Add minimal runtime filters

sailfish/src/runtime/filter.rs

@@ -0,0 +1,87 @@
+// TODO: performance improvement
+
+use std::fmt;
+
+use super::{Buffer, Render, RenderError};
+
+pub struct Display<'a, T>(&'a T);
+
+impl<'a, T: fmt::Display> Render for Display<'a, T> {
+    fn render(&self, b: &mut Buffer) -> Result<(), RenderError> {
+        use fmt::Write;
+
+        write!(b, "{}", self.0).map_err(|e| RenderError::from(e))
+    }
+}
+
+/// render using `std::fmt::Display` trait
+#[inline]
+pub fn disp<T: fmt::Display>(expr: &T) -> Display<T> {
+    Display(expr)
+}
+
+pub struct Debug<'a, T>(&'a T);
+
+impl<'a, T: fmt::Debug> Render for Debug<'a, T> {
+    fn render(&self, b: &mut Buffer) -> Result<(), RenderError> {
+        use fmt::Write;
+
+        write!(b, "{:?}", self.0).map_err(|e| RenderError::from(e))
+    }
+}
+
+/// render using `std::fmt::Debug` trait
+#[inline]
+pub fn dbg<T: fmt::Debug>(expr: &T) -> Debug<T> {
+    Debug(expr)
+}
+
+pub struct Upper<'a, T>(&'a T);
+
+impl<'a, T: Render> Render for Upper<'a, T> {
+    fn render(&self, b: &mut Buffer) -> Result<(), RenderError> {
+        let old_len = b.len();
+        self.0.render(b)?;
+
+        let s = b.as_str()[old_len..].to_uppercase();
+        unsafe { b.set_len(old_len) };
+        b.push_str(&*s);
+        Ok(())
+    }
+}
+
+/// convert the rendered contents to uppercase
+#[inline]
+pub fn upper<T: Render>(expr: &T) -> Upper<T> {
+    Upper(expr)
+}
+
+pub struct Lower<'a, T>(&'a T);
+
+impl<'a, T: Render> Render for Lower<'a, T> {
+    fn render(&self, b: &mut Buffer) -> Result<(), RenderError> {
+        let old_len = b.len();
+        self.0.render(b)?;
+
+        let s = b.as_str()[old_len..].to_lowercase();
+        unsafe { b.set_len(old_len) };
+        b.push_str(&*s);
+        Ok(())
+    }
+
+    fn render_escaped(&self, b: &mut Buffer) -> Result<(), RenderError> {
+        let old_len = b.len();
+        self.0.render_escaped(b)?;
+
+        let s = b.as_str()[old_len..].to_lowercase();
+        unsafe { b.set_len(old_len) };
+        b.push_str(&*s);
+        Ok(())
+    }
+}
+
+/// convert the rendered contents to lowercase
+#[inline]
+pub fn lower<T: Render>(expr: &T) -> Lower<T> {
+    Lower(expr)
+}

sailfish/src/runtime/mod.rs

@@ -5,6 +5,7 @@ mod utils;
 
 mod buffer;
 pub mod escape;
+pub mod filter;
 mod macros;
 mod render;
 mod size_hint;