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-rw-r--r--src/tools/parser.cpp369
1 files changed, 0 insertions, 369 deletions
diff --git a/src/tools/parser.cpp b/src/tools/parser.cpp
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1/*
2 * Copyright (C) 2007-2012 Xagasoft, All rights reserved.
3 *
4 * This file is part of the libbu++ library and is released under the
5 * terms of the license contained in the file LICENSE.
6 */
7
8#include <bu/parser.h>
9#include <bu/lexer.h>
10#include <bu/file.h>
11#include <bu/sio.h>
12#include <bu/queuebuf.h>
13#include <stdlib.h>
14
15using namespace Bu;
16
17enum Tok
18{
19 tokNumber,
20 tokPlus,
21 tokMinus,
22 tokDivide,
23 tokMultiply,
24 tokOpenParen,
25 tokCloseParen,
26 tokCompute,
27 tokEndOfInput=-1
28};
29
30Bu::Formatter &operator<<( Bu::Formatter &f, Tok e )
31{
32 switch( e )
33 {
34 case tokNumber: return f << "tokNumber";
35 case tokPlus: return f << "tokPlus";
36 case tokMinus: return f << "tokMinus";
37 case tokDivide: return f << "tokDivide";
38 case tokMultiply: return f << "tokMultiply";
39 case tokOpenParen: return f << "tokOpenParen";
40 case tokCloseParen: return f << "tokCloseParen";
41 case tokCompute: return f << "tokCompute";
42 case tokEndOfInput: return f << "tokEndOfInput";
43 }
44
45 return f << "***error***";
46}
47
48class MathLexer : public Lexer
49{
50public:
51 MathLexer( Bu::Stream &rSrc ) :
52 rSrc( rSrc )
53 {
54 }
55
56 virtual ~MathLexer()
57 {
58 }
59
60 enum TokenTypes
61 {
62 tokStuff
63 };
64
65 virtual Token *nextToken()
66 {
67 for(;;)
68 {
69 if( qbIn.getSize() == 0 )
70 {
71 char buf[4096];
72 qbIn.write( buf, rSrc.read( buf, 4096 ) );
73
74 if( rSrc.isEos() && qbIn.getSize() == 0 )
75 return new Token( tokEndOfInput );
76 }
77
78 char b;
79 qbIn.peek( &b, 1 );
80 switch( b )
81 {
82 case '+':
83 qbIn.seek( 1 );
84 return new Token( tokPlus );
85
86 case '-':
87 qbIn.seek( 1 );
88 return new Token( tokMinus );
89
90 case '/':
91 qbIn.seek( 1 );
92 return new Token( tokDivide );
93
94 case '*':
95 qbIn.seek( 1 );
96 return new Token( tokMultiply );
97
98 case ' ':
99 case '\t':
100 case '\n':
101 qbIn.seek( 1 );
102 break;
103
104 case '=':
105 qbIn.seek( 1 );
106 return new Token( tokCompute );
107
108 case '(':
109 qbIn.seek( 1 );
110 return new Token( tokOpenParen );
111
112 case ')':
113 qbIn.seek( 1 );
114 return new Token( tokCloseParen );
115
116 case '.':
117 case '0':
118 case '1':
119 case '2':
120 case '3':
121 case '4':
122 case '5':
123 case '6':
124 case '7':
125 case '8':
126 case '9':
127 {
128 Bu::String sTmp;
129 sTmp += b;
130 qbIn.seek( 1 );
131 for(;;)
132 {
133 qbIn.peek( &b, 1 );
134 if( b != '.' && (b < '0' || b > '9') )
135 {
136 sio << "!! Convert '" << sTmp << "' to "
137 << strtod( sTmp.getStr(), NULL ) << sio.nl;
138 return new Token(
139 tokNumber, strtod( sTmp.getStr(), NULL )
140 );
141 }
142 qbIn.seek( 1 );
143 sTmp += b;
144 }
145 }
146 break;
147
148 default:
149 throw Bu::ExceptionBase("Unexpected character '%c'.", b );
150 }
151 }
152 }
153
154private:
155 Bu::Stream &rSrc;
156 QueueBuf qbIn;
157};
158
159void redAdd( Bu::Parser &p )
160{
161 Lexer::Token *a = p.popToken();
162 Lexer::Token *b = p.popToken();
163
164 sio << "Add! " << b->vExtra.get<double>() << " + "
165 << a->vExtra.get<double>() << sio.nl;
166
167 Lexer::Token *c = new Lexer::Token( tokNumber,
168 b->vExtra.get<double>() + a->vExtra.get<double>()
169 );
170 p.pushToken( c );
171
172 delete a;
173 delete b;
174}
175
176void redSubtract( Bu::Parser &p )
177{
178 Lexer::Token *a = p.popToken();
179 Lexer::Token *b = p.popToken();
180
181 sio << "Subtract! " << b->vExtra.get<double>() << " - "
182 << a->vExtra.get<double>() << sio.nl;
183
184 Lexer::Token *c = new Lexer::Token( tokNumber,
185 b->vExtra.get<double>() - a->vExtra.get<double>()
186 );
187 p.pushToken( c );
188
189 delete a;
190 delete b;
191}
192
193void redPrint( Bu::Parser &p )
194{
195 Lexer::Token *a = p.popToken();
196 sio << "Print! = " << a->vExtra.get<double>() << sio.nl;
197 delete a;
198}
199
200/* Basic grammer example:
201 *
202 * input: expr '='
203 * ;
204 *
205 * expr: expr '+' expr
206 * | '(' expr ')'
207 * | NUMBER
208 * ;
209 *
210 * The problem is, that we can't actually make something left hand recursive,
211 * so we break it into two exprs:
212 *
213 * expr-sub1: '(' expr ')'
214 * | NUMBER
215 * ;
216 *
217 * expr: expr-sub1 expr-sub2
218 * ;
219 *
220 * expr-sub2: '+' expr
221 * | '-' expr
222 * |
223 * ;
224 *
225 * 5 + 5 + 5 =
226 */
227
228int main( int argc, char *argv[] )
229{
230 if( argc < 2 )
231 {
232 println("Provide an input filename as the first parameter.");
233 return 0;
234 }
235 File fIn( argv[1], File::Read );
236
237 Parser p;
238
239 p.addNonTerminal("expr");
240 p.addNonTerminal("expr-sub1");
241 p.addNonTerminal("expr-sub2");
242 {
243 Parser::NonTerminal nt;
244 nt.addProduction(
245 Parser::Production(
246 Parser::State(
247 Parser::State::typeTerminal,
248 tokPlus
249 )
250 ).append(
251 Parser::State(
252 Parser::State::typeNonTerminal,
253 p.getNonTerminalId("expr")
254 )
255 ).append(
256 Parser::State(
257 Parser::State::typeReduction,
258 p.addReduction("add")
259 )
260 )
261 );
262 nt.addProduction(
263 Parser::Production(
264 Parser::State(
265 Parser::State::typeTerminal,
266 tokMinus
267 )
268 ).append(
269 Parser::State(
270 Parser::State::typeNonTerminal,
271 p.getNonTerminalId("expr")
272 )
273 ).append(
274 Parser::State(
275 Parser::State::typeReduction,
276 p.addReduction("subtract")
277 )
278 )
279 );
280 nt.addProduction(
281 Parser::Production(
282 )
283 );
284 nt.setCanSkip();
285 p.setNonTerminal("expr-sub2", nt );
286 }
287 {
288 Parser::NonTerminal nt;
289 nt.addProduction(
290 Parser::Production(
291 Parser::State(
292 Parser::State::typeTerminalPush,
293 tokNumber
294 )
295 )
296 );
297 nt.addProduction(
298 Parser::Production(
299 Parser::State(
300 Parser::State::typeTerminal,
301 tokOpenParen
302 )
303 ).append(
304 Parser::State(
305 Parser::State::typeNonTerminal,
306 p.getNonTerminalId("expr")
307 )
308 ).append(
309 Parser::State(
310 Parser::State::typeTerminal,
311 tokCloseParen
312 )
313 )
314 );
315 p.setNonTerminal("expr-sub1", nt );
316 }
317 {
318 Parser::NonTerminal nt;
319 nt.addProduction(
320 Parser::Production(
321 Parser::State(
322 Parser::State::typeNonTerminal,
323 p.getNonTerminalId("expr-sub1")
324 )
325 ).append(
326 Parser::State(
327 Parser::State::typeNonTerminal,
328 p.getNonTerminalId("expr-sub2")
329 )
330 )
331 );
332 p.setNonTerminal("expr", nt );
333 }
334 {
335 Parser::NonTerminal nt;
336 nt.addProduction(
337 Parser::Production(
338 Parser::State(
339 Parser::State::typeNonTerminal,
340 p.getNonTerminalId("expr")
341 )
342 ).append(
343 Parser::State(
344 Parser::State::typeTerminal,
345 tokCompute
346 )
347 ).append(
348 Parser::State(
349 Parser::State::typeReduction,
350 p.addReduction("print")
351 )
352 )
353 );
354 p.addNonTerminal("input", nt );
355 }
356
357 p.setRootNonTerminal("input");
358
359 p.setReduction("add", Bu::slot( &redAdd ) );
360 p.setReduction("subtract", Bu::slot( &redSubtract ) );
361 p.setReduction("print", Bu::slot( &redPrint ) );
362
363 p.pushLexer( new MathLexer( fIn ) );
364
365 p.parse();
366
367 return 0;
368}
369
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