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
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
local TK_CREATE = 1
local TK_TEMP = 2
local TK_TRIGGER = 3
local TK_CASE = 4
local TK_END = 5
local TK_SEMI = 6
local TK_EMPTY = 7
local TK_TEXT = 8
-- Read comment of the specified type and propagate the offset.
-- @param context Map {sql: string, offset: number}.
-- @param comment_type Either '-' for '-- ...' comments or
-- '*' for '/* ... */' comments.
local function read_comment(context, comment_type)
-- Skip '/*' or '--'.
local chars_read = 2
for i = context.offset + 2, context.sql:len() do
local c = context.sql:sub(i, i)
local next_c = context.sql:sub(i + 1, i + 1)
chars_read = chars_read + 1
if comment_type == '-' and c == '\n' then
goto finish
elseif comment_type == '*' and c == '*' and next_c == '/' then
chars_read = chars_read + 1
goto finish
end
end
::finish::
context.offset = context.offset + chars_read
end
-- Read spaces and propagate the offset.
-- @param context Map {sql: string, offset: number}.
local function read_spaces(context)
-- Skip the first space.
local chars_read = 1
for i = context.offset + 1, context.sql:len() do
local c = context.sql:sub(i, i)
if c ~= ' ' and c ~= '\n' and c ~= '\t' then
goto finish
end
chars_read = chars_read + 1
end
::finish::
context.offset = context.offset + chars_read
end
-- Read a text. It can be an identifier consisted of letters and
-- digits or another single symbol (,.:;^&?! etc). Propagate the
-- offset.
-- @param context Map {sql: string, offset: number}.
--
-- Retvals identify words without case sensitivity.
-- @retval not TK_TEXT means word TK_'word'.
-- @retval TK_TEXT means another, not special word.
local function read_text(context)
local chars_read = 0
local tk_type = TK_TEXT
for i = context.offset, context.sql:len() do
local c = context.sql:sub(i, i)
if not c:match('[%d%a_]') then
if chars_read == 0 then
-- Read nontext symbol only if it is the first
-- symbol in the token. It is needed to avoid
-- mixing of SQL special words
-- (CREATE, TRIGGER, ...) with nontext symbols.
chars_read = 1
if c == ';' then
tk_type = TK_SEMI
end
assert(c ~= '"' and c ~= "'")
end
goto finish
end
chars_read = chars_read + 1
end
::finish::
local new_offset = context.offset + chars_read
local end_pos = new_offset - 1
if chars_read == 6 and context.sql:sub(context.offset, end_pos):upper() == 'CREATE' then
tk_type = TK_CREATE
elseif chars_read == 4 then
local word = context.sql:sub(context.offset, end_pos):upper()
if word == 'TEMP' then
tk_type = TK_TEMP
elseif word == 'CASE' then
tk_type = TK_CASE
end
elseif chars_read == 7 and context.sql:sub(context.offset, end_pos):upper() == 'TRIGGER' then
tk_type = TK_TRIGGER
elseif chars_read == 3 and context.sql:sub(context.offset, end_pos):upper() == 'END' then
tk_type = TK_END
end
context.offset = new_offset
return tk_type
end
-- Read a string in '' or "" quotes. Inside a string all special
-- words and symbols lose their special meanings. Single quote '
-- can be escaped using double-single quote: ''. For example:
-- 'Example of the ''string'' with escape'. Double quote can not
-- be escaped.
-- @param context Map {sql: string, offset: number}.
local function read_string(context)
local i = context.offset
local quote = context.sql:sub(i, i)
i = i + 1
while i <= context.sql:len() do
local c = context.sql:sub(i, i)
i = i + 1
if c == quote then
if quote == "'" then
local next_c = context.sql:sub(i, i)
if next_c ~= c then
goto finish
else
i = i + 1
end
else
goto finish
end
end
end
::finish::
context.offset = i
end
-- Get next token from the SQL request at the specified offset.
-- Context.offset is propagated on count of read characters.
-- @param context Table with two keys: sql and offset. sql -
-- request string, offset - start position, from which need
-- to extract a next token.
--
-- @retval Token type. If the rest of the SQL request consists of
-- spaces and comments, then return TK_EMPTY.
local function get_next_token(context)
local c = ''
repeat
local i = context.offset
c = context.sql:sub(i, i)
local next_c = context.sql:sub(i + 1, i + 1)
if (c == '-' and next_c == '-') or (c == '/' and next_c == '*') then
read_comment(context, next_c)
elseif c == ' ' or c == '\n' or c == '\t' then
read_spaces(context)
elseif c == "'" or c == '"' then
read_string(context, c)
elseif c ~= '' then
return read_text(context)
end
until c == ''
return TK_EMPTY
end
local function split_sql(request)
-- Array of result statements
local res = {}
-- True, if the splitter reads the trigger body. In such a
-- case the ';' can not be used as end of the statement.
local in_trigger = false
-- True, if the splitter reads the 'CASE WHEN ... END'
-- statement. It is a special case, because 'END' is used
-- to determine both end of 'CASE' and end of
-- 'CREATE TRIGGER'. And 'CASE' can be inside trigger body.
-- Tracking of 'CASE ... END' helps to determine true borders
-- of 'CREATE TRIGGER' statement.
local in_case = false
-- End of the previous statement.
local prev_sub_i = 1
-- Tokenizer context.
local context = { sql = request, offset = 1 }
local token = get_next_token(context)
local is_not_empty = token ~= TK_EMPTY and token ~= TK_SEMI
-- Read until multistatement request is finished.
while token ~= TK_EMPTY do
if not in_trigger and token == TK_SEMI then
if is_not_empty then
table.insert(res, request:sub(prev_sub_i, context.offset - 1))
end
is_not_empty = false
prev_sub_i = context.offset
elseif token == TK_CREATE then
token = get_next_token(context)
is_not_empty = is_not_empty or token ~= TK_EMPTY and token ~= TK_SEMI
-- 'TEMP' can be a part of 'CREATE TRIGGER' or
-- 'CREATE TABLE' or 'CREATE VIEW'. Skip it.
if token == TK_TEMP then
token = get_next_token(context)
is_not_empty = is_not_empty or token ~= TK_EMPTY and token ~= TK_SEMI
end
if token == TK_TRIGGER then
in_trigger = true
end
elseif token == TK_CASE then
in_case = true
elseif token == TK_END then
-- 'TRIGGER' can contain 'CASE', but not vice versa.
-- In a case: CREATE TRIGGER ... BEGIN
-- SELECT ... CASE ... END;
-- END;
-- At first close CASE and then close TRIGGER.
if in_case then
in_case = false
elseif in_trigger then
in_trigger = false
end
end
token = get_next_token(context)
is_not_empty = is_not_empty or token ~= TK_EMPTY and token ~= TK_SEMI
end
if prev_sub_i < context.offset and is_not_empty then
table.insert(res, request:sub(prev_sub_i, context.offset))
end
return res
end
return {split_sql = split_sql}
|
