(0)
65
66 # We want what the parser has, minus the last newline and space.
67 self.rawtext = parser.code[:-2]
68 # Parser.code apparently preserves the statement we are in, so
69 # that stopatindex can be used to synchronize the string with
70 # the text box indices.
71 self.stopatindex = stopatindex
72 self.bracketing = parser.get_last_stmt_bracketing()
73 # find which pairs of bracketing are openers. These always
74 # correspond to a character of rawtext.
75 self.isopener = [i>0 and self.bracketing[i][1] >
76 self.bracketing[i-1][1]
77 for i in range(len(self.bracketing))]
78
79 self.set_index(index)
80
81 def set_index(self, index):
82 """Set the index to which the functions relate.
83
84 The index must be in the same statement.
85 """
86 indexinrawtext = (len(self.rawtext) -
87 len(self.text.get(index, self.stopatindex)))
88 if indexinrawtext < 0:
89 raise ValueError("Index %s precedes the analyzed statement"
90 % index)
91 self.indexinrawtext = indexinrawtext
92 # find the rightmost bracket to which index belongs
93 self.indexbracket = 0
94 while (self.indexbracket < len(self.bracketing)-1 and
95 self.bracketing[self.indexbracket+1][0] < self.indexinrawtext):
96 self.indexbracket += 1
97 if (self.indexbracket < len(self.bracketing)-1 and
98 self.bracketing[self.indexbracket+1][0] == self.indexinrawtext and
99 not self.isopener[self.indexbracket+1]):
100 self.indexbracket += 1
101
102 def is_in_string(self):
103 """Is the index given to the HyperParser in a string?"""
104 # The bracket to which we belong should be an opener.
105 # If it's an opener, it has to have a character.
106 return (self.isopener[self.indexbracket] and
107 self.rawtext[self.bracketing[self.indexbracket][0]]
108 in ('"', "'"))
109
110 def is_in_code(self):
111 """Is the index given to the HyperParser in normal code?"""
112 return (not self.isopener[self.indexbracket] or
113 self.rawtext[self.bracketing[self.indexbracket][0]]
114 not in ('#', '"', "'"))
115
116 def get_surrounding_brackets(self, openers='([{', mustclose=False):
117 """Return bracket indexes or None.
118
119 If the index given to the HyperParser is surrounded by a
120 bracket defined in openers (or at least has one before it),
121 return the indices of the opening bracket and the closing
122 bracket (or the end of line, whichever comes first).
123
124 If it is not surrounded by brackets, or the end of line comes
125 before the closing bracket and mustclose is True, returns None.
126 """
127
128 bracketinglevel = self.bracketing[self.indexbracket][1]
129 before = self.indexbracket
130 while (not self.isopener[before] or
131 self.rawtext[self.bracketing[before][0]] not in openers or
132 self.bracketing[before][1] > bracketinglevel):
133 before -= 1
134 if before < 0:
135 return None
136 bracketinglevel = min(bracketinglevel, self.bracketing[before][1])
137 after = self.indexbracket + 1
138 while (after < len(self.bracketing) and
139 self.bracketing[after][1] >= bracketinglevel):
140 after += 1
141
142 beforeindex = self.text.index("%s-%dc" %
143 (self.stopatindex, len(self.rawtext)-self.bracketing[before][0]))
144 if (after >= len(self.bracketing) or
145 self.bracketing[after][0] > len(self.rawtext)):
146 if mustclose:
147 return None
148 afterindex = self.stopatindex
149 else:
150 # We are after a real char, so it is a ')' and we give the
151 # index before it.
152 afterindex = self.text.index(
153 "%s-%dc" % (self.stopatindex,
154 len(self.rawtext)-(self.bracketing[after][0]-1)))
155
156 return beforeindex, afterindex
157
158 # the set of built-in identifiers which are also keywords,
159 # i.e. keyword.iskeyword() returns True for them
160 _ID_KEYWORDS = frozenset({"True", "False", "None"})
161
162 @classmethod
163 def _eat_identifier(cls, str, limit, pos):
164 """Given a string and pos, return the number of chars in the
165 identifier which ends at pos, or 0 if there is no such one.
166
167 This ignores non-identifier eywords are not identifiers.
168 """
169 is_ascii_id_char = _IS_ASCII_ID_CHAR
170
171 # Start at the end (pos) and work backwards.
172 i = pos
173
174 # Go backwards as long as the characters are valid ASCII
175 # identifier characters. This is an optimization, since it
176 # is faster in the common case where most of the characters
177 # are ASCII.
178 while i > limit and (
179 ord(str[i - 1]) < 128 and
180 is_ascii_id_char[ord(str[i - 1])]
181 ):
182 i -= 1
183
184 # If the above loop ended due to reaching a non-ASCII
185 # character, continue going backwards using the most generic
186 # test for whether a string contains only valid identifier
187 # characters.
188 if i > limit and ord(str[i - 1]) >= 128:
189 while i - 4 >= limit and ('a' + str[i - 4:pos]).isidentifier():
190 i -= 4
191 if i - 2 >= limit and ('a' + str[i - 2:pos]).isidentifier():
192 i -= 2
193 if i - 1 >= limit and ('a' + str[i - 1:pos]).isidentifier():
194 i -= 1
195
196 # The identifier candidate starts here. If it isn't a valid
197 # identifier, don't eat anything. At this point that is only
198 # possible if the first character isn't a valid first
199 # character for an identifier.
200 if not str[i:pos].isidentifier():
201 return 0
202 elif i < pos:
203 # All characters in str[i:pos] are valid ASCII identifier
204 # characters, so it is enough to check that the first is
205 # valid as the first character of an identifier.
206 if not _IS_ASCII_ID_FIRST_CHAR[ord(str[i])]:
207 return 0
208
209 # All keywords are valid identifiers, but should not be
210 # considered identifiers here, except for True, False and None.
211 if i < pos and (
212 iskeyword(str[i:pos]) and
213 str[i:pos] not in cls._ID_KEYWORDS
214 ):
215 return 0
216
217 return pos - i
218
219 # This string includes all chars that may be in a white space
220 _whitespace_chars = " \t\n\\"
221
222 def get_expression(self):
223 """Return a string with the Python expression which ends at the
224 given index, which is empty if there is no real one.
225 """
226 if not self.is_in_code():
227 raise ValueError("get_expression should only be called "
228 "if index is inside a code.")
229
230 rawtext = self.rawtext
231 bracketing = self.bracketing
232
233 brck_index = self.indexbracket
234 brck_limit = bracketing[brck_index][0]
235 pos = self.indexinrawtext
236
237 last_identifier_pos = pos
238 postdot_phase = True
239
240 while True:
241 # Eat whitespaces, comments, and if postdot_phase is False - a dot
242 while True:
243 if pos>brck_limit and rawtext[pos-1] in self._whitespace_chars:
244 # Eat a whitespace
245 pos -= 1
246 elif (not postdot_phase and
247 pos > brck_limit and rawtext[pos-1] == '.'):
248 # Eat a dot
249 pos -= 1
250 postdot_phase = True
251 # The next line will fail if we are *inside* a comment,
252 # but we shouldn't be.
253 elif (pos == brck_limit and brck_index > 0 and
254 rawtext[bracketing[brck_index-1][0]] == '#'):
255 # Eat a comment
256 brck_index -= 2
257 brck_limit = bracketing[brck_index][0]
258 pos = bracketing[brck_index+1][0]
259 else:
260 # If we didn't eat anything, quit.
261 break
262
263 if not postdot_phase:
264 # We didn't find a dot, so the expression end at the
265 # last identifier pos.
266 break
267
268 ret = self._eat_identifier(rawtext, brck_limit, pos)
269 if ret:
270 # There is an identifier to eat
271 pos = pos - ret
272 last_identifier_pos = pos
273 # Now, to continue the search, we must find a dot.
274 postdot_phase = False
275 # (the loop continues now)
276
277 elif pos == brck_limit:
278 # We are at a bracketing limit. If it is a closing
279 # bracket, eat the bracket, otherwise, stop the search.
280 level = bracketing[brck_index][1]
281 while brck_index > 0 and bracketing[brck_index-1][1] > level:
282 brck_index -= 1
283 if bracketing[brck_index][0] == brck_limit:
284 # We were not at the end of a closing bracket
285 break
286 pos = bracketing[brck_index][0]
287 brck_index -= 1
288 brck_limit = bracketing[brck_index][0]
289 last_identifier_pos = pos
290 if rawtext[pos] in "([":
291 # [] and () may be used after an identifier, so we
292 # continue. postdot_phase is True, so we don't allow a dot.
293 pass
294 else:
295 # We can't continue after other types of brackets
296 if rawtext[pos] in "'\"":
297 # Scan a string prefix
298 while pos > 0 and rawtext[pos - 1] in "rRbBuU":
299 pos -= 1
300 last_identifier_pos = pos
301 break
302
303 else:
304 # We've found an operator or something.
305 break
306
307 return rawtext[last_identifier_pos:self.indexinrawtext]
308
309
310 if __name__ == '__main__':
311 from unittest import main
312 main('idlelib.idle_test.test_hyperparser', verbosity=2)