Merge pull request #213 from urbit/eamsden/flog

add format-to-cord implementation and flog! macro

rust/ares/src/flog.rs

@@ -0,0 +1,73 @@
+use crate::interpreter::Context;
+use crate::mem::NockStack;
+use crate::noun::{Atom, IndirectAtom};
+use std::fmt::Arguments;
+use std::io::{Result, Write};
+
+struct NockWriter<'s, 'b> {
+    stack: &'s mut NockStack,
+    buffer: &'b mut [u8],
+    indirect: IndirectAtom,
+    cursor: usize, //bytes
+}
+
+const INITIAL_CAPACITY_BYTES: usize = 256;
+
+impl<'s, 'b> NockWriter<'s, 'b> {
+    unsafe fn new(stack: &'s mut NockStack) -> Self {
+        let (indirect, buffer) = IndirectAtom::new_raw_mut_bytes(stack, INITIAL_CAPACITY_BYTES);
+        NockWriter {
+            stack,
+            buffer,
+            indirect,
+            cursor: 0,
+        }
+    }
+
+    unsafe fn finalize(mut self) -> Atom {
+        self.indirect.normalize_as_atom()
+    }
+
+    unsafe fn expand(&mut self) {
+        let sz = self.buffer.len();
+        let (new_indirect, new_buffer) = IndirectAtom::new_raw_mut_bytes(self.stack, sz * 2);
+        new_buffer[0..sz].copy_from_slice(self.buffer);
+        self.buffer = new_buffer;
+        self.indirect = new_indirect;
+    }
+}
+
+impl Write for NockWriter<'_, '_> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize> {
+        let sz = buf.len();
+        while (self.buffer.len() - self.cursor) < sz {
+            unsafe { self.expand() };
+        }
+        self.buffer[self.cursor..self.cursor + sz].copy_from_slice(buf);
+        self.cursor += sz;
+        Ok(sz)
+    }
+
+    fn flush(&mut self) -> Result<()> {
+        Ok(())
+    }
+}
+
+pub fn nock_fmt(context: &mut Context, fmt: Arguments<'_>) -> Result<Atom> {
+    let mut nw = unsafe { NockWriter::new(&mut context.stack) };
+    nw.write_fmt(fmt)?;
+    Ok(unsafe { nw.finalize() })
+}
+
+pub fn flog_fmt(context: &mut Context, fmt: Arguments<'_>) -> Result<()> {
+    let cord = nock_fmt(context, fmt)?;
+    context.newt.flog(&mut context.stack, cord.as_noun());
+    Ok(())
+}
+
+#[macro_export]
+macro_rules! flog {
+    ($ctx:expr, $($arg:tt)*) => {
+        $crate::flog::flog_fmt($ctx, std::format_args!($($arg)*))
+    }
+}

rust/ares/src/lib.rs

@@ -3,6 +3,7 @@ extern crate num_derive;
 extern crate lazy_static;
 #[macro_use]
 extern crate static_assertions;
+pub mod flog;
 pub mod guard;
 pub mod hamt;
 pub mod interpreter;