Q Programming Language

A programming language to allow simple queue manipulation

Features

1. Manipulate a single queue per program
2. Queue elements may be integers from 0 - 10
3. All major queue methods are implemented
4. Two versions of our language: compiled and interpreted
5. Displays parsing and analysis data in real time as it runs

Available Functionality

ADD

ADD will add an element to the back of the queue

REMOVE

REMOVE will remove an element to the front of the queue

PEEK

PEEK will display the element at the front of the queue

LENGTH

LENGTH will display the current length of the queue

EMPTY

• Boolean expression to be placed inside an IF statement.
• Evaluates to true if the queue is empty.

NOT_EMPTY

Works like EMPTY only evaluates to true if the queue is not empty.

VIEW

Shows the queue in its current state

IF ()

• Can only take EMPTY or NOT_EMPTY as an argument.
• The line following the IF statement will be evaluated only if the IF statement is true.

BNF

    <line>        ----> <expression>;
    
    <expression>  ----> ADD <element> |
                        REMOVE        |
                        PEEK          |
                        LENGTH        |
                        VIEW          |
                        IF (<if_expr>)
    
    <if_expr>     ----> EMPTY         |
                        NOT_EMPTY
    
    <element>     ----> <int>
    
    <int>         ----> 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10

How It Works - Compiled Version

Get The Tokens

1. Read in a text file to a string
2. Pass the source code string to Parser.java
3. Parser.java finds all the tokens and puts them in an array
4. The array is passed back to our main driver

Output

############## Parsing.... #################
Next token is ADD
Next token is 1
Next token is ;
Next token is ADD
Next token is 5
Next token is ;
Next token is ADD
Next token is 9
Next token is ;
Next token is ADD
Next token is 8
Next token is ;
Next token is VIEW
Next token is ;
Next token is REMOVE
Next token is ;
Next token is VIEW
Next token is ;
Next token is PEEK
Next token is ;
Next token is LENGTH
Next token is ;
Next token is VIEW
Next token is ;
Next token is IF
Next token is (
Next token is NOT_EMPTY
Next token is )
Next token is ;
Next token is VIEW
Next token is ;
Next token is IF
Next token is (
Next token is EMPTY
Next token is )
Next token is ;
Next token is VIEW
Next token is ;

Analyze The Tokens

This stage combines token analysis and writing to "machine code" (java)

1. The token array is passed into LexicalAnalyzer.java
2. Tokens are converted from our Q Language code to java code
3. The java code is written to output.java

Output

############## Analyzing.... #################
Next line of execution: queue.add(1);

Next line of execution: queue.add(5);

Next line of execution: queue.add(9);

Next line of execution: queue.add(8);

Next line of execution: queue.view();

Next line of execution: queue.remove();

Next line of execution: queue.view();

Next line of execution: queue.showFirst((Integer) queue.peek());

Next line of execution: queue.getLength(queue.size());

Next line of execution: queue.view();

Next line of execution: queue.view();

Next line of execution: queue.view();

Compile The Program

1. output.java is compiled to output.class using Runtime.exec().
2. output.class acts as our executable, the output from our pseudo-compiler

Output

############## Compiling.... #################


############## Done! #################
Your file is compiled. You can run it by running: 

  java output

Happy queueing!

Use Case Example

   $ java Queue myfile.queue 
   $ java output

How It Works - Interpreted Version

All The Steps At Once

• The logic behind the interpreted version is nearly identical to that of the compiled version.

• The major difference is the order in which everything runs

• No more separate parsing, analyzing, compiling, and running.

• A verbose option allows users to see how to program steps through the code.

The Giant Loop

1. Like the compiled version, our source code is translated into a string.
2. The string of Q Language code is passed to our Interpreter.java
3. The Interpreter has one loop that runs through the source code, parsing, analyzing, and executing as it goes.
4. Once a token is found, it is analyzed.
5. If the analysis finds an instruction to run, the instruction will be run right away.

Verbose Option

Adding -v before the source file will display the parsing data along with the runtime data.

Got token ADD
Got token 1
Got token ;
Got token ADD
Got token 5
Got token ;
Got token ADD
Got token 9
Got token ;
Got token ADD
Got token 8
Got token ;
Got token VIEW
1 <- 5 <- 9 <- 8 <- 
Got token ;
Got token REMOVE
Got token ;
Got token VIEW
5 <- 9 <- 8 <- 
Got token ;
Got token PEEK
The first element is: 5
Got token ;
Got token LENGTH
The length is: 3
Got token ;
Got token VIEW
5 <- 9 <- 8 <- 
Got token ;
Got token IF
-IN IF-
Got token (
Got token NOT_EMPTY
Got token )
Got token ;
Got token VIEW
5 <- 9 <- 8 <- 
Got token ;
-OUT IF-
Got token IF
-IN IF-
Got token (
Got token EMPTY
Got token )
Got token ;
Got token VIEW
Got token ;

Non-Verbose Option

Without the -v option, the program will only display what was requested in the source file:

1 <- 5 <- 9 <- 8 <- 
5 <- 9 <- 8 <- 
The first element is: 5
The length is: 3
5 <- 9 <- 8 <- 
5 <- 9 <- 8 <- 

Use Case Example

   $ java Queue -v myfile.queue