Javacc LOOKAHEAD - Lvalue in MiniJava

Sometimes you need to break a choice conflict out into a new function in order to
eliminate the choice conflict.

Choice conflict in [...] construct at line 298, column 5.
Expansion nested within construct and expansion following construct
have common prefixes, one of which is: "."
Consider using a lookahead of 2 or more for nested expansion.

This Grammar:
Factor -> ('-'|'!') Factor
| Lvalue ['.' "length" '(' ')' | '(' [Args] ')']
| '(' Expr ')'
| Literal

Lvalue -> ["this" '.'] {'[' Expr ']' | '.' }


Had to be expanded to :

Exp Factor(): {}
{
("-"|"!") Factor()
| Lvalue() ["." "length" "(" ")" | "(" [Args()] ")"]
| "(" Expr() ")"
| Literal()
}


//Lvalue -> ["this" '.'] {LvalueLower}
Exp Lvalue(): {}
{
["this" "."]
[ LOOKAHEAD(2) LvalueLower()]
}

// LvalueLower -> '[' Expr ']' | '.'
void LvalueLower():{}
{
"." | "[" Expr() "]"
}

https://bitbucket.org/aaron_skomra/minijava2/src/af557e14135e/proj3/parser/miniParser.jj

error: invalid operands of types ‘const char

code.cpp:126: error: invalid operands of types ‘const char [5]’ and ‘const char [2]’ to binary ‘operator+’

message = string("DATA" + "\n");

to

message = string("DATA\n");

tar

Making a tar file (from http://web.cecs.pdx.edu/~suhui/classes/cs201/inst-submit.html)


Below is an example that creates a tar file for email submission. Assume that your CS login name is "john". First, you will create the directory "john-A1" (say, under /u/john/cs201) and copy all the files and directories to be submitted into the directory /u/john/cs201/john-A1/. Below shows a screen shot of making the tar ball, assuming that you've created the directory for submission in /u/john/cs201/john-A1 and you are at /u/john/cs201/.

/u/john/cs201/> ls john-A1/
Makefile test.c typescript
/u/john/cs201/> tar cvf john-A1.tar john-A1/*
john-A1/Makefile
john-A1/test.c
john-A1/typescript
/u/john/cs201/> ls -l john-A1.tar
-rw------- 1 john them 10240 Mar 31 10:00 john-A1.tar

Related commands:

1. To verify the content of a tar file, say "john-A1.tar", do the following:
tar tvf john-A1.tar
Note this command does not extract files from john-A1.tar, but rather it shows what're inside it. This is very useful before you actually extract a tar file.
2. To untar a tar file, say "john-A1.tar", do the following:
tar xvf john-A1.tar
This will create the directory "john" with all the files that are inside it. Warning: whatever files and directories in john-A1.tar will overwrite existing ones with the same names. To test this command, it's better that you do it under a temporary directory so that you don't overwrite anything by accident.

here document

(Because the document is right
here in the source code rather than in an external file.)

The Ruby Programming Language, 1st Edition p 51

c++ ** stack smashing detected ***

http://ubuntuforums.org/archive/index.php/t-352672.html

changed

char wordFromFile[36];

to

char wordFromFile[256];

to make it work

I think the stack smashing was detected only after the function returned, not when the stack was actually getting smashed.

unix utils

ldd a.out
strace

moving pointers around

if(*(*(args->arg_array+i)+1) == '\0'){
args->rdfilename[0] = (args->arg_array[i+1]); // point to the filename
}
// if the next character is a character make that character the start of the filename
else{
args->rdfilename[0] = (*(args->arg_array+i)+1);// point to the filename
//not args->rdfilename[0] = *(*(args->arg_array+i)+1);

// **(args->arg_array+i) = '\0'; // remove the < // I deleted the < but the pointer is still pointing to its slot