1 files changed, 83 insertions, 0 deletions
diff --git a/js/src/process.ts b/js/src/process.ts
new file mode 100644
index 0000000..537aba8
--- /dev/null
+++ b/js/src/process.ts
@@ -0,0 +1,83 @@
+type Proc = {
+    connect(sig: "stdout" | "stderr", fn: (_: any, out: string) => void): number
+}
+
+type Config<P extends Proc> = {
+    defaultOut(stdout: string): void
+    defaultErr(stdout: string): void
+    subprocess(cmd: string): P
+    subprocessv(cmd: string[]): P
+    exec(cmd: string): string | null
+    execv(cmd: string[]): string | null
+    execAsync(cmd: string): P
+    execAsyncv(cmd: string[]): P
+}
+
+type Args<Out = void, Err = void> = {
+    cmd: string | string[],
+    out?: (stdout: string) => Out,
+    err?: (stderr: string) => Err,
+}
+
+export default function <P extends Proc>(config: Config<P>) {
+    function args<O, E>(argsOrCmd: Args | string | string[], onOut: O, onErr: E) {
+        const params = Array.isArray(argsOrCmd) || typeof argsOrCmd === "string"
+        return {
+            cmd: params ? argsOrCmd : argsOrCmd.cmd,
+            err: params ? onErr : argsOrCmd.err || onErr,
+            out: params ? onOut : argsOrCmd.out || onOut,
+        }
+    }
+
+    function subprocess(args: Args): P
+    function subprocess(
+        cmd: string | string[],
+        onOut?: (stdout: string) => void,
+        onErr?: (stderr: string) => void,
+    ): P
+    function subprocess(
+        argsOrCmd: Args | string | string[],
+        onOut: (stdout: string) => void = config.defaultOut,
+        onErr: (stderr: string) => void = config.defaultErr,
+    ) {
+        const { cmd, err, out } = args(argsOrCmd, onOut, onErr)
+        const proc = Array.isArray(cmd)
+            ? config.subprocessv(cmd)
+            : config.subprocess(cmd)
+
+        proc.connect("stdout", (_, stdout: string) => out(stdout))
+        proc.connect("stderr", (_, stderr: string) => err(stderr))
+        return proc
+    }
+
+    function exec<Out = string, Err = string>(
+        args: Args<Out, Err>
+    ): Out | Err
+    function exec<Out = string, Err = string>(
+        cmd: string | string[],
+        onOut?: (stdout: string) => Out,
+        onErr?: (stderr: string) => Err,
+    ): Out | Err
+    function exec<Out = string, Err = string>(
+        argsOrCmd: Args<Out, Err> | string | string[],
+        onOut: (stdout: string) => Out = out => out as Out,
+        onErr: (stderr: string) => Err = out => out as Err,
+    ): Out | Err {
+        const { cmd, err, out } = args(argsOrCmd, onOut, onErr)
+        return Array.isArray(cmd)
+            ? out(config.execv(cmd)!) as Out
+            : err(config.exec(cmd)!) as Err
+    }
+
+    function execAsync(cmd: string | string[]): Promise<string> {
+        const proc = Array.isArray(cmd)
+            ? config.execAsyncv(cmd)
+            : config.execAsync(cmd)
+        return new Promise((resolve, reject) => {
+            proc.connect("stdout", (_, out: string) => resolve(out))
+            proc.connect("stderr", (_, err: string) => reject(err))
+        })
+    }
+
+    return { subprocess, exec, execAsync }
+}