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|
//! Value types for extracting function arguments.
use fontdock::{FontStyle, FontWeight, FontWidth};
use crate::Feedback;
use crate::layout::prelude::*;
use crate::length::{Length, ScaleLength};
use crate::paper::Paper;
use super::span::Spanned;
use super::expr::*;
/// Value types are used to extract values from functions, tuples and
/// objects. They represent the value part of an argument.
/// ```typst
/// [func: value, key=value]
/// ^^^^^ ^^^^^
/// ```
pub trait Value: Sized {
/// Try to parse this value from an expression.
///
/// Returns `None` and generates an appropriate error if the expression is
/// not valid for this value type
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self>;
}
impl<V: Value> Value for Spanned<V> {
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self> {
let span = expr.span;
V::parse(expr, f).map(|v| Spanned { v, span })
}
}
macro_rules! match_value {
($type:ty, $name:expr, $($p:pat => $r:expr),* $(,)?) => {
impl Value for $type {
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self> {
#[allow(unreachable_patterns)]
match expr.v {
$($p => Some($r)),*,
other => {
error!(
@f, expr.span,
"expected {}, found {}", $name, other.name()
);
None
}
}
}
}
};
}
match_value!(Expr, "expression", e => e);
match_value!(Ident, "identifier", Expr::Ident(i) => i);
match_value!(String, "string", Expr::Str(s) => s);
match_value!(f64, "number", Expr::Number(n) => n);
match_value!(bool, "bool", Expr::Bool(b) => b);
match_value!(Length, "length", Expr::Length(l) => l);
match_value!(Tuple, "tuple", Expr::Tuple(t) => t);
match_value!(Object, "object", Expr::Object(o) => o);
match_value!(ScaleLength, "number or length",
Expr::Length(length) => ScaleLength::Absolute(length),
Expr::Number(scale) => ScaleLength::Scaled(scale),
);
/// A value type that matches [`Expr::Ident`] and [`Expr::Str`] and implements
/// `Into<String>`.
pub struct StringLike(pub String);
impl From<StringLike> for String {
fn from(like: StringLike) -> String {
like.0
}
}
match_value!(StringLike, "identifier or string",
Expr::Ident(Ident(s)) => StringLike(s),
Expr::Str(s) => StringLike(s),
);
macro_rules! ident_value {
($type:ty, $name:expr, $parse:expr) => {
impl Value for $type {
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self> {
if let Expr::Ident(ident) = expr.v {
let val = $parse(ident.as_str());
if val.is_none() {
error!(@f, expr.span, "invalid {}", $name);
}
val
} else {
error!(
@f, expr.span,
"expected {}, found {}", $name, expr.v.name()
);
None
}
}
}
};
}
ident_value!(Dir, "direction", |s| match s {
"ltr" => Some(LTT),
"rtl" => Some(RTL),
"ttb" => Some(TTB),
"btt" => Some(BTT),
_ => None,
});
ident_value!(SpecAlign, "alignment", |s| match s {
"left" => Some(SpecAlign::Left),
"right" => Some(SpecAlign::Right),
"top" => Some(SpecAlign::Top),
"bottom" => Some(SpecAlign::Bottom),
"center" => Some(SpecAlign::Center),
_ => None,
});
ident_value!(FontStyle, "font style", FontStyle::from_name);
ident_value!(Paper, "paper", Paper::from_name);
impl Value for FontWeight {
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self> {
match expr.v {
Expr::Number(weight) => {
const MIN: u16 = 100;
const MAX: u16 = 900;
Some(FontWeight(if weight < MIN as f64 {
error!(@f, expr.span, "the minimum font weight is {}", MIN);
MIN
} else if weight > MAX as f64 {
error!(@f, expr.span, "the maximum font weight is {}", MAX);
MAX
} else {
weight.round() as u16
}))
}
Expr::Ident(ident) => {
let weight = Self::from_name(ident.as_str());
if weight.is_none() {
error!(@f, expr.span, "invalid font weight");
}
weight
}
other => {
error!(
@f, expr.span,
"expected font weight (name or number), found {}",
other.name(),
);
None
}
}
}
}
impl Value for FontWidth {
fn parse(expr: Spanned<Expr>, f: &mut Feedback) -> Option<Self> {
match expr.v {
Expr::Number(width) => {
const MIN: u16 = 1;
const MAX: u16 = 9;
FontWidth::new(if width < MIN as f64 {
error!(@f, expr.span, "the minimum font width is {}", MIN);
MIN
} else if width > MAX as f64 {
error!(@f, expr.span, "the maximum font width is {}", MAX);
MAX
} else {
width.round() as u16
})
}
Expr::Ident(ident) => {
let width = Self::from_name(ident.as_str());
if width.is_none() {
error!(@f, expr.span, "invalid font width");
}
width
}
other => {
error!(
@f, expr.span,
"expected font width (name or number), found {}",
other.name(),
);
None
}
}
}
}
|
