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-rw-r--r--crates/libsyntax2/src/parser_api.rs178
1 files changed, 0 insertions, 178 deletions
diff --git a/crates/libsyntax2/src/parser_api.rs b/crates/libsyntax2/src/parser_api.rs
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--- a/crates/libsyntax2/src/parser_api.rs
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@@ -1,178 +0,0 @@
1use {
2 token_set::TokenSet,
3 parser_impl::ParserImpl,
4 SyntaxKind::{self, ERROR},
5 drop_bomb::DropBomb,
6};
7
8/// `Parser` struct provides the low-level API for
9/// navigating through the stream of tokens and
10/// constructing the parse tree. The actual parsing
11/// happens in the `grammar` module.
12///
13/// However, the result of this `Parser` is not a real
14/// tree, but rather a flat stream of events of the form
15/// "start expression, consume number literal,
16/// finish expression". See `Event` docs for more.
17pub(crate) struct Parser<'t>(pub(super) ParserImpl<'t>);
18
19impl<'t> Parser<'t> {
20 /// Returns the kind of the current token.
21 /// If parser has already reached the end of input,
22 /// the special `EOF` kind is returned.
23 pub(crate) fn current(&self) -> SyntaxKind {
24 self.nth(0)
25 }
26
27 /// Lookahead operation: returns the kind of the next nth
28 /// token.
29 pub(crate) fn nth(&self, n: u32) -> SyntaxKind {
30 self.0.nth(n)
31 }
32
33 /// Checks if the current token is `kind`.
34 pub(crate) fn at(&self, kind: SyntaxKind) -> bool {
35 self.current() == kind
36 }
37
38 /// Checks if the current token is `kind`.
39 pub(crate) fn at_ts(&self, kinds: TokenSet) -> bool {
40 kinds.contains(self.current())
41 }
42
43 pub(crate) fn next2(&self) -> Option<(SyntaxKind, SyntaxKind)> {
44 self.0.next2()
45 }
46
47 pub(crate) fn next3(&self) -> Option<(SyntaxKind, SyntaxKind, SyntaxKind)> {
48 self.0.next3()
49 }
50
51 /// Checks if the current token is contextual keyword with text `t`.
52 pub(crate) fn at_contextual_kw(&self, t: &str) -> bool {
53 self.0.at_kw(t)
54 }
55
56 /// Starts a new node in the syntax tree. All nodes and tokens
57 /// consumed between the `start` and the corresponding `Marker::complete`
58 /// belong to the same node.
59 pub(crate) fn start(&mut self) -> Marker {
60 Marker::new(self.0.start())
61 }
62
63 /// Advances the parser by one token.
64 pub(crate) fn bump(&mut self) {
65 self.0.bump();
66 }
67
68 /// Advances the parser by one token, remapping its kind.
69 /// This is useful to create contextual keywords from
70 /// identifiers. For example, the lexer creates an `union`
71 /// *identifier* token, but the parser remaps it to the
72 /// `union` keyword, and keyword is what ends up in the
73 /// final tree.
74 pub(crate) fn bump_remap(&mut self, kind: SyntaxKind) {
75 self.0.bump_remap(kind);
76 }
77
78 /// Advances the parser by `n` tokens, remapping its kind.
79 /// This is useful to create compound tokens from parts. For
80 /// example, an `<<` token is two consecutive remapped `<` tokens
81 pub(crate) fn bump_compound(&mut self, kind: SyntaxKind, n: u8) {
82 self.0.bump_compound(kind, n);
83 }
84
85 /// Emit error with the `message`
86 /// TODO: this should be much more fancy and support
87 /// structured errors with spans and notes, like rustc
88 /// does.
89 pub(crate) fn error<T: Into<String>>(&mut self, message: T) {
90 self.0.error(message.into())
91 }
92
93 /// Consume the next token if it is `kind`.
94 pub(crate) fn eat(&mut self, kind: SyntaxKind) -> bool {
95 if !self.at(kind) {
96 return false;
97 }
98 self.bump();
99 true
100 }
101
102 /// Consume the next token if it is `kind` or emit an error
103 /// otherwise.
104 pub(crate) fn expect(&mut self, kind: SyntaxKind) -> bool {
105 if self.eat(kind) {
106 return true;
107 }
108 self.error(format!("expected {:?}", kind));
109 false
110 }
111
112 /// Create an error node and consume the next token.
113 pub(crate) fn err_and_bump(&mut self, message: &str) {
114 self.err_recover(message, TokenSet::EMPTY);
115 }
116
117 /// Create an error node and consume the next token.
118 pub(crate) fn err_recover(&mut self, message: &str, recovery: TokenSet) {
119 if self.at(SyntaxKind::L_CURLY)
120 || self.at(SyntaxKind::R_CURLY)
121 || self.at_ts(recovery) {
122 self.error(message);
123 } else {
124 let m = self.start();
125 self.error(message);
126 self.bump();
127 m.complete(self, ERROR);
128 };
129 }
130}
131
132/// See `Parser::start`.
133pub(crate) struct Marker {
134 pos: u32,
135 bomb: DropBomb,
136}
137
138impl Marker {
139 fn new(pos: u32) -> Marker {
140 Marker {
141 pos,
142 bomb: DropBomb::new("Marker must be either completed or abandoned"),
143 }
144 }
145
146 /// Finishes the syntax tree node and assigns `kind` to it.
147 pub(crate) fn complete(mut self, p: &mut Parser, kind: SyntaxKind) -> CompletedMarker {
148 self.bomb.defuse();
149 p.0.complete(self.pos, kind);
150 CompletedMarker(self.pos, kind)
151 }
152
153 /// Abandons the syntax tree node. All its children
154 /// are attached to its parent instead.
155 pub(crate) fn abandon(mut self, p: &mut Parser) {
156 self.bomb.defuse();
157 p.0.abandon(self.pos);
158 }
159}
160
161pub(crate) struct CompletedMarker(u32, SyntaxKind);
162
163impl CompletedMarker {
164 /// This one is tricky :-)
165 /// This method allows to create a new node which starts
166 /// *before* the current one. That is, parser could start
167 /// node `A`, then complete it, and then after parsing the
168 /// whole `A`, decide that it should have started some node
169 /// `B` before starting `A`. `precede` allows to do exactly
170 /// that. See also docs about `forward_parent` in `Event::Start`.
171 pub(crate) fn precede(self, p: &mut Parser) -> Marker {
172 Marker::new(p.0.precede(self.0))
173 }
174
175 pub(crate) fn kind(&self) -> SyntaxKind {
176 self.1
177 }
178}
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