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Recursive self-contained AST.

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This commit is contained in:
Stephen Chung 2021-01-09 16:52:22 +08:00
parent 637f47d259
commit ad250fc973
7 changed files with 190 additions and 74 deletions
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1
RELEASES.md
View File

@ -16,6 +16,7 @@ New features
------------
* `Engine::compile_to_self_contained` compiles a script into an `AST` and _eagerly_ resolves all `import` statements with string literal paths. The resolved modules are directly embedded into the `AST`. When the `AST` is later evaluated, `import` statements directly yield the pre-resolved modules without going through the resolution process once again.
* `AST::walk`, `Stmt::walk` and `Expr::walk` internal API's to recursively walk an `AST`.
Enhancements
------------

135
src/ast.rs
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@ -682,6 +682,47 @@ impl AST {
pub fn clear_statements(&mut self) {
self.statements = vec![];
}
/// Recursively walk the [`AST`], including function bodies (if any).
#[cfg(not(feature = "internals"))]
#[inline(always)]
pub(crate) fn walk(&self, on_node: &mut impl FnMut(&[ASTNode])) {
let mut path = Default::default();
self.statements()
.iter()
.chain({
#[cfg(not(feature = "no_function"))]
{
self.iter_fn_def().map(|f| &f.body)
}
#[cfg(feature = "no_function")]
{
crate::stdlib::iter::empty()
}
})
.for_each(|stmt| stmt.walk(&mut path, on_node));
}
/// _(INTERNALS)_ Recursively walk the [`AST`], including function bodies (if any).
/// Exported under the `internals` feature only.
#[cfg(feature = "internals")]
#[inline(always)]
pub fn walk(&self, on_node: &mut impl FnMut(&[ASTNode])) {
let mut path = Default::default();
self.statements()
.iter()
.chain({
#[cfg(not(feature = "no_function"))]
{
self.iter_fn_def().map(|f| &f.body)
}
#[cfg(feature = "no_function")]
{
crate::stdlib::iter::empty()
}
})
.for_each(|stmt| stmt.walk(&mut path, on_node));
}
}
impl<A: AsRef<AST>> Add<A> for &AST {
@ -749,6 +790,30 @@ pub enum ReturnType {
Exception,
}
/// _(INTERNALS)_ An [`AST`] node, consisting of either an [`Expr`] or a [`Stmt`].
/// Exported under the `internals` feature only.
///
/// # WARNING
///
/// This type is volatile and may change.
#[derive(Debug, Clone, Hash)]
pub enum ASTNode<'a> {
Stmt(&'a Stmt),
Expr(&'a Expr),
}
impl<'a> From<&'a Stmt> for ASTNode<'a> {
fn from(stmt: &'a Stmt) -> Self {
Self::Stmt(stmt)
}
}
impl<'a> From<&'a Expr> for ASTNode<'a> {
fn from(expr: &'a Expr) -> Self {
Self::Expr(expr)
}
}
/// _(INTERNALS)_ A statement.
/// Exported under the `internals` feature only.
///
@ -949,50 +1014,50 @@ impl Stmt {
}
/// Recursively walk this statement.
#[inline(always)]
pub fn walk(&self, process_stmt: &mut impl FnMut(&Stmt), process_expr: &mut impl FnMut(&Expr)) {
process_stmt(self);
pub fn walk<'a>(&'a self, path: &mut Vec<ASTNode<'a>>, on_node: &mut impl FnMut(&[ASTNode])) {
path.push(self.into());
on_node(path);
match self {
Self::Let(_, Some(e), _, _) | Self::Const(_, Some(e), _, _) => {
e.walk(process_stmt, process_expr)
}
Self::Let(_, Some(e), _, _) | Self::Const(_, Some(e), _, _) => e.walk(path, on_node),
Self::If(e, x, _) => {
e.walk(process_stmt, process_expr);
x.0.walk(process_stmt, process_expr);
e.walk(path, on_node);
x.0.walk(path, on_node);
if let Some(ref s) = x.1 {
s.walk(process_stmt, process_expr);
s.walk(path, on_node);
}
}
Self::Switch(e, x, _) => {
e.walk(process_stmt, process_expr);
x.0.values()
.for_each(|s| s.walk(process_stmt, process_expr));
e.walk(path, on_node);
x.0.values().for_each(|s| s.walk(path, on_node));
if let Some(ref s) = x.1 {
s.walk(process_stmt, process_expr);
s.walk(path, on_node);
}
}
Self::While(e, s, _) | Self::Do(s, e, _, _) => {
e.walk(process_stmt, process_expr);
s.walk(process_stmt, process_expr);
e.walk(path, on_node);
s.walk(path, on_node);
}
Self::For(e, x, _) => {
e.walk(process_stmt, process_expr);
x.1.walk(process_stmt, process_expr);
e.walk(path, on_node);
x.1.walk(path, on_node);
}
Self::Assignment(x, _) => {
x.0.walk(process_stmt, process_expr);
x.2.walk(process_stmt, process_expr);
x.0.walk(path, on_node);
x.2.walk(path, on_node);
}
Self::Block(x, _) => x.iter().for_each(|s| s.walk(process_stmt, process_expr)),
Self::Block(x, _) => x.iter().for_each(|s| s.walk(path, on_node)),
Self::TryCatch(x, _, _) => {
x.0.walk(process_stmt, process_expr);
x.2.walk(process_stmt, process_expr);
x.0.walk(path, on_node);
x.2.walk(path, on_node);
}
Self::Expr(e) | Self::Return(_, Some(e), _) => e.walk(process_stmt, process_expr),
Self::Expr(e) | Self::Return(_, Some(e), _) => e.walk(path, on_node),
#[cfg(not(feature = "no_module"))]
Self::Import(e, _, _) => e.walk(process_stmt, process_expr),
Self::Import(e, _, _) => e.walk(path, on_node),
_ => (),
}
path.pop().unwrap();
}
}
@ -1416,25 +1481,23 @@ impl Expr {
}
/// Recursively walk this expression.
#[inline(always)]
pub fn walk(&self, process_stmt: &mut impl FnMut(&Stmt), process_expr: &mut impl FnMut(&Expr)) {
process_expr(self);
pub fn walk<'a>(&'a self, path: &mut Vec<ASTNode<'a>>, on_node: &mut impl FnMut(&[ASTNode])) {
path.push(self.into());
on_node(path);
match self {
Self::Stmt(x, _) => x.iter().for_each(|s| s.walk(process_stmt, process_expr)),
Self::Array(x, _) => x.iter().for_each(|e| e.walk(process_stmt, process_expr)),
Self::Map(x, _) => x
.iter()
.for_each(|(_, e)| e.walk(process_stmt, process_expr)),
Self::Stmt(x, _) => x.iter().for_each(|s| s.walk(path, on_node)),
Self::Array(x, _) => x.iter().for_each(|e| e.walk(path, on_node)),
Self::Map(x, _) => x.iter().for_each(|(_, e)| e.walk(path, on_node)),
Self::Index(x, _) | Expr::In(x, _) | Expr::And(x, _) | Expr::Or(x, _) => {
x.lhs.walk(process_stmt, process_expr);
x.rhs.walk(process_stmt, process_expr);
x.lhs.walk(path, on_node);
x.rhs.walk(path, on_node);
}
Self::Custom(x, _) => x
.keywords
.iter()
.for_each(|e| e.walk(process_stmt, process_expr)),
Self::Custom(x, _) => x.keywords.iter().for_each(|e| e.walk(path, on_node)),
_ => (),
}
path.pop().unwrap();
}
}

66
src/engine_api.rs
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@ -903,47 +903,53 @@ impl Engine {
script: &str,
) -> Result<AST, Box<EvalAltResult>> {
use crate::{
ast::{Expr, Stmt},
ast::{ASTNode, Expr, Stmt},
fn_native::shared_take_or_clone,
module::resolvers::StaticModuleResolver,
stdlib::collections::HashMap,
stdlib::collections::HashSet,
ImmutableString,
};
let mut ast = self.compile_scripts_with_scope(scope, &[script])?;
let mut imports = HashMap::<ImmutableString, Position>::new();
ast.statements()
.iter()
.chain({
#[cfg(not(feature = "no_function"))]
fn collect_imports(
ast: &AST,
resolver: &StaticModuleResolver,
imports: &mut HashSet<ImmutableString>,
) {
ast.walk(&mut |path| match path.last().unwrap() {
// Collect all `import` statements with a string constant path
ASTNode::Stmt(Stmt::Import(Expr::StringConstant(s, _), _, _))
if !resolver.contains_path(s) && !imports.contains(s) =>
{
ast.iter_fn_def().map(|f| &f.body)
}
#[cfg(feature = "no_function")]
{
crate::stdlib::iter::empty()
}
})
.for_each(|stmt| {
stmt.walk(
&mut |stmt| match stmt {
Stmt::Import(Expr::StringConstant(s, pos), _, _)
if !imports.contains_key(s) =>
{
imports.insert(s.clone(), *pos);
imports.insert(s.clone());
}
_ => (),
},
&mut |_| {},
)
});
}
let mut resolver = StaticModuleResolver::new();
let mut ast = self.compile_scripts_with_scope(scope, &[script])?;
let mut imports = HashSet::<ImmutableString>::new();
collect_imports(&ast, &mut resolver, &mut imports);
if !imports.is_empty() {
let mut resolver = StaticModuleResolver::new();
for (path, pos) in imports {
let module = self.module_resolver.resolve(self, &path, pos)?;
let module = shared_take_or_clone(module);
while let Some(path) = imports.iter().next() {
let path = path.clone();
if let Some(module_ast) =
self.module_resolver
.resolve_ast(self, &path, Position::NONE)?
{
collect_imports(&module_ast, &mut resolver, &mut imports);
}
let module = shared_take_or_clone(self.module_resolver.resolve(
self,
&path,
Position::NONE,
)?);
imports.remove(&path);
resolver.insert(path, module);
}
ast.set_resolver(resolver);

3
src/lib.rs
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@ -184,7 +184,8 @@ pub use token::{get_next_token, parse_string_literal, InputStream, Token, Tokeni
#[cfg(feature = "internals")]
#[deprecated = "this type is volatile and may change"]
pub use ast::{
BinaryExpr, CustomExpr, Expr, FloatWrapper, FnCallExpr, Ident, ReturnType, ScriptFnDef, Stmt,
ASTNode, BinaryExpr, CustomExpr, Expr, FloatWrapper, FnCallExpr, Ident, ReturnType,
ScriptFnDef, Stmt,
};
#[cfg(feature = "internals")]

26
src/module/resolvers/file.rs
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@ -227,4 +227,30 @@ impl ModuleResolver for FileModuleResolver {
Ok(m)
}
fn resolve_ast(
&self,
engine: &Engine,
path: &str,
pos: Position,
) -> Result<Option<crate::AST>, Box<EvalAltResult>> {
// Construct the script file path
let mut file_path = self.base_path.clone();
file_path.push(path);
file_path.set_extension(&self.extension); // Force extension
// Load the script file and compile it
let mut ast = engine
.compile_file(file_path.clone())
.map_err(|err| match *err {
EvalAltResult::ErrorSystem(_, err) if err.is::<IoError>() => {
Box::new(EvalAltResult::ErrorModuleNotFound(path.to_string(), pos))
}
_ => Box::new(EvalAltResult::ErrorInModule(path.to_string(), err, pos)),
})?;
ast.set_source(path);
Ok(Some(ast))
}
}

21
src/module/resolvers/mod.rs
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@ -1,6 +1,6 @@
use crate::fn_native::SendSync;
use crate::stdlib::boxed::Box;
use crate::{Engine, EvalAltResult, Module, Position, Shared};
use crate::{Engine, EvalAltResult, Module, Position, Shared, AST};
mod dummy;
pub use dummy::DummyModuleResolver;
@ -28,4 +28,23 @@ pub trait ModuleResolver: SendSync {
path: &str,
pos: Position,
) -> Result<Shared<Module>, Box<EvalAltResult>>;
/// Resolve a module into an `AST` based on a path string.
///
/// Returns [`None`] (default) if such resolution is not supported
/// (e.g. if the module is Rust-based).
///
/// ## Low-Level API
///
/// Override the default implementation of this method if the module resolver
/// serves modules based on compiled Rhai scripts.
#[allow(unused_variables)]
fn resolve_ast(
&self,
engine: &Engine,
path: &str,
pos: Position,
) -> Result<Option<AST>, Box<EvalAltResult>> {
Ok(None)
}
}