DegeSharp

How does one pronounce it?

DegeSharp ([degešárp])

How does it work?

The compiler takes in a source file (.deges), tokenizes it, parses it and interprets it in C. The following tools were used:

• Flex - for tokenizing
• Bison - for parsing
• GCC - for compiling the generated C code
• Make - for building the project

Usage

1. Clone the repository

git clone git@github.com:Pzdrs/degesharp.git
cd degesharp

2. Build the compiler

make build

3. Compile the source file

./degesharp -f <source_file>.deges

There are three verbosity flags:

• --vflex - prints the tokens generated by Flex
• --vast - prints traces of the parsing process and the final AST
• --veval - prints traces of the evaluation process (quite verbose)

VSCode extension (optional)

The directory lang-server contains a simple language server for VSCode. It provides syntax highlighting and basic autocompletion.

cd vsc-ext 
npm install
npm run full

Syntax

Variables

• Three data types: int, bool, string
• Decimal and hexadecimal integers

# Base 10 integer
-?[0-9]+
# Base 16 integer
0x[0-9a-f]+

• Variable declaration with/without initialization

jakoby : int x = 10;
jakoby : str y = "Hello world";
jakoby : bool z = true;

jakoby : int a;
jakoby : str b;
jakoby : bool c;

a = 10;
b = "Hello world";
c = true;

Comparing values

# Analogically to C
x > y
x >= y
x < y
x <= y

# Relation == replaced by "je"
x je y
# Relation != replaced by "neni"
x neni y

Arithmetic

# Unary operations
-y

# Binary operations
x + y;
x - y;
x * y;
x / y;

String operations

# Concatenation
"Hello " + "world"; // "Hello world"

Functions

No support for user functions, but you can use the built-in functions.

• povidam(arg) - prints the argument to the console (accepts int, bool, string)
• print_st() - prints the symbol table for debugging purposes

Logical operations

# Conjunction (AND) replaced by "a"
# Disjunction (OR) replaced by "nebo"
# Negation (NOT) replaced by "nene"

jakoby both_positive : bool = x > 0 a y > 0;
jakoby one_positive : bool = x > 0 nebo y > 0;
jakoby positive_or_negative : bool = (x > 0 a y > 0) nebo (x < 0 a y < 0);
jakoby negation = nene positive_or_negative;

# Conditional statement

cokdyz (<condition>) {
    // do something
} [jinak] {
    // do something else
}

Iteration

For loops

For reasons, the for loop's initialization doesn't support variable declarations, i.e. it conforms to the C89 standard instead of C99.

// int initializes to 0 by default, so lets initialize it to 69 for the sake of example
jakoby i : int = 69;

loop (i = 0; i < 10; i = i + 1) {
    // do something
}

// The iteration section is optional
loop (i = 0; i < 10;) i++;

// Infinite loop
loop (;;) {
    // do something
}

Things to keep in mind

• As mentioned, C89 standard is used for the for loop, so the initialization section doesn't support variable declarations.
• The language doesn't support floating point numbers, so the float and double types are not available.
• The internal symbol table doesn't support scoping, so all variables are global. This means that you cannot have the same variable name in different functions or blocks.