toggledbits / lexpjs Goto Github PK

Having found the CHOOSE array function so helpful in LuaXP, it would be nice to see it implemented here in LEXPJS. Example:

CHOOSE ( arg , [<array>] )

Useful when binary strings are used to mimic or manipulate device on/off status, such as in VirtualSwitch.

It is likely that variable assignments (and in conjunction, compound expressions) would be a useful addition to simplify complex expressions or give callers access to interim results.

For example, a = minval+(maxval-minval)/2 ; a * a would execute two expressions: the first would compute the median of minval and maxval and store it in the context object with the name a; the second would square a; the value returned by run() directly would be the computed value of the last expression, which in this example is the square of a. The interim result created by the first expression would be available by examining the a property in the context object passed to run().

context = { "minval": somevalue, "maxval": someothervalue }
var rr = lexp.evaluate("a = minval+(maxval-minval)/2 ; a * a", context);
// Remember that run() is called for us by evaluate()
console.log("The square of the median is " + rr + ", and the median is " + context.a);

LuaXP, from which this project was born, has an extensive unit test library. Need to bring that here.

On: https://github.com/toggledbits/lexpjs

the phrase:

"...you can carry it down.?a.?long.?list.?of.?member.?names without crashing..."

should read:

"...down?.a?.long?.list?.of?.member?.names..."

I would like to measure the distance between 2 latitudes and longitudes for a simple expression that I am creating. I was unable to find any Reactor function for distance so I was going to create my own expression. The function is defined below:

acos(sin(Radians(Lat1))*sin(Radians(Lat2))+cos(Radians(Lat1))*cos(Radians(Lat2))*cos(Radians(Long2)-Radians(Long1)))*6371/1.6
Note: (the 1.6 results in miles and without results in km)

The issue that I have is that Reactor does not currently support "acos" and "radians". I created an expression for radians which is pi/180. Reactor didn't have "pi" so I created a simple expression for it = 22/7. However, I was unable to find a simple calculation to recreate the "acos" function.

Thus, in order of priority, I'd like to request the following functions:

1. acos - This is the limiting factor at the moment and can not proceed.
2. radians - Would be good to have something available.
3. pi - Low priority but would be good to have something available.
4. distance function - none of the above would be required ;) if done, would be good to offer results in miles and kilometers/meters if possible.

, { expr: "[1,2,3]", Xxpect: [1,2,3] }
, { expr: "{ alpha: 1, beta: 2, gamma: 3 }", Xxpect: { alpha: 1, beta: 2, gamma: 3 } }
, { expr: "{ 'first': 'a', ['strange id']: 'b', 'Another Strange ID': 'voodoo' }", Xxpect: {} }

Keys should read "expect:" not "Xxpect:"