AsYacc – first alpha release

Order Of Writing A Research Paper

Long Should Admissions Essay College

Distributed Systems Security Research Papers

Proposal And Dissertation Help Case Study

Buy Essay Online Uk

http://www.meandergroep.com/?research-papers-on-cars Research Papers On Cars

Literature Review Writing Assistance

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
/* Infix notation calculator. */
%{
%}
%token NUM
%left '-' '+'
%left '*' '/'
%left NEG
%right '^' /* exponentiation */
%%
input:
exp         { trace( $1 ); }
;
exp:
NUM         { $$ = $1; }
| exp '+' exp     { $$ = $1 + $3; }
| exp '-' exp     { $$ = $1 - $3; }
| exp '*' exp     { $$ = $1 * $3; }
| exp '/' exp     { $$ = $1 / $3; }
| '-' exp %prec NEG  { $$ = -$2; }
| exp '^' exp     { $$ = Math.pow( $1, $3 ); }
| '(' exp ')'     { $$ = $2; }
;
%%

Top Down or Bottom Up for Expression Evaluation ?

Literary Analysis Essay Edgar Allan Poe

Writing Masters Degree Thesis I will not release today the port because actually I had not time to make sure it is bugfree and I’ve only a working version for Mac, but I plan to release it shortly if you will ever need it for your own tasks. My goal for today was to compare the speed of the parser I wrote with an automatically generated bottom up parser, to see which is the faster approach.

The parser grammar is really simple and really readable:

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
%{
%}
%token NUMBER SYMBOL
%left '+' '-'
%left '*' '/'
%left NEG
%%
program
: expr                { Vars.result = $1; }
;
expr
: expr '+' expr       { $$ = $1 + $3; }
| expr '-' expr       { $$ = $1 - $3; }
| expr '*' expr       { $$ = $1 * $3; }
| expr '/' expr       { $$ = $1 / $3; }
| '-' expr %prec NEG  { $$ = -$2; }
| '(' expr ')'        { $$ = $2; }
| SYMBOL '(' expr ')' {
if( Vars.SYMBOL_TABLE[ $1 ] )
{
$$ = Vars.SYMBOL_TABLE[ $1 ]( $3 );
} else
{
trace( "can't find function" );
}
}
| SYMBOL              {
if( Vars.SYMBOL_TABLE[ $1 ] )
{
$$ = Vars.SYMBOL_TABLE[ $1 ];
} else
{
trace( "can't find symbol" );
}
}
| NUMBER              { $$ = yyval; }
;
%%

http://www.valevafotografos.com/?help-with-school-work Help With School Work

ActionScript Parsing, the YACC revenge :)

http://www.dm.ufrpe.br/sites/dm.ufrpe.br/index.php?1-page-customized-paper 1 Page Customized Paper So first I need to wrote from scratch the grammar/lexer files using only the ECMAScript 4 specifications and much patience (the elastic grammar file help me a lot too).

The result was unbelievable: 0.02 seconds for that file!

http://www.felicotrans.com/?pay-my-assignment Pay My Assignment

Science In Society Coursework Help Now, the next step is to finish and test the parser and finally create a python library using pyrex, then a benchmark test again.

Write My Paper For Me In 3 Hours

An experience with antlr, java and python

I was trying first to create the parser using GNU Flex and Bison in C, probably the best way for a very performancing parser.
Yeah, that’s right.. but looking at the antlr syntax I realized that’s easier and easier.
Moreover I start using this very useful eclipse plugin for antlr debugging which made my life easier!

The grammar file I created is a compromise between the asdt grammar file and the ECMA-262 grammar specification.

Once finished working on my eclipse project I’ve managed to parse succesfully all the adobe corelibs files using this java test file:

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
package org.sepy.core.parsers.as3;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import antlr.CommonAST;
import antlr.RecognitionException;
import antlr.TokenStreamException;
public class Application {
public static void main(String argv[])
{
if(argv.length > 0)
{
File file = new File(argv[0]);
if(file.exists())
{
FileInputStream is = null;
try {
is = new FileInputStream(file);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
AS3Lexer L = new AS3Lexer(is);
AS3Parser P = new AS3Parser(L);
try {
P.compilationUnit();
} catch (RecognitionException e) {
// TODO Auto-generated catch block
System.out.println(" line=" + e.line + ", column="+ e.column);
System.out.println(e.getMessage());
e.printStackTrace(System.err);
} catch (TokenStreamException e) {
// TODO Auto-generated catch block
System.out.println(" line=" + L.getLine() + ", column="+ L.getColumn());
System.out.println(L.getGuessInfo());
System.out.println(e.getMessage());
e.printStackTrace(System.err);
}
CommonAST.setVerboseStringConversion(false, P.getTokenNames());
CommonAST ast = (CommonAST) P.getAST();
System.out.println("Tree:");
System.out.println(ast.toStringTree());
}
}
}
}

Ok, done that I decided to export the grammar file for python (thanks to antrl python export feature).
Everything works fine also for python, but I realized that the python script were so much slower than the java one!

1
2
3
4
5
6
7
8
9
10
11
12
import sys
import antlr
import AS3Parser
import AS3Lexer
L = AS3Lexer.Lexer(filename);
P = AS3Parser.Parser(L);
P.setFilename(filename)
try:
   P.compilationUnit();
   ast = P.getAST();
except:
   pass

On a 75Kb actionscript file the python script took about 7 seconds to run, while the java application only 2 seconds. I know python interpreter caould be slower than many other languages, but I never thought so much slower.
So I run the python hotshot profiler to see which could be the bottleneck in the python script and I found most of the problems were due to unuseless antlr (the python module) method’s calls.
After making corrections to the antlr.py file the same script took exactly half of the time. Now 3 seconds. Wow 🙂
But not fast enough.
So I enabled for the antlr python script psyco module and this time the same script took Working Bibliography Mla only 1.6 seconds.
Now the python script is fast enough, even if I’m sure I can make more optimizations in the antlr module…