derived 0.4.2

Derive macros for automating the boring stuff
Documentation 
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
106
107
108
109

use super::types::{DefExpr, CONSTDEF};
use ::quote::{quote, ToTokens};
use ::syn::{Type, TypeArray, TypePath, TypeTuple};

pub(crate) fn analyze_type_path(t: &TypePath) -> Option<DefExpr> {
    if t.path.segments.len() == 1 {
        // single, no need for extended analysis
        let fpath = t.path.segments[0].clone().into_token_stream().to_string();
        CONSTDEF.get(fpath.as_str()).cloned()
    } else {
        let r = t
            .path
            .segments
            .iter()
            .map(|seg| seg.ident.clone().into_token_stream().to_string())
            .collect();
        try_minimize_typepath(r)
            .ok()
            .and_then(|minimized| CONSTDEF.get(minimized.as_str()))
            .cloned()
    }
}

/// Attempt to minimize the type path
fn try_minimize_typepath(tpath: Vec<String>) -> Result<String, Vec<String>> {
    let mut path = tpath.iter();
    let mut ret = None;
    match path.next().map(|v| v.as_ref()) {
        Some(p) => match p {
            // attempt to evaluate paths like core::primitive::<ty> or std::primitive::<ty>
            "core" | "std" => match path.next() {
                Some(s) => match s.as_str() {
                    "primitive" => match path.next() {
                        Some(ty) => {
                            ret = Some(ty.to_owned());
                        }
                        None => {}
                    },
                    _ => {}
                },
                None => {}
            },
            _ => {}
        },
        None => {}
    }
    ret.ok_or(tpath)
}

pub(super) fn recursive_process_tuple(tuple: &TypeTuple) -> Option<DefExpr> {
    let mut inner_decl = quote! {};
    for elem in tuple.elems.iter() {
        match elem {
            Type::Path(ref tpath) => {
                let ret = self::analyze_type_path(tpath)?.into_base_token();
                inner_decl = quote! {
                    #inner_decl
                    #ret,
                };
            }
            Type::Tuple(ref tuple) => {
                let ret = self::recursive_process_tuple(tuple)?.into_base_token();
                inner_decl = quote! {
                    #inner_decl
                    #ret,
                };
            }
            Type::Array(ref arr) => {
                let ret = self::process_array(arr)?.into_base_token();
                inner_decl = quote! {
                    #inner_decl
                    #ret,
                };
            }
            _ => return None,
        }
    }
    Some(DefExpr::CustomTuple(inner_decl.to_string()))
}

pub(super) fn process_array(array: &TypeArray) -> Option<DefExpr> {
    let mut inner_decl = quote! {};
    let len = &array.len;
    match &*array.elem {
        Type::Path(tpath) => {
            let ret = self::analyze_type_path(tpath)?.into_base_token();
            inner_decl = quote! {
                #inner_decl
                #ret; #len
            };
        }
        Type::Array(arr) => {
            let ret = self::process_array(arr)?.into_base_token();
            inner_decl = quote! {
                #inner_decl
                #ret; #len
            };
        }
        Type::Tuple(ref tuple) => {
            let ret = self::recursive_process_tuple(tuple)?.into_base_token();
            inner_decl = quote! {
                #inner_decl
                #ret; #len
            };
        }
        _ => return None,
    }
    Some(DefExpr::CustomArray(inner_decl.to_string()))
}