Add standard `align` function and support right-alignment ➡️

1 files changed, 64 insertions, 0 deletions

diff --git a/src/library/styles.rs b/src/library/styles.rs
new file mode 100644
index 00000000..c84b9fed
--- /dev/null
+++ b/src/library/styles.rs
@@ -0,0 +1,64 @@
+//! Basic style functions: bold, italic, monospace.
+
+use super::prelude::*;
+use toddle::query::FontClass;
+
+
+
+macro_rules! style_func {
+    ($(#[$outer:meta])* pub struct $struct:ident { $name:expr },
+     $style:ident => $style_change:block) => {
+        $(#[$outer])*
+        #[derive(Debug, PartialEq)]
+        pub struct $struct { body: SyntaxTree }
+
+        impl Function for $struct {
+            fn parse(header: &FuncHeader, body: Option<&str>, ctx: ParseContext)
+                -> ParseResult<Self> where Self: Sized {
+                // Accept only invocations without arguments and with body.
+                if header.args.is_empty() && header.kwargs.is_empty() {
+                    if let Some(body) = body {
+                        Ok($struct { body: parse(body, ctx)? })
+                    } else {
+                        Err(ParseError::new(format!("expected body for function `{}`", $name)))
+                    }
+                } else {
+                    Err(ParseError::new(format!("unexpected arguments to function `{}`", $name)))
+                }
+            }
+
+            fn layout(&self, ctx: LayoutContext) -> LayoutResult<Option<Layout>> {
+                // Change the context.
+                let mut $style = ctx.style.clone();
+                $style_change
+
+                // Create a box and put it into a flex layout.
+                let boxed = layout(&self.body, LayoutContext {
+                    style: &$style,
+                    .. ctx
+                })?;
+                let flex = FlexLayout::from_box(boxed);
+
+                Ok(Some(Layout::Flex(flex)))
+            }
+        }
+    };
+}
+
+style_func! {
+    /// Typesets text in bold.
+    pub struct BoldFunc { "bold" },
+    style => { style.toggle_class(FontClass::Bold) }
+}
+
+style_func! {
+    /// Typesets text in italics.
+    pub struct ItalicFunc { "italic" },
+    style => { style.toggle_class(FontClass::Italic) }
+}
+
+style_func! {
+    /// Typesets text in monospace.
+    pub struct MonospaceFunc { "mono" },
+    style => { style.toggle_class(FontClass::Monospace) }
+}