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compiler as final year project.

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compiler as final year project., related to the topic i posted in Java forum.
mdew_47
15 Aug, 2008 - 06:42 AM
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my C side code for the JNI interface is:


CODE

# include <C:\j2sdk1.4.2_03\include\jni.h>
# include <C:\Program Files\InstallShield\InstallShield for Microsoft Visual C++ 6\Include\project.h>
# include <stdio.h>
# include <string.h>

JNIEXPORT jstring JNICALL Java_project_test
(JNIEnv *env , jobject obj, jstring s)
{
char (*str)[40] =(*env)->GetStringUTFChars(env,s,0);
int i;
for(i=0;(*str)[0]=='^'&&(*str)[1]=='c';i++)
do{
strupr(str);
}while((*str)[i]!='c'&&(*str)[i+1]!='^');
return((*env)->NewStringUTF(env,str));
(*env)->ReleaseStringUTFChars(env,s,str);
}


it is not working as i thouht might be i got a wrong logic:

i thing off converting to capital all the characters that are between

^c<char array>c^

if anyone can help thanks in advance.
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mdew_47
RE: Compiler As Final Year Project.
15 Aug, 2008 - 06:57 AM
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pls it is urgent, if anyone can please help! rolleyes.gif

This post has been edited by mdew_47: 15 Aug, 2008 - 09:19 AM
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NickDMax
RE: Compiler As Final Year Project.
15 Aug, 2008 - 10:16 AM
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well (*env)->ReleaseStringUTFChars(env,s,str);

is after the return statement and so it will never execute...

not really familiar with JNI. but I would think it would be something like this: (note code not compiled)

CODE
JNIEXPORT jstring JNICALL Java_project_test
(JNIEnv *env , jobject obj, jstring s)
{
    char str[256] =(*env)->GetStringUTFChars(env,s,0);
    int i = 2;
    if(str[0]=='^'&&str[1]=='c') {
        do{
            toupper(str[i++]);
        } while(i < 255 && (str[i]!='c' && str[i+1]!='^'));
    }
    (*env)->ReleaseStringUTFChars(env,s,str);
    return((*env)->NewStringUTF(env,str));
}


this is based upon code from here.

Note: Why are you doing this in JNI? -- this far easier to do in java proper!

This post has been edited by NickDMax: 16 Aug, 2008 - 06:49 AM
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perfectly.insane
RE: Compiler As Final Year Project.
15 Aug, 2008 - 01:48 PM
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Is JNI necessary for this? I looked at your requirements in the Java section, but I don't see why you couldn't still implement it like a traditional compiler. By this I mean that the compiler would be a standalone executable, and the Java would simply be a front end to it.

Here are some examples (it covers utilizing the executing process's standard input and output streams also):
http://www.rgagnon.com/javadetails/java-0014.html

Also, with respect to the code, you cannot initialize C/C++ arrays at runtime with array initializes. What this means is that you can't do:

char somestr[100] = some_non_const_expr();

------

You can do:
char somestr[100] = "xxxx";

-- or --
char somestr[100] = { 'a', 'b', 'c', ... };


But for what you're doing, you need to do:

const char* str = (*env)->GetStringUTFChars(env,s,0);
int len = strlen(str);
/* Process the string, from 0 .. len - 1 */

This post has been edited by perfectly.insane: 15 Aug, 2008 - 01:49 PM
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 01:39 AM
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my guide asked me to get a Java interface for the compiler, to make it user friendly. He say there are things in the C actual compiler part which cannot be implemented from Java proper. Hence the result is the combination of both the language one for this and the other for that.
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 02:08 AM
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QUOTE(NickDMax @ 15 Aug, 2008 - 11:16 AM) *

well (*env)->ReleaseStringUTFChars(env,s,str);

is after the return statement and so it will never execute...

not really familiar with JNI. but I would think it would be something like this: (note code not compiled)

CODE
JNIEXPORT jstring JNICALL Java_project_test
(JNIEnv *env , jobject obj, jstring s)
{
    char str[256] =(*env)->GetStringUTFChars(env,s,0);
    int i = 2;
    if(str[0]=='^'&&(*str)[1]=='c') {
        do{
            toupper(str[i++]);
        } while(i < 255 && (str[i]!='c' && str[i+1]!='^'));
    }
    (*env)->ReleaseStringUTFChars(env,s,str);
    return((*env)->NewStringUTF(env,str));
}


this is based upon code from here.

Note: Why are you doing this in JNI? -- this far easier to do in java proper!


sorry, nick your code got the same problem as of me. Instead of returning capital it is returning garbage value.

i am using the string between ^c<char array>c^ because ^c and c^ is my command which is to be passed to make the required string capital.

this project is similar to the Latex software if anyone can help in that case.

QUOTE(perfectly.insane @ 15 Aug, 2008 - 02:48 PM) *

Is JNI necessary for this? I looked at your requirements in the Java section, but I don't see why you couldn't still implement it like a traditional compiler. By this I mean that the compiler would be a standalone executable, and the Java would simply be a front end to it.

Here are some examples (it covers utilizing the executing process's standard input and output streams also):
http://www.rgagnon.com/javadetails/java-0014.html

Also, with respect to the code, you cannot initialize C/C++ arrays at runtime with array initializes. What this means is that you can't do:

char somestr[100] = some_non_const_expr();

------

You can do:
char somestr[100] = "xxxx";

-- or --
char somestr[100] = { 'a', 'b', 'c', ... };


But for what you're doing, you need to do:

const char* str = (*env)->GetStringUTFChars(env,s,0);
int len = strlen(str);
/* Process the string, from 0 .. len - 1 */



Thanks, i just forgot that, i will try and let you know.
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:02 AM
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after using strlen the strupr is giving error.
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perfectly.insane
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:09 AM
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A compile error, a runtime error, or it simply doesn't function as needed?
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:10 AM
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i am thinking of storing the pointer object to character array "*str" in another pointer and then applying strlen on str to get the length such as

char *t;
*t=*str;
int len =strlen(str)
.....
....
strupr(t);
....
...
will it work ?



This post has been edited by mdew_47: 16 Aug, 2008 - 08:11 AM
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perfectly.insane
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:13 AM
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The variable t hasn't been initialized, so you can't do that. It would have to be:

char* t;
t = str;

Not:
*t = *str, which assigns the first character of str to the first character of t, and since t isn't initialized, it won't work (it will likely cause a crash).

This post has been edited by perfectly.insane: 16 Aug, 2008 - 08:14 AM
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:18 AM
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QUOTE(perfectly.insane @ 16 Aug, 2008 - 09:09 AM) *

A compile error, a runtime error, or it simply doesn't function as needed?





during compile time only warnings are given:


and the when i click the compile button garbage values are printed for infinite times.

QUOTE(perfectly.insane @ 16 Aug, 2008 - 09:13 AM) *

The variable t hasn't been initialized, so you can't do that. It would have to be:

char* t;
t = str;

Not:
*t = *str, which assigns the first character of str to the first character of t, and since t isn't initialized, it won't work (it will likely cause a crash).



so now i know why the JVM crashes.
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mdew_47
RE: Compiler As Final Year Project.
16 Aug, 2008 - 08:24 AM
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QUOTE(perfectly.insane @ 16 Aug, 2008 - 09:13 AM) *

The variable t hasn't been initialized, so you can't do that. It would have to be:

char* t;
t = str;




it is now giving warning that: warning c4090: '=' : different 'const' qualifiers.

so i must the const out of: const char* str = (*env)->.......

isn't it?
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