summaryrefslogtreecommitdiff
path: root/sqlparse/lexer.py
blob: d7a8d28c92a173bddf870d5b834719698421bcf8 (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
# -*- coding: utf-8 -*-

# Copyright (C) 2008 Andi Albrecht, albrecht.andi@gmail.com
#
# This module is part of python-sqlparse and is released under
# the BSD License: http://www.opensource.org/licenses/bsd-license.php.

"""SQL Lexer"""

# This code is based on the SqlLexer in pygments.
# http://pygments.org/
# It's separated from the rest of pygments to increase performance
# and to allow some customizations.

import re
import sys

from sqlparse import tokens
from sqlparse.keywords import SQL_REGEX
from sqlparse.compat import StringIO, string_types, text_type


class Lexer(object):
    encoding = 'utf-8'
    flags = re.IGNORECASE | re.UNICODE

    def __init__(self):
        self._tokens = {}

        for state in SQL_REGEX:
            self._tokens[state] = []

            for tdef in SQL_REGEX[state]:
                rex = re.compile(tdef[0], self.flags).match
                new_state = None
                if len(tdef) > 2:
                    # Only Multiline comments
                    if tdef[2] == '#pop':
                        new_state = -1
                    elif tdef[2] in SQL_REGEX:
                        new_state = (tdef[2],)
                self._tokens[state].append((rex, tdef[1], new_state))

    def _decode(self, text):
        if sys.version_info[0] == 3:
            if isinstance(text, str):
                return text
        if self.encoding == 'guess':
            try:
                text = text.decode('utf-8')
                if text.startswith(u'\ufeff'):
                    text = text[len(u'\ufeff'):]
            except UnicodeDecodeError:
                text = text.decode('latin1')
        else:
            try:
                text = text.decode(self.encoding)
            except UnicodeDecodeError:
                text = text.decode('unicode-escape')
        return text

    def get_tokens(self, text):
        """
        Return an iterable of (tokentype, value) pairs generated from
        `text`. If `unfiltered` is set to `True`, the filtering mechanism
        is bypassed even if filters are defined.

        Also preprocess the text, i.e. expand tabs and strip it if
        wanted and applies registered filters.
        """
        if isinstance(text, string_types):
            if sys.version_info[0] < 3 and isinstance(text, text_type):
                text = StringIO(text.encode('utf-8'))
                self.encoding = 'utf-8'
            else:
                text = StringIO(text)

        def streamer():
            for i, t, v in self.get_tokens_unprocessed(text):
                yield t, v
        stream = streamer()
        return stream

    def get_tokens_unprocessed(self, stream):
        """
        Split ``text`` into (tokentype, text) pairs.

        ``stack`` is the inital stack (default: ``['root']``)
        """
        pos = 0
        tokendefs = self._tokens  # see __call__, pylint:disable=E1101
        statestack = ['root', ]
        statetokens = tokendefs[statestack[-1]]
        known_names = {}

        text = stream.read()
        text = self._decode(text)

        while 1:
            for rexmatch, action, new_state in statetokens:
                m = rexmatch(text, pos)
                if m:
                    value = m.group()
                    if value in known_names:
                        yield pos, known_names[value], value
                    elif type(action) is tokens._TokenType:
                        yield pos, action, value
                    elif hasattr(action, '__call__'):
                        ttype, value = action(value)
                        known_names[value] = ttype
                        yield pos, ttype, value
                    else:
                        for item in action(self, m):
                            yield item
                    pos = m.end()
                    if new_state is not None:
                        # state transition
                        if isinstance(new_state, tuple):
                            for state in new_state:
                                if state == '#pop':
                                    statestack.pop()
                                elif state == '#push':
                                    statestack.append(statestack[-1])
                                elif (
                                    # Ugly hack - multiline-comments
                                    # are not stackable
                                    state != 'multiline-comments'
                                    or not statestack
                                    or statestack[-1] != 'multiline-comments'
                                ):
                                    statestack.append(state)
                        elif isinstance(new_state, int):
                            # pop
                            del statestack[new_state:]
                        elif new_state == '#push':
                            statestack.append(statestack[-1])
                        statetokens = tokendefs[statestack[-1]]
                    break
            else:
                try:
                    if text[pos] == '\n':
                        # at EOL, reset state to "root"
                        pos += 1
                        statestack = ['root']
                        statetokens = tokendefs['root']
                        yield pos, tokens.Text, u'\n'
                        continue
                    yield pos, tokens.Error, text[pos]
                    pos += 1
                except IndexError:
                    break


def tokenize(sql, encoding=None):
    """Tokenize sql.

    Tokenize *sql* using the :class:`Lexer` and return a 2-tuple stream
    of ``(token type, value)`` items.
    """
    lexer = Lexer()
    if encoding is not None:
        lexer.encoding = encoding
    return lexer.get_tokens(sql)