brittainscript 0.2.0

The BrittainScript programming language interpreter

BrittainScript

A custom scripting language built in Python using PLY (Python Lex-Yacc), created as a genius hour project.

Requirements

Python 3 and PLY must be installed:

pip install ply

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Running BrittainScript

All commands below are run from the BrittainScriptInternals/ directory.

Run a .bs file

Pass the path to any .bs file as an argument:

python3 main.py path/to/yourfile.bs

For example, to run the included test file:

python3 main.py ../TestFiles/test.bs

Each non-blank line in the file is parsed and executed top to bottom. Lines starting with # are treated as comments and skipped.

Interactive REPL

Run without any arguments to get a live prompt where you can type expressions one at a time:

python3 main.py

BrittainScript — type 'exit' to quit
bs> 3 + 4
7
bs> push("hello")
hello
bs> exit

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Language Syntax

Basic Math

3 + 4
10 - 3 * 2
8 / 2

Power and Square Root

4^2          => 16
sqrroot(16)  => 4.0

Pi

5 * pi       => 15.707...

Trigonometry (input in degrees)

sin(90)      => 1.0
cos(0)       => 1.0
tan(45)      => 1.0

Print (push)

push(3 + 4)        => prints 7
push("hello")      => prints hello

push() only prints. It does not return the printed value.

Variables

name = "BrittainScript"
count = 3

Comments

# Full-line comment
push("hello") # Inline comment

Conditionals

cond (count > 1)
    push("count is greater than one")
end

Loops

x = 0
while x < 3:
    x = x + 1
    push(x)
end

for i in space(1, 4):
    push(i)
end

Use break to exit a loop and continue to skip to the next iteration.

Functions

func double(x):
    return x * 2
end

push(double(5))

Functions return values with return.

Input

name = input("Enter your name: ")
push(name)

Strings

push("hello" + " world")
push(len("hello"))

name = " BrittainScript "
push(name[1])
push(name[1:5])
push(name.trim().upper())

push(tonum("42") + 8)
push(tostr(42) + "!")

Lists

nums = [1, 2, 3, 4]
push(nums[0])
nums.add(5)
push(len(nums))

Grouping

(2 + 3) * 4   => 20

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Test Files

There are two standalone test suites in TestFiles/. These are self-contained and independent from the main interpreter — they were used to prototype the lexer and parser separately.

Math test (TestFiles/TestMath/)

Tests a basic arithmetic lexer and parser (addition, subtraction, multiplication, division). Run from inside the TestMath folder:

cd TestFiles/TestMath
python3 testcalc.py

You'll see a Test: prompt. Type a math expression and it prints the tokens it found, then the parsed result:

Test: 3 + 4
LexToken(NUMBER,3,1,0)
LexToken(PLUS,'+',1,2)
LexToken(NUMBER,4,1,4)
Yacc parsed:  7

Text test (TestFiles/TestText/)

Tests a minimal text lexer and parser. Run from inside the TestText folder:

cd TestFiles/TestText
python3 testtext.py

You'll see an Enter some text: prompt. Type anything and it prints the token and the parsed result:

Enter some text: hello world
LexToken(TEXT,'hello world',1,0)
Parsed: hello world

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Project Structure

BrittainScript/
├── BrittainScriptInternals/
│   ├── main.py       — entry point (REPL + file runner)
│   ├── lexer.py      — tokenizer
│   └── parser.py     — grammar and evaluator
├── TestFiles/
│   ├── TestMath/     — standalone arithmetic test
│   └── TestText/     — standalone text test
└── Documentation/
    └── mathdocs.txt  — language reference for math features