summaryrefslogtreecommitdiff
path: root/coverage/phystokens.py
blob: 4b69c47668b6a0e7ce07b6a2cdb1290ed812f4d4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
# For details: https://github.com/nedbat/coveragepy/blob/master/NOTICE.txt

"""Better tokenizing for coverage.py."""

import keyword
import re
import token
import tokenize

from coverage.misc import contract


def phys_tokens(toks):
    """Return all physical tokens, even line continuations.

    tokenize.generate_tokens() doesn't return a token for the backslash that
    continues lines.  This wrapper provides those tokens so that we can
    re-create a faithful representation of the original source.

    Returns the same values as generate_tokens()

    """
    last_line = None
    last_lineno = -1
    last_ttext = None
    for ttype, ttext, (slineno, scol), (elineno, ecol), ltext in toks:
        if last_lineno != elineno:
            if last_line and last_line.endswith("\\\n"):
                # We are at the beginning of a new line, and the last line
                # ended with a backslash.  We probably have to inject a
                # backslash token into the stream. Unfortunately, there's more
                # to figure out.  This code::
                #
                #   usage = """\
                #   HEY THERE
                #   """
                #
                # triggers this condition, but the token text is::
                #
                #   '"""\\\nHEY THERE\n"""'
                #
                # so we need to figure out if the backslash is already in the
                # string token or not.
                inject_backslash = True
                if last_ttext.endswith("\\"):
                    inject_backslash = False
                elif ttype == token.STRING:
                    if "\n" in ttext and ttext.split('\n', 1)[0][-1] == '\\':
                        # It's a multi-line string and the first line ends with
                        # a backslash, so we don't need to inject another.
                        inject_backslash = False
                if inject_backslash:
                    # Figure out what column the backslash is in.
                    ccol = len(last_line.split("\n")[-2]) - 1
                    # Yield the token, with a fake token type.
                    yield (
                        99999, "\\\n",
                        (slineno, ccol), (slineno, ccol+2),
                        last_line
                        )
            last_line = ltext
        if ttype not in (tokenize.NEWLINE, tokenize.NL):
            last_ttext = ttext
        yield ttype, ttext, (slineno, scol), (elineno, ecol), ltext
        last_lineno = elineno


@contract(source='unicode')
def source_token_lines(source):
    """Generate a series of lines, one for each line in `source`.

    Each line is a list of pairs, each pair is a token::

        [('key', 'def'), ('ws', ' '), ('nam', 'hello'), ('op', '('), ... ]

    Each pair has a token class, and the token text.

    If you concatenate all the token texts, and then join them with newlines,
    you should have your original `source` back, with two differences:
    trailing whitespace is not preserved, and a final line with no newline
    is indistinguishable from a final line with a newline.

    """

    ws_tokens = {token.INDENT, token.DEDENT, token.NEWLINE, tokenize.NL}
    line = []
    col = 0

    source = source.expandtabs(8).replace('\r\n', '\n')
    tokgen = generate_tokens(source)

    for ttype, ttext, (_, scol), (_, ecol), _ in phys_tokens(tokgen):
        mark_start = True
        for part in re.split('(\n)', ttext):
            if part == '\n':
                yield line
                line = []
                col = 0
                mark_end = False
            elif part == '':
                mark_end = False
            elif ttype in ws_tokens:
                mark_end = False
            else:
                if mark_start and scol > col:
                    line.append(("ws", u" " * (scol - col)))
                    mark_start = False
                tok_class = tokenize.tok_name.get(ttype, 'xx').lower()[:3]
                if ttype == token.NAME and keyword.iskeyword(ttext):
                    tok_class = "key"
                line.append((tok_class, part))
                mark_end = True
            scol = 0
        if mark_end:
            col = ecol

    if line:
        yield line


class CachedTokenizer(object):
    """A one-element cache around tokenize.generate_tokens.

    When reporting, coverage.py tokenizes files twice, once to find the
    structure of the file, and once to syntax-color it.  Tokenizing is
    expensive, and easily cached.

    This is a one-element cache so that our twice-in-a-row tokenizing doesn't
    actually tokenize twice.

    """
    def __init__(self):
        self.last_text = None
        self.last_tokens = None

    @contract(text='unicode')
    def generate_tokens(self, text):
        """A stand-in for `tokenize.generate_tokens`."""
        if text != self.last_text:
            self.last_text = text
            readline = iter(text.splitlines(True)).__next__
            self.last_tokens = list(tokenize.generate_tokens(readline))
        return self.last_tokens

# Create our generate_tokens cache as a callable replacement function.
generate_tokens = CachedTokenizer().generate_tokens


COOKIE_RE = re.compile(r"^[ \t]*#.*coding[:=][ \t]*([-\w.]+)", flags=re.MULTILINE)

@contract(source='bytes')
def source_encoding(source):
    """Determine the encoding for `source`, according to PEP 263.

    `source` is a byte string: the text of the program.

    Returns a string, the name of the encoding.

    """
    readline = iter(source.splitlines(True)).__next__
    return tokenize.detect_encoding(readline)[0]


@contract(source='unicode')
def compile_unicode(source, filename, mode):
    """Just like the `compile` builtin, but works on any Unicode string.

    Python 2's compile() builtin has a stupid restriction: if the source string
    is Unicode, then it may not have a encoding declaration in it.  Why not?
    Who knows!  It also decodes to utf8, and then tries to interpret those utf8
    bytes according to the encoding declaration.  Why? Who knows!

    This function neuters the coding declaration, and compiles it.

    """
    source = neuter_encoding_declaration(source)
    code = compile(source, filename, mode)
    return code


@contract(source='unicode', returns='unicode')
def neuter_encoding_declaration(source):
    """Return `source`, with any encoding declaration neutered."""
    if COOKIE_RE.search(source):
        source_lines = source.splitlines(True)
        for lineno in range(min(2, len(source_lines))):
            source_lines[lineno] = COOKIE_RE.sub("# (deleted declaration)", source_lines[lineno])
        source = "".join(source_lines)
    return source