# Running the example program
Compilation, e.g.: clang++-7 -std=c++17 main.cpp

Running: ./a.out "7 l / 100 km" (mind the double quotes and spaces between tokens).

# Unit Conversion Scripting Language (UCSL)
A language for unit conversions. UCSL is able to find a chain of implicit conversions needed to end up with desired result unit.

# Hello world

print 1 Hello / 1 World!

# Statements
## constant
Defines a constant that is used for conversion. E.g.

```
constant 1000 m <-> 1 km
constant 0.01 m <-> 1 cm
```
To properly categorize units, make sure that the units from one category are always 'chained'. E.g. here the units are not chained and two categories are created, instead of just one.

```
constant 1 cm <-> 10 mm
constant 1 km <-> 1000 m
constant 1 m <-> 100 cm
```
There is no connection between defining cm <-> mm and km <-> m. To chain the units properly, rearrange constants in such way:

```
constant 1 cm <-> 10 mm
constant 1 m <-> 100 cm
constant 1 km <-> 1000 m
```
Chaining units from one category can be interrupted. E.g. this script is valid:

```
constant 1 cm <-> 10 mm
constant 1000 g <-> 1 kg
constant 1 m <-> 100 cm
print 1 g / 42.42 mm to X g / 20 m
```

## value
Defines a named value with a result of value expression. Later on, the name can be referred.

```
value value_name 42 km / 1 h
value another_value value_name
```

## print
Prints result of a value expression to stdout.

```
print 1 m / 2 s
```
Prints: 1 m / 2 s

## to operator
Converts a value in one unit to a value in another unit. Conversion has to be known based on constants.

```
constant 1.605 km <-> 1 mi
constant 3.785 l <-> 1 gal
value l_per_100_km 7 l / 100 km
value conversion_result l_per_100_km to X mi / 1 gal
print conversion_result
```
This script prints `33.605 mi / 1 gal` to stdout.

The X indicates that the mi value can change. That's why the result is some amount of miles per one gallon. X can appear in the denominator as well. X must apprear exactly once in the desired unit, otherwise the behavior is undefined.

to operator automatically detects conversion chain. Here, it detects that it needs to convert m to km and then km to mi to meet desired unit.

```
constant 1.605 km <-> 1 mi
constant 1000 m <-> 1 km
constant 3.785 l <-> 1 gal
value l_per_m 0.00007 l / 1 m
value conversion_result l_per_100_km to X mi / 1 gal
print conversion_result
```