forked from lsdev/LiteStep
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathMathScanner.cpp
More file actions
executable file
·314 lines (261 loc) · 6.72 KB
/
MathScanner.cpp
File metadata and controls
executable file
·314 lines (261 loc) · 6.72 KB
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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
//
// This is a part of the Litestep Shell source code.
//
// Copyright (C) 1997-2015 LiteStep Development Team
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
#include "../utility/stringutility.h"
#include "MathScanner.h"
#include "MathException.h"
#include <string.h> // needed for _stricmp
#include <stdio.h> // needed for EOF
using namespace std;
// Reserved words
StringKeyedMaps<LPCWSTR, int>::ConstUnorderedMap gReservedWords(
{
{ L"false", TT_FALSE },
{ L"true", TT_TRUE },
{ L"infinity", TT_INFINITY },
{ L"nan", TT_NAN },
{ L"defined", TT_DEFINED },
{ L"div", TT_DIV },
{ L"mod", TT_MOD },
{ L"and", TT_AND },
{ L"or", TT_OR },
{ L"not", TT_NOT }
});
// Operators and punctuation
// Checked in this order so for example "<=" must precede "<". Must have enough
// lookahead to recognize the longest symbol.
struct SymbolTable { const wchar_t *str; int length; int type; } gSymbols[] = \
{
{ L"(", 1, TT_LPAREN },
{ L")", 1, TT_RPAREN },
{ L",", 1, TT_COMMA },
{ L"+", 1, TT_PLUS },
{ L"-", 1, TT_MINUS },
{ L"*", 1, TT_STAR },
{ L"/", 1, TT_SLASH },
{ L"&", 1, TT_AMPERSAND },
{ L"=", 1, TT_EQUAL },
{ L">=", 2, TT_GREATEREQ },
{ L">", 1, TT_GREATER },
{ L"<>", 2, TT_NOTEQUAL },
{ L"<=", 2, TT_LESSEQ },
{ L"<", 1, TT_LESS },
{ L"!=", 2, TT_NOTEQUAL }
};
const int gNumSymbols = sizeof(gSymbols) / sizeof(gSymbols[0]);
MathScanner::MathScanner(const wstring& expression) :
mStream(expression)
{
// Fill the lookahead buffer
Next(LOOKAHEAD);
}
MathToken MathScanner::NextToken()
{
// Skip past whitespace
SkipSpace();
if (mLookahead[0] == WEOF)
{
// End of input
return MathToken(TT_END);
}
else if (IsFirstNameChar(mLookahead[0]))
{
// Identifier or reserved word
return ScanIdentifier();
}
else if (IsDigit(mLookahead[0]))
{
// Numeric literal
return ScanNumber();
}
else if (mLookahead[0] == L'\"' || mLookahead[0] == L'\'')
{
// String literal
return ScanString();
}
// Operators and punctuation symbols
for (int i = 0; i < gNumSymbols; ++i)
{
bool match = true;
for (int j = 0; j < gSymbols[i].length; ++j)
{
if (mLookahead[j] != gSymbols[i].str[j])
{
match = false;
break;
}
}
if (match)
{
Next(gSymbols[i].length);
return MathToken(gSymbols[i].type);
}
}
// Error
throw MathException(L"Illegal character");
}
MathToken MathScanner::CheckReservedWord(const wstring& identifier)
{
auto const & reserverdWord = gReservedWords.find(identifier.c_str());
if (reserverdWord != gReservedWords.end())
{
// It's a reserved word
return MathToken(reserverdWord->second);
}
// It's just an identifier
return MathToken(TT_ID, identifier);
}
void MathScanner::Next(int count)
{
for (int i = 0; i < count; ++i)
{
for (int j = 0; j < LOOKAHEAD - 1; ++j)
{
mLookahead[j] = mLookahead[j + 1];
}
if (!mStream.get(mLookahead[LOOKAHEAD - 1]))
{
mLookahead[LOOKAHEAD - 1] = WEOF;
}
}
}
MathToken MathScanner::ScanIdentifier()
{
wostringstream value;
while (IsNameChar(mLookahead[0]))
{
value.put(mLookahead[0]);
Next();
}
return CheckReservedWord(value.str());
}
MathToken MathScanner::ScanNumber()
{
wostringstream value;
while (IsDigit(mLookahead[0]))
{
value.put(mLookahead[0]);
Next();
}
if (mLookahead[0] == L'.')
{
value.put(mLookahead[0]);
Next();
while (IsDigit(mLookahead[0]))
{
value.put(mLookahead[0]);
Next();
}
}
return MathToken(TT_NUMBER, value.str());
}
MathToken MathScanner::ScanString()
{
wostringstream value;
wchar_t quote = mLookahead[0];
Next();
while (mLookahead[0] != WEOF && mLookahead[0] != quote)
{
if (mLookahead[0] == L'\\')
{
// Escape sequence
Next();
switch (mLookahead[0])
{
case L'\\':
value.put(L'\\');
break;
case L'\"':
value.put(L'\"');
break;
case L'\'':
value.put(L'\'');
break;
default:
throw MathException(L"Illegal string escape sequence");
}
}
else
{
// Just a character
value.put(mLookahead[0]);
}
Next();
}
if (mLookahead[0] == WEOF)
{
throw MathException(L"Unterminated string literal");
}
Next();
return MathToken(TT_STRING, value.str());
}
void MathScanner::SkipSpace()
{
while (IsSpace(mLookahead[0]))
{
Next();
}
}
bool MathScanner::IsDigit(wchar_t ch)
{
return (ch >= L'0' && ch <= L'9');
}
bool MathScanner::IsFirstNameChar(wchar_t ch)
{
return !IsDigit(ch) && IsNameChar(ch);
}
bool MathScanner::IsNameChar(wchar_t ch)
{
if (ch == WEOF || IsSpace(ch))
{
return false;
}
switch (ch)
{
case L'!':
// case '@': Will be reserved in 0.25
// case '#': Will be reserved in 0.25
case L'$':
case L'&':
case L'*':
case L'(':
case L')':
case L'-':
case L'+':
case L'=':
case L'[':
case L']':
// case '|': Will be reserved in 0.25
case L';':
case L'"':
case L'\'':
case L'<':
case L'>':
case L',':
case L'/':
return false;
}
return true;
}
bool MathScanner::IsSpace(wchar_t ch)
{
return (ch == L' ' || ch == L'\t'); // More than this?
}