C+- toy language parser and compiler

Project description

Flex (Fast Lexical Analyzer Generator) and Bison (parser generator) are being used to parse C+- toy language source file .cpm and create abstract syntax tree (AST). Then corresponding C++ file .cpp is generated and compiled into executable.

C+- description

C+- consists only of
1. Variables var a; and constants val b;
2. Numeric and string literals (43, 12.3, "my string", etc)
3. Addition, subtraction and assignment operators +, -, =
4. Output function print()
5. Input function input()
6. Single line and multi-line comments (wasn't specified in the task)
There are only 3 types of values
1. Int - 8 byte
2. String - sequence of characters
3. Float - 8 byte
C+- is an implicit dynamic typization language
1. Same variable can store numbers and strings, the following is correct
```
var a = 5.5;
a = "Hello";
a = 34.5;
```
2. Operators follow rules (order of arguments doesn't matter)
  - String + Int/Float: Numeric is converted to string
  - String - Int/Float: String is converted to Int/Float, if it's not possible String value considered to be 0
  - Int/Float + Int/Float: Integer is converted to Float if necessary

Code example

var str = "Hello"; // variable declared using var
str = str + "1";   // variables can be changed
print(str);        // print function takes only one argument

str = 21 + 2 + 18; // same variable can store numbers
print(str);        // -> 41

val worldString = "World"; // constant declared using val
val answerNumber = 42;

print(worldString + answerNumber); // -> World42
print(worldString - answerNumber); // -> -42

val pi = 3.14;
print(pi + answerNumber); // -> 45.14

val numberString = "134";
print(numberString + answerNumber); // -> 92
print(numberString - answerNumber); // -> 13442

val name = input("Name: "); // prints "Name: " and waits for input
print("Your name is " + name);

Output

Hello1
41
World42
-42
45.14
92
13442
Name: Vladimir
Your name is Vladimir

Requirements

Ubuntu >= 18
g++ >= 9.3.0

Setup

Download cpm_compiler.zip archive. Files inside:

c+- - compiler from .cpm source to .out executable
mixed.h - mixed type declaration header
libmixed.a - mixed methods definition static library

To use the compiler specify the path to source .cpm file and (optionally) destination directory. Note that header and library files are required to be in the same location as compiler. Created directory contains both transpiled a.cpp and compiled a.out files.

$ cpm_compiler/c+- --help
Usage: cpm_compiler/c+- FILE [DIRECTORY]
Options:
        -h, --help      Show this help message
Specify the path to .cpm source FILE to create DIRECTORY with a.cpp and a.out files. Directory is "./out" by default.

Parsing Example

$ pwd
/home/vladimir/projects/cpm_compiler
$ cpm_compiler/c+- examples/perimeter.cpm
cpm_compiler/out/a.out successfully compiled
cpm_compiler/out successfully moved to .
$ out/a.out
Calculating perimeter of rectangle
Enter length of one side: 5.5
Enter length of another side: 123.4
Perimeter: 5.55.5123.4123.4
Oops... strings concatenated
Let's try another time!
Perimeter: 257.8

perimeter.cpm source file

print("Calculating perimeter of rectangle");
val a = input("Enter length of one side: ");
val b = input("Enter length of another side: ");
var answer = a + a + b + b;
print("Perimeter: " + answer);
print("Oops... strings concatenated");
val a_numeric = a - 0;
val b_numeric = b - 0;
answer = a_numeric + a_numeric + b_numeric + b_numeric;
print("Let's try another time!");
print("Perimeter: " + answer);

a.cpp transpiled file

#include "../mixed.h"

int main() {
print(Mixed("Calculating perimeter of rectangle"));
const Mixed a = input(Mixed("Enter length of one side: "));
const Mixed b = input(Mixed("Enter length of another side: "));
Mixed answer = a + a + b + b;
print(Mixed("Perimeter: ") + answer);
print(Mixed("Oops... strings concatenated"));
const Mixed a_numeric = a - Mixed(0);
const Mixed b_numeric = b - Mixed(0);
answer = a_numeric + a_numeric + b_numeric + b_numeric;
print(Mixed("Let's try another time!"));
print(Mixed("Perimeter: ") + answer);
return 0;
}

Example with errors

$ pwd
/home/vladimir/projects/cpm_compiler
$ cpm_compiler/c+- examples/errors.cpm
Compilation failed
Command(s) with errors: 4
Redeclaration(s) of constant: 1
Redeclaration(s) of variable: 0
Usage(s) of undefined identifier: 2
Redifinition(s) of constant: 1

Makefile

Makefile can be used to do the following:

$ make create cpm_compiler directory and its files
$ make run compile example and run produced executable, change $(example) variale in Makefile to try another example
$ make rerun delete out directory and then execute make run
$ make pack make cpm_compiler.zip archive with compiler files
$ make clean delete all files except sources. Note that you'll need to generate parser files again using flex >= 2.6.4 and bison >= 3.5.1

i582 / cpm_compiler