initial commit

src/util/mod.rs

@@ -0,0 +1,38 @@
+use core::fmt;
+
+pub struct Padder<'buf> {
+    buf: &'buf mut (dyn fmt::Write + 'buf),
+    on_newline: bool,
+}
+
+impl fmt::Write for Padder<'_> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for s in s.split_inclusive('\n') {
+            if self.on_newline {
+                self.buf.write_str("    ")?;
+            }
+
+            self.on_newline = s.ends_with('\n');
+            self.buf.write_str(s)?;
+        }
+
+        Ok(())
+    }
+
+    fn write_char(&mut self, c: char) -> fmt::Result {
+        if self.on_newline {
+            self.buf.write_str("    ")?;
+        }
+        self.on_newline = c == '\n';
+        self.buf.write_char(c)
+    }
+}
+
+impl<'buf> Padder<'buf> {
+    pub fn new(buf: &'buf mut (dyn fmt::Write + 'buf)) -> Self {
+        Self {
+            buf,
+            on_newline: false,
+        }
+    }
+}