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feat(tazjin/rlox): Intern all string constants

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This is again a step closer to the book, but there are some notable
differences:

* Only constants encountered by the compiler are interned, all other
  string operations (well, concatenation) happen with heap objects.

* OpReturn will always ensure that a returned string value is newly
  heap allocated and does not reference the interner.

Change-Id: If4f04309446e01b8ff2db51094e9710d465dbc50
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2582
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI
This commit is contained in:
Vincent Ambo 2021-03-02 13:11:21 +02:00 • committed by tazjin
parent bcea8e0d16
commit 432e7a7ddd
4 changed files with 65 additions and 19 deletions
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22
users/tazjin/rlox/src/bytecode/compiler.rs
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@ -1,5 +1,6 @@
use super::chunk::Chunk;
use super::errors::{Error, ErrorKind, LoxResult};
use super::interner::Interner;
use super::opcode::OpCode;
use super::value::Value;
use crate::scanner::{self, Token, TokenKind};
@ -12,8 +13,8 @@ struct Compiler<T: Iterator<Item = Token>> {
chunk: Chunk,
panic: bool,
errors: Vec<Error>,
strings: Interner,
// TODO(tazjin): Restructure so that these don't need to be Option?
current: Option<Token>,
previous: Option<Token>,
}
@ -146,7 +147,7 @@ fn rule_for<T: Iterator<Item = Token>>(token: &TokenKind) -> ParseRule<T> {
TokenKind::String(_) => {
ParseRule::new(Some(Compiler::string), None, Precedence::None)
},
}
_ => ParseRule::new(None, None, Precedence::None),
}
@ -260,13 +261,13 @@ impl<T: Iterator<Item = Token>> Compiler<T> {
}
fn string(&mut self) -> LoxResult<()> {
match &self.previous().kind {
TokenKind::String(s) => {
let s = s.clone();
self.emit_constant(Value::String(s));
}
let val = match &self.previous().kind {
TokenKind::String(s) => s.clone(),
_ => unreachable!("only called for strings"),
}
};
let id = self.strings.intern(val);
self.emit_constant(Value::String(id.into()));
Ok(())
}
@ -353,7 +354,7 @@ impl<T: Iterator<Item = Token>> Compiler<T> {
}
}
pub fn compile(code: &str) -> Result<Chunk, Vec<Error>> {
pub fn compile(code: &str) -> Result<(Interner, 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>>()
@ -364,6 +365,7 @@ pub fn compile(code: &str) -> Result<Chunk, Vec<Error>> {
chunk: Default::default(),
panic: false,
errors: vec![],
strings: Interner::with_capacity(1024),
current: None,
previous: None,
};
@ -371,7 +373,7 @@ pub fn compile(code: &str) -> Result<Chunk, Vec<Error>> {
compiler.compile()?;
if compiler.errors.is_empty() {
Ok(compiler.chunk)
Ok((compiler.strings, compiler.chunk))
} else {
Err(compiler.errors)
}