WIP/UNTESTED Add := for simple math operations

expressions still aren't supported and probably won't for a long time, but now you can write basic additions etc. in a single line. Example usage: `my_var := other_var * (16 + 5)`
So you'll need to omit percentage signs around variables. This is done for compatibility purposes, even though this adds unnecessary complexity. Expression syntax was a mistake!!1

README.md

@@ -106,7 +106,7 @@ Still, here is a brief peek at the syntax. (click the arrows)
     </details>
 
 
-AHK_X11 is a very basic but functional reimplementation AutoHotkey v1.0.24 (2004) for Unix-like systems with an X window system (X11), written from ground up in [Crystal](https://crystal-lang.org/), with the eventual goal of 80% feature parity, but most likely never full compatibility. Currently about 80% of work of getting there is done, but even at 100%, because of the old version of the spec (at least for now), many modern AHK features are missing, especially expressions (`:=`, `% v`), classes, objects and functions, so you probably can't just port your scripts from Windows. More to read: [Project goals](https://github.com/phil294/AHK_X11/issues/8)
+AHK_X11 is a very basic but functional reimplementation AutoHotkey v1.0.24 (2004) for Unix-like systems with an X window system (X11), written from ground up in [Crystal](https://crystal-lang.org/), with the eventual goal of 80% feature parity, but most likely never full compatibility. Currently about 80% of work of getting there is done, but even at 100%, because of the old version of the spec (at least for now), many modern AHK features are missing, especially advanced expressions and functions (`x := y(z)`, `% v`), classes, and objects, so you probably can't just port your scripts from Windows. More to read: [Project goals](https://github.com/phil294/AHK_X11/issues/8)
 
 This AHK is shipped as a single executable native binary with very low resource overhead and fast execution time. You can use AHK_X11 to create stand-alone binaries with no dependencies, including full functionality like Hotkeys and GUIs. (just like on Windows)
 
@@ -289,6 +289,7 @@ Besides the [Legacy Syntax](https://www.autohotkey.com/docs/v1/Language.htm#lega
 - `x := 1` -> `x = 1`
 - `x := y` -> `x = %y%`
 - `b := a + 3` ->
+  Simple math instructions with `:=` like this one are actually wonkily supported, so chances are you can leave it as is. In this case, you'd omit the percent signs `%` unless you want to double-deref, just like on Windows. But for more complicated stuff such as string concatenation, you'll have to resort back to classic syntax:
   ```ahk
   b = %a%
   b += 3

docs/index.html

@@ -8855,6 +8855,7 @@ <h2 class="calibre9"><span class="calibre23">The "Last Found" Window </span></h2
           <p class="calibre8">Variables can be increased or decreased by 1 by using Var++, Var--, ++Var, or --Var.</p>
           <p class="calibre8">If either <em class="calibre21">Var</em> or <em class="calibre21">Value</em> is blank or does not start with a number, it is considered to be 0 for the purpose of the calculation (except when using <em class="calibre21">TimeUnits</em>, see above).</p>
           <p class="calibre8">If either <em class="calibre21">Var</em> or <em class="calibre21">Value</em> contains a decimal point, the end result will be a floating point number in the format set by <a href="#SetFormat.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">SetFormat</a>. </p>
+          <p class="calibre8 x11">For general math operations, you can also resort back to the more modern := operator, which you might know from modern Windows AHK. In this case, you want to omit the percent signs % unless you want to double-deref. This := operator (for "expressions") is much more limited on AHK_X11 though, and also performs poorly. Example usage: my_var := other_var * (16 + 5)</p>
           <p class="calibre8"> </p>
           <p class="calibre8"><strong class="calibre14">Related</strong></p>
           <p class="calibre8"><a href="#EnvSub.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">EnvSub</a>, <a href="#EnvMult.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">EnvMult</a>, <a href="#EnvDiv.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">EnvDiv</a>, <a href="#SetFormat.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">SetFormat</a>, <a href="#IfIs.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">If var is [not] type</a>, <a href="#SetEnv.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">SetEnv</a>, <a href="#FileGetTime.htm" class="pcalibre3 pcalibre1 pcalibre calibre5 pcalibre2">FileGetTime</a></p>

src/build/parser.cr

@@ -223,6 +223,8 @@ module Build
 				case second_word
 				when "="
 					cmd_class = Cmd::Math::SetEnv
+				when ":="
+					cmd_class = Cmd::Math::EnvMath
 				when "+="
 					cmd_class = Cmd::Math::EnvAdd
 					raise "Add value missing for '+=' expression" if ! other_arg

src/cmd/math/env-math.cr

@@ -0,0 +1,22 @@
+class Cmd::Math::EnvMath < Cmd::Base
+	def self.min_args; 1 end
+	def self.max_args; 2 end
+	def self.sets_error_level; true end
+
+	def run(thread, args)
+		var = args[0]
+		formula = args[1]? || ""
+		formula = formula.replace_all /\b[^0-9.()%/*<>+-]\w*\b/g do |word|
+			thread.runner.get_var(word)
+		end
+		stdout_m = IO::Memory.new
+		stderr_m = IO::Memory.new
+		result = Process.run "awk", "BEGIN {print #{formula}}", output: stdout_m, error: stderr_m
+		if result.exit_code != 0
+			thread.runner.set_user_var var, ""
+			return stderr_m.to_s
+		end
+		thread.runner.set_user_var var, stdout_m.to_s
+		return "0"
+	end
+end