1 files changed, 163 insertions, 0 deletions
diff --git a/src/exec/state.rs b/src/exec/state.rs
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+++ b/src/exec/state.rs
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+use std::rc::Rc;
+
+use fontdock::{fallback, FallbackTree, FontStretch, FontStyle, FontVariant, FontWeight};
+
+use crate::geom::{
+    Align, ChildAlign, Dir, LayoutDirs, Length, Linear, Relative, Sides, Size, Spec,
+};
+use crate::layout::Expansion;
+use crate::paper::{Paper, PaperClass, PAPER_A4};
+
+/// The evaluation state.
+#[derive(Debug, Clone, PartialEq)]
+pub struct State {
+    /// The current page settings.
+    pub page: PageSettings,
+    /// The current paragraph settings.
+    pub par: ParSettings,
+    /// The current font settings.
+    pub font: FontSettings,
+    /// The current layouting directions.
+    pub dirs: LayoutDirs,
+    /// The current alignments of an item in its parent.
+    pub align: ChildAlign,
+}
+
+impl Default for State {
+    fn default() -> Self {
+        Self {
+            page: PageSettings::default(),
+            par: ParSettings::default(),
+            font: FontSettings::default(),
+            dirs: LayoutDirs::new(Dir::TTB, Dir::LTR),
+            align: ChildAlign::new(Align::Start, Align::Start),
+        }
+    }
+}
+
+/// Defines page properties.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub struct PageSettings {
+    /// The class of this page.
+    pub class: PaperClass,
+    /// The width and height of the page.
+    pub size: Size,
+    /// Whether the expand the pages to the `size` or to fit the content.
+    pub expand: Spec<Expansion>,
+    /// The amount of white space in the order [left, top, right, bottom]. If a
+    /// side is set to `None`, the default for the paper class is used.
+    pub margins: Sides<Option<Linear>>,
+}
+
+impl PageSettings {
+    /// The default page style for the given paper.
+    pub fn new(paper: Paper) -> Self {
+        Self {
+            class: paper.class,
+            size: paper.size(),
+            expand: Spec::uniform(Expansion::Fill),
+            margins: Sides::uniform(None),
+        }
+    }
+
+    /// The margins.
+    pub fn margins(&self) -> Sides<Linear> {
+        let default = self.class.default_margins();
+        Sides {
+            left: self.margins.left.unwrap_or(default.left),
+            top: self.margins.top.unwrap_or(default.top),
+            right: self.margins.right.unwrap_or(default.right),
+            bottom: self.margins.bottom.unwrap_or(default.bottom),
+        }
+    }
+}
+
+impl Default for PageSettings {
+    fn default() -> Self {
+        Self::new(PAPER_A4)
+    }
+}
+
+/// Defines paragraph properties.
+#[derive(Debug, Copy, Clone, PartialEq)]
+pub struct ParSettings {
+    /// The spacing between words (dependent on scaled font size).
+    pub word_spacing: Linear,
+    /// The spacing between lines (dependent on scaled font size).
+    pub line_spacing: Linear,
+    /// The spacing between paragraphs (dependent on scaled font size).
+    pub par_spacing: Linear,
+}
+
+impl Default for ParSettings {
+    fn default() -> Self {
+        Self {
+            word_spacing: Relative::new(0.25).into(),
+            line_spacing: Relative::new(0.2).into(),
+            par_spacing: Relative::new(0.5).into(),
+        }
+    }
+}
+
+/// Defines font properties.
+#[derive(Debug, Clone, PartialEq)]
+pub struct FontSettings {
+    /// A tree of font family names and generic class names.
+    pub families: Rc<FallbackTree>,
+    /// The selected font variant.
+    pub variant: FontVariant,
+    /// The font size.
+    pub size: Length,
+    /// The linear to apply on the base font size.
+    pub scale: Linear,
+    /// Whether the strong toggle is active or inactive. This determines
+    /// whether the next `*` adds or removes font weight.
+    pub strong: bool,
+    /// Whether the emphasis toggle is active or inactive. This determines
+    /// whether the next `_` makes italic or non-italic.
+    pub emph: bool,
+}
+
+impl FontSettings {
+    /// Access the `families` mutably.
+    pub fn families_mut(&mut self) -> &mut FallbackTree {
+        Rc::make_mut(&mut self.families)
+    }
+
+    /// The absolute font size.
+    pub fn font_size(&self) -> Length {
+        self.scale.resolve(self.size)
+    }
+}
+
+impl Default for FontSettings {
+    fn default() -> Self {
+        Self {
+            /// The default tree of font fallbacks.
+            families: Rc::new(fallback! {
+                list: ["sans-serif"],
+                classes: {
+                    "serif"      => ["source serif pro", "noto serif"],
+                    "sans-serif" => ["source sans pro", "noto sans"],
+                    "monospace"  => ["source code pro", "noto sans mono"],
+                },
+                base: [
+                    "source sans pro",
+                    "noto sans",
+                    "segoe ui emoji",
+                    "noto emoji",
+                    "latin modern math",
+                ],
+            }),
+            variant: FontVariant {
+                style: FontStyle::Normal,
+                weight: FontWeight::REGULAR,
+                stretch: FontStretch::Normal,
+            },
+            size: Length::pt(11.0),
+            scale: Linear::ONE,
+            strong: false,
+            emph: false,
+        }
+    }
+}