# Dangl.Calculator

This calculator is using the ANTLR4 C# target to calculate results from formulas that are passed in as string.

Whenever a calculation is performed, a `CalculationResult`

is returned with the following properties:

Property | Type | |
---|---|---|

IsValid | bool | `true` if the formula could be parsed and calculated, else `false` |

ErrorPosition | int | Position of the offending symbol in the line, 0 based index, for invalid results, else null |

ErrorMessage | string | ANTLR error message for invalid formulas, else null |

Result | double | `NaN` for invalid formulas, else the actual result |

## Installation

Install it via NuGet: `Dangl.Calculator`

CI builds are available via MyGet.

```
https://www.myget.org/F/dangl/api/v3/index.json
```

## Compatibility

This project targets `netstandard2.0`

, `netstandard1.1`

, `net45`

and `net40`

. Due to .Net 4.5.2 being the currently latest supported version
by Microsoft and the xUnit test suite, no tests are run for `net45`

and `net451`

.

The .NET 4.0 target is for compatibility reasons, it is not tested and requires .NET compilers for version 4.5 or newer to properly function.

## Project Configuration

If this project is consumed in a project using the full .Net framework with a newer version of
`Antlr4.Runtime`

, the necessary AssemblyBindingRedirects are not automatically generated with the current
dotnet CLI tooling. This is scheduled to be fixed with the 2.0 release. In the meantime, the following should
be added to the consumers `csproj`

:

```
<PropertyGroup Condition=" '$(TargetFramework)' == 'net461' ">
<AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
<GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
</PropertyGroup>
```

The `Condition=" '$(TargetFramework)' == 'net461' "`

attribute may be changed as necessary or removed.

## Example

```
using Dangl.Calculator;
public void Example()
{
var formula = "5+5";
var calculation = Calculator.Calculate(formula);
Console.WriteLine(calculation.Result);
Console.WriteLine(calculation.IsValid);
// 10.0
// true
}
```

## Supported functions

Expression | |
---|---|

`FLOOR expression` |
Round down to zero accuracy |

`CEIL expression` |
Round up to zero accuracy |

`ABS expression` |
Absolute value |

`ROUNDK '(' expression ';' expression ')'` |
Round expr_1 with expr_2 accuracy |

`ROUND expression` |
Round with zero accuracy |

`TRUNC expression` |
Trim decimal digits |

`SIN expression` |
Sinus |

`COS expression` |
Cosinus |

`TAN expression` |
Tangens |

`COT expression` |
Cotangens |

`SINH expression` |
Sinus Hypererbolicus |

`COSH expression` |
Cosinus Hyperbolicus |

`TANH expression` |
Tangens Hyperbolicus |

`ARCSIN expression` |
Inverse Sinus |

`ARCCOS expression` |
Inverse Cosinus |

`ARCTAN expression` |
Inverse Tangens |

`ARCTAN2 '(' expression ';' expression ')'` |
Atan2 |

`ARCCOT expression` |
Inverse Cotangens |

`EXP expression` |
e ^ expr |

`LN expression` |
Logarithm to e |

`EEX expression` |
10 ^ expr |

`LOG expression` |
Logarithm to 10 |

`RAD expression` |
Angle to radians (360° base) |

`DEG expression` |
Radians to angle (360° base) |

`SQRT expression` |
Square root |

`SQR expression` |
Square product |

`expression op = ('^'\|'**') expression` |
expr_1 to the expr_2 th power |

`expression (MOD \| '%' ) expression` |
Modulo |

`expression DIV expression` |
Whole part of division rest |

`expression op = ('~'\|'//') expression` |
expr_1 nth root of expr_2 |

`expression op = ('*'\|'/') expression` |
Multiplication or division |

`expression op = ('+'\|'-') expression` |
Addition or subtraction |

`NUMBER` |
Single integer or float number |

`'(' expression ')'` |
Expression within parentheses |

`PI '()'?` |
Mathematical constant pi = 3,141593 |

`expression E+ expression` |
Exponent, e.g. 10e+43 |

`expression E- expression` |
Inverted Exponent, e.g. 10e-43 |

`EULER` |
Mathematical constant e = 2,718282 |

`'-' expression` |
Unary minus sign (negative numbers) |

`'+' expression` |
Unary plus sign (positive numbers) |

`'(' expression ')' expression` |
Expressions without multiplication sign, e.g. `2(3)` -> `2*(3)` |

`expression '(' expression ')'` |
Expressions without multiplication sign, e.g. `2(3)` -> `2*(3)` |

*expression* may be any expression as functions can be nested. Example: `DEG(2*PI)`

or `LOG(10^3)`

.

Formulas can be case invariant, e.g. `SIN`

, `sin`

and `siN`

are all considered the same.

An optional equals sign `=`

at the end of the function is allowed.

## Comments in Formulas

Comments in Formulas are supported by encapsulating them either in `/*...*/`

, `'...'`

or `"..."`

quote styles. Examples:

`4/*Length*/*3/*Width*/`

resolves to `12`

`4'Length'*3'Width'`

resolves to `12`

`4"Length"*3"Width"`

resolves to `12`

## Substitutions

The calculator can be called with an overload that accepts a callback function for substitution values. For example, take the following formula:`1,2*#Z4+3`

Here, `#Z4`

is a *substitution*, which is a placeholder that can be externally supplied. Let's say you want to resolve `#Z4`

to the value three, you could
make this simple call:

```
var formula = "1,2*#Z4+3";
var result = Calculator.Calculate(formula, substitution =>
{
if (substitution == "#Z4")
{
return 3;
}
return null;
});
```

The callback is in the form of a `Func<string, double?>`

, and it will be called for every substitution found in the formula. Multiple substitutions are supported.
If duplicates in substitutions are present, the calculator will request each one individually. If a substitution resolves to `null`

, the formula is considered invalid.

Substitutions must always start with the `#`

character and can then have the following characters: `[a-z] | [A-Z] | [äÄöÖüÜ] | [0-9]`

## Assembly Strong Naming & Usage in Signed Applications

This module produces strong named assemblies when compiled. When consumers of this package require strongly named assemblies, for example when they
themselves are signed, the outputs should work as-is.
The key file to create the strong name is adjacent to the `csproj`

file in the root of the source project. Please note that this does not increase
security or provide tamper-proof binaries, as the key is available in the source code per
Microsoft guidelines