eclipsetrading / vcel

Simple Expression Language that has support for composition level features like graceful null handling and asynchronous expressions.

VCEL

VCEL is short for View Client Expression Language. Its a simple expression language designed as a replacement for SPEL used in an internal project called ViewClient.

The main thing that differentiates this project from SPEL (and many other expression languages) is that it gives us control over how things are composed in the expression using a Monad pattern. This allows things like gracefully handling null references without exceptions or handling asynchronous operations whilst also keeping the expression simple and intuitive to the user, and abstracting away such concerns.

VCEL currently supports C# and JavaScript runtimes.

CLI

A simple CLI tool is also included as a way to execute and test VCEL expressions easily from the command line.

This can be installed using the .NET tool command which downloads the latest package version from NuGet.

dotnet tool install --global VCEL.Cli

The application vcel will now be available as a global command.

vcel's Issues

Add csharp key value context for CSharp parser

Add support to access context inside function

Support dictionary access

Add Support for Member Access

Need to add support for expressions that access properties of objects e.g.

SomeObject.SomeProperty
SomeObject.someMethod()
(SomeObject - SomeObject).SomeProperty

Be specific on parsing member/function expression

We allow any kinds of expr to be match with member expr, which take huge amount of time to parse the expression with lots of member/function access.

Code cleanup

Goals

• Formatting code
• Remove unnecessary lines
• Remove unused using
• Remove unused variables
• Add "this." quantification preferences

Translate expression to actual javascript code

Return Parse Exception Information in Parse Result

The Expression Parser currently ignores any antlr parse exceptions, and returns the whatever it was able to match. No indication that the expression parsing did not match the entire expression is given.

The parser should return a parse result that contains information about any expression errors.