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
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
use proc_macro2::{TokenStream, TokenTree};
use proc_macro2_diagnostics::{Diagnostic, Level};
use syn::{
parse::{discouraged::Speculative, Parse, ParseStream, Parser},
spanned::Spanned,
};
use crate::recoverable::{ParseRecoverable, RecoverableContext};
impl RecoverableContext {
/// Like [`parse_simple`], but splits the tokenstream at `E` first only
/// parsing the tokens before it as `T`.
///
/// **Note:** This is an internal function exported to make parsing of
/// custom nodes easier. It has some quirks, e.g.,
/// `parse_simple_until<Expr, Token![>]>`, would not support any
/// [`Expr`] containing a `>`.
///
/// It is not considered stable.
///
/// [`parse_simple`]: #method.parse_simple
/// [`Expr`]: https://docs.rs/syn/latest/syn/enum.Expr.html
pub fn parse_simple_until<T: Parse, E: Parse>(&mut self, input: ParseStream) -> Option<(T, E)> {
let mut tokens = TokenStream::new();
let res = loop {
// Use fork, because we can't limit separator to be only Peekable for custom
// tokens but we also need to parse complex expressions like
// "foo=x/y" or "/>"
let fork = input.fork();
if let Ok(end) = fork.parse() {
input.advance_to(&fork);
break Some(end);
}
if input.is_empty() {
break None;
}
let next: TokenTree = self
.parse_simple(input)
.expect("TokenTree should always be parsable");
tokens.extend([next]);
};
res.and_then(|res| {
self.save_diagnostics(syn::parse2(tokens))
.map(|val| (val, res))
})
}
/// Parse array of toknes using recoverable parser.
/// Stops parsing when other branch could parse anything.
///
/// **Note:** This is an internal function exported to make parsing of
/// custom nodes easier.
/// It is not considered stable.
///
/// Example:
/// ```ignore
/// # use syn::{parse::{Parser, ParseStream}, Ident, Result, parse_macro_input, Token};
/// # use rstml::{parse_tokens_until};
/// # fn main() -> syn::Result<()>{
/// let tokens:proc_macro2::TokenStream = quote::quote!(few idents seperated by spaces and then minus sign - that will stop parsing).into();
/// let concat_idents_without_minus = |input: ParseStream| -> Result<String> {
/// let (idents, _minus) = parser.parse_tokens_until::<Ident, _, _>(input, |i|
/// i.parse::<Token![-]>()
/// )?;
/// let mut new_str = String::new();
/// for ident in idents {
/// new_str.push_str(&ident.to_string())
/// }
/// // .. skip rest idents in input
/// # while !input.is_empty() {
/// # input.parse::<Ident>()?;
/// # }
/// Ok(new_str)
/// };
/// let concated = concat_idents_without_minus.parse2(tokens)?;
/// assert_eq!(concated, "fewidentsseperatedbyspacesandthenminussign");
/// # Ok(())
/// # }
/// ```
pub fn parse_tokens_until_call<T, F, U>(
&mut self,
input: ParseStream,
stop_fn: F,
) -> (Vec<T>, Option<U>)
where
T: ParseRecoverable + Spanned,
F: Fn(ParseStream) -> syn::Result<U>,
{
let mut collection = vec![];
let res = loop {
let old_cursor = input.cursor();
let fork = input.fork();
if let Ok(res) = stop_fn(&fork) {
input.advance_to(&fork);
break Some(res);
}
if let Some(o) = self.parse_recoverable(input) {
collection.push(o)
}
if old_cursor == input.cursor() {
break None;
}
};
(collection, res)
}
/// Two-phase parsing, firstly find separator, and then parses array of
/// tokens before separator.
/// For simple input this method will work like
/// `parse_tokens_until`.
/// Internally it creates intermediate `TokenStream`` and
/// copy of all tokens until separator token is found. It is usefull
/// when separator (or it's part) can be treated as part of token T.
///
///
/// **Note:** This is an internal function exported to make parsing of
/// custom nodes easier.
/// It is not considered stable.
///
/// Example:
/// ```ignore
/// let tokens = quote!(some_expr_seperated + with - lt_gt * tokens <> other part);
/// ```
/// In this example "<" can can be parsed as part of expression, but we want
/// to split tokens after "<>" was found. So instead of parsing all
/// input as expression, firstly we need to seperate it into two chunks.
pub fn parse_tokens_with_conflicted_ending<T, F, U>(
&mut self,
input: ParseStream,
separator: F,
) -> (Vec<T>, Option<U>)
where
T: ParseRecoverable,
F: Fn(ParseStream) -> syn::Result<U>,
{
let parser = |parser: &mut Self, tokens: TokenStream| {
let parse = |input: ParseStream| {
let mut collection = vec![];
while !input.is_empty() {
let old_cursor = input.cursor();
if let Some(o) = parser.parse_recoverable(input) {
collection.push(o)
}
if old_cursor == input.cursor() {
break;
}
}
let eated_tokens = input.parse::<TokenStream>()?;
Ok((collection, eated_tokens))
};
let (collection, eaten_tokens) = parse.parse2(tokens).expect("No errors allowed");
if !eaten_tokens.is_empty() {
parser.push_diagnostic(Diagnostic::spanned(
eaten_tokens.span(),
Level::Error,
"tokens was ignored during parsing",
))
}
collection
};
self.parse_with_ending(input, parser, separator)
}
pub(crate) fn parse_with_ending<F, CNV, V, U>(
&mut self,
input: ParseStream,
parser: CNV,
ending: F,
) -> (V, Option<U>)
where
F: Fn(ParseStream) -> syn::Result<U>,
CNV: Fn(&mut Self, TokenStream) -> V,
{
let mut tokens = TokenStream::new();
let res = loop {
// Use fork, because we can't limit separator to be only Peekable for custom
// tokens but we also need to parse complex expressions like
// "foo=x/y" or "/>"
let fork = input.fork();
if let Ok(end) = ending(&fork) {
input.advance_to(&fork);
break Some(end);
}
if input.is_empty() {
break None;
}
let next: TokenTree = self
.parse_simple(input)
.expect("TokenTree should always be parsable");
tokens.extend([next]);
};
(parser(self, tokens), res)
}
}