Revise CLI example

examples/cli/platform/src/lib.rs

@@ -1,50 +1,124 @@
+#![allow(non_snake_case)]
+
+use roc_std::alloca;
 use roc_std::RocCallResult;
-use roc_std::RocList;
+use roc_std::RocStr;
+use std::alloc::Layout;
 use std::time::SystemTime;
 
 extern "C" {
     #[link_name = "roc__mainForHost_1_exposed"]
-    fn quicksort(list: RocList<i64>, output: &mut RocCallResult<RocList<i64>>) -> ();
+    fn roc_main(output: *mut u8) -> ();
+
+    #[link_name = "roc__mainForHost_1_size"]
+    fn roc_main_size() -> i64;
+
+    #[link_name = "roc__mainForHost_1_Fx_caller"]
+    fn call_Fx(
+        flags: &(),
+        function_pointer: *const u8,
+        closure_data: *const u8,
+        output: *mut u8,
+    ) -> ();
+
+    #[link_name = "roc__mainForHost_1_Fx_size"]
+    fn size_Fx() -> i64;
+
+    #[link_name = "roc__mainForHost_1_Fx_result_size"]
+    fn size_Fx_result() -> i64;
 }
 
-const NUM_NUMS: usize = 100;
+#[no_mangle]
+pub fn roc_fx_putLine(line: RocStr) -> () {
+    let bytes = line.as_slice();
+    let string = unsafe { std::str::from_utf8_unchecked(bytes) };
+    println!("{}", string);
+
+    ()
+}
+
+#[no_mangle]
+pub fn roc_fx_getLine() -> RocStr {
+    use std::io::{self, BufRead};
+
+    let stdin = io::stdin();
+    let line1 = stdin.lock().lines().next().unwrap().unwrap();
+
+    RocStr::from_slice_with_capacity(line1.as_bytes(), line1.len())
+}
+
+unsafe fn call_the_closure(function_pointer: *const u8, closure_data_ptr: *const u8) -> i64 {
+    let size = size_Fx_result() as usize;
+
+    alloca::with_stack_bytes(size, |buffer| {
+        let buffer: *mut std::ffi::c_void = buffer;
+        let buffer: *mut u8 = buffer as *mut u8;
+
+        call_Fx(
+            &(),
+            function_pointer,
+            closure_data_ptr as *const u8,
+            buffer as *mut u8,
+        );
+
+        let output = &*(buffer as *mut RocCallResult<()>);
+
+        match output.into() {
+            Ok(_) => 0,
+            Err(e) => panic!("failed with {}", e),
+        }
+    })
+}
 
 #[no_mangle]
 pub fn rust_main() -> isize {
-    let nums: RocList<i64> = {
-        let mut nums = Vec::with_capacity(NUM_NUMS);
-
-        for index in 0..nums.capacity() {
-            let num = index as i64 % 12;
-
-            nums.push(num);
-        }
-
-        RocList::from_slice(&nums)
-    };
-
-    println!("Running Roc quicksort on {} numbers...", nums.len());
+    println!("Running Roc closure");
     let start_time = SystemTime::now();
+
+    let size = unsafe { roc_main_size() } as usize;
+    let layout = Layout::array::<u8>(size).unwrap();
     let answer = unsafe {
-        use std::mem::MaybeUninit;
-        let mut output = MaybeUninit::uninit();
+        // TODO if this is 1024B or less, put it in a global scratch buffer
+        let buffer = std::alloc::alloc(layout);
 
-        quicksort(nums, &mut *output.as_mut_ptr());
+        roc_main(buffer);
 
-        match output.assume_init().into() {
-            Ok(value) => value,
-            Err(msg) => panic!("roc failed with message {}", msg),
+        let output = &*(buffer as *mut RocCallResult<()>);
+
+        match output.into() {
+            Ok(()) => {
+                let function_pointer = {
+                    // this is a pointer to the location where the function pointer is stored
+                    // we pass just the function pointer
+                    let temp = buffer.offset(8) as *const i64;
+
+                    (*temp) as *const u8
+                };
+
+                let closure_data_ptr = buffer.offset(16);
+
+                let result =
+                    call_the_closure(function_pointer as *const u8, closure_data_ptr as *const u8);
+
+                std::alloc::dealloc(buffer, layout);
+
+                result
+            }
+            Err(msg) => {
+                std::alloc::dealloc(buffer, layout);
+
+                panic!("Roc failed with message: {}", msg);
+            }
         }
     };
-
     let end_time = SystemTime::now();
     let duration = end_time.duration_since(start_time).unwrap();
 
     println!(
-        "Roc quicksort took {:.4} ms to compute this answer: {:?}",
+        "Roc closure took {:.4} ms to compute this answer: {:?}",
         duration.as_secs_f64() * 1000.0,
         // truncate the answer, so stdout is not swamped
-        &answer.as_slice()[0..20]
+        answer
     );
 
     // Exit code