data_encoding_macro_internal/
lib.rs

1//! Internal library for data-encoding-macro
2//!
3//! Do **not** use this library. Use [data-encoding-macro] instead.
4//!
5//! This library is for internal use by data-encoding-macro because procedural
6//! macros require a separate crate.
7//!
8//! [data-encoding-macro]: https://crates.io/crates/data-encoding-macro
9
10#![warn(unused_results)]
11
12use std::collections::HashMap;
13
14use data_encoding::{BitOrder, Encoding, Specification, Translate, Wrap};
15use proc_macro::token_stream::IntoIter;
16use proc_macro::{TokenStream, TokenTree};
17
18fn parse_op(tokens: &mut IntoIter, op: char, key: &str) {
19    match tokens.next() {
20        Some(TokenTree::Punct(ref x)) if x.as_char() == op => (),
21        _ => panic!("expected {:?} after {}", op, key),
22    }
23}
24
25fn parse_map(mut tokens: IntoIter) -> HashMap<String, TokenTree> {
26    let mut map = HashMap::new();
27    while let Some(key) = tokens.next() {
28        let key = match key {
29            TokenTree::Ident(ident) => format!("{}", ident),
30            _ => panic!("expected key got {}", key),
31        };
32        parse_op(&mut tokens, ':', &key);
33        let value = match tokens.next() {
34            None => panic!("expected value for {}", key),
35            Some(value) => value,
36        };
37        parse_op(&mut tokens, ',', &key);
38        let _ = map.insert(key, value);
39    }
40    map
41}
42
43fn get_string(map: &mut HashMap<String, TokenTree>, key: &str) -> String {
44    let node = match map.remove(key) {
45        None => return String::new(),
46        Some(node) => node,
47    };
48    match syn::parse::<syn::LitStr>(node.into()) {
49        Ok(result) => result.value(),
50        _ => panic!("expected string for {}", key),
51    }
52}
53
54fn get_usize(map: &mut HashMap<String, TokenTree>, key: &str) -> usize {
55    let node = match map.remove(key) {
56        None => return 0,
57        Some(node) => node,
58    };
59    let literal = match node {
60        TokenTree::Literal(literal) => literal,
61        _ => panic!("expected literal for {}", key),
62    };
63    match literal.to_string().parse() {
64        Ok(result) => result,
65        Err(error) => panic!("expected usize for {}: {}", key, error),
66    }
67}
68
69fn get_padding(map: &mut HashMap<String, TokenTree>) -> Option<char> {
70    let node = map.remove("padding")?;
71    if let Ok(result) = syn::parse::<syn::LitChar>(node.clone().into()) {
72        return Some(result.value());
73    }
74    match syn::parse::<syn::Ident>(node.into()) {
75        Ok(ref result) if result == "None" => None,
76        _ => panic!("expected None or char for padding"),
77    }
78}
79
80fn get_bool(map: &mut HashMap<String, TokenTree>, key: &str) -> Option<bool> {
81    let node = map.remove(key)?;
82    match syn::parse::<syn::LitBool>(node.into()) {
83        Ok(result) => Some(result.value),
84        _ => panic!("expected bool for {}", key),
85    }
86}
87
88fn get_bit_order(map: &mut HashMap<String, TokenTree>) -> BitOrder {
89    let node = match map.remove("bit_order") {
90        None => return BitOrder::MostSignificantFirst,
91        Some(node) => node,
92    };
93    let msb = "MostSignificantFirst";
94    let lsb = "LeastSignificantFirst";
95    match node {
96        TokenTree::Ident(ref ident) if format!("{}", ident) == msb => {
97            BitOrder::MostSignificantFirst
98        }
99        TokenTree::Ident(ref ident) if format!("{}", ident) == lsb => {
100            BitOrder::LeastSignificantFirst
101        }
102        _ => panic!("expected {} or {} for bit_order", msb, lsb),
103    }
104}
105
106fn check_present<T>(hash_map: &HashMap<String, T>, key: &str) {
107    assert!(hash_map.contains_key(key), "{} is required", key);
108}
109
110fn get_encoding(hash_map: &mut HashMap<String, TokenTree>) -> Encoding {
111    check_present(hash_map, "symbols");
112    let spec = Specification {
113        symbols: get_string(hash_map, "symbols"),
114        bit_order: get_bit_order(hash_map),
115        check_trailing_bits: get_bool(hash_map, "check_trailing_bits").unwrap_or(true),
116        padding: get_padding(hash_map),
117        ignore: get_string(hash_map, "ignore"),
118        wrap: Wrap {
119            width: get_usize(hash_map, "wrap_width"),
120            separator: get_string(hash_map, "wrap_separator"),
121        },
122        translate: Translate {
123            from: get_string(hash_map, "translate_from"),
124            to: get_string(hash_map, "translate_to"),
125        },
126    };
127    spec.encoding().unwrap()
128}
129
130fn check_empty<T>(hash_map: HashMap<String, T>) {
131    assert!(hash_map.is_empty(), "Unexpected keys {:?}", hash_map.keys());
132}
133
134#[proc_macro]
135#[doc(hidden)]
136pub fn internal_new_encoding(input: TokenStream) -> TokenStream {
137    let mut hash_map = parse_map(input.into_iter());
138    let encoding = get_encoding(&mut hash_map);
139    check_empty(hash_map);
140    format!("{:?}", encoding.internal_implementation()).parse().unwrap()
141}
142
143#[proc_macro]
144#[doc(hidden)]
145pub fn internal_decode_array(input: TokenStream) -> TokenStream {
146    let mut hash_map = parse_map(input.into_iter());
147    let encoding = get_encoding(&mut hash_map);
148    check_present(&hash_map, "name");
149    let name = get_string(&mut hash_map, "name");
150    check_present(&hash_map, "input");
151    let input = get_string(&mut hash_map, "input");
152    check_empty(hash_map);
153    let output = encoding.decode(input.as_bytes()).unwrap();
154    format!("{}: [u8; {}] = {:?};", name, output.len(), output).parse().unwrap()
155}
156
157#[proc_macro]
158#[doc(hidden)]
159pub fn internal_decode_slice(input: TokenStream) -> TokenStream {
160    let mut hash_map = parse_map(input.into_iter());
161    let encoding = get_encoding(&mut hash_map);
162    check_present(&hash_map, "input");
163    let input = get_string(&mut hash_map, "input");
164    check_empty(hash_map);
165    format!("{:?}", encoding.decode(input.as_bytes()).unwrap()).parse().unwrap()
166}
data_encoding_macro_internal/lib.rs

data_encoding_macro_internal/
lib.rs
