feat(tvix/value): introduce string representation with &'static str
For cases where the strings are statically known (such as the oft-occuring name/value), this can be a useful optimisation. It's also much more convenient in tests. Change-Id: Ie462b684805bd4986ea5e85ca4bff663bc2d3c3c Reviewed-on: https://cl.tvl.fyi/c/depot/+/6111 Tested-by: BuildkiteCI Reviewed-by: eta <tvl@eta.st>
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4 changed files with 44 additions and 26 deletions
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@ -111,7 +111,7 @@ impl Compiler {
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rnix::StrPart::Ast(node) => self.compile(node)?,
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rnix::StrPart::Literal(lit) => {
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let idx = self.chunk.add_constant(Value::String(NixString(lit)));
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let idx = self.chunk.add_constant(Value::String(lit.into()));
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self.chunk.add_op(OpCode::OpConstant(idx));
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}
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}
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@ -206,9 +206,9 @@ impl Compiler {
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let ident = rnix::types::Ident::cast(fragment).unwrap();
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// TODO(tazjin): intern!
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let idx = self
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.chunk
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.add_constant(Value::String(NixString(ident.as_str().to_string())));
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let idx = self.chunk.add_constant(Value::String(NixString::Heap(
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ident.as_str().to_string(),
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)));
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self.chunk.add_op(OpCode::OpConstant(idx));
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}
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@ -71,14 +71,8 @@ impl NixAttrs {
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NixAttrs::KV { name, value } => {
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*self = NixAttrs::Map(BTreeMap::from([
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(
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NixString("name".into()),
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std::mem::replace(name, Value::Blackhole),
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),
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(
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NixString("value".into()),
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std::mem::replace(value, Value::Blackhole),
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),
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("name".into(), std::mem::replace(name, Value::Blackhole)),
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("value".into(), std::mem::replace(value, Value::Blackhole)),
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]));
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self.map_mut()
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}
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@ -155,14 +149,14 @@ impl NixAttrs {
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fn attempt_optimise_kv(slice: &mut [Value]) -> Option<NixAttrs> {
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let (name_idx, value_idx) = {
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match (&slice[2], &slice[0]) {
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(Value::String(NixString(s1)), Value::String(NixString(s2)))
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if (s1 == "name" && s2 == "value") =>
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(Value::String(s1), Value::String(s2))
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if (*s1 == NixString::NAME && *s2 == NixString::VALUE) =>
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{
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(3, 1)
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}
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(Value::String(NixString(s1)), Value::String(NixString(s2)))
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if (s1 == "value" && s2 == "name") =>
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(Value::String(s1), Value::String(s2))
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if (*s1 == NixString::VALUE && *s2 == NixString::NAME) =>
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{
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(1, 3)
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}
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@ -189,7 +183,7 @@ fn set_attr(attrs: &mut NixAttrs, key: NixString, value: Value) -> EvalResult<()
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match entry {
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std::collections::btree_map::Entry::Occupied(entry) => {
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return Err(Error::DuplicateAttrsKey {
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key: entry.key().0.clone(),
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key: entry.key().as_str().to_string(),
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})
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}
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@ -254,7 +248,7 @@ fn set_nested_attr(
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_ => {
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return Err(Error::DuplicateAttrsKey {
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key: entry.key().0.clone(),
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key: entry.key().as_str().to_string(),
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})
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}
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},
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@ -4,16 +4,40 @@ use std::fmt::Display;
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/// backing implementations.
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#[derive(Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
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pub struct NixString(pub String);
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pub enum NixString {
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Static(&'static str),
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Heap(String),
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}
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impl Display for NixString {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.write_str(self.0.as_str())
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match self {
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NixString::Static(s) => f.write_str(s),
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NixString::Heap(s) => f.write_str(s),
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}
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}
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}
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impl From<&str> for NixString {
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fn from(s: &str) -> Self {
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NixString(s.to_string())
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impl From<&'static str> for NixString {
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fn from(s: &'static str) -> Self {
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NixString::Static(s)
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}
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}
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impl From<String> for NixString {
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fn from(s: String) -> Self {
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NixString::Heap(s)
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}
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}
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impl NixString {
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pub const NAME: Self = NixString::Static("name");
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pub const VALUE: Self = NixString::Static("value");
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pub fn as_str(&self) -> &str {
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match self {
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NixString::Static(s) => s,
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NixString::Heap(s) => s,
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}
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}
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}
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@ -7,7 +7,7 @@ use crate::{
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chunk::Chunk,
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errors::{Error, EvalResult},
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opcode::OpCode,
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value::{NixAttrs, NixList, NixString, Value},
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value::{NixAttrs, NixList, Value},
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};
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pub struct VM {
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@ -159,10 +159,10 @@ impl VM {
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let mut out = String::new();
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for _ in 0..count {
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out.push_str(&self.pop().as_string()?.0);
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out.push_str(&self.pop().as_string()?.as_str());
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}
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self.push(Value::String(NixString(out)));
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self.push(Value::String(out.into()));
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Ok(())
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}
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