A-Basic-C-Interpreter

A basic C interpreter for the first project of Laboratório de Programação (CC2013) 2018-2019 FCUP This program is designed to take user instructions and execute them. The instructions are simple/basic:

goto <label>;----jumps execution to block with given label

label <namelabel>;----creates a code label

print(<info>);----displays var information or expression result

read(<var>);---creates/updates a var
    Note that on the read, once you input the value do not give <;> but <\n>
open <file>;--changes interpreter mode and reads from file 

quit;--terminates execution and exits the interpreter

<var>=<exp>;---creates/updates a var with the value of <exp>
<var>+=<exp>;---adds the value of <exp> to <var> and updates <var>
<var>-=<exp>;---subtracts the value of <exp> to <var> ,updates <var>
<var>/=<exp>;---divides the value of <var> by <exp> and updates <var>
<var>*=<exp>;---multiplies the value of <var> by <exp>, updates <var>
<var>%=<exp>;---performs mod division between <var> and <exp>

This implementation has several files:

Structures.h--representation of data

ParserExpression.(h/c)--descendent recursive parser for <exp>

LinkedListHashVar.(h/c)--list of variables in an index of Hashtable<var>
HashTableVar.(h/c)--HashTable to store <var>, supported by LinkedList

LinkedListHashLabel.(h/c)--list of labels in an index of Hahtable<label>
HashTableLabel.(h/c)--HashTable to store <label>, supported by LinkedList

LinkedListProgramSequence.(h/c)--list of <process> to store execution sequence

CInterpreter.(h/c)--the actual interpreter, contains the main code of
    parsing a command and executing it 

Shell(File/Interactive).(h/c)--the two modes of the interpreter, reading 
    from a given file (.txt/.text) and reading from real-time commands, each
    one of them implements an REPL (Read-Execute-Print-Loop) system, where
    the parsing and execution of a command read is done by CInterpreter

Main.(h/c)--initialiser for this program, depending on the lauching method
    it picks one of the Shell(<>).c files:
        ./Main <file>.<text/txt> -->ShellFile
        ./Main -->ShellInteractive

The .h file are stored in the include/ directory, the .c files in the src/ directory and the created objects .o in obj/ directory

To compile and execute this program:

$ make exe  -->creates the executable file
$ ./exe [<file>]

make -->this creates the package with the headers in include/

To eliminate the compiled objects: $ make clean

A grammar for this program can be as follows:

<S> ->  <Space><Statment><Space>;
<Space> ->  _<Space> | _ | e
<Statment> ->   <Action> | read(<Space><var><Space>)
                | print(<Space><exp><Space>)
                | open <Space> [filename]
                | goto <Space> <lab>
                | if <Space><var> <Space>goto <Space><lab>
                | label <Space> <lab>
<Alpha> ->  a | b | c | d | e | f | g | h | i | j | k | l | m | n | o | p
            | q | r | s | t | u | v | w | y | z | A | B | C | D | E | F | G
            | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W
            | Y | Z
<Num>   ->  0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
<AlphaNum>  ->  <Alpha> | <Num> | <Alpha><AlphaNum> | <Num><AlphaNum>
<lab>   ->  <AlphaNum>
<var>   ->  <Alpha> | <Alpha><var>
<expNum>    ->  <Num> | <Num><expNum>
<exp>   ->  (<Space><exp><Space>) | <exp><Space><Operation><Space><exp>
            |   <var> | -<exp> | <expNum>~
<Operation> ->  + | - | * | / | %
<Action>    ->  <var><Space><Operation>=<Space><exp>
                | <var><Space>=<Space><exp>