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// ================================================================
// Wraps 'sh -c foo bar' or 'cmd /c foo bar', nominally for regression-testing.
// ================================================================
//go:build windows
// +build windows
package platform
import (
"os"
)
// PowerShell or CMD?
//
// * Either PowerShell or CMD is fine for everything except the '...' in inline
// put/filter statements.
//
// * PowerShell allows fractionally more, e.g. in mlr put '$flag = $x > 10' CMD
// sees the ">" as a file-redirect (before our main() is ever entered) and
// PowerShell lets it be operator it is intended to be.
//
// * Neither of them allows multi-line '...' inputs.
//
// * Both of the previous mean that a large number of regression tests need to
// use mlr -f .../cases/.../0047.mlr .../cases/.../0047.input and PowerShell
// doesn't help us eliminate this.
//
// * PowerShell has about a 2-second startup time per invocation so if we
// use it for regression testing, we'd have to move away from one shell
// invocation per Miller invocation and back to batching lots of Miller
// statements into a file, doing diff/findstr to check status. That was the
// case for Miller's original bash/file regtest framework and it was hard to
// debug.
//
// In conclusion, we stick with CMD because it's faster, and PowerShell while
// more powerful isn't *sufficiently* more powerful to justify the
// batching-complexity to overcome its startup-latency overhead.
func GetShellRunArray(command string) []string {
if os.Getenv("MSYSTEM") != "" {
// Running inside MSYS2; sufficiently Unix-like already.
return []string{"/bin/sh", "-c", command}
} else {
cmd := os.Getenv("COMSPEC")
if cmd == "" {
cmd = "C:\\Windows\\System32\\cmd.exe"
}
return []string{cmd, "/c", command}
}
}
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