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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<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, kind: &TokenKind) -> LoxResult<()> {
// 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 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)
}
}
|
