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
|
use super::chunk::Chunk;
use super::errors::{Error, ErrorKind, LoxResult};
use super::opcode::OpCode;
use super::value::Value;
use crate::scanner::{self, Token, TokenKind};
#[cfg(test)]
mod tests;
struct Compiler<T: Iterator<Item = Token>> {
tokens: T,
chunk: Chunk,
panic: bool,
errors: Vec<Error>,
// TODO(tazjin): Restructure so that these don't need to be Option?
current: Option<Token>,
previous: Option<Token>,
}
#[derive(Debug, PartialEq, PartialOrd)]
enum Precedence {
None,
Assignment, // =
Or, // or
And, // and
Equality, // == !=
Comparison, // < > <= >=
Term, // + -
Factor, // * /
Unary, // ! -
Call, // . ()
Primary,
}
impl Precedence {
// Return the next highest precedence, if there is one.
fn next(&self) -> Self {
match self {
Precedence::None => Precedence::Assignment,
Precedence::Assignment => Precedence::Or,
Precedence::Or => Precedence::And,
Precedence::And => Precedence::Equality,
Precedence::Equality => Precedence::Comparison,
Precedence::Comparison => Precedence::Term,
Precedence::Term => Precedence::Factor,
Precedence::Factor => Precedence::Unary,
Precedence::Unary => Precedence::Call,
Precedence::Call => Precedence::Primary,
Precedence::Primary => panic!(
"invalid parser state: no higher precedence than Primary"
),
}
}
}
impl<T: Iterator<Item = Token>> Compiler<T> {
fn compile(&mut self) -> LoxResult<()> {
self.advance();
self.expression()?;
self.consume(
&TokenKind::Eof,
ErrorKind::ExpectedToken("Expected end of expression"),
)?;
self.end_compiler()
}
fn advance(&mut self) {
self.previous = self.current.take();
self.current = self.tokens.next();
}
fn expression(&mut self) -> LoxResult<()> {
self.parse_precedence(Precedence::Assignment)
}
// TODO(tazjin): Assumption is that we have access to the previous
// token wherever this ends up invoked. True?
fn number(&mut self, num: f64) {
self.emit_constant(num);
}
fn grouping(&mut self, num: f64) -> LoxResult<()> {
self.expression()?;
self.consume(
&TokenKind::RightParen,
ErrorKind::ExpectedToken("Expected ')' after expression"),
)
}
fn unary(&mut self) -> LoxResult<()> {
// TODO(tazjin): Avoid clone
let kind = self.previous().kind.clone();
// Compile the operand
self.parse_precedence(Precedence::Unary)?;
// Emit operator instruction
match kind {
TokenKind::Minus => self.emit_op(OpCode::OpNegate),
_ => unreachable!("only called for unary operator tokens"),
}
Ok(())
}
fn binary(&mut self) -> LoxResult<()> {
// Remember the operator
let operator = self.previous().kind.clone();
// Compile the right operand
let rule = self.get_rule(&operator);
self.parse_precedence(unimplemented!("rule.precendece.next()"))?;
// Emit operator instruction
match operator {
TokenKind::Minus => self.emit_op(OpCode::OpSubtract),
TokenKind::Plus => self.emit_op(OpCode::OpAdd),
TokenKind::Star => self.emit_op(OpCode::OpMultiply),
TokenKind::Slash => self.emit_op(OpCode::OpDivide),
_ => unreachable!("only called for binary operator tokens"),
}
unimplemented!()
}
fn get_rule(&mut self, op: &TokenKind) -> usize {
unimplemented!();
}
fn parse_precedence(&mut self, precedence: Precedence) -> LoxResult<()> {
unimplemented!("what goes here?")
}
fn consume(
&mut self,
expected: &TokenKind,
err: ErrorKind,
) -> LoxResult<()> {
unimplemented!()
}
fn current_chunk(&mut self) -> &mut Chunk {
&mut self.chunk
}
fn end_compiler(&mut self) -> LoxResult<()> {
self.emit_op(OpCode::OpReturn);
Ok(())
}
fn emit_op(&mut self, op: OpCode) {
let line = self.previous().line;
self.current_chunk().add_op(op, line);
}
fn emit_constant(&mut self, val: Value) {
let idx = self.chunk.add_constant(val);
self.emit_op(OpCode::OpConstant(idx));
}
fn previous(&self) -> &Token {
self.previous
.as_ref()
.expect("invalid internal compiler state: missing previous token")
}
fn error_at(&mut self, token: &Token, kind: ErrorKind) {
if self.panic {
return;
}
self.panic = true;
self.errors.push(Error {
kind,
line: token.line,
})
}
}
pub fn compile(code: &str) -> Result<Chunk, Vec<Error>> {
let chars = code.chars().collect::<Vec<char>>();
let tokens = scanner::scan(&chars).map_err(|errors| {
errors.into_iter().map(Into::into).collect::<Vec<Error>>()
})?;
let mut compiler = Compiler {
tokens: tokens.into_iter().peekable(),
chunk: Default::default(),
panic: false,
errors: vec![],
current: None,
previous: None,
};
compiler.compile()?;
if compiler.errors.is_empty() {
Ok(unimplemented!())
} else {
Err(compiler.errors)
}
}
|
