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Add AST optimizer.

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This commit is contained in:
Stephen Chung 2020-03-09 21:57:07 +08:00
parent c467ffd58d
commit 55e7af7b04
5 changed files with 349 additions and 88 deletions
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35
src/api.rs
View File

@ -95,13 +95,13 @@ impl<'e> Engine<'e> {
}
/// Compile a string into an AST
pub fn compile(input: &str) -> Result<AST, ParseError> {
pub fn compile(&self, input: &str) -> Result<AST, ParseError> {
let tokens = lex(input);
parse(&mut tokens.peekable())
parse(&mut tokens.peekable(), self.optimize)
}
/// Compile a file into an AST
pub fn compile_file(filename: &str) -> Result<AST, EvalAltResult> {
pub fn compile_file(&self, filename: &str) -> Result<AST, EvalAltResult> {
use std::fs::File;
use std::io::prelude::*;
@ -112,7 +112,7 @@ impl<'e> Engine<'e> {
f.read_to_string(&mut contents)
.map_err(|err| EvalAltResult::ErrorReadingScriptFile(filename.into(), err))
.and_then(|_| Self::compile(&contents).map_err(EvalAltResult::ErrorParsing))
.and_then(|_| self.compile(&contents).map_err(EvalAltResult::ErrorParsing))
}
/// Evaluate a file
@ -142,7 +142,7 @@ impl<'e> Engine<'e> {
scope: &mut Scope,
input: &str,
) -> Result<T, EvalAltResult> {
let ast = Self::compile(input).map_err(EvalAltResult::ErrorParsing)?;
let ast = self.compile(input).map_err(EvalAltResult::ErrorParsing)?;
self.eval_ast_with_scope(scope, &ast)
}
@ -229,7 +229,7 @@ impl<'e> Engine<'e> {
) -> Result<(), EvalAltResult> {
let tokens = lex(input);
parse(&mut tokens.peekable())
parse(&mut tokens.peekable(), self.optimize)
.map_err(|err| EvalAltResult::ErrorParsing(err))
.and_then(|AST(ref statements, ref functions)| {
for f in functions {
@ -258,11 +258,12 @@ impl<'e> Engine<'e> {
/// # Example
///
/// ```rust
/// # use rhai::{Engine, EvalAltResult};
/// # fn main() -> Result<(), EvalAltResult> {
/// # fn main() -> Result<(), rhai::EvalAltResult> {
/// use rhai::Engine;
///
/// let mut engine = Engine::new();
///
/// let ast = Engine::compile("fn add(x, y) { x.len() + y }")?;
/// let ast = engine.compile("fn add(x, y) { x.len() + y }")?;
///
/// let result: i64 = engine.call_fn("add", &ast, (&mut String::from("abc"), &mut 123_i64))?;
///
@ -309,16 +310,20 @@ impl<'e> Engine<'e> {
/// # Example
///
/// ```rust
/// # use rhai::Engine;
/// # fn main() -> Result<(), rhai::EvalAltResult> {
/// use rhai::Engine;
///
/// let mut result = String::from("");
/// {
/// let mut engine = Engine::new();
///
/// // Override action of 'print' function
/// engine.on_print(|s| result.push_str(s));
/// engine.consume("print(40 + 2);").unwrap();
/// engine.consume("print(40 + 2);")?;
/// }
/// assert_eq!(result, "42");
/// # Ok(())
/// # }
/// ```
pub fn on_print(&mut self, callback: impl FnMut(&str) + 'e) {
self.on_print = Box::new(callback);
@ -329,16 +334,20 @@ impl<'e> Engine<'e> {
/// # Example
///
/// ```rust
/// # use rhai::Engine;
/// # fn main() -> Result<(), rhai::EvalAltResult> {
/// use rhai::Engine;
///
/// let mut result = String::from("");
/// {
/// let mut engine = Engine::new();
///
/// // Override action of 'debug' function
/// engine.on_debug(|s| result.push_str(s));
/// engine.consume(r#"debug("hello");"#).unwrap();
/// engine.consume(r#"debug("hello");"#)?;
/// }
/// assert_eq!(result, "\"hello\"");
/// # Ok(())
/// # }
/// ```
pub fn on_debug(&mut self, callback: impl FnMut(&str) + 'e) {
self.on_debug = Box::new(callback);

104
src/engine.rs
View File

@ -4,7 +4,7 @@ use crate::any::{Any, AnyExt, Dynamic, Variant};
use crate::parser::{Expr, FnDef, Position, Stmt};
use crate::result::EvalAltResult;
use crate::scope::Scope;
use std::any::TypeId;
use std::any::{type_name, TypeId};
use std::borrow::Cow;
use std::cmp::{PartialEq, PartialOrd};
use std::collections::HashMap;
@ -20,11 +20,11 @@ pub type FnAny = dyn Fn(FnCallArgs, Position) -> Result<Dynamic, EvalAltResult>;
type IteratorFn = dyn Fn(&Dynamic) -> Box<dyn Iterator<Item = Dynamic>>;
const KEYWORD_PRINT: &'static str = "print";
const KEYWORD_DEBUG: &'static str = "debug";
const KEYWORD_TYPE_OF: &'static str = "type_of";
const FUNC_GETTER: &'static str = "get$";
const FUNC_SETTER: &'static str = "set$";
pub(crate) const KEYWORD_PRINT: &'static str = "print";
pub(crate) const KEYWORD_DEBUG: &'static str = "debug";
pub(crate) const KEYWORD_TYPE_OF: &'static str = "type_of";
pub(crate) const FUNC_GETTER: &'static str = "get$";
pub(crate) const FUNC_SETTER: &'static str = "set$";
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq, PartialOrd, Ord)]
enum IndexSourceType {
@ -42,17 +42,20 @@ pub struct FnSpec<'a> {
/// Rhai main scripting engine.
///
/// ```rust
/// # fn main() -> Result<(), rhai::EvalAltResult> {
/// use rhai::Engine;
///
/// fn main() {
/// let mut engine = Engine::new();
/// let mut engine = Engine::new();
///
/// if let Ok(result) = engine.eval::<i64>("40 + 2") {
/// println!("Answer: {}", result); // prints 42
/// }
/// }
/// let result = engine.eval::<i64>("40 + 2")?;
///
/// println!("Answer: {}", result); // prints 42
/// # Ok(())
/// # }
/// ```
pub struct Engine<'e> {
/// Optimize the AST after compilation
pub(crate) optimize: bool,
/// A hashmap containing all compiled functions known to the engine
pub(crate) ext_functions: HashMap<FnSpec<'e>, Arc<FnIntExt<'e>>>,
/// A hashmap containing all script-defined functions
@ -72,6 +75,42 @@ pub enum FnIntExt<'a> {
}
impl Engine<'_> {
/// Create a new `Engine`
pub fn new() -> Self {
// User-friendly names for built-in types
let type_names = [
(type_name::<String>(), "string"),
(type_name::<Array>(), "array"),
(type_name::<Dynamic>(), "dynamic"),
]
.iter()
.map(|(k, v)| (k.to_string(), v.to_string()))
.collect();
// Create the new scripting Engine
let mut engine = Engine {
optimize: true,
ext_functions: HashMap::new(),
script_functions: HashMap::new(),
type_iterators: HashMap::new(),
type_names,
on_print: Box::new(default_print), // default print/debug implementations
on_debug: Box::new(default_print),
};
engine.register_core_lib();
#[cfg(not(feature = "no_stdlib"))]
engine.register_stdlib(); // Register the standard library when no_stdlib is not set
engine
}
/// Control whether the `Engine` will optimize an AST after compilation
pub fn set_optimization(&mut self, optimize: bool) {
self.optimize = optimize
}
/// Universal method for calling functions, that are either
/// registered with the `Engine` or written in Rhai
pub(crate) fn call_fn_raw(
@ -151,7 +190,7 @@ impl Engine<'_> {
);
// Evaluate
match self.eval_stmt(&mut scope, &*func.body) {
match self.eval_stmt(&mut scope, &func.body) {
// Convert return statement to return value
Err(EvalAltResult::Return(x, _)) => Ok(x),
other => other,
@ -726,7 +765,7 @@ impl Engine<'_> {
.map(|(_, _, _, x)| x),
// Statement block
Expr::Block(block, _) => self.eval_stmt(scope, block),
Expr::Stmt(stmt, _) => self.eval_stmt(scope, stmt),
// lhs = rhs
Expr::Assignment(lhs, rhs, _) => {
@ -850,11 +889,14 @@ impl Engine<'_> {
stmt: &Stmt,
) -> Result<Dynamic, EvalAltResult> {
match stmt {
// No-op
Stmt::Noop(_) => Ok(().into_dynamic()),
// Expression as statement
Stmt::Expr(expr) => self.eval_expr(scope, expr),
// Block scope
Stmt::Block(block) => {
Stmt::Block(block, _) => {
let prev_len = scope.len();
let mut last_result: Result<Dynamic, EvalAltResult> = Ok(().into_dynamic());
@ -988,38 +1030,6 @@ impl Engine<'_> {
.map(|s| s.as_str())
.unwrap_or(name)
}
/// Make a new engine
pub fn new<'a>() -> Engine<'a> {
use std::any::type_name;
// User-friendly names for built-in types
let type_names = [
(type_name::<String>(), "string"),
(type_name::<Array>(), "array"),
(type_name::<Dynamic>(), "dynamic"),
]
.iter()
.map(|(k, v)| (k.to_string(), v.to_string()))
.collect();
// Create the new scripting Engine
let mut engine = Engine {
ext_functions: HashMap::new(),
script_functions: HashMap::new(),
type_iterators: HashMap::new(),
type_names,
on_print: Box::new(default_print), // default print/debug implementations
on_debug: Box::new(default_print),
};
engine.register_core_lib();
#[cfg(not(feature = "no_stdlib"))]
engine.register_stdlib(); // Register the standard library when no_stdlib is not set
engine
}
}
/// Print/debug to stdout

2
src/lib.rs
View File

@ -68,7 +68,7 @@ mod call;
mod engine;
mod error;
mod fn_register;
//mod optimize;
mod optimize;
mod parser;
mod result;
mod scope;

212
src/optimize.rs Normal file
View File

@ -0,0 +1,212 @@
use crate::parser::{Expr, Stmt};
fn optimize_stmt(stmt: Stmt, changed: &mut bool) -> Stmt {
match stmt {
Stmt::IfElse(expr, stmt1, None) => match *expr {
Expr::False(pos) => {
*changed = true;
Stmt::Noop(pos)
}
Expr::True(_) => optimize_stmt(*stmt1, changed),
_ => Stmt::IfElse(
Box::new(optimize_expr(*expr, changed)),
Box::new(optimize_stmt(*stmt1, changed)),
None,
),
},
Stmt::IfElse(expr, stmt1, Some(stmt2)) => match *expr {
Expr::False(_) => optimize_stmt(*stmt2, changed),
Expr::True(_) => optimize_stmt(*stmt1, changed),
_ => Stmt::IfElse(
Box::new(optimize_expr(*expr, changed)),
Box::new(optimize_stmt(*stmt1, changed)),
Some(Box::new(optimize_stmt(*stmt2, changed))),
),
},
Stmt::While(expr, stmt) => match *expr {
Expr::False(pos) => {
*changed = true;
Stmt::Noop(pos)
}
Expr::True(_) => Stmt::Loop(Box::new(optimize_stmt(*stmt, changed))),
_ => Stmt::While(
Box::new(optimize_expr(*expr, changed)),
Box::new(optimize_stmt(*stmt, changed)),
),
},
Stmt::Loop(stmt) => Stmt::Loop(Box::new(optimize_stmt(*stmt, changed))),
Stmt::For(id, expr, stmt) => Stmt::For(
id,
Box::new(optimize_expr(*expr, changed)),
Box::new(optimize_stmt(*stmt, changed)),
),
Stmt::Let(id, Some(expr), pos) => {
Stmt::Let(id, Some(Box::new(optimize_expr(*expr, changed))), pos)
}
Stmt::Let(_, None, _) => stmt,
Stmt::Block(statements, pos) => {
let original_len = statements.len();
let mut result: Vec<_> = statements
.into_iter() // For each statement
.map(|s| optimize_stmt(s, changed)) // Optimize the statement
.filter(Stmt::is_op) // Remove no-op's
.collect();
*changed = *changed || original_len != result.len();
match result[..] {
[] => {
// No statements in block - change to No-op
*changed = true;
Stmt::Noop(pos)
}
[Stmt::Let(_, _, _)] => {
// Only one let statement, but cannot promote
// (otherwise the variable gets declared in the scope above)
// and still need to run just in case there are side effects
Stmt::Block(result, pos)
}
[_] => {
// No statements in block - change to No-op
*changed = true;
result.remove(0)
}
_ => Stmt::Block(result, pos),
}
}
Stmt::Expr(expr) => Stmt::Expr(Box::new(optimize_expr(*expr, changed))),
Stmt::ReturnWithVal(Some(expr), is_return, pos) => Stmt::ReturnWithVal(
Some(Box::new(optimize_expr(*expr, changed))),
is_return,
pos,
),
Stmt::ReturnWithVal(None, _, _) => stmt,
Stmt::Noop(_) | Stmt::Break(_) => stmt,
}
}
fn optimize_expr(expr: Expr, changed: &mut bool) -> Expr {
match expr {
Expr::IntegerConstant(_, _)
| Expr::FloatConstant(_, _)
| Expr::Identifier(_, _)
| Expr::CharConstant(_, _)
| Expr::StringConstant(_, _)
| Expr::True(_)
| Expr::False(_)
| Expr::Unit(_) => expr,
Expr::Stmt(stmt, pos) => match optimize_stmt(*stmt, changed) {
Stmt::Noop(_) => {
*changed = true;
Expr::Unit(pos)
}
Stmt::Expr(expr) => {
*changed = true;
*expr
}
stmt => Expr::Stmt(Box::new(stmt), pos),
},
Expr::Assignment(id, expr, pos) => {
Expr::Assignment(id, Box::new(optimize_expr(*expr, changed)), pos)
}
Expr::Dot(lhs, rhs, pos) => Expr::Dot(
Box::new(optimize_expr(*lhs, changed)),
Box::new(optimize_expr(*rhs, changed)),
pos,
),
Expr::Index(lhs, rhs, pos) => Expr::Index(
Box::new(optimize_expr(*lhs, changed)),
Box::new(optimize_expr(*rhs, changed)),
pos,
),
Expr::Array(items, pos) => {
let original_len = items.len();
let items: Vec<_> = items
.into_iter()
.map(|expr| optimize_expr(expr, changed))
.collect();
*changed = *changed || original_len != items.len();
Expr::Array(items, pos)
}
Expr::And(lhs, rhs) => match (*lhs, *rhs) {
(Expr::True(_), rhs) => {
*changed = true;
rhs
}
(Expr::False(pos), _) => {
*changed = true;
Expr::False(pos)
}
(lhs, Expr::True(_)) => {
*changed = true;
lhs
}
(lhs, rhs) => Expr::And(
Box::new(optimize_expr(lhs, changed)),
Box::new(optimize_expr(rhs, changed)),
),
},
Expr::Or(lhs, rhs) => match (*lhs, *rhs) {
(Expr::False(_), rhs) => {
*changed = true;
rhs
}
(Expr::True(pos), _) => {
*changed = true;
Expr::True(pos)
}
(lhs, Expr::False(_)) => {
*changed = true;
lhs
}
(lhs, rhs) => Expr::Or(
Box::new(optimize_expr(lhs, changed)),
Box::new(optimize_expr(rhs, changed)),
),
},
Expr::FunctionCall(id, args, def_value, pos) => {
let original_len = args.len();
let args: Vec<_> = args
.into_iter()
.map(|a| optimize_expr(a, changed))
.collect();
*changed = *changed || original_len != args.len();
Expr::FunctionCall(id, args, def_value, pos)
}
}
}
pub(crate) fn optimize(mut statements: Vec<Stmt>) -> Vec<Stmt> {
loop {
let mut changed = false;
statements = statements
.into_iter()
.map(|stmt| optimize_stmt(stmt, &mut changed))
.filter(Stmt::is_op)
.collect();
if !changed {
break;
}
}
statements
}

84
src/parser.rs
View File

@ -2,7 +2,8 @@
use crate::any::Dynamic;
use crate::error::{LexError, ParseError, ParseErrorType};
use std::{borrow::Cow, char, fmt, iter::Peekable, str::Chars, usize};
use crate::optimize::optimize;
use std::{borrow::Cow, char, fmt, iter::Peekable, str::Chars, str::FromStr, usize};
type LERR = LexError;
type PERR = ParseErrorType;
@ -128,23 +129,33 @@ pub struct AST(pub(crate) Vec<Stmt>, pub(crate) Vec<FnDef<'static>>);
pub struct FnDef<'a> {
pub name: Cow<'a, str>,
pub params: Vec<Cow<'a, str>>,
pub body: Box<Stmt>,
pub body: Stmt,
pub pos: Position,
}
#[derive(Debug, Clone)]
pub enum Stmt {
Noop(Position),
IfElse(Box<Expr>, Box<Stmt>, Option<Box<Stmt>>),
While(Box<Expr>, Box<Stmt>),
Loop(Box<Stmt>),
For(String, Box<Expr>, Box<Stmt>),
Let(String, Option<Box<Expr>>, Position),
Block(Vec<Stmt>),
Block(Vec<Stmt>, Position),
Expr(Box<Expr>),
Break(Position),
ReturnWithVal(Option<Box<Expr>>, bool, Position),
}
impl Stmt {
pub fn is_op(&self) -> bool {
match self {
Stmt::Noop(_) => false,
_ => true,
}
}
}
#[derive(Debug, Clone)]
pub enum Expr {
IntegerConstant(i64, Position),
@ -152,7 +163,7 @@ pub enum Expr {
Identifier(String, Position),
CharConstant(char, Position),
StringConstant(String, Position),
Block(Box<Stmt>, Position),
Stmt(Box<Stmt>, Position),
FunctionCall(String, Vec<Expr>, Option<Dynamic>, Position),
Assignment(Box<Expr>, Box<Expr>, Position),
Dot(Box<Expr>, Box<Expr>, Position),
@ -174,7 +185,7 @@ impl Expr {
| Expr::CharConstant(_, pos)
| Expr::StringConstant(_, pos)
| Expr::FunctionCall(_, _, _, pos)
| Expr::Block(_, pos)
| Expr::Stmt(_, pos)
| Expr::Array(_, pos)
| Expr::True(pos)
| Expr::False(pos)
@ -666,24 +677,23 @@ impl<'a> TokenIterator<'a> {
let out: String = result.iter().skip(2).filter(|&&c| c != '_').collect();
return Some((
if let Ok(val) = i64::from_str_radix(&out, radix) {
Token::IntegerConstant(val)
} else {
Token::LexError(LERR::MalformedNumber(result.iter().collect()))
},
i64::from_str_radix(&out, radix)
.map(Token::IntegerConstant)
.unwrap_or_else(|_| {
Token::LexError(LERR::MalformedNumber(result.iter().collect()))
}),
pos,
));
} else {
let out: String = result.iter().filter(|&&c| c != '_').collect();
return Some((
if let Ok(val) = out.parse::<i64>() {
Token::IntegerConstant(val)
} else if let Ok(val) = out.parse::<f64>() {
Token::FloatConstant(val)
} else {
Token::LexError(LERR::MalformedNumber(result.iter().collect()))
},
i64::from_str(&out)
.map(Token::IntegerConstant)
.or_else(|_| f64::from_str(&out).map(Token::FloatConstant))
.unwrap_or_else(|_| {
Token::LexError(LERR::MalformedNumber(result.iter().collect()))
}),
pos,
));
}
@ -1288,7 +1298,7 @@ fn parse_primary<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Expr, Pa
// Block statement as expression
match input.peek() {
Some(&(Token::LeftBrace, pos)) => {
return parse_block(input).map(|block| Expr::Block(Box::new(block), pos))
return parse_block(input).map(|block| Expr::Stmt(Box::new(block), pos))
}
_ => (),
}
@ -1667,7 +1677,7 @@ fn parse_block<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Pars
None => return Err(ParseError::new(PERR::MissingLeftBrace, Position::eof())),
}
input.next();
let pos = input.next().unwrap().1;
let mut statements = Vec::new();
@ -1695,7 +1705,7 @@ fn parse_block<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<Stmt, Pars
match input.peek() {
Some(&(Token::RightBrace, _)) => {
input.next();
Ok(Stmt::Block(statements))
Ok(Stmt::Block(statements, pos))
}
Some(&(_, pos)) => Err(ParseError::new(
PERR::MissingRightBrace("end of block".into()),
@ -1811,13 +1821,16 @@ fn parse_fn<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<FnDef<'static
Ok(FnDef {
name: name.into(),
params: params,
body: Box::new(body),
pos: pos,
params,
body,
pos,
})
}
fn parse_top_level<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<AST, ParseError> {
fn parse_top_level<'a>(
input: &mut Peekable<TokenIterator<'a>>,
optimize_ast: bool,
) -> Result<AST, ParseError> {
let mut statements = Vec::new();
let mut functions = Vec::new();
@ -1833,9 +1846,26 @@ fn parse_top_level<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<AST, P
}
}
Ok(AST(statements, functions))
return Ok(if optimize_ast {
AST(
optimize(statements),
functions
.into_iter()
.map(|mut fn_def| {
let mut body = optimize(vec![fn_def.body]);
fn_def.body = body.pop().unwrap();
fn_def
})
.collect(),
)
} else {
AST(statements, functions)
});
}
pub fn parse<'a>(input: &mut Peekable<TokenIterator<'a>>) -> Result<AST, ParseError> {
parse_top_level(input)
pub fn parse<'a>(
input: &mut Peekable<TokenIterator<'a>>,
optimize_ast: bool,
) -> Result<AST, ParseError> {
parse_top_level(input, optimize_ast)
}