formula

A simple extensible formula language for .NET

Syntax

• Arithmetic: + - * % / ^ ( )
• Functions: FunctionName(Parameter, Parameter, ...)
• Variables: VariableName OR [Variable Name With Spaces]
  • Ranges: VariableName|LowerExpr:UpperExpr| OR [Variable Name With Spaces]|LowerExpr:UpperExpr|
  • Indices: VariableName|IndexExpr| OR [Variable Name With Spaces]|IndexExpr|
• Constants:
  • Number: 123.0
  • Boolean: true/false
  • Text: "A string"
  • Nothing: null
• Branching: IF Expr THEN Expr ELSE Expr
• Logical: = <> > < >= <= ! && ||

Examples

• (1 + 2) * 3
• SQRT(16)
• MyVar * 2

Usage

• From C#
  • CsWrapper.InterpretFormula("Test * 2", new Dictionary<string, double>() { { "Test", 1 } }, DefaultFunctionProvider.Instance)
  • CsWrapper.ParseFormula("Test * 2")
• From F#
  • Formula.Parser.Parser.parseFormulaString
  • Formula.Parser.Interpreter.interpretFormula

Version History

1.1.0

• IL emit based compiler
• ExtractExpressionDependenciesWithRanges bug fix for partially resolved ranges

1.0.0

• Bug fix for large expressions

0.13.0

• Constant folder supports folding functions with constant arguments
  • Function implementations can declare they are deterministic
  • EmptyFunctionProvider created
• Implicit cast from nullables fix/improvement

0.12.0

• Support for 'Nothing' data type
  • Compiler & interpreter return an Option float value
  • C# wrapper returns Nullable
  • Handling of Nothing values in aggregation functions
• IFunctionProvider returns typed results
• 'null' keyword added

0.11.0

• Parser detection of ranges used outside of function parameters
• Remove implicit use of the first range value in operations

0.10.1

• Bug fix for duplicate dependencies being returned from DependencyExtractor

0.10.0

• Syntax support for offsets/indices on variables e.g. MyVar|1|
• FIRST, LAST, MIN, MAX functions
• Added FunctionValidator to validate function calls after parsing

0.9.0

• Support escaped characters in string literals
• Missing dependencies reported from dependency extractor with function defined ranges

0.8.0

• Better parser error reporting - new ParserException
• Position information reported from parser
• Position information reported by dependency extractor

0.7.0

• Syntax support for ranges on variables e.g. MyVar|1:5|
• Range support for variable providers
• Range dependency information
• SUM, AVG functions

0.6.0

• Typing changes to allow for typed function parameters - number, boolean, text

0.5.1

• Target .NETStandard 2.0

0.5.0

• Syntax changes
  • Support for escaping identifiers between []
  • Change function parameters to use ()

0.4.0

• Financial functions
• Dependency extractor
• Composite IVariableProvider
• Mutable IVariableProvider
• Testing enhancements

0.3.0

• Expression compiler
• Branching & logical operators
• Expression based IVariableProvider
• Composite IFunctionProvider

0.2.0

• Extension points for functions and variables
  • IFunctionProvider
  • IVariableProvider
• Modulus function & operator
  • MOD
  • %

0.1.0

• Support basic arithmetic
  • Addition/Subtraction
  • Multiplication/Division
  • Exponentiation
  • Negation
• Handful of functions
  • SQRT
  • PI
  • POW
  • COUNT
• Constant valued variables