This copmiler relies on linux syscalls to operate with files. My compiler is capable of doing the following:
- outputting pcode from expressions
- emulating pcode expressions from file
- parsing pascal declarations and adding varaibles to symbol table
- outputting human readible pcode
- basic syntax error message on line number
There are 3 flags defined at the top of main.cpp to adjust, they are:
- DEBUG
- BINARY
- EXP_PARSER
If the DEBUG flag is set then all scanned token will be printed in terminal.
If the BINARY flag is set then the compiler will output a binary pcode file and the emulator will run it. If it is false then the compiler will output human readible pcode which is not emulated, such as:
PUSHI 5
PUSHI 2
ADD
If the EXP_PARSER flag is set then the input file should only be an expression such as:
((4234+545)*144) % 5
end.
If the EXP_PARSER flag is not set then we can only do varaible declarations and no pcode will be generated, such as:
var x,y,z : integer;
r, p : real;
t : char;
begin
end.
To download the code, run the following command:
git clone https://github.com/Matthew1172/PascalCompilerLinux
To run the variable expression prebuild binary, run the following code:
./PascalCompilerLinux PascalTestFile.txt PascalTestFileOutput.pcode
To compile and run the code, paste these comands in your terminal:
cd PascalCompilerLinux/cmake-build-debug
make
./PascalCompilerLinux <input-file> <output-file>
to run a test example, make sure DEBUG flag is ON, EXP_PARSER flag is ON, BINARY flag is ON. Create a file in the 'cmake-build-debug' directory called `mytest.pascal' which looks like:
(25252+4363634+124*2 DIV 7)/2.1
end.
Then run:
./PascalCompilerLinux mytest.pascal mytest_output.pcode
The result will be printed in the terminal.
Although it is mainly an expression parser right now, it can be used to insert variables into a symbol table with all appropriate attributes. However, I did not get to assignment and statements this semester. If you have a debugger, set a breakpoint on line 212. Set DEBUG to ON, set EXP_PARSER to OFF, set BINARY to OFF. Create a file in the 'cmake-build-debug' directory called myVarsTest.pascal and copy the following code:
var x,y,z : integer;
j,k : real;
p : char;
begin
end.
And then debug the code and inspect the vars symbol table. It will be a C++ map keyed by the name of the variable and it's value is a MyVar class with the specific attributes set.