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
|
pub grammar peg() for FlatTokenStream {
use crate::ast::*;
use crate::ast::Expr::*;
use crate::tokens::FlatTokenStream;
use proc_macro2::{ TokenStream, Ident, Group, Literal, Delimiter, Span };
pub rule peg_grammar() -> Grammar
= doc:rust_doc_comment() visibility:rust_visibility() "grammar" name:IDENT() lifetime_params:rust_lifetime_params()? args:grammar_args() "for" input_type:$(rust_type()) "{" items:item()* "}"
{ Grammar { doc, visibility, name, lifetime_params, args, input_type, items } }
rule rust_lifetime_params() -> Vec<TokenStream>
= "<" p:(($(LIFETIME())) ++ ",") ","? ">" { p }
rule grammar_args() -> Vec<(Ident, TokenStream)>
= "(" args:((i:IDENT() ":" t:$(rust_type()) { (i, t) })**",") ","? ")" { args }
rule peg_rule() -> Rule
= doc:rust_doc_comment() cache:cacheflag() no_eof:no_eof_flag() visibility:rust_visibility()
span:sp() "rule"
header:(
&("_" / "__" / "___") name:IDENT() ("(" ")")? { (name, None, Vec::new()) }
/ name:IDENT() ty_params:rust_ty_params()? params:rule_params() { (name, ty_params, params) }
)
ret_type:("->" t:$(rust_type()) {t})?
where_clause:$(rust_where_clause())?
"=" expr:expression() ";"?
{ Rule { span, doc, name:header.0, ty_params:header.1, params:header.2, expr, ret_type, where_clause, visibility, no_eof, cache } }
rule cacheflag() -> Option<Cache> = "#" "[" "cache" "]" {Some(Cache::Simple)} / "#" "[" "cache_left_rec" "]" {Some(Cache::Recursive)} / {None}
rule no_eof_flag() -> bool = "#" "[" "no_eof" "]" {true} / {false}
rule rule_param_ty() -> RuleParamTy
= "rule" "<" r:$(rust_type()) ">" { RuleParamTy::Rule(r) }
/ t:$(rust_type()) { RuleParamTy::Rust(t) }
rule rule_params() -> Vec<RuleParam>
= "(" params:(x:(name:IDENT() ":" ty:rule_param_ty() { RuleParam { name, ty} }) ++ "," ","? {x})? ")" { params.unwrap_or_default() }
rule item() -> Item
= u:rust_use() { Item::Use(u) }
/ r:peg_rule() { Item::Rule(r) }
rule rust_doc_comment() -> Option<TokenStream> = $(("#" "[" "doc" "=" LITERAL() "]")*)?
rule rust_visibility() -> Option<TokenStream> = $("pub" PAREN_GROUP()?)?
rule rust_use() -> TokenStream
= v:$("use" rust_path() (
"::" "*"
/ "::" "{" ((IDENT() ("as" IDENT())?) ++ "," ","?) "}"
/ ("as" IDENT())?
) ";") { v.to_owned() }
rule rust_path()
= ("crate" "::")? IDENT() ++ "::"
rule rust_type()
= BRACKET_GROUP()
/ "&" LIFETIME()? "mut"? rust_type()
/ "dyn" rust_ty_param_bound() ++ "+"
/ "impl" rust_ty_param_bound() ++ "+"
/ "(" (rust_type() ++ "," ","?)? ")"
/ ("<" rust_type() ("as" rust_ty_path())? ">")? rust_ty_path()
rule rust_ty_path()
= "::"? (IDENT() ("::"? (rust_generic_args() / PAREN_GROUP() ("->" rust_type())?))?) ++ "::"
rule rust_ty_params() -> Vec<TokenStream>
= "<" p:($(rust_generic_param()) ++ ",") ","? ">" { p }
rule rust_where_clause()
= "where" (
LIFETIME() (":" LIFETIME() ++ "+")?
/ rust_for_lifetimes()? rust_type() ":" rust_ty_param_bound() ++ "+"
) ** "," ","?
rule rust_generic_param()
= LIFETIME() (":" LIFETIME() ++ "+")?
/ IDENT() (":" rust_ty_param_bound() ++ "+")?
rule rust_for_lifetimes()
= "for" rust_ty_params()
rule rust_ty_param_bound()
= LIFETIME()
/ "?"? rust_for_lifetimes()? rust_ty_path()
/ "(" "?"? rust_for_lifetimes()? rust_ty_path() ")"
rule rust_generic_args()
= "<" (LIFETIME() / rust_type() / BRACE_GROUP() / LITERAL()) ++ "," ","? ">"
rule expression() -> SpannedExpr = choice()
rule choice() -> SpannedExpr = sp:sp() s:sequence() ++ "/" {
if s.len() == 1 {
s.into_iter().next().unwrap()
} else {
ChoiceExpr(s).at(sp)
}
}
rule sequence() -> SpannedExpr
= sp:sp() elements:labeled()* code:BRACE_GROUP()? {
if let Some(code) = code {
ActionExpr(elements, Some(code)).at(sp)
} else if elements.len() != 1 {
ActionExpr(elements, None).at(sp)
} else {
elements.into_iter().next().unwrap().expr
}
}
rule labeled() -> TaggedExpr
= label:(l:IDENT() ":" {l})? expression:suffixed()
{ TaggedExpr{ name: label, expr: expression } }
rule suffixed() -> SpannedExpr
= e:prefixed() sp:sp() "?" { OptionalExpr(Box::new(e)).at(sp) }
/ e:prefixed() sp:sp() "**" count:repeatcount() sep:primary() { Repeat { inner: Box::new(e), bound: count, sep: Some(Box::new(sep)) }.at(sp) }
/ e:prefixed() sp:sp() "++" sep:primary() { Repeat { inner: Box::new(e), bound: BoundedRepeat::Plus, sep: Some(Box::new(sep)) }.at(sp )}
/ e:prefixed() sp:sp() "*" count:repeatcount() { Repeat { inner: Box::new(e), bound: count, sep: None }.at(sp) }
/ e:prefixed() sp:sp() "+" { Repeat { inner: Box::new(e), bound: BoundedRepeat::Plus, sep: None }.at(sp) }
/ prefixed()
rule repeatcount() -> BoundedRepeat
= "<" n:repeatnum() ">" { BoundedRepeat::Exact(n) }
/ "<" min:repeatnum()? "," max:repeatnum()? ">" { BoundedRepeat::Both(min, max) }
/ { BoundedRepeat::None }
rule repeatnum() -> TokenStream = $(INTEGER() / BRACE_GROUP())
rule prefixed() -> SpannedExpr
= sp:sp() "$" expression:primary() { MatchStrExpr(Box::new(expression)).at(sp) }
/ sp:sp() "&" expression:primary() { PosAssertExpr(Box::new(expression)).at(sp) }
/ sp:sp() "!" expression:primary() { NegAssertExpr(Box::new(expression)).at(sp) }
/ primary()
#[cache]
rule primary() -> SpannedExpr
= sp:sp() "precedence" "!" "{" levels:precedence_level()**"--" "}" { PrecedenceExpr{ levels:levels }.at(sp) }
/ sp:sp() "position" "!" "(" ")" { PositionExpr.at(sp) }
/ sp:sp() "quiet" "!" "{" e:expression() "}" { QuietExpr(Box::new(e)).at(sp) }
/ sp:sp() "expected" "!" s:PAREN_GROUP() { FailExpr(s).at(sp) }
/ &("_" / "__" / "___") sp:sp() name:IDENT() { RuleExpr(name, None, Vec::new()).at(sp) }
/ sp:sp() name:IDENT() generics:$("::" rust_generic_args())? "(" args:(rule_arg() ** ",") ")" { RuleExpr(name, generics, args).at(sp) }
/ sp:sp() l:LITERAL() { LiteralExpr(l).at(sp) }
/ sp:sp() p:BRACKET_GROUP() { PatternExpr(p).at(sp) }
/ "(" sp:sp() "@" ")" { MarkerExpr(true).at(sp) }
/ sp:sp() "@" { MarkerExpr(false).at(sp) }
/ sp:sp() "##" method:IDENT() args:PAREN_GROUP() { MethodExpr(method, args.stream()).at(sp) }
/ sp:sp() "#" code:BRACE_GROUP() { CustomExpr(code).at(sp) }
/ "(" expression:expression() ")" { expression }
rule rule_arg() -> RuleArg
= "<" e:expression() ">" { RuleArg::Peg(e) }
/ tt:$( #{|input, pos| input.eat_until(pos, ',')}+ ) { RuleArg::Rust(tt) }
rule precedence_level() -> PrecedenceLevel
= operators:precedence_op()+
{ PrecedenceLevel{ operators: operators } }
rule precedence_op() -> PrecedenceOperator
= span:sp() elements:labeled()* action:BRACE_GROUP()
{ PrecedenceOperator{ span, elements, action } }
rule sp() -> Span = #{|input, pos| input.next_span(pos)}
rule KEYWORD() = "pub" / "rule" / "use" / "type" / "where"
rule IDENT() -> Ident = !KEYWORD() i:#{|input, pos| input.ident(pos)} {i}
rule LITERAL() -> Literal = #{|input, pos| input.literal(pos)}
rule PAREN_GROUP() -> Group = #{|input, pos| input.group(pos, Delimiter::Parenthesis)}
rule BRACE_GROUP() -> Group = #{|input, pos| input.group(pos, Delimiter::Brace)}
rule BRACKET_GROUP() -> Group = #{|input, pos| input.group(pos, Delimiter::Bracket)}
rule LIFETIME() = "'" IDENT()
rule INTEGER() = LITERAL()
}
|
