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|
use crate::size::ScaleSize;
use super::*;
/// An argument or return value.
#[derive(Clone, PartialEq)]
pub enum Expression {
Ident(Ident),
Str(String),
Number(f64),
Size(Size),
Bool(bool),
Tuple(Tuple),
Object(Object),
}
impl Display for Expression {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
use Expression::*;
match self {
Ident(i) => write!(f, "{}", i),
Str(s) => write!(f, "{:?}", s),
Number(n) => write!(f, "{}", n),
Size(s) => write!(f, "{}", s),
Bool(b) => write!(f, "{}", b),
Tuple(t) => write!(f, "{}", t),
Object(o) => write!(f, "{}", o),
}
}
}
/// An identifier.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct Ident(pub String);
impl Ident {
pub fn new<S>(ident: S) -> Option<Ident> where S: AsRef<str> + Into<String> {
if is_identifier(ident.as_ref()) {
Some(Ident(ident.into()))
} else {
None
}
}
pub fn as_str(&self) -> &str {
self.0.as_str()
}
}
impl Display for Ident {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}", self.0)
}
}
/// A sequence of expressions.
#[derive(Clone, PartialEq)]
pub struct Tuple {
pub items: Vec<Spanned<Expression>>,
}
impl Tuple {
pub fn new() -> Tuple {
Tuple { items: vec![] }
}
pub fn add(&mut self, item: Spanned<Expression>) {
self.items.push(item);
}
}
impl Display for Tuple {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "(")?;
let mut first = true;
for item in &self.items {
if !first {
write!(f, ", ")?;
}
write!(f, "{}", item.v)?;
first = false;
}
write!(f, ")")
}
}
/// A key-value collection of identifiers and associated expressions.
#[derive(Clone, PartialEq)]
pub struct Object {
pub pairs: Vec<Pair>,
}
impl Object {
pub fn new() -> Object {
Object { pairs: vec![] }
}
pub fn add(&mut self, key: Spanned<Ident>, value: Spanned<Expression>) {
self.pairs.push(Pair { key, value });
}
pub fn add_pair(&mut self, pair: Pair) {
self.pairs.push(pair);
}
}
impl Display for Object {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
if self.pairs.len() == 0 {
return write!(f, "{{}}");
}
write!(f, "{{ ")?;
let mut first = true;
for pair in &self.pairs {
if !first {
write!(f, ", ")?;
}
write!(f, "{}", pair)?;
first = false;
}
write!(f, " }}")
}
}
/// A key-value pair in an object.
#[derive(Clone, PartialEq)]
pub struct Pair {
pub key: Spanned<Ident>,
pub value: Spanned<Expression>,
}
impl Display for Pair {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}: {}", self.key.v, self.value.v)
}
}
debug_display!(Ident);
debug_display!(Expression);
debug_display!(Tuple);
debug_display!(Object);
debug_display!(Pair);
/// Kinds of expressions.
pub trait ExpressionKind: Sized {
/// The name of the expression in an `expected <name>` error.
const NAME: &'static str;
/// Create from expression.
fn from_expr(expr: Spanned<Expression>) -> ParseResult<Self>;
}
/// Implements the expression kind trait for a type.
macro_rules! kind {
($type:ty, $name:expr, $($patterns:tt)*) => {
impl ExpressionKind for $type {
const NAME: &'static str = $name;
fn from_expr(expr: Spanned<Expression>) -> ParseResult<Self> {
#[allow(unreachable_patterns)]
Ok(match expr.v {
$($patterns)*,
_ => error!("expected {}", Self::NAME),
})
}
}
};
}
kind!(Expression, "expression", e => e);
kind!(Ident, "identifier", Expression::Ident(ident) => ident);
kind!(String, "string", Expression::Str(string) => string);
kind!(f64, "number", Expression::Number(num) => num);
kind!(bool, "boolean", Expression::Bool(boolean) => boolean);
kind!(Size, "size", Expression::Size(size) => size);
kind!(Tuple, "tuple", Expression::Tuple(tuple) => tuple);
kind!(Object, "object", Expression::Object(object) => object);
kind!(ScaleSize, "number or size",
Expression::Size(size) => ScaleSize::Absolute(size),
Expression::Number(scale) => ScaleSize::Scaled(scale as f32)
);
impl<T> ExpressionKind for Spanned<T> where T: ExpressionKind {
const NAME: &'static str = T::NAME;
fn from_expr(expr: Spanned<Expression>) -> ParseResult<Spanned<T>> {
let span = expr.span;
T::from_expr(expr).map(|v| Spanned { v, span })
}
}
|
