627dfabef1
With this all other "weird scope" logic starts working for `with` as well. Change-Id: I0ea1d8c5fbd9cec5084bd574224f77b71ff2b487 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6487 Tested-by: BuildkiteCI Reviewed-by: sterni <sternenseemann@systemli.org>
1552 lines
57 KiB
Rust
1552 lines
57 KiB
Rust
//! This module implements a compiler for compiling the rnix AST
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//! representation to Tvix bytecode.
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//!
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//! A note on `unwrap()`: This module contains a lot of calls to
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//! `unwrap()` or `expect(...)` on data structures returned by `rnix`.
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//! The reason for this is that rnix uses the same data structures to
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//! represent broken and correct ASTs, so all typed AST variants have
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//! the ability to represent an incorrect node.
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//!
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//! However, at the time that the AST is passed to the compiler we
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//! have verified that `rnix` considers the code to be correct, so all
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//! variants are fulfilled. In cases where the invariant is guaranteed
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//! by the code in this module, `debug_assert!` has been used to catch
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//! mistakes early during development.
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mod scope;
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use path_clean::PathClean;
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use rnix::ast::{self, AstToken, HasEntry};
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use rowan::ast::{AstChildren, AstNode};
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use std::collections::HashMap;
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use std::path::{Path, PathBuf};
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use std::rc::Rc;
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use crate::chunk::Chunk;
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use crate::errors::{Error, ErrorKind, EvalResult};
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use crate::observer::Observer;
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use crate::opcode::{CodeIdx, Count, JumpOffset, OpCode, UpvalueIdx};
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use crate::value::{Closure, Lambda, Thunk, Value};
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use crate::warnings::{EvalWarning, WarningKind};
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use self::scope::{LocalIdx, LocalPosition, Scope, Upvalue, UpvalueKind};
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/// Represents the result of compiling a piece of Nix code. If
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/// compilation was successful, the resulting bytecode can be passed
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/// to the VM.
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pub struct CompilationOutput {
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pub lambda: Rc<Lambda>,
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pub warnings: Vec<EvalWarning>,
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pub errors: Vec<Error>,
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}
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/// Represents the lambda currently being compiled.
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struct LambdaCtx {
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lambda: Lambda,
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scope: Scope,
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captures_with_stack: bool,
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}
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impl LambdaCtx {
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fn new() -> Self {
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LambdaCtx {
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lambda: Lambda::new_anonymous(),
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scope: Default::default(),
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captures_with_stack: false,
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}
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}
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fn inherit(&self) -> Self {
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LambdaCtx {
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lambda: Lambda::new_anonymous(),
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scope: self.scope.inherit(),
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captures_with_stack: false,
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}
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}
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}
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/// Alias for the map of globally available functions that should
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/// implicitly be resolvable in the global scope.
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type GlobalsMap = HashMap<&'static str, Rc<dyn Fn(&mut Compiler, rnix::ast::Ident)>>;
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struct Compiler<'code, 'observer> {
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contexts: Vec<LambdaCtx>,
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warnings: Vec<EvalWarning>,
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errors: Vec<Error>,
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root_dir: PathBuf,
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/// Carries all known global tokens; the full set of which is
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/// created when the compiler is invoked.
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///
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/// Each global has an associated token, which when encountered as
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/// an identifier is resolved against the scope poisoning logic,
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/// and a function that should emit code for the token.
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globals: GlobalsMap,
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/// File reference in the codemap contains all known source code
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/// and is used to track the spans from which instructions where
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/// derived.
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file: &'code codemap::File,
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/// Carry an observer for the compilation process, which is called
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/// whenever a chunk is emitted.
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observer: &'observer mut dyn Observer,
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}
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// Helper functions for emitting code and metadata to the internal
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// structures of the compiler.
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impl Compiler<'_, '_> {
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fn context(&self) -> &LambdaCtx {
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&self.contexts[self.contexts.len() - 1]
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}
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fn context_mut(&mut self) -> &mut LambdaCtx {
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let idx = self.contexts.len() - 1;
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&mut self.contexts[idx]
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}
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fn chunk(&mut self) -> &mut Chunk {
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&mut self.context_mut().lambda.chunk
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}
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fn scope(&self) -> &Scope {
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&self.context().scope
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}
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fn scope_mut(&mut self) -> &mut Scope {
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&mut self.context_mut().scope
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}
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fn span_for<N: AstNode>(&self, node: &N) -> codemap::Span {
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let rowan_span = node.syntax().text_range();
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self.file.span.subspan(
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u32::from(rowan_span.start()) as u64,
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u32::from(rowan_span.end()) as u64,
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)
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}
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/// Push a single instruction to the current bytecode chunk and
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/// track the source span from which it was compiled.
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fn push_op<T: AstNode>(&mut self, data: OpCode, node: &T) -> CodeIdx {
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let span = self.span_for(node);
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self.chunk().push_op(data, span)
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}
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/// Emit a single constant to the current bytecode chunk and track
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/// the source span from which it was compiled.
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fn emit_constant<T: AstNode>(&mut self, value: Value, node: &T) {
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let idx = self.chunk().push_constant(value);
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self.push_op(OpCode::OpConstant(idx), node);
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}
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}
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// Actual code-emitting AST traversal methods.
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impl Compiler<'_, '_> {
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fn compile(&mut self, slot: LocalIdx, expr: ast::Expr) {
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match expr {
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ast::Expr::Literal(literal) => self.compile_literal(literal),
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ast::Expr::Path(path) => self.compile_path(path),
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ast::Expr::Str(s) => self.compile_str(slot, s),
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ast::Expr::UnaryOp(op) => self.compile_unary_op(slot, op),
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ast::Expr::BinOp(binop) => {
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self.thunk(slot, &binop, move |c, o, s| c.compile_binop(s, o.clone()))
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}
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ast::Expr::HasAttr(has_attr) => self.compile_has_attr(slot, has_attr),
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ast::Expr::List(list) => {
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self.thunk(slot, &list, move |c, l, s| c.compile_list(s, l.clone()))
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}
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ast::Expr::AttrSet(attrs) => self.thunk(slot, &attrs, move |c, a, s| {
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c.compile_attr_set(s, a.clone())
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}),
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ast::Expr::Select(select) => self.thunk(slot, &select, move |c, sel, s| {
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c.compile_select(s, sel.clone())
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}),
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ast::Expr::Assert(assert) => self.compile_assert(slot, assert),
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ast::Expr::IfElse(if_else) => self.compile_if_else(slot, if_else),
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ast::Expr::LetIn(let_in) => self.compile_let_in(slot, let_in),
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ast::Expr::Ident(ident) => self.compile_ident(slot, ident),
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ast::Expr::With(with) => {
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self.thunk(slot, &with, |c, w, s| c.compile_with(s, w.clone()))
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}
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ast::Expr::Lambda(lambda) => self.compile_lambda(slot, lambda),
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ast::Expr::Apply(apply) => {
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self.thunk(slot, &apply, move |c, a, s| c.compile_apply(s, a.clone()))
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}
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// Parenthesized expressions are simply unwrapped, leaving
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// their value on the stack.
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ast::Expr::Paren(paren) => self.compile(slot, paren.expr().unwrap()),
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ast::Expr::LegacyLet(_) => todo!("legacy let"),
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ast::Expr::Root(_) => unreachable!("there cannot be more than one root"),
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ast::Expr::Error(_) => unreachable!("compile is only called on validated trees"),
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}
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}
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fn compile_literal(&mut self, node: ast::Literal) {
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match node.kind() {
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ast::LiteralKind::Float(f) => {
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self.emit_constant(Value::Float(f.value().unwrap()), &node);
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}
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ast::LiteralKind::Integer(i) => {
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self.emit_constant(Value::Integer(i.value().unwrap()), &node);
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}
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ast::LiteralKind::Uri(u) => {
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self.emit_warning(self.span_for(&node), WarningKind::DeprecatedLiteralURL);
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self.emit_constant(Value::String(u.syntax().text().into()), &node);
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}
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}
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}
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fn compile_path(&mut self, node: ast::Path) {
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// TODO(tazjin): placeholder implementation while waiting for
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// https://github.com/nix-community/rnix-parser/pull/96
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let raw_path = node.to_string();
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let path = if raw_path.starts_with('/') {
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Path::new(&raw_path).to_owned()
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} else if raw_path.starts_with('~') {
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let mut buf = match dirs::home_dir() {
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Some(buf) => buf,
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None => {
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self.emit_error(
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self.span_for(&node),
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ErrorKind::PathResolution("failed to determine home directory".into()),
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);
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return;
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}
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};
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buf.push(&raw_path);
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buf
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} else if raw_path.starts_with('.') {
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let mut buf = self.root_dir.clone();
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buf.push(&raw_path);
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buf
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} else {
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// TODO: decide what to do with findFile
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todo!("other path types (e.g. <...> lookups) not yet implemented")
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};
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// TODO: Use https://github.com/rust-lang/rfcs/issues/2208
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// once it is available
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let value = Value::Path(path.clean());
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self.emit_constant(value, &node);
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}
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fn compile_str(&mut self, slot: LocalIdx, node: ast::Str) {
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let mut count = 0;
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// The string parts are produced in literal order, however
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// they need to be reversed on the stack in order to
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// efficiently create the real string in case of
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// interpolation.
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for part in node.normalized_parts().into_iter().rev() {
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count += 1;
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match part {
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// Interpolated expressions are compiled as normal and
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// dealt with by the VM before being assembled into
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// the final string.
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ast::InterpolPart::Interpolation(node) => self.compile(slot, node.expr().unwrap()),
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ast::InterpolPart::Literal(lit) => {
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self.emit_constant(Value::String(lit.into()), &node);
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}
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}
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}
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if count != 1 {
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self.push_op(OpCode::OpInterpolate(Count(count)), &node);
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}
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}
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fn compile_unary_op(&mut self, slot: LocalIdx, op: ast::UnaryOp) {
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self.compile(slot, op.expr().unwrap());
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self.emit_force(&op);
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let opcode = match op.operator().unwrap() {
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ast::UnaryOpKind::Invert => OpCode::OpInvert,
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ast::UnaryOpKind::Negate => OpCode::OpNegate,
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};
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self.push_op(opcode, &op);
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}
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fn compile_binop(&mut self, slot: LocalIdx, op: ast::BinOp) {
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use ast::BinOpKind;
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// Short-circuiting and other strange operators, which are
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// under the same node type as NODE_BIN_OP, but need to be
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// handled separately (i.e. before compiling the expressions
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// used for standard binary operators).
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match op.operator().unwrap() {
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BinOpKind::And => return self.compile_and(slot, op),
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BinOpKind::Or => return self.compile_or(slot, op),
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BinOpKind::Implication => return self.compile_implication(slot, op),
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_ => {}
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};
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// For all other operators, the two values need to be left on
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// the stack in the correct order before pushing the
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// instruction for the operation itself.
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self.compile(slot, op.lhs().unwrap());
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self.emit_force(&op.lhs().unwrap());
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self.compile(slot, op.rhs().unwrap());
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self.emit_force(&op.rhs().unwrap());
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match op.operator().unwrap() {
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BinOpKind::Add => self.push_op(OpCode::OpAdd, &op),
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BinOpKind::Sub => self.push_op(OpCode::OpSub, &op),
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BinOpKind::Mul => self.push_op(OpCode::OpMul, &op),
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BinOpKind::Div => self.push_op(OpCode::OpDiv, &op),
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BinOpKind::Update => self.push_op(OpCode::OpAttrsUpdate, &op),
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BinOpKind::Equal => self.push_op(OpCode::OpEqual, &op),
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BinOpKind::Less => self.push_op(OpCode::OpLess, &op),
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BinOpKind::LessOrEq => self.push_op(OpCode::OpLessOrEq, &op),
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BinOpKind::More => self.push_op(OpCode::OpMore, &op),
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BinOpKind::MoreOrEq => self.push_op(OpCode::OpMoreOrEq, &op),
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BinOpKind::Concat => self.push_op(OpCode::OpConcat, &op),
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BinOpKind::NotEqual => {
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self.push_op(OpCode::OpEqual, &op);
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self.push_op(OpCode::OpInvert, &op)
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}
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// Handled by separate branch above.
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BinOpKind::And | BinOpKind::Implication | BinOpKind::Or => {
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unreachable!()
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}
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};
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}
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fn compile_and(&mut self, slot: LocalIdx, node: ast::BinOp) {
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debug_assert!(
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matches!(node.operator(), Some(ast::BinOpKind::And)),
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"compile_and called with wrong operator kind: {:?}",
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node.operator(),
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);
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// Leave left-hand side value on the stack.
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self.compile(slot, node.lhs().unwrap());
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self.emit_force(&node.lhs().unwrap());
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// If this value is false, jump over the right-hand side - the
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// whole expression is false.
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let end_idx = self.push_op(OpCode::OpJumpIfFalse(JumpOffset(0)), &node);
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// Otherwise, remove the previous value and leave the
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// right-hand side on the stack. Its result is now the value
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// of the whole expression.
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self.push_op(OpCode::OpPop, &node);
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self.compile(slot, node.rhs().unwrap());
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self.emit_force(&node.rhs().unwrap());
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self.patch_jump(end_idx);
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self.push_op(OpCode::OpAssertBool, &node);
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}
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fn compile_or(&mut self, slot: LocalIdx, node: ast::BinOp) {
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debug_assert!(
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matches!(node.operator(), Some(ast::BinOpKind::Or)),
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"compile_or called with wrong operator kind: {:?}",
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node.operator(),
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);
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// Leave left-hand side value on the stack
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self.compile(slot, node.lhs().unwrap());
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self.emit_force(&node.lhs().unwrap());
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// Opposite of above: If this value is **true**, we can
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// short-circuit the right-hand side.
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let end_idx = self.push_op(OpCode::OpJumpIfTrue(JumpOffset(0)), &node);
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self.push_op(OpCode::OpPop, &node);
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self.compile(slot, node.rhs().unwrap());
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self.emit_force(&node.rhs().unwrap());
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self.patch_jump(end_idx);
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self.push_op(OpCode::OpAssertBool, &node);
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}
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fn compile_implication(&mut self, slot: LocalIdx, node: ast::BinOp) {
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debug_assert!(
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matches!(node.operator(), Some(ast::BinOpKind::Implication)),
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"compile_implication called with wrong operator kind: {:?}",
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node.operator(),
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);
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// Leave left-hand side value on the stack and invert it.
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self.compile(slot, node.lhs().unwrap());
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self.emit_force(&node.lhs().unwrap());
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self.push_op(OpCode::OpInvert, &node);
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// Exactly as `||` (because `a -> b` = `!a || b`).
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let end_idx = self.push_op(OpCode::OpJumpIfTrue(JumpOffset(0)), &node);
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self.push_op(OpCode::OpPop, &node);
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self.compile(slot, node.rhs().unwrap());
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self.emit_force(&node.rhs().unwrap());
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self.patch_jump(end_idx);
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self.push_op(OpCode::OpAssertBool, &node);
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}
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fn compile_has_attr(&mut self, slot: LocalIdx, node: ast::HasAttr) {
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// Put the attribute set on the stack.
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self.compile(slot, node.expr().unwrap());
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// Push all path fragments with an operation for fetching the
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// next nested element, for all fragments except the last one.
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for (count, fragment) in node.attrpath().unwrap().attrs().enumerate() {
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if count > 0 {
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self.push_op(OpCode::OpAttrsTrySelect, &fragment);
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}
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|
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self.compile_attr(slot, fragment);
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}
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|
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// After the last fragment, emit the actual instruction that
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// leaves a boolean on the stack.
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self.push_op(OpCode::OpAttrsIsSet, &node);
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}
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|
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fn compile_attr(&mut self, slot: LocalIdx, node: ast::Attr) {
|
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match node {
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ast::Attr::Dynamic(dynamic) => {
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self.compile(slot, dynamic.expr().unwrap());
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self.emit_force(&dynamic.expr().unwrap());
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}
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ast::Attr::Str(s) => {
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self.compile_str(slot, s.clone());
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self.emit_force(&s);
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}
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|
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ast::Attr::Ident(ident) => self.emit_literal_ident(&ident),
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}
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}
|
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|
|
/// Compile list literals into equivalent bytecode. List
|
|
/// construction is fairly simple, consisting of pushing code for
|
|
/// each literal element and an instruction with the element
|
|
/// count.
|
|
///
|
|
/// The VM, after evaluating the code for each element, simply
|
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/// constructs the list from the given number of elements.
|
|
fn compile_list(&mut self, slot: LocalIdx, node: ast::List) {
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let mut count = 0;
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|
|
// Open a temporary scope to correctly account for stack items
|
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// that exist during the construction.
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self.begin_scope();
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|
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for item in node.items() {
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// Start tracing new stack slots from the second list
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// element onwards. The first list element is located in
|
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// the stack slot of the list itself.
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let item_slot = match count {
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0 => slot,
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_ => {
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let item_span = self.span_for(&item);
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self.scope_mut().declare_phantom(item_span, false)
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}
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};
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|
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count += 1;
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self.compile(item_slot, item);
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self.scope_mut().mark_initialised(item_slot);
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}
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self.push_op(OpCode::OpList(Count(count)), &node);
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self.scope_mut().end_scope();
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}
|
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|
|
/// Compiles inherited values in an attribute set. Inherited
|
|
/// values are *always* inherited from the outer scope, even if
|
|
/// there is a matching name within a recursive attribute set.
|
|
fn compile_inherit_attrs(
|
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&mut self,
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slot: LocalIdx,
|
|
inherits: AstChildren<ast::Inherit>,
|
|
) -> usize {
|
|
// Count the number of inherited values, so that the outer
|
|
// constructor can emit the correct number of pairs when
|
|
// constructing attribute sets.
|
|
let mut count = 0;
|
|
|
|
for inherit in inherits {
|
|
match inherit.from() {
|
|
Some(from) => {
|
|
for ident in inherit.idents() {
|
|
count += 1;
|
|
|
|
// First emit the identifier itself (this
|
|
// becomes the new key).
|
|
self.emit_literal_ident(&ident);
|
|
let ident_span = self.span_for(&ident);
|
|
self.scope_mut().declare_phantom(ident_span, true);
|
|
|
|
// Then emit the node that we're inheriting
|
|
// from.
|
|
//
|
|
// TODO: Likely significant optimisation
|
|
// potential in having a multi-select
|
|
// instruction followed by a merge, rather
|
|
// than pushing/popping the same attrs
|
|
// potentially a lot of times.
|
|
let val_idx = self.scope_mut().declare_phantom(ident_span, false);
|
|
self.compile(val_idx, from.expr().unwrap());
|
|
self.emit_force(&from.expr().unwrap());
|
|
self.emit_literal_ident(&ident);
|
|
self.push_op(OpCode::OpAttrsSelect, &ident);
|
|
self.scope_mut().mark_initialised(val_idx);
|
|
}
|
|
}
|
|
|
|
None => {
|
|
for ident in inherit.idents() {
|
|
let ident_span = self.span_for(&ident);
|
|
count += 1;
|
|
|
|
// Emit the key to use for OpAttrs
|
|
self.emit_literal_ident(&ident);
|
|
self.scope_mut().declare_phantom(ident_span, true);
|
|
|
|
// Emit the value.
|
|
self.compile_ident(slot, ident);
|
|
self.scope_mut().declare_phantom(ident_span, true);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
count
|
|
}
|
|
|
|
/// Compile attribute set literals into equivalent bytecode.
|
|
///
|
|
/// This is complicated by a number of features specific to Nix
|
|
/// attribute sets, most importantly:
|
|
///
|
|
/// 1. Keys can be dynamically constructed through interpolation.
|
|
/// 2. Keys can refer to nested attribute sets.
|
|
/// 3. Attribute sets can (optionally) be recursive.
|
|
fn compile_attr_set(&mut self, slot: LocalIdx, node: ast::AttrSet) {
|
|
if node.rec_token().is_some() {
|
|
todo!("recursive attribute sets are not yet implemented")
|
|
}
|
|
|
|
// Open a scope to track the positions of the temporaries used
|
|
// by the `OpAttrs` instruction.
|
|
self.begin_scope();
|
|
|
|
let mut count = self.compile_inherit_attrs(slot, node.inherits());
|
|
|
|
for kv in node.attrpath_values() {
|
|
count += 1;
|
|
|
|
// Because attribute set literals can contain nested keys,
|
|
// there is potentially more than one key fragment. If
|
|
// this is the case, a special operation to construct a
|
|
// runtime value representing the attribute path is
|
|
// emitted.
|
|
let mut key_count = 0;
|
|
let key_span = self.span_for(&kv.attrpath().unwrap());
|
|
let key_idx = self.scope_mut().declare_phantom(key_span, false);
|
|
|
|
for fragment in kv.attrpath().unwrap().attrs() {
|
|
// Key fragments can contain dynamic expressions,
|
|
// which makes accounting for their stack slots very
|
|
// tricky.
|
|
//
|
|
// In order to ensure the locals are correctly cleaned
|
|
// up, we essentially treat any key fragment after the
|
|
// first one (which has a locals index that will
|
|
// become that of the final key itself) as being part
|
|
// of a separate scope, which results in the somewhat
|
|
// annoying setup logic below.
|
|
let fragment_slot = match key_count {
|
|
0 => key_idx,
|
|
1 => {
|
|
self.begin_scope();
|
|
self.scope_mut().declare_phantom(key_span, false)
|
|
}
|
|
_ => self.scope_mut().declare_phantom(key_span, false),
|
|
};
|
|
|
|
key_count += 1;
|
|
self.compile_attr(fragment_slot, fragment);
|
|
self.scope_mut().mark_initialised(fragment_slot);
|
|
}
|
|
|
|
// We're done with the key if there was only one fragment,
|
|
// otherwise we need to emit an instruction to construct
|
|
// the attribute path.
|
|
if key_count > 1 {
|
|
self.push_op(
|
|
OpCode::OpAttrPath(Count(key_count)),
|
|
&kv.attrpath().unwrap(),
|
|
);
|
|
|
|
// Close the temporary scope that was set up for the
|
|
// key fragments.
|
|
self.scope_mut().end_scope();
|
|
}
|
|
|
|
// The value is just compiled as normal so that its
|
|
// resulting value is on the stack when the attribute set
|
|
// is constructed at runtime.
|
|
let value_span = self.span_for(&kv.value().unwrap());
|
|
let value_slot = self.scope_mut().declare_phantom(value_span, false);
|
|
self.compile(slot, kv.value().unwrap());
|
|
self.scope_mut().mark_initialised(value_slot);
|
|
}
|
|
|
|
self.push_op(OpCode::OpAttrs(Count(count)), &node);
|
|
|
|
// Remove the temporary scope, but do not emit any additional
|
|
// cleanup (OpAttrs consumes all of these locals).
|
|
self.scope_mut().end_scope();
|
|
}
|
|
|
|
fn compile_select(&mut self, slot: LocalIdx, node: ast::Select) {
|
|
let set = node.expr().unwrap();
|
|
let path = node.attrpath().unwrap();
|
|
|
|
if node.or_token().is_some() {
|
|
self.compile_select_or(slot, set, path, node.default_expr().unwrap());
|
|
return;
|
|
}
|
|
|
|
// Push the set onto the stack
|
|
self.compile(slot, set.clone());
|
|
self.emit_force(&set);
|
|
|
|
// Compile each key fragment and emit access instructions.
|
|
//
|
|
// TODO: multi-select instruction to avoid re-pushing attrs on
|
|
// nested selects.
|
|
for fragment in path.attrs() {
|
|
self.compile_attr(slot, fragment);
|
|
self.push_op(OpCode::OpAttrsSelect, &node);
|
|
}
|
|
}
|
|
|
|
/// Compile an `or` expression into a chunk of conditional jumps.
|
|
///
|
|
/// If at any point during attribute set traversal a key is
|
|
/// missing, the `OpAttrOrNotFound` instruction will leave a
|
|
/// special sentinel value on the stack.
|
|
///
|
|
/// After each access, a conditional jump evaluates the top of the
|
|
/// stack and short-circuits to the default value if it sees the
|
|
/// sentinel.
|
|
///
|
|
/// Code like `{ a.b = 1; }.a.c or 42` yields this bytecode and
|
|
/// runtime stack:
|
|
///
|
|
/// ```notrust
|
|
/// Bytecode Runtime stack
|
|
/// ┌────────────────────────────┐ ┌─────────────────────────┐
|
|
/// │ ... │ │ ... │
|
|
/// │ 5 OP_ATTRS(1) │ → │ 5 [ { a.b = 1; } ] │
|
|
/// │ 6 OP_CONSTANT("a") │ → │ 6 [ { a.b = 1; } "a" ] │
|
|
/// │ 7 OP_ATTR_OR_NOT_FOUND │ → │ 7 [ { b = 1; } ] │
|
|
/// │ 8 JUMP_IF_NOT_FOUND(13) │ → │ 8 [ { b = 1; } ] │
|
|
/// │ 9 OP_CONSTANT("C") │ → │ 9 [ { b = 1; } "c" ] │
|
|
/// │ 10 OP_ATTR_OR_NOT_FOUND │ → │ 10 [ NOT_FOUND ] │
|
|
/// │ 11 JUMP_IF_NOT_FOUND(13) │ → │ 11 [ ] │
|
|
/// │ 12 JUMP(14) │ │ .. jumped over │
|
|
/// │ 13 CONSTANT(42) │ → │ 12 [ 42 ] │
|
|
/// │ 14 ... │ │ .. .... │
|
|
/// └────────────────────────────┘ └─────────────────────────┘
|
|
/// ```
|
|
fn compile_select_or(
|
|
&mut self,
|
|
slot: LocalIdx,
|
|
set: ast::Expr,
|
|
path: ast::Attrpath,
|
|
default: ast::Expr,
|
|
) {
|
|
self.compile(slot, set.clone());
|
|
self.emit_force(&set);
|
|
let mut jumps = vec![];
|
|
|
|
for fragment in path.attrs() {
|
|
self.compile_attr(slot, fragment.clone());
|
|
self.push_op(OpCode::OpAttrsTrySelect, &fragment);
|
|
jumps.push(self.push_op(OpCode::OpJumpIfNotFound(JumpOffset(0)), &fragment));
|
|
}
|
|
|
|
let final_jump = self.push_op(OpCode::OpJump(JumpOffset(0)), &path);
|
|
|
|
for jump in jumps {
|
|
self.patch_jump(jump);
|
|
}
|
|
|
|
// Compile the default value expression and patch the final
|
|
// jump to point *beyond* it.
|
|
self.compile(slot, default);
|
|
self.patch_jump(final_jump);
|
|
}
|
|
|
|
fn compile_assert(&mut self, slot: LocalIdx, node: ast::Assert) {
|
|
// Compile the assertion condition to leave its value on the stack.
|
|
self.compile(slot, node.condition().unwrap());
|
|
self.push_op(OpCode::OpAssert, &node);
|
|
|
|
// The runtime will abort evaluation at this point if the
|
|
// assertion failed, if not the body simply continues on like
|
|
// normal.
|
|
self.compile(slot, node.body().unwrap());
|
|
}
|
|
|
|
/// Compile conditional expressions using jumping instructions in the VM.
|
|
///
|
|
/// ```notrust
|
|
/// ┌────────────────────┐
|
|
/// │ 0 [ conditional ] │
|
|
/// │ 1 JUMP_IF_FALSE →┼─┐
|
|
/// │ 2 [ main body ] │ │ Jump to else body if
|
|
/// ┌┼─3─← JUMP │ │ condition is false.
|
|
/// Jump over else body ││ 4 [ else body ]←┼─┘
|
|
/// if condition is true.└┼─5─→ ... │
|
|
/// └────────────────────┘
|
|
/// ```
|
|
fn compile_if_else(&mut self, slot: LocalIdx, node: ast::IfElse) {
|
|
self.compile(slot, node.condition().unwrap());
|
|
self.emit_force(&node.condition().unwrap());
|
|
|
|
let then_idx = self.push_op(
|
|
OpCode::OpJumpIfFalse(JumpOffset(0)),
|
|
&node.condition().unwrap(),
|
|
);
|
|
|
|
self.push_op(OpCode::OpPop, &node); // discard condition value
|
|
self.compile(slot, node.body().unwrap());
|
|
|
|
let else_idx = self.push_op(OpCode::OpJump(JumpOffset(0)), &node);
|
|
|
|
self.patch_jump(then_idx); // patch jump *to* else_body
|
|
self.push_op(OpCode::OpPop, &node); // discard condition value
|
|
self.compile(slot, node.else_body().unwrap());
|
|
|
|
self.patch_jump(else_idx); // patch jump *over* else body
|
|
}
|
|
|
|
/// Compile an `inherit` node of a `let`-expression.
|
|
fn compile_let_inherit<I: Iterator<Item = ast::Inherit>>(
|
|
&mut self,
|
|
slot: LocalIdx,
|
|
inherits: I,
|
|
) {
|
|
for inherit in inherits {
|
|
match inherit.from() {
|
|
// Within a `let` binding, inheriting from the outer
|
|
// scope is a no-op *if* the identifier can be
|
|
// statically resolved.
|
|
None if !self.scope().has_with() => {
|
|
self.emit_warning(self.span_for(&inherit), WarningKind::UselessInherit);
|
|
continue;
|
|
}
|
|
|
|
None => {
|
|
for ident in inherit.idents() {
|
|
// If the identifier resolves statically, it
|
|
// has precedence over dynamic bindings, and
|
|
// the inherit is useless.
|
|
if matches!(
|
|
self.scope_mut()
|
|
.resolve_local(ident.ident_token().unwrap().text()),
|
|
LocalPosition::Known(_)
|
|
) {
|
|
self.emit_warning(self.span_for(&ident), WarningKind::UselessInherit);
|
|
continue;
|
|
}
|
|
|
|
self.compile_ident(slot, ident.clone());
|
|
let idx = self.declare_local(&ident, ident.ident_token().unwrap().text());
|
|
self.scope_mut().mark_initialised(idx);
|
|
}
|
|
}
|
|
|
|
Some(from) => {
|
|
for ident in inherit.idents() {
|
|
self.compile(slot, from.expr().unwrap());
|
|
self.emit_force(&from.expr().unwrap());
|
|
|
|
self.emit_literal_ident(&ident);
|
|
self.push_op(OpCode::OpAttrsSelect, &ident);
|
|
let idx = self.declare_local(&ident, ident.ident_token().unwrap().text());
|
|
self.scope_mut().mark_initialised(idx);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Compile a standard `let ...; in ...` statement.
|
|
///
|
|
/// Unless in a non-standard scope, the encountered values are
|
|
/// simply pushed on the stack and their indices noted in the
|
|
/// entries vector.
|
|
fn compile_let_in(&mut self, slot: LocalIdx, node: ast::LetIn) {
|
|
self.begin_scope();
|
|
|
|
self.compile_let_inherit(slot, node.inherits());
|
|
|
|
// First pass to ensure that all identifiers are known;
|
|
// required for resolving recursion.
|
|
let mut entries: Vec<(LocalIdx, ast::Expr)> = vec![];
|
|
for entry in node.attrpath_values() {
|
|
let mut path = match self.normalise_ident_path(entry.attrpath().unwrap().attrs()) {
|
|
Ok(p) => p,
|
|
Err(err) => {
|
|
self.errors.push(err);
|
|
continue;
|
|
}
|
|
};
|
|
|
|
if path.len() != 1 {
|
|
todo!("nested bindings in let expressions :(")
|
|
}
|
|
|
|
let idx = self.declare_local(&entry.attrpath().unwrap(), path.pop().unwrap());
|
|
|
|
entries.push((idx, entry.value().unwrap()));
|
|
}
|
|
|
|
// Second pass to place the values in the correct stack slots.
|
|
let mut indices: Vec<LocalIdx> = vec![];
|
|
for (idx, value) in entries.into_iter() {
|
|
indices.push(idx);
|
|
self.compile(idx, value);
|
|
|
|
// Any code after this point will observe the value in the
|
|
// right stack slot, so mark it as initialised.
|
|
self.scope_mut().mark_initialised(idx);
|
|
}
|
|
|
|
// Third pass to emit finaliser instructions if necessary.
|
|
for idx in indices {
|
|
if self.scope()[idx].needs_finaliser {
|
|
let stack_idx = self.scope().stack_index(idx);
|
|
self.push_op(OpCode::OpFinalise(stack_idx), &node);
|
|
}
|
|
}
|
|
|
|
// Deal with the body, then clean up the locals afterwards.
|
|
self.compile(slot, node.body().unwrap());
|
|
self.cleanup_scope(&node);
|
|
}
|
|
|
|
fn compile_ident(&mut self, slot: LocalIdx, node: ast::Ident) {
|
|
let ident = node.ident_token().unwrap();
|
|
|
|
// If the identifier is a global, and it is not poisoned, emit
|
|
// the global directly.
|
|
if let Some(global) = self.globals.get(ident.text()) {
|
|
if !self.scope().is_poisoned(ident.text()) {
|
|
global.clone()(self, node.clone());
|
|
return;
|
|
}
|
|
}
|
|
|
|
match self.scope_mut().resolve_local(ident.text()) {
|
|
LocalPosition::Unknown => {
|
|
// Are we possibly dealing with an upvalue?
|
|
if let Some(idx) =
|
|
self.resolve_upvalue(self.contexts.len() - 1, ident.text(), &node)
|
|
{
|
|
self.push_op(OpCode::OpGetUpvalue(idx), &node);
|
|
return;
|
|
}
|
|
|
|
// If there is a non-empty `with`-stack (or a parent
|
|
// context with one), emit a runtime dynamic
|
|
// resolution instruction.
|
|
if self.has_dynamic_ancestor() {
|
|
self.emit_literal_ident(&node);
|
|
self.push_op(OpCode::OpResolveWith, &node);
|
|
return;
|
|
}
|
|
|
|
// Otherwise, this variable is missing.
|
|
self.emit_error(self.span_for(&node), ErrorKind::UnknownStaticVariable);
|
|
return;
|
|
}
|
|
|
|
LocalPosition::Known(idx) => {
|
|
let stack_idx = self.scope().stack_index(idx);
|
|
self.push_op(OpCode::OpGetLocal(stack_idx), &node);
|
|
}
|
|
|
|
// This identifier is referring to a value from the same
|
|
// scope which is not yet defined. This identifier access
|
|
// must be thunked.
|
|
LocalPosition::Recursive(idx) => self.thunk(slot, &node, move |compiler, node, _| {
|
|
let upvalue_idx = compiler.add_upvalue(
|
|
compiler.contexts.len() - 1,
|
|
node,
|
|
UpvalueKind::Local(idx),
|
|
);
|
|
compiler.push_op(OpCode::OpGetUpvalue(upvalue_idx), node);
|
|
}),
|
|
};
|
|
}
|
|
|
|
/// Compile `with` expressions by emitting instructions that
|
|
/// pop/remove the indices of attribute sets that are implicitly
|
|
/// in scope through `with` on the "with-stack".
|
|
fn compile_with(&mut self, slot: LocalIdx, node: ast::With) {
|
|
self.begin_scope();
|
|
// TODO: Detect if the namespace is just an identifier, and
|
|
// resolve that directly (thus avoiding duplication on the
|
|
// stack).
|
|
self.compile(slot, node.namespace().unwrap());
|
|
|
|
let span = self.span_for(&node.namespace().unwrap());
|
|
|
|
// The attribute set from which `with` inherits values
|
|
// occupies a slot on the stack, but this stack slot is not
|
|
// directly accessible. As it must be accounted for to
|
|
// calculate correct offsets, what we call a "phantom" local
|
|
// is declared here.
|
|
let local_idx = self.scope_mut().declare_phantom(span, true);
|
|
let with_idx = self.scope().stack_index(local_idx);
|
|
|
|
self.scope_mut().push_with();
|
|
|
|
self.push_op(OpCode::OpPushWith(with_idx), &node);
|
|
|
|
self.compile(slot, node.body().unwrap());
|
|
|
|
self.push_op(OpCode::OpPopWith, &node);
|
|
self.scope_mut().pop_with();
|
|
self.cleanup_scope(&node);
|
|
}
|
|
|
|
/// Compiles pattern function arguments, such as `{ a, b }: ...`.
|
|
///
|
|
/// These patterns are treated as a special case of locals binding
|
|
/// where the attribute set itself is placed on the first stack
|
|
/// slot of the call frame (either as a phantom, or named in case
|
|
/// of an `@` binding), and the function call sets up the rest of
|
|
/// the stack as if the parameters were rewritten into a `let`
|
|
/// binding.
|
|
///
|
|
/// For example:
|
|
///
|
|
/// ```nix
|
|
/// ({ a, b ? 2, c ? a * b, ... }@args: <body>) { a = 10; }
|
|
/// ```
|
|
///
|
|
/// would be compiled similarly to a binding such as
|
|
///
|
|
/// ```nix
|
|
/// let args = { a = 10; };
|
|
/// in let a = args.a;
|
|
/// b = args.a or 2;
|
|
/// c = args.c or a * b;
|
|
/// in <body>
|
|
/// ```
|
|
///
|
|
/// The only tricky bit being that bindings have to fail if too
|
|
/// many arguments are provided. This is done by emitting a
|
|
/// special instruction that checks the set of keys from a
|
|
/// constant containing the expected keys.
|
|
fn compile_param_pattern(&mut self, pattern: ast::Pattern) {
|
|
let span = self.span_for(&pattern);
|
|
let set_idx = match pattern.pat_bind() {
|
|
Some(name) => self.declare_local(&name, name.ident().unwrap().to_string()),
|
|
None => self.scope_mut().declare_phantom(span, true),
|
|
};
|
|
|
|
// At call time, the attribute set is already at the top of
|
|
// the stack.
|
|
self.scope_mut().mark_initialised(set_idx);
|
|
self.emit_force(&pattern);
|
|
|
|
// Similar to `let ... in ...`, we now do multiple passes over
|
|
// the bindings to first declare them, then populate them, and
|
|
// then finalise any necessary recursion into the scope.
|
|
let mut entries: Vec<(LocalIdx, ast::PatEntry)> = vec![];
|
|
let mut indices: Vec<LocalIdx> = vec![];
|
|
|
|
for entry in pattern.pat_entries() {
|
|
let ident = entry.ident().unwrap();
|
|
let idx = self.declare_local(&ident, ident.to_string());
|
|
entries.push((idx, entry));
|
|
indices.push(idx);
|
|
}
|
|
|
|
// For each of the bindings, push the set on the stack and
|
|
// attempt to select from it.
|
|
let stack_idx = self.scope().stack_index(set_idx);
|
|
for (idx, entry) in entries.into_iter() {
|
|
self.push_op(OpCode::OpGetLocal(stack_idx), &pattern);
|
|
self.emit_literal_ident(&entry.ident().unwrap());
|
|
|
|
// Use the same mechanism as `compile_select_or` if a
|
|
// default value was provided, or simply select otherwise.
|
|
if let Some(default_expr) = entry.default() {
|
|
self.push_op(OpCode::OpAttrsTrySelect, &entry.ident().unwrap());
|
|
|
|
let jump_to_default =
|
|
self.push_op(OpCode::OpJumpIfNotFound(JumpOffset(0)), &default_expr);
|
|
|
|
let jump_over_default = self.push_op(OpCode::OpJump(JumpOffset(0)), &default_expr);
|
|
|
|
self.patch_jump(jump_to_default);
|
|
self.compile(idx, default_expr);
|
|
self.patch_jump(jump_over_default);
|
|
} else {
|
|
self.push_op(OpCode::OpAttrsSelect, &entry.ident().unwrap());
|
|
}
|
|
|
|
self.scope_mut().mark_initialised(idx);
|
|
}
|
|
|
|
for idx in indices {
|
|
if self.scope()[idx].needs_finaliser {
|
|
let stack_idx = self.scope().stack_index(idx);
|
|
self.push_op(OpCode::OpFinalise(stack_idx), &pattern);
|
|
}
|
|
}
|
|
|
|
// TODO: strictly check if all keys have been consumed if
|
|
// there is no ellipsis.
|
|
if pattern.ellipsis_token().is_none() {
|
|
self.emit_warning(span, WarningKind::NotImplemented("closed formals"));
|
|
}
|
|
}
|
|
|
|
fn compile_lambda(&mut self, outer_slot: LocalIdx, node: ast::Lambda) {
|
|
self.new_context();
|
|
let span = self.span_for(&node);
|
|
let slot = self.scope_mut().declare_phantom(span, false);
|
|
self.begin_scope();
|
|
|
|
// Compile the function itself
|
|
match node.param().unwrap() {
|
|
ast::Param::Pattern(pat) => self.compile_param_pattern(pat),
|
|
|
|
ast::Param::IdentParam(param) => {
|
|
let name = param
|
|
.ident()
|
|
.unwrap()
|
|
.ident_token()
|
|
.unwrap()
|
|
.text()
|
|
.to_string();
|
|
|
|
let idx = self.declare_local(¶m, &name);
|
|
self.scope_mut().mark_initialised(idx);
|
|
}
|
|
}
|
|
|
|
self.compile(slot, node.body().unwrap());
|
|
self.cleanup_scope(&node);
|
|
|
|
// TODO: determine and insert enclosing name, if available.
|
|
|
|
// Pop the lambda context back off, and emit the finished
|
|
// lambda as a constant.
|
|
let mut compiled = self.contexts.pop().unwrap();
|
|
|
|
// Check if tail-call optimisation is possible and perform it.
|
|
optimise_tail_call(&mut compiled.lambda.chunk);
|
|
|
|
// Capturing the with stack counts as an upvalue, as it is
|
|
// emitted as an upvalue data instruction.
|
|
if compiled.captures_with_stack {
|
|
compiled.lambda.upvalue_count += 1;
|
|
}
|
|
|
|
let lambda = Rc::new(compiled.lambda);
|
|
self.observer.observe_compiled_lambda(&lambda);
|
|
|
|
// If the function is not a closure, just emit it directly and
|
|
// move on.
|
|
if lambda.upvalue_count == 0 {
|
|
self.emit_constant(Value::Closure(Closure::new(lambda)), &node);
|
|
return;
|
|
}
|
|
|
|
// If the function is a closure, we need to emit the variable
|
|
// number of operands that allow the runtime to close over the
|
|
// upvalues and leave a blueprint in the constant index from
|
|
// which the runtime closure can be constructed.
|
|
let blueprint_idx = self.chunk().push_constant(Value::Blueprint(lambda));
|
|
|
|
self.push_op(OpCode::OpClosure(blueprint_idx), &node);
|
|
self.emit_upvalue_data(
|
|
outer_slot,
|
|
&node,
|
|
compiled.scope.upvalues,
|
|
compiled.captures_with_stack,
|
|
);
|
|
}
|
|
|
|
fn compile_apply(&mut self, slot: LocalIdx, node: ast::Apply) {
|
|
// To call a function, we leave its arguments on the stack,
|
|
// followed by the function expression itself, and then emit a
|
|
// call instruction. This way, the stack is perfectly laid out
|
|
// to enter the function call straight away.
|
|
self.compile(slot, node.argument().unwrap());
|
|
self.compile(slot, node.lambda().unwrap());
|
|
self.emit_force(&node.lambda().unwrap());
|
|
self.push_op(OpCode::OpCall, &node);
|
|
}
|
|
|
|
/// Compile an expression into a runtime thunk which should be
|
|
/// lazily evaluated when accessed.
|
|
// TODO: almost the same as Compiler::compile_lambda; unify?
|
|
fn thunk<N, F>(&mut self, outer_slot: LocalIdx, node: &N, content: F)
|
|
where
|
|
N: AstNode + Clone,
|
|
F: FnOnce(&mut Compiler, &N, LocalIdx),
|
|
{
|
|
self.new_context();
|
|
let span = self.span_for(node);
|
|
let slot = self.scope_mut().declare_phantom(span, false);
|
|
self.begin_scope();
|
|
content(self, node, slot);
|
|
self.cleanup_scope(node);
|
|
|
|
let mut thunk = self.contexts.pop().unwrap();
|
|
optimise_tail_call(&mut thunk.lambda.chunk);
|
|
|
|
// Capturing the with stack counts as an upvalue, as it is
|
|
// emitted as an upvalue data instruction.
|
|
if thunk.captures_with_stack {
|
|
thunk.lambda.upvalue_count += 1;
|
|
}
|
|
|
|
let lambda = Rc::new(thunk.lambda);
|
|
self.observer.observe_compiled_thunk(&lambda);
|
|
|
|
// Emit the thunk directly if it does not close over the
|
|
// environment.
|
|
if lambda.upvalue_count == 0 {
|
|
self.emit_constant(Value::Thunk(Thunk::new(lambda)), node);
|
|
return;
|
|
}
|
|
|
|
// Otherwise prepare for runtime construction of the thunk.
|
|
let blueprint_idx = self.chunk().push_constant(Value::Blueprint(lambda));
|
|
|
|
self.push_op(OpCode::OpThunk(blueprint_idx), node);
|
|
self.emit_upvalue_data(
|
|
outer_slot,
|
|
node,
|
|
thunk.scope.upvalues,
|
|
thunk.captures_with_stack,
|
|
);
|
|
}
|
|
|
|
/// Emit the data instructions that the runtime needs to correctly
|
|
/// assemble the upvalues struct.
|
|
fn emit_upvalue_data<T: AstNode>(
|
|
&mut self,
|
|
slot: LocalIdx,
|
|
node: &T,
|
|
upvalues: Vec<Upvalue>,
|
|
capture_with: bool,
|
|
) {
|
|
let this_depth = self.scope()[slot].depth;
|
|
let this_stack_slot = self.scope().stack_index(slot);
|
|
|
|
for upvalue in upvalues {
|
|
match upvalue.kind {
|
|
UpvalueKind::Local(idx) => {
|
|
let target_depth = self.scope()[idx].depth;
|
|
let stack_idx = self.scope().stack_index(idx);
|
|
|
|
// If the upvalue slot is located at the same
|
|
// depth, but *after* the closure, the upvalue
|
|
// resolution must be deferred until the scope is
|
|
// fully initialised and can be finalised.
|
|
if this_depth == target_depth && this_stack_slot < stack_idx {
|
|
self.push_op(OpCode::DataDeferredLocal(stack_idx), &upvalue.node);
|
|
self.scope_mut().mark_needs_finaliser(slot);
|
|
} else {
|
|
self.push_op(OpCode::DataLocalIdx(stack_idx), &upvalue.node);
|
|
}
|
|
}
|
|
|
|
UpvalueKind::Upvalue(idx) => {
|
|
self.push_op(OpCode::DataUpvalueIdx(idx), &upvalue.node);
|
|
}
|
|
};
|
|
}
|
|
|
|
if capture_with {
|
|
// TODO(tazjin): probably better to emit span for the ident that caused this
|
|
self.push_op(OpCode::DataCaptureWith, node);
|
|
}
|
|
}
|
|
|
|
/// Emit the literal string value of an identifier. Required for
|
|
/// several operations related to attribute sets, where
|
|
/// identifiers are used as string keys.
|
|
fn emit_literal_ident(&mut self, ident: &ast::Ident) {
|
|
self.emit_constant(
|
|
Value::String(ident.ident_token().unwrap().text().into()),
|
|
ident,
|
|
);
|
|
}
|
|
|
|
/// Patch the jump instruction at the given index, setting its
|
|
/// jump offset from the placeholder to the current code position.
|
|
///
|
|
/// This is required because the actual target offset of jumps is
|
|
/// not known at the time when the jump operation itself is
|
|
/// emitted.
|
|
fn patch_jump(&mut self, idx: CodeIdx) {
|
|
let offset = JumpOffset(self.chunk().code.len() - 1 - idx.0);
|
|
|
|
match &mut self.chunk().code[idx.0] {
|
|
OpCode::OpJump(n)
|
|
| OpCode::OpJumpIfFalse(n)
|
|
| OpCode::OpJumpIfTrue(n)
|
|
| OpCode::OpJumpIfNotFound(n) => {
|
|
*n = offset;
|
|
}
|
|
|
|
op => panic!("attempted to patch unsupported op: {:?}", op),
|
|
}
|
|
}
|
|
|
|
/// Increase the scope depth of the current function (e.g. within
|
|
/// a new bindings block, or `with`-scope).
|
|
fn begin_scope(&mut self) {
|
|
self.scope_mut().scope_depth += 1;
|
|
}
|
|
|
|
/// Decrease scope depth of the current function and emit
|
|
/// instructions to clean up the stack at runtime.
|
|
fn cleanup_scope<N: AstNode>(&mut self, node: &N) {
|
|
// When ending a scope, all corresponding locals need to be
|
|
// removed, but the value of the body needs to remain on the
|
|
// stack. This is implemented by a separate instruction.
|
|
let (popcount, unused_spans) = self.scope_mut().end_scope();
|
|
|
|
for span in unused_spans {
|
|
self.emit_warning(span, WarningKind::UnusedBinding);
|
|
}
|
|
|
|
if popcount > 0 {
|
|
self.push_op(OpCode::OpCloseScope(Count(popcount)), node);
|
|
}
|
|
|
|
self.scope_mut().scope_depth -= 1;
|
|
}
|
|
|
|
/// Open a new lambda context within which to compile a function,
|
|
/// closure or thunk.
|
|
fn new_context(&mut self) {
|
|
// This must inherit the scope-poisoning status of the parent
|
|
// in order for upvalue resolution to work correctly with
|
|
// poisoned identifiers.
|
|
self.contexts.push(self.context().inherit());
|
|
}
|
|
|
|
/// Declare a local variable known in the scope that is being
|
|
/// compiled by pushing it to the locals. This is used to
|
|
/// determine the stack offset of variables.
|
|
fn declare_local<S: Into<String>, N: AstNode>(&mut self, node: &N, name: S) -> LocalIdx {
|
|
let name = name.into();
|
|
let depth = self.scope().scope_depth;
|
|
|
|
// Do this little dance to get ahold of the *static* key and
|
|
// use it for poisoning if required.
|
|
let key: Option<&'static str> = match self.globals.get_key_value(name.as_str()) {
|
|
Some((key, _)) => Some(*key),
|
|
None => None,
|
|
};
|
|
|
|
if let Some(global_ident) = key {
|
|
self.emit_warning(
|
|
self.span_for(node),
|
|
WarningKind::ShadowedGlobal(global_ident),
|
|
);
|
|
self.scope_mut().poison(global_ident, depth);
|
|
}
|
|
|
|
let mut shadowed = false;
|
|
for other in self.scope().locals.iter().rev() {
|
|
if other.has_name(&name) && other.depth == depth {
|
|
shadowed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if shadowed {
|
|
self.emit_error(
|
|
self.span_for(node),
|
|
ErrorKind::VariableAlreadyDefined(name.clone()),
|
|
);
|
|
}
|
|
|
|
let span = self.span_for(node);
|
|
self.scope_mut().declare_local(name, span)
|
|
}
|
|
|
|
fn resolve_upvalue(
|
|
&mut self,
|
|
ctx_idx: usize,
|
|
name: &str,
|
|
node: &rnix::ast::Ident,
|
|
) -> Option<UpvalueIdx> {
|
|
if ctx_idx == 0 {
|
|
// There can not be any upvalue at the outermost context.
|
|
return None;
|
|
}
|
|
|
|
// Determine whether the upvalue is a local in the enclosing context.
|
|
match self.contexts[ctx_idx - 1].scope.resolve_local(name) {
|
|
// recursive upvalues are dealt with the same way as
|
|
// standard known ones, as thunks and closures are
|
|
// guaranteed to be placed on the stack (i.e. in the right
|
|
// position) *during* their runtime construction
|
|
LocalPosition::Known(idx) | LocalPosition::Recursive(idx) => {
|
|
return Some(self.add_upvalue(ctx_idx, node, UpvalueKind::Local(idx)))
|
|
}
|
|
|
|
LocalPosition::Unknown => { /* continue below */ }
|
|
};
|
|
|
|
// If the upvalue comes from even further up, we need to
|
|
// recurse to make sure that the upvalues are created at each
|
|
// level.
|
|
if let Some(idx) = self.resolve_upvalue(ctx_idx - 1, name, node) {
|
|
return Some(self.add_upvalue(ctx_idx, node, UpvalueKind::Upvalue(idx)));
|
|
}
|
|
|
|
None
|
|
}
|
|
|
|
/// Determine whether the current lambda context has any ancestors
|
|
/// that use dynamic scope resolution, and mark contexts as
|
|
/// needing to capture their enclosing `with`-stack in their
|
|
/// upvalues.
|
|
fn has_dynamic_ancestor(&mut self) -> bool {
|
|
let mut ancestor_has_with = false;
|
|
|
|
for ctx in self.contexts.iter_mut() {
|
|
if ancestor_has_with {
|
|
// If the ancestor has an active with stack, mark this
|
|
// lambda context as needing to capture it.
|
|
ctx.captures_with_stack = true;
|
|
} else {
|
|
// otherwise, check this context and move on
|
|
ancestor_has_with = ctx.scope.has_with();
|
|
}
|
|
}
|
|
|
|
ancestor_has_with
|
|
}
|
|
|
|
fn add_upvalue(
|
|
&mut self,
|
|
ctx_idx: usize,
|
|
node: &rnix::ast::Ident,
|
|
kind: UpvalueKind,
|
|
) -> UpvalueIdx {
|
|
// If there is already an upvalue closing over the specified
|
|
// index, retrieve that instead.
|
|
for (idx, existing) in self.contexts[ctx_idx].scope.upvalues.iter().enumerate() {
|
|
if existing.kind == kind {
|
|
return UpvalueIdx(idx);
|
|
}
|
|
}
|
|
|
|
self.contexts[ctx_idx].scope.upvalues.push(Upvalue {
|
|
kind,
|
|
node: node.clone(),
|
|
});
|
|
|
|
let idx = UpvalueIdx(self.contexts[ctx_idx].lambda.upvalue_count);
|
|
self.contexts[ctx_idx].lambda.upvalue_count += 1;
|
|
idx
|
|
}
|
|
|
|
fn emit_force<N: AstNode>(&mut self, node: &N) {
|
|
self.push_op(OpCode::OpForce, node);
|
|
}
|
|
|
|
fn emit_warning(&mut self, span: codemap::Span, kind: WarningKind) {
|
|
self.warnings.push(EvalWarning { kind, span })
|
|
}
|
|
|
|
fn emit_error(&mut self, span: codemap::Span, kind: ErrorKind) {
|
|
self.errors.push(Error { kind, span })
|
|
}
|
|
|
|
/// Convert a non-dynamic string expression to a string if possible,
|
|
/// or raise an error.
|
|
fn expr_str_to_string(&self, expr: ast::Str) -> EvalResult<String> {
|
|
if expr.normalized_parts().len() == 1 {
|
|
if let ast::InterpolPart::Literal(s) = expr.normalized_parts().pop().unwrap() {
|
|
return Ok(s);
|
|
}
|
|
}
|
|
|
|
return Err(Error {
|
|
kind: ErrorKind::DynamicKeyInLet(expr.syntax().clone()),
|
|
span: self.span_for(&expr),
|
|
});
|
|
}
|
|
|
|
/// Convert a single identifier path fragment to a string if possible,
|
|
/// or raise an error about the node being dynamic.
|
|
fn attr_to_string(&self, node: ast::Attr) -> EvalResult<String> {
|
|
match node {
|
|
ast::Attr::Ident(ident) => Ok(ident.ident_token().unwrap().text().into()),
|
|
ast::Attr::Str(s) => self.expr_str_to_string(s),
|
|
|
|
// The dynamic node type is just a wrapper. C++ Nix does not
|
|
// care about the dynamic wrapper when determining whether the
|
|
// node itself is dynamic, it depends solely on the expression
|
|
// inside (i.e. `let ${"a"} = 1; in a` is valid).
|
|
ast::Attr::Dynamic(ref dynamic) => match dynamic.expr().unwrap() {
|
|
ast::Expr::Str(s) => self.expr_str_to_string(s),
|
|
_ => Err(Error {
|
|
kind: ErrorKind::DynamicKeyInLet(node.syntax().clone()),
|
|
span: self.span_for(&node),
|
|
}),
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Normalises identifier fragments into a single string vector
|
|
/// for `let`-expressions; fails if fragments requiring dynamic
|
|
/// computation are encountered.
|
|
fn normalise_ident_path<I: Iterator<Item = ast::Attr>>(
|
|
&self,
|
|
path: I,
|
|
) -> EvalResult<Vec<String>> {
|
|
path.map(|node| self.attr_to_string(node)).collect()
|
|
}
|
|
}
|
|
|
|
/// Perform tail-call optimisation if the last call within a
|
|
/// compiled chunk is another call.
|
|
fn optimise_tail_call(chunk: &mut Chunk) {
|
|
let last_op = chunk
|
|
.code
|
|
.last_mut()
|
|
.expect("compiler bug: chunk should never be empty");
|
|
|
|
if matches!(last_op, OpCode::OpCall) {
|
|
*last_op = OpCode::OpTailCall;
|
|
}
|
|
}
|
|
|
|
/// Prepare the full set of globals from additional globals supplied
|
|
/// by the caller of the compiler, as well as the built-in globals
|
|
/// that are always part of the language.
|
|
///
|
|
/// Note that all builtin functions are *not* considered part of the
|
|
/// language in this sense and MUST be supplied as additional global
|
|
/// values, including the `builtins` set itself.
|
|
fn prepare_globals(additional: HashMap<&'static str, Value>) -> GlobalsMap {
|
|
let mut globals: GlobalsMap = HashMap::new();
|
|
|
|
globals.insert(
|
|
"true",
|
|
Rc::new(|compiler, node| {
|
|
compiler.push_op(OpCode::OpTrue, &node);
|
|
}),
|
|
);
|
|
|
|
globals.insert(
|
|
"false",
|
|
Rc::new(|compiler, node| {
|
|
compiler.push_op(OpCode::OpFalse, &node);
|
|
}),
|
|
);
|
|
|
|
globals.insert(
|
|
"null",
|
|
Rc::new(|compiler, node| {
|
|
compiler.push_op(OpCode::OpNull, &node);
|
|
}),
|
|
);
|
|
|
|
for (ident, value) in additional.into_iter() {
|
|
globals.insert(
|
|
ident,
|
|
Rc::new(move |compiler, node| compiler.emit_constant(value.clone(), &node)),
|
|
);
|
|
}
|
|
|
|
globals
|
|
}
|
|
|
|
pub fn compile(
|
|
expr: ast::Expr,
|
|
location: Option<PathBuf>,
|
|
file: &codemap::File,
|
|
globals: HashMap<&'static str, Value>,
|
|
observer: &mut dyn Observer,
|
|
) -> EvalResult<CompilationOutput> {
|
|
let mut root_dir = match location {
|
|
Some(dir) => Ok(dir),
|
|
None => std::env::current_dir().map_err(|e| Error {
|
|
kind: ErrorKind::PathResolution(format!(
|
|
"could not determine current directory: {}",
|
|
e
|
|
)),
|
|
span: file.span,
|
|
}),
|
|
}?;
|
|
|
|
// If the path passed from the caller points to a file, the
|
|
// filename itself needs to be truncated as this must point to a
|
|
// directory.
|
|
if root_dir.is_file() {
|
|
root_dir.pop();
|
|
}
|
|
|
|
let mut c = Compiler {
|
|
root_dir,
|
|
file,
|
|
observer,
|
|
globals: prepare_globals(globals),
|
|
contexts: vec![LambdaCtx::new()],
|
|
warnings: vec![],
|
|
errors: vec![],
|
|
};
|
|
|
|
let root_span = c.span_for(&expr);
|
|
let root_slot = c.scope_mut().declare_phantom(root_span, false);
|
|
c.compile(root_slot, expr.clone());
|
|
|
|
// The final operation of any top-level Nix program must always be
|
|
// `OpForce`. A thunk should not be returned to the user in an
|
|
// unevaluated state (though in practice, a value *containing* a
|
|
// thunk might be returned).
|
|
c.emit_force(&expr);
|
|
|
|
let lambda = Rc::new(c.contexts.pop().unwrap().lambda);
|
|
c.observer.observe_compiled_toplevel(&lambda);
|
|
|
|
Ok(CompilationOutput {
|
|
lambda,
|
|
warnings: c.warnings,
|
|
errors: c.errors,
|
|
})
|
|
}
|