feat: Add starship_precmd_user_func support for PowerShell. (#3115)

docs/advanced-config/README.md

@@ -42,6 +42,21 @@ trap blastoff DEBUG     # Trap DEBUG *before* running starship
 eval $(starship init bash)
 ```
 
+## Custom pre-prompt and pre-execution Commands in PowerShell
+
+PowerShell does not have a formal preexec/precmd framework like most other shells.
+Because of this, it is difficult to provide fully customizable hooks in `powershell`.
+However, Starship does give you limited ability to insert your own functions
+into the prompt-rendering procedure:
+
+Create a function named `Invoke-Starship-PreCommand`
+
+```powershell
+function Invoke-Starship-PreCommand {
+    $host.ui.Write("🚀")
+}
+```
+
 ## Change Window Title
 
 Some shell prompts will automatically change the window title for you (e.g. to
@@ -85,6 +100,17 @@ function set_win_title(){
 starship_precmd_user_func="set_win_title"
 ```
 
+You can also set a similar output with PowerShell by creating a function named `Invoke-Starship-PreCommand`.
+
+```powershell
+# edit $PROFILE
+function Invoke-Starship-PreCommand {
+  $host.ui.Write("`e]0; PS> $env:USERNAME@$env:COMPUTERNAME`: $pwd `a")
+}
+
+Invoke-Expression (&starship init powershell)
+```
+
 ## Enable Right Prompt
 
 Some shells support a right prompt which renders on the same line as the input. Starship can

src/init/starship.ps1

@@ -63,6 +63,13 @@ function global:prompt {
         $process.StandardOutput.ReadToEnd();
     }
 
+    # Invoke precmd, if specified
+    try {
+        if (Test-Path function:Invoke-Starship-PreCommand) {
+            Invoke-Starship-PreCommand
+        }
+    } catch {}
+
     $origDollarQuestion = $global:?
     $origLastExitCode = $global:LASTEXITCODE