Merge conditions and expressions

[TPGamesNL]

Description

This PR makes all conditions boolean expressions, and all boolean expressions can be used as conditions (mostly).

Examples

set {_a} to true
if {_a}: # passes

Boolean operations:

set {_a} to true
set {_b} to true
if {_a} and {_b}: # passes

set {_a} to true
set {_b} to false
if {_a} and {_b}: # fails

set {_a} to true
set {_b} to false
if {_a} or {_b}: # passes

if player can fly and player is alive:

But:

set {_a} to 1
# set {_b} to 1
if {_a} is set and {_b} is not set: 

does not pass, because it is parsed as if (({_a} is set) and {_b}) is not set, where ({_a} is set) and {_b} is a boolean 'and' operation with the condition and the variable. If you use parentheses, if ({_a} is set) and ({_b} is not set):

Also
set {_a} to {_b} is set
set {_x} to player is online

Only limitation is that inline conditions can't be expressions, for example:

set {_b} to false
{_b} # would exit the current section

doesn't parse, but I'm not even sure if having that would be beneficial.

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Target Minecraft Versions: any
Requirements: none
Related Issues: #2207

[Mwexim]

Lovely changes! Something that had to be done, possibly way earlier.

I’ll give you this link. It is a PR of mine where I fix the parsing issue that still remains (the fact that boolean operators and list literals clash with each other).

Do what you want with it, I’ll leave it here for convenience.

Also, you might want to look at how skript-parser handles conditional expressions. They aren’t allowed in normal syntaxes, unless the type has a ‘=‘ prefix.
For example:

• ‘=boolean’ will allow boolean expressions and conditional expressions
• ‘boolean’ will only allow boolean expressions

This might be a more clean approach. Conditional expressions can then be called by using something like ‘check if {var} is set’, for example.

[Nicofisi]

Hey! What's the status of this?

[TPGamesNL]

@Nicofisi There's no progress on this, I've been busy with other stuff and this has lost my attention. I'm also still unsure over the design, for example if all %boolean% (or %object%) should allow conditions by default (and without extra syntax) and if all conditions should be expressions by default. But that is for if I ever pick this up again.

[APickledWalrus]

Closing in favor of #6748