rust_dynamic/
ctx.rs

1use crate::value::{Value};
2
3pub type CtxAppFn  = fn(&dyn Context,&str,Value) -> Option<Value>;
4
5//
6// Number of required operands for the Applicatives
7//
8pub const NOEXTRA: u16         = 0;
9pub const JUSTONE: u16         = 1;
10pub const JUSTTWO: u16         = 2;
11pub const TAKEALL: u16         = 3;
12
13
14#[derive(Clone)]
15pub struct CtxApplicative {
16    pub name:   String,
17    pub extra:  u16,
18    pub f:      CtxAppFn,
19}
20
21impl CtxApplicative {
22    pub fn new<N: AsRef<str> + std::fmt::Display>(name: N, e: u16, f: CtxAppFn) -> Self {
23        Self {
24            name:   name.as_ref().to_string(),
25            extra:  e,
26            f:      f,
27        }
28    }
29}
30
31
32pub trait Context {
33    fn new() -> Self where Self: Sized;
34    fn resolve(&self, name: &str) -> Option<CtxApplicative>;
35    fn get_association(&self, name: &str) -> Option<Value>;
36    fn register(&mut self, name: &str, f: CtxApplicative) -> bool;
37    fn register_association(&mut self, name: &str, v: Value) -> bool;
38    fn eval(&mut self, a: Option<CtxApplicative>, v: Value) -> Option<Value>;
39}
40
41pub struct NullContext {}
42
43impl Context for NullContext {
44    fn new() -> NullContext {
45        Self {
46
47        }
48    }
49    fn resolve(&self, _name: &str) -> Option<CtxApplicative> {
50        fn none_fn(_ctx: &dyn Context, _name: &str, _value: Value) -> Option<Value> {
51            None
52        }
53        Some(CtxApplicative::new("none_fn", NOEXTRA, none_fn))
54    }
55    fn get_association(&self, _name: &str) -> Option<Value> {
56        None
57    }
58    fn register(&mut self, _name: &str, _f: CtxApplicative) -> bool {
59        true
60    }
61    fn register_association(&mut self, _name: &str, _v: Value) -> bool {
62        true
63    }
64    fn eval(&mut self, _a: Option<CtxApplicative>, _v: Value) -> Option<Value> {
65        None
66    }
67}
68
69
70pub fn context(mut ctx: impl Context, value: Value) -> Option<Value> {
71    ctx.eval(None, value)
72}
rust_dynamic/ctx.rs

rust_dynamic/
ctx.rs
