typst/src/eval/value.rs
2021-01-12 18:55:12 +01:00

550 lines
15 KiB
Rust

use std::any::Any;
use std::collections::BTreeMap;
use std::fmt::{self, Debug, Display, Formatter};
use std::ops::Deref;
use std::rc::Rc;
use super::{Args, Eval, EvalContext};
use crate::color::Color;
use crate::geom::{Angle, Length, Linear, Relative};
use crate::pretty::{pretty, Pretty, Printer};
use crate::syntax::{Spanned, Tree, WithSpan};
/// A computational value.
#[derive(Debug, Clone, PartialEq)]
pub enum Value {
/// The value that indicates the absence of a meaningful value.
None,
/// A boolean: `true, false`.
Bool(bool),
/// An integer: `120`.
Int(i64),
/// A floating-point number: `1.2`, `10e-4`.
Float(f64),
/// A length: `12pt`, `3cm`.
Length(Length),
/// An angle: `1.5rad`, `90deg`.
Angle(Angle),
/// A relative value: `50%`.
Relative(Relative),
/// A combination of an absolute length and a relative value: `20% + 5cm`.
Linear(Linear),
/// A color value: `#f79143ff`.
Color(Color),
/// A string: `"string"`.
Str(String),
/// An array value: `(1, "hi", 12cm)`.
Array(ValueArray),
/// A dictionary value: `(color: #f79143, pattern: dashed)`.
Dict(ValueDict),
/// A template value: `[*Hi* there]`.
Template(ValueTemplate),
/// An executable function.
Func(ValueFunc),
/// Any object.
Any(ValueAny),
/// The result of invalid operations.
Error,
}
impl Value {
/// Try to cast the value into a specific type.
pub fn cast<T>(self) -> CastResult<T, Self>
where
T: Cast<Value>,
{
T::cast(self)
}
/// The name of the stored value's type.
pub fn type_name(&self) -> &'static str {
match self {
Self::None => "none",
Self::Bool(_) => bool::TYPE_NAME,
Self::Int(_) => i64::TYPE_NAME,
Self::Float(_) => f64::TYPE_NAME,
Self::Length(_) => Length::TYPE_NAME,
Self::Angle(_) => Angle::TYPE_NAME,
Self::Relative(_) => Relative::TYPE_NAME,
Self::Linear(_) => Linear::TYPE_NAME,
Self::Color(_) => Color::TYPE_NAME,
Self::Str(_) => String::TYPE_NAME,
Self::Array(_) => ValueArray::TYPE_NAME,
Self::Dict(_) => ValueDict::TYPE_NAME,
Self::Template(_) => ValueTemplate::TYPE_NAME,
Self::Func(_) => ValueFunc::TYPE_NAME,
Self::Any(v) => v.type_name(),
Self::Error => "error",
}
}
/// Whether the value is numeric.
pub fn is_numeric(&self) -> bool {
matches!(self,
Value::Int(_)
| Value::Float(_)
| Value::Length(_)
| Value::Angle(_)
| Value::Relative(_)
| Value::Linear(_)
)
}
}
impl Eval for &Value {
type Output = ();
/// Evaluate everything contained in this value.
fn eval(self, ctx: &mut EvalContext) -> Self::Output {
ctx.push(ctx.make_text_node(match self {
Value::None => return,
Value::Str(s) => s.clone(),
Value::Template(tree) => return tree.eval(ctx),
other => pretty(other),
}));
}
}
impl Default for Value {
fn default() -> Self {
Value::None
}
}
impl Pretty for Value {
fn pretty(&self, p: &mut Printer) {
match self {
Value::None => p.push_str("none"),
Value::Bool(v) => write!(p, "{}", v).unwrap(),
Value::Int(v) => write!(p, "{}", v).unwrap(),
Value::Float(v) => write!(p, "{}", v).unwrap(),
Value::Length(v) => write!(p, "{}", v).unwrap(),
Value::Angle(v) => write!(p, "{}", v).unwrap(),
Value::Relative(v) => write!(p, "{}", v).unwrap(),
Value::Linear(v) => write!(p, "{}", v).unwrap(),
Value::Color(v) => write!(p, "{}", v).unwrap(),
Value::Str(v) => write!(p, "{:?}", v).unwrap(),
Value::Array(v) => v.pretty(p),
Value::Dict(v) => v.pretty(p),
Value::Template(v) => {
p.push_str("[");
v.pretty(p);
p.push_str("]");
}
Value::Func(v) => v.pretty(p),
Value::Any(v) => v.pretty(p),
Value::Error => p.push_str("(error)"),
}
}
}
/// An array value: `(1, "hi", 12cm)`.
pub type ValueArray = Vec<Value>;
impl Pretty for ValueArray {
fn pretty(&self, p: &mut Printer) {
p.push_str("(");
p.join(self, ", ", |item, p| item.pretty(p));
if self.len() == 1 {
p.push_str(",");
}
p.push_str(")");
}
}
/// A dictionary value: `(color: #f79143, pattern: dashed)`.
pub type ValueDict = BTreeMap<String, Value>;
impl Pretty for ValueDict {
fn pretty(&self, p: &mut Printer) {
p.push_str("(");
if self.is_empty() {
p.push_str(":");
} else {
p.join(self, ", ", |(key, value), p| {
p.push_str(key);
p.push_str(": ");
value.pretty(p);
});
}
p.push_str(")");
}
}
/// A template value: `[*Hi* there]`.
pub type ValueTemplate = Tree;
/// A wrapper around a reference-counted executable function.
#[derive(Clone)]
pub struct ValueFunc {
name: String,
f: Rc<dyn Fn(&mut EvalContext, &mut Args) -> Value>,
}
impl ValueFunc {
/// Create a new function value from a rust function or closure.
pub fn new<F>(name: impl Into<String>, f: F) -> Self
where
F: Fn(&mut EvalContext, &mut Args) -> Value + 'static,
{
Self { name: name.into(), f: Rc::new(f) }
}
}
impl PartialEq for ValueFunc {
fn eq(&self, _: &Self) -> bool {
false
}
}
impl Deref for ValueFunc {
type Target = dyn Fn(&mut EvalContext, &mut Args) -> Value;
fn deref(&self) -> &Self::Target {
self.f.as_ref()
}
}
impl Pretty for ValueFunc {
fn pretty(&self, p: &mut Printer) {
write!(p, "(function {})", self.name).unwrap();
}
}
impl Debug for ValueFunc {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_struct("ValueFunc").field("name", &self.name).finish()
}
}
/// A wrapper around a dynamic value.
pub struct ValueAny(Box<dyn Bounds>);
impl ValueAny {
/// Create a new instance from any value that satisifies the required bounds.
pub fn new<T>(any: T) -> Self
where
T: Type + Debug + Display + Clone + PartialEq + 'static,
{
Self(Box::new(any))
}
/// Whether the wrapped type is `T`.
pub fn is<T: 'static>(&self) -> bool {
self.0.as_any().is::<T>()
}
/// Try to downcast to a specific type.
pub fn downcast<T: 'static>(self) -> Result<T, Self> {
if self.is::<T>() {
Ok(*self.0.into_any().downcast().unwrap())
} else {
Err(self)
}
}
/// Try to downcast to a reference to a specific type.
pub fn downcast_ref<T: 'static>(&self) -> Option<&T> {
self.0.as_any().downcast_ref()
}
/// The name of the stored value's type.
pub fn type_name(&self) -> &'static str {
self.0.dyn_type_name()
}
}
impl Clone for ValueAny {
fn clone(&self) -> Self {
Self(self.0.dyn_clone())
}
}
impl PartialEq for ValueAny {
fn eq(&self, other: &Self) -> bool {
self.0.dyn_eq(other)
}
}
impl Pretty for ValueAny {
fn pretty(&self, p: &mut Printer) {
write!(p, "{}", self.0).unwrap();
}
}
impl Debug for ValueAny {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.debug_tuple("ValueAny").field(&self.0).finish()
}
}
trait Bounds: Debug + Display + 'static {
fn as_any(&self) -> &dyn Any;
fn into_any(self: Box<Self>) -> Box<dyn Any>;
fn dyn_eq(&self, other: &ValueAny) -> bool;
fn dyn_clone(&self) -> Box<dyn Bounds>;
fn dyn_type_name(&self) -> &'static str;
}
impl<T> Bounds for T
where
T: Type + Debug + Display + Clone + PartialEq + 'static,
{
fn as_any(&self) -> &dyn Any {
self
}
fn into_any(self: Box<Self>) -> Box<dyn Any> {
self
}
fn dyn_eq(&self, other: &ValueAny) -> bool {
if let Some(other) = other.downcast_ref::<Self>() {
self == other
} else {
false
}
}
fn dyn_clone(&self) -> Box<dyn Bounds> {
Box::new(self.clone())
}
fn dyn_type_name(&self) -> &'static str {
T::TYPE_NAME
}
}
/// Types that can be stored in values.
pub trait Type {
/// The name of the type.
const TYPE_NAME: &'static str;
}
impl<T> Type for Spanned<T>
where
T: Type,
{
const TYPE_NAME: &'static str = T::TYPE_NAME;
}
/// Cast from a value to a specific type.
pub trait Cast<V>: Type + Sized {
/// Try to cast the value into an instance of `Self`.
fn cast(value: V) -> CastResult<Self, V>;
}
/// The result of casting a value to a specific type.
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum CastResult<T, V> {
/// The value was cast successfully.
Ok(T),
/// The value was cast successfully, but with a warning message.
Warn(T, String),
/// The value could not be cast into the specified type.
Err(V),
}
impl<T, V> CastResult<T, V> {
/// Access the conversion result, discarding a possibly existing warning.
pub fn ok(self) -> Option<T> {
match self {
CastResult::Ok(t) | CastResult::Warn(t, _) => Some(t),
CastResult::Err(_) => None,
}
}
}
impl Type for Value {
const TYPE_NAME: &'static str = "value";
}
impl Cast<Value> for Value {
fn cast(value: Value) -> CastResult<Self, Value> {
CastResult::Ok(value)
}
}
impl<T> Cast<Spanned<Value>> for T
where
T: Cast<Value>,
{
fn cast(value: Spanned<Value>) -> CastResult<Self, Spanned<Value>> {
let span = value.span;
match T::cast(value.v) {
CastResult::Ok(t) => CastResult::Ok(t),
CastResult::Warn(t, m) => CastResult::Warn(t, m),
CastResult::Err(v) => CastResult::Err(v.with_span(span)),
}
}
}
impl<T> Cast<Spanned<Value>> for Spanned<T>
where
T: Cast<Value>,
{
fn cast(value: Spanned<Value>) -> CastResult<Self, Spanned<Value>> {
let span = value.span;
match T::cast(value.v) {
CastResult::Ok(t) => CastResult::Ok(t.with_span(span)),
CastResult::Warn(t, m) => CastResult::Warn(t.with_span(span), m),
CastResult::Err(v) => CastResult::Err(v.with_span(span)),
}
}
}
macro_rules! impl_primitive {
($type:ty:
$type_name:literal,
$variant:path
$(, $pattern:pat => $out:expr)* $(,)?
) => {
impl Type for $type {
const TYPE_NAME: &'static str = $type_name;
}
impl From<$type> for Value {
fn from(v: $type) -> Self {
$variant(v)
}
}
impl Cast<Value> for $type {
fn cast(value: Value) -> CastResult<Self, Value> {
match value {
$variant(v) => CastResult::Ok(v),
$($pattern => CastResult::Ok($out),)*
v => CastResult::Err(v),
}
}
}
};
}
impl_primitive! { bool: "boolean", Value::Bool }
impl_primitive! { i64: "integer", Value::Int }
impl_primitive! {
f64: "float",
Value::Float,
Value::Int(v) => v as f64,
}
impl_primitive! { Length: "length", Value::Length }
impl_primitive! { Angle: "angle", Value::Angle }
impl_primitive! { Relative: "relative", Value::Relative }
impl_primitive! {
Linear: "linear",
Value::Linear,
Value::Length(v) => v.into(),
Value::Relative(v) => v.into(),
}
impl_primitive! { Color: "color", Value::Color }
impl_primitive! { String: "string", Value::Str }
impl_primitive! { ValueArray: "array", Value::Array }
impl_primitive! { ValueDict: "dictionary", Value::Dict }
impl_primitive! { ValueTemplate: "template", Value::Template }
impl_primitive! { ValueFunc: "function", Value::Func }
impl From<&str> for Value {
fn from(v: &str) -> Self {
Self::Str(v.to_string())
}
}
impl From<ValueAny> for Value {
fn from(v: ValueAny) -> Self {
Self::Any(v)
}
}
/// Make a type usable as a [`Value`].
///
/// Given a type `T`, this always implements the following traits:
/// - [`Type`] for `T`,
/// - [`Cast<Value>`](Cast) for `T`.
#[macro_export]
macro_rules! impl_type {
($type:ty:
$type_name:literal
$(, $pattern:pat => $out:expr)*
$(, #($anyvar:ident: $anytype:ty) => $anyout:expr)*
$(,)?
) => {
impl $crate::eval::Type for $type {
const TYPE_NAME: &'static str = $type_name;
}
impl $crate::eval::Cast<$crate::eval::Value> for $type {
fn cast(
value: $crate::eval::Value,
) -> $crate::eval::CastResult<Self, $crate::eval::Value> {
use $crate::eval::*;
#[allow(unreachable_code)]
match value {
$($pattern => CastResult::Ok($out),)*
Value::Any(mut any) => {
any = match any.downcast::<Self>() {
Ok(t) => return CastResult::Ok(t),
Err(any) => any,
};
$(any = match any.downcast::<$anytype>() {
Ok($anyvar) => return CastResult::Ok($anyout),
Err(any) => any,
};)*
CastResult::Err(Value::Any(any))
},
v => CastResult::Err(v),
}
}
}
};
}
#[cfg(test)]
mod tests {
use super::*;
use crate::color::RgbaColor;
use crate::parse::parse;
use crate::pretty::pretty;
use crate::syntax::Node;
#[track_caller]
fn test_pretty(value: impl Into<Value>, exp: &str) {
assert_eq!(pretty(&value.into()), exp);
}
#[test]
fn test_pretty_print_simple_values() {
test_pretty(Value::None, "none");
test_pretty(false, "false");
test_pretty(12.4, "12.4");
test_pretty(Length::pt(5.5), "5.5pt");
test_pretty(Angle::deg(90.0), "90deg");
test_pretty(Relative::ONE / 2.0, "50%");
test_pretty(Relative::new(0.3) + Length::cm(2.0), "30% + 2cm");
test_pretty(Color::Rgba(RgbaColor::new(1, 1, 1, 0xff)), "#010101");
test_pretty("hello", r#""hello""#);
test_pretty(vec![Spanned::zero(Node::Strong)], "[*]");
test_pretty(ValueFunc::new("nil", |_, _| Value::None), "(function nil)");
test_pretty(ValueAny::new(1), "1");
test_pretty(Value::Error, "(error)");
}
#[test]
fn test_pretty_print_collections() {
// Array.
test_pretty(Value::Array(vec![]), "()");
test_pretty(vec![Value::None], "(none,)");
test_pretty(vec![Value::Int(1), Value::Int(2)], "(1, 2)");
// Dictionary.
let mut dict = BTreeMap::new();
dict.insert("one".into(), Value::Int(1));
dict.insert("two".into(), Value::Template(parse("[f]").output));
test_pretty(BTreeMap::new(), "(:)");
test_pretty(dict, "(one: 1, two: [[f]])");
}
}