swc_ecma_fast_parser/parser/
pat.rs

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
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
//! Pattern parser implementation
//!
//! This module contains methods for parsing JavaScript patterns (destructuring,
//! etc.).

use swc_common::{Span, Spanned};
use swc_ecma_ast::{
    ArrayPat, AssignPat, AssignPatProp, BindingIdent, ComputedPropName, IdentName, KeyValuePatProp,
    ObjectPat, ObjectPatProp, Pat, PropName, RestPat,
};

use crate::{
    error::{Error, ErrorKind, Result},
    parser::{util, Parser},
    token::TokenType,
};

impl Parser<'_> {
    /// Parse a pattern (destructuring pattern or binding identifier)
    pub fn parse_pat(&mut self) -> Result<Pat> {
        // Check if the pattern starts with a destructuring pattern
        match self.current_token_type() {
            TokenType::LBracket => self.parse_array_pat(),
            TokenType::LBrace => self.parse_object_pat(),
            TokenType::Ident => {
                // Parse a binding identifier
                let span = self.current_span();
                let ident = util::token_value_to_binding_ident(self.current(), span);
                self.lexer.next_token()?; // Consume identifier

                // Check for assignment pattern
                if self.is(TokenType::Eq) {
                    self.lexer.next_token()?; // Consume '='
                    let right = self.parse_expr()?;
                    let ident_span = ident.span();
                    let right_span = right.span();
                    let span = Span::new(ident_span.lo, right_span.hi);
                    Ok(Pat::Assign(AssignPat {
                        span,
                        left: Box::new(Pat::Ident(ident)),
                        right,
                    }))
                } else {
                    Ok(Pat::Ident(ident))
                }
            }
            _ => {
                // Unexpected token
                let span = self.current_span();
                Err(Error {
                    kind: ErrorKind::UnexpectedToken {
                        expected: Some("pattern"),
                        got: self.current_token_type().as_str().to_string(),
                    },
                    span,
                })
            }
        }
    }

    /// Parse an array pattern
    fn parse_array_pat(&mut self) -> Result<Pat> {
        let start_span = self.current_span();
        self.lexer.next_token()?; // Consume '['

        let mut elements = Vec::new();

        // Parse array pattern elements until we reach ']'
        while !self.is(TokenType::RBracket) {
            if self.is(TokenType::Comma) {
                // Empty element
                elements.push(None);
                self.lexer.next_token()?; // Consume ','
            } else if self.is(TokenType::DotDotDot) {
                // Rest element
                let dot3_span = self.current_span();
                self.lexer.next_token()?; // Consume '...'

                // Parse the rest element
                let arg = self.parse_pat()?;
                let arg_span = arg.span();

                // Create the rest pattern
                let span = Span::new(dot3_span.lo, arg_span.hi);
                elements.push(Some(Pat::Rest(RestPat {
                    span,
                    dot3_token: dot3_span,
                    arg: Box::new(arg),
                    type_ann: None,
                })));

                // Rest element must be the last element
                if !self.is(TokenType::RBracket) {
                    let span = self.current_span();
                    return Err(Error {
                        kind: ErrorKind::General {
                            message: "Rest element must be the last element in array pattern"
                                .to_string(),
                        },
                        span,
                    });
                }
            } else {
                // Regular element
                let element = self.parse_pat()?;
                elements.push(Some(element));

                // Check for comma or end of array
                if !self.is(TokenType::RBracket) {
                    self.expect(TokenType::Comma)?;
                }
            }
        }

        let end_span = self.current_span();
        self.lexer.next_token()?; // Consume ']'

        let span = Span::new(start_span.lo, end_span.hi);
        Ok(Pat::Array(ArrayPat {
            span,
            elems: elements,
            optional: false,
            type_ann: None,
        }))
    }

    /// Parse an object pattern
    fn parse_object_pat(&mut self) -> Result<Pat> {
        let start_span = self.current_span();
        self.lexer.next_token()?; // Consume '{'

        let mut properties = Vec::new();

        // Parse object pattern properties until we reach '}'
        while !self.is(TokenType::RBrace) {
            if self.is(TokenType::DotDotDot) {
                // Rest property
                let dot3_span = self.current_span();
                self.lexer.next_token()?; // Consume '...'

                // Parse the rest element
                let arg = self.parse_pat()?;
                let arg_span = arg.span();

                // Create the rest pattern
                let span = Span::new(dot3_span.lo, arg_span.hi);
                properties.push(ObjectPatProp::Rest(RestPat {
                    span,
                    dot3_token: dot3_span,
                    arg: Box::new(arg),
                    type_ann: None,
                }));

                // Rest property must be the last property
                if !self.is(TokenType::RBrace) {
                    let span = self.current_span();
                    return Err(Error {
                        kind: ErrorKind::General {
                            message: "Rest property must be the last property in object pattern"
                                .to_string(),
                        },
                        span,
                    });
                }
            } else {
                // Regular property
                let property = self.parse_object_pat_prop()?;
                properties.push(property);

                // Check for comma or end of object
                if !self.is(TokenType::RBrace) {
                    self.expect(TokenType::Comma)?;
                }
            }
        }

        let end_span = self.current_span();
        self.lexer.next_token()?; // Consume '}'

        let span = Span::new(start_span.lo, end_span.hi);
        Ok(Pat::Object(ObjectPat {
            span,
            props: properties,
            optional: false,
            type_ann: None,
        }))
    }

    /// Parse an object pattern property
    fn parse_object_pat_prop(&mut self) -> Result<ObjectPatProp> {
        let start_span = self.current_span();

        // Check for shorthand property
        if self.is(TokenType::Ident) {
            let key_span = self.current_span();
            let key = util::token_value_to_ident(self.current(), key_span);
            self.lexer.next_token()?; // Consume identifier

            // Check for key-value pattern
            if self.is(TokenType::Colon) {
                self.lexer.next_token()?; // Consume ':'
                let value = self.parse_pat()?;

                // Convert Ident to IdentName for PropName::Ident
                let ident_name = IdentName {
                    span: key.span,
                    sym: key.sym,
                };

                Ok(ObjectPatProp::KeyValue(KeyValuePatProp {
                    key: PropName::Ident(ident_name),
                    value: Box::new(value),
                }))
            } else if self.is(TokenType::Eq) {
                // Shorthand with default value
                self.lexer.next_token()?; // Consume '='
                let right = self.parse_expr()?;
                let right_span = right.span();
                let span = Span::new(start_span.lo, right_span.hi);

                // Convert Ident to BindingIdent
                let binding_ident = BindingIdent {
                    id: key,
                    type_ann: None,
                };

                Ok(ObjectPatProp::Assign(AssignPatProp {
                    span,
                    key: binding_ident,
                    value: Some(right),
                }))
            } else {
                // Simple shorthand property
                // Convert Ident to BindingIdent
                let binding_ident = BindingIdent {
                    id: key,
                    type_ann: None,
                };

                Ok(ObjectPatProp::Assign(AssignPatProp {
                    span: key_span,
                    key: binding_ident,
                    value: None,
                }))
            }
        } else if self.is(TokenType::LBracket) {
            // Computed property name
            self.lexer.next_token()?; // Consume '['
            let key_expr = self.parse_expr()?;
            self.expect(TokenType::RBracket)?;
            self.expect(TokenType::Colon)?;
            let value = self.parse_pat()?;

            // Create a computed property name
            let computed_key = ComputedPropName {
                span: start_span,
                expr: key_expr,
            };

            Ok(ObjectPatProp::KeyValue(KeyValuePatProp {
                key: PropName::Computed(computed_key),
                value: Box::new(value),
            }))
        } else if self.is(TokenType::Str) || self.is(TokenType::Num) {
            // String or number literal property name
            let key_span = self.current_span();
            let key = if self.is(TokenType::Str) {
                let str_lit = util::token_value_to_str(self.current(), key_span);
                self.lexer.next_token()?; // Consume string
                PropName::Str(str_lit)
            } else {
                let num_lit = util::token_value_to_number(self.current(), key_span);
                self.lexer.next_token()?; // Consume number
                PropName::Num(num_lit)
            };

            self.expect(TokenType::Colon)?;
            let value = self.parse_pat()?;

            Ok(ObjectPatProp::KeyValue(KeyValuePatProp {
                key,
                value: Box::new(value),
            }))
        } else {
            // Unexpected token
            let span = self.current_span();
            Err(Error {
                kind: ErrorKind::UnexpectedToken {
                    expected: Some("object pattern property"),
                    got: self.current_token_type().as_str().to_string(),
                },
                span,
            })
        }
    }
}