1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
//! Dynamic typesetting functions.
use std::any::Any;
use std::collections::HashMap;
use std::fmt::{self, Debug, Formatter};
use crate::syntax::FuncHeader;
use crate::parsing::{ParseContext, ParseResult};
use crate::layout::{Layout, LayoutContext, LayoutResult};
/// Types that act as functions.
///
/// These types have to be able to parse tokens into themselves and store the
/// relevant information from the parsing to do their role in typesetting later.
///
/// The trait `FunctionBounds` is automatically implemented for types which can be
/// used as functions, that is they fulfill the bounds `Debug + PartialEq + 'static`.
pub trait Function: FunctionBounds {
/// Parse the header and body into this function given this context.
fn parse(header: &FuncHeader, body: Option<&str>, ctx: &ParseContext)
-> ParseResult<Self> where Self: Sized;
/// Layout this function given a context.
///
/// Returns optionally the resulting layout and a if changes to the context
/// should be made new context.
fn layout(&self, ctx: &LayoutContext)
-> LayoutResult<(Option<Layout>, Option<LayoutContext>)>;
}
impl PartialEq for dyn Function {
fn eq(&self, other: &dyn Function) -> bool {
self.help_eq(other)
}
}
/// A helper trait that describes requirements for types that can implement [`Function`].
///
/// Automatically implemented for all types which fulfill to the bounds
/// `Debug + PartialEq + 'static`. There should be no need to implement this manually.
pub trait FunctionBounds: Debug {
/// Cast self into `Any`.
fn help_cast_as_any(&self) -> &dyn Any;
/// Compare self with another function.
fn help_eq(&self, other: &dyn Function) -> bool;
}
impl<T> FunctionBounds for T where T: Debug + PartialEq + 'static {
fn help_cast_as_any(&self) -> &dyn Any {
self
}
fn help_eq(&self, other: &dyn Function) -> bool {
if let Some(other) = other.help_cast_as_any().downcast_ref::<Self>() {
self == other
} else {
false
}
}
}
/// A map from identifiers to functions.
pub struct Scope {
parsers: HashMap<String, Box<ParseFunc>>,
}
/// A function which transforms a parsing context into a boxed function.
type ParseFunc = dyn Fn(&FuncHeader, Option<&str>, &ParseContext)
-> ParseResult<Box<dyn Function>>;
impl Scope {
/// Create a new empty scope.
pub fn new() -> Scope {
Scope { parsers: HashMap::new() }
}
/// Create a new scope with the standard functions contained.
pub fn with_std() -> Scope {
Scope::new()
}
/// Add a function type to the scope with a given name.
pub fn add<F: Function + 'static>(&mut self, name: &str) {
self.parsers.insert(
name.to_owned(),
Box::new(|h, b, c| {
F::parse(h, b, c).map(|func| Box::new(func) as Box<dyn Function>)
})
);
}
/// Return the parser with the given name if there is one.
pub(crate) fn get_parser(&self, name: &str) -> Option<&ParseFunc> {
self.parsers.get(name).map(|x| &**x)
}
}
impl Debug for Scope {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "Scope ")?;
write!(f, "{:?}", self.parsers.keys())
}
}
|
