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//! Computational values.
use std::fmt::{self, Debug, Formatter};
use std::ops::Deref;
use std::rc::Rc;
use super::{Args, Dict, Eval, EvalContext, SpannedEntry};
use crate::color::RgbaColor;
use crate::geom::{Length, Linear, Relative};
use crate::syntax::{Ident, SynTree};
/// A computational value.
#[derive(Clone, PartialEq)]
pub enum Value {
/// The value that indicates the absence of a meaningful value.
None,
/// An identifier: `ident`.
Ident(Ident),
/// A boolean: `true, false`.
Bool(bool),
/// An integer: `120`.
Int(i64),
/// A floating-point number: `1.2, 200%`.
Float(f64),
/// A length: `2cm, 5.2in`.
Length(Length),
/// A relative value: `50%`.
Relative(Relative),
/// A combination of an absolute length and a relative value: `20% + 5cm`.
Linear(Linear),
/// A color value with alpha channel: `#f79143ff`.
Color(RgbaColor),
/// A string: `"string"`.
Str(String),
/// A dictionary value: `(false, 12cm, greeting="hi")`.
Dict(ValueDict),
/// A content value: `{*Hi* there}`.
Content(SynTree),
/// An executable function.
Func(ValueFunc),
/// The result of invalid operations.
Error,
}
impl Value {
/// The natural-language name of this value's type for use in error
/// messages.
pub fn ty(&self) -> &'static str {
match self {
Self::None => "none",
Self::Ident(_) => "identifier",
Self::Bool(_) => "bool",
Self::Int(_) => "integer",
Self::Float(_) => "float",
Self::Relative(_) => "relative",
Self::Length(_) => "length",
Self::Linear(_) => "linear",
Self::Color(_) => "color",
Self::Str(_) => "string",
Self::Dict(_) => "dict",
Self::Content(_) => "content",
Self::Func(_) => "function",
Self::Error => "error",
}
}
}
impl Eval for Value {
type Output = ();
/// Evaluate everything contained in this value.
fn eval(&self, ctx: &mut EvalContext) -> Self::Output {
match self {
// Don't print out none values.
Value::None => {}
// Pass through.
Value::Content(tree) => tree.eval(ctx),
// Forward to each dictionary entry.
Value::Dict(dict) => {
for entry in dict.values() {
entry.value.v.eval(ctx);
}
}
// Format with debug.
val => ctx.push(ctx.make_text_node(format!("{:?}", val))),
}
}
}
impl Default for Value {
fn default() -> Self {
Value::None
}
}
impl Debug for Value {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
match self {
Self::None => f.pad("none"),
Self::Ident(v) => v.fmt(f),
Self::Bool(v) => v.fmt(f),
Self::Int(v) => v.fmt(f),
Self::Float(v) => v.fmt(f),
Self::Length(v) => v.fmt(f),
Self::Relative(v) => v.fmt(f),
Self::Linear(v) => v.fmt(f),
Self::Color(v) => v.fmt(f),
Self::Str(v) => v.fmt(f),
Self::Dict(v) => v.fmt(f),
Self::Content(v) => v.fmt(f),
Self::Func(v) => v.fmt(f),
Self::Error => f.pad("<error>"),
}
}
}
/// A dictionary of values.
///
/// # Example
/// ```typst
/// (false, 12cm, greeting="hi")
/// ```
pub type ValueDict = Dict<SpannedEntry<Value>>;
/// An wrapper around a reference-counted executable function value.
///
/// The dynamic function object is wrapped in an `Rc` to keep [`Value`]
/// clonable.
///
/// _Note_: This is needed because the compiler can't `derive(PartialEq)` for
/// [`Value`] when directly putting the boxed function in there, see the
/// [Rust Issue].
///
/// [`Value`]: enum.Value.html
/// [Rust Issue]: https://github.com/rust-lang/rust/issues/31740
#[derive(Clone)]
pub struct ValueFunc(pub Rc<Func>);
/// The signature of executable functions.
type Func = dyn Fn(Args, &mut EvalContext) -> Value;
impl ValueFunc {
/// Create a new function value from a rust function or closure.
pub fn new<F>(f: F) -> Self
where
F: Fn(Args, &mut EvalContext) -> Value + 'static,
{
Self(Rc::new(f))
}
}
impl PartialEq for ValueFunc {
fn eq(&self, _: &Self) -> bool {
false
}
}
impl Deref for ValueFunc {
type Target = Func;
fn deref(&self) -> &Self::Target {
self.0.as_ref()
}
}
impl Debug for ValueFunc {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.pad("<function>")
}
}
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