[Pas2js] array literals

[Mattias Gaertner]

On Fri, 15 Feb 2019 19:39:21 -0700 (MST)
warleyalex via Pas2js <pas2js at lists.freepascal.org> wrote:

Tests of Array literals

Note: array literals work since a long time.

> ***********************************************************
> Test I
> ==============================================
>   const PId = 3.141592653589793 * 2; // compiler generates possible
> dead code
>   const LETTERS   = ['A'..'Z', 'a'..'z']; // it's OK
>   console.log(PId);
> 
> Note:-> the pas2js emits this JS
> this.PId = 3.141592653589793 * 2;  ---> this is probably a dead code
> window.console.log(6.2831853071795862);

First of all 2*pi is usually called tau.

And yes, the WPO currently does not check if all references of a
constant are replaced by the literal.
Note: In this particular case it would be shorter to use this.PId
instead of the literal.


> ==============================================
> Test II
> ==============================================
> const
>   a1 : array [0..2] of String = ('zero', 'one', 'two');  //--> hum it
> uses parenteses delimiter, it's OK.
> 
> var 
>   a2 : array [0..2] of String;
> 
> console.log(a1);
> a2 := ['zero', 'one', 'two'];
> console.log(a2);
> 
> Note: it emits this:
> this.a1 = ["zero","one","two"]; // OK initialization
> $mod.a2 = ["zero","one","two"];
> window.console.log($mod.a1.slice(0));  // slice(0) allows you to
> return an array of the existing array you're referencing, a simple
> window.console.log($mod.a1) is enough a think;

That's because the log function parameter was not 'const'. I changed
that now.


>[...]
> ==============================================
> test V
> ==============================================
>   type TEnum = (en1, en2, en3);
> 
>   const ace : array [TEnum] of String = ('one', 'two', 'three');
>   const ac2 = ace;  ---> project1.lpr(57,15) Error: Constant
> expression expected

This is FPC/Delphi compatible.
They do not even support it when using {$writeableconst off}

 
> ==============================================
> test VI
> ==============================================
>   type TEnum = (en1, en2, en3);
> 
>   const ace : array [TEnum] of String = ('one', 'two', 'three');
>   //const ac2 = ace;
> 
>   var j : TEnum;
> 
>  type TEnum2 = (en1, en2, en3);    //----> I think this is a bug,
> project1.lpr(61,19) Error: Duplicate identifier "en1" at
> project1.lpr(54,20)

What exactly is a bug?
Maybe you meant {$scopedenums on} ?

 
> ==============================================
> test VII
> ==============================================
>   type TEnum = (en1, en2, en3);
> 
>   const ace : array [TEnum] of String = ('one', 'two', 'three');
>   //const ac2 = ace;
> 
>   var j : TEnum;
> 
> type TEnum2 = (en01, en02, en03);
> type TEnumArray = array [TEnum2] of string;    
> 
> const acb : TEnumArray = ('one', 'two', 'three');
> const ac21 : TEnumArray = acb; //--> it compiles as expected!

Note that FPC/Delphi do not allow this.
pas2js gives an error when using ac21. It should give an error right
away, or it should be implemented.

 
>[...]
> ==============================================
> test VIII
> ==============================================
> const
>   X: array [0..1, 0..2] of Integer = ([1, 2, 3], [4, 5, 6]);
> 
> console.log(X[0,0]);
> 
> for w := Low(X) to High(X) do
>    for z := Low(X[w]) to High(X[w]) do  // ---> we got "Error: Wrong
> number of parameters for array"
>       console.log(IntToStr(w)+', '+IntToStr(z)+' : '+IntToStr(X[w,
> z])); 

Please create a bug report.

>[...]

Mattias