Sublime build system to open file at local server address - bash

Question

For a website I'm developing with the help of a local server (running at http://127.0.0.1:4000), I try to write a build system for my Sublime Text project settings.
I have access to these variables (provided by Sublime Text):
$file: Stores the absolute path to the file on disk:C:\Users\User\dev\repos\base\dir\index.html
$project_path: Stores the location of the project file (usually the root of the project):C:\Users\User\dev\repos\base
Now what I want is the content of $file but instead of the $project_path I want http://127.0.0.1:4000/~base. For that task I tried the following with Bash cmd.exe:
CALL SET result=%file:%project_path%=http://127.0.0.1:4000\~base\% && echo %result%
This gives the desired result, however I can't seem to be able to apply it to the build system inside Sublime Text.
For now, I try to generate the correct address and output it via cmd.exe:
{
"build_systems":
[
{
"name": "Preview in browser",
"selector": "text.html",
"windows":
{
"shell": true,
"cmd": [
"start", "cmd", "/k",
"CALL SET result=$file:$project_path=http://127.0.0.1:4000\\~base\\ && echo $result"
]
}
}
]
}
Result:
> echo %result%
C:\Users\Philipp\dev\repos\base\dir\index.html:C:\Users\Philipp\dev\repos
\base=http://127.0.0.1:4000\~base\
So the substitution is not working when doing it in the build system, but in cmd.exe it does. I'm confused.

Answer 1

You can do something like this:
{
"build_systems":
[
{
"name": "Preview in browser",
"selector": "text.html",
"windows":
{
"shell_cmd": "CALL SET filePath=$file && CALL SET result=%filePath:$project_path=http://127.0.0.1:4000\\~base% && CALL C:/Progra~2/Google/Chrome/Application/chrome.exe %result%"
}
}
]
}
The problem was with windows replacement and variable asignation rather than with sublime builds.
As it has been said in chat and comments multiple CALL are necessary to use the real value variable because if not used windows will expand their value at parse time before the wanted value is asigned at execution time. In addition, shell_cmd can be used to run a unique command in shell.