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Expr::Stmt takes a statements block.

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This commit is contained in:
Stephen Chung 2020-11-04 11:49:02 +08:00
parent 32f41c69bd
commit 2168fd5361
6 changed files with 80 additions and 44 deletions
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4
src/ast.rs
View File

@ -908,7 +908,7 @@ pub enum Expr {
/// Property access - (getter, setter), prop
Property(Box<((String, String), IdentX)>),
/// { stmt }
Stmt(Box<Stmt>, Position),
Stmt(Box<StaticVec<Stmt>>, Position),
/// Wrapped expression - should not be optimized away.
Expr(Box<Expr>),
/// func(expr, ... )
@ -1092,7 +1092,7 @@ impl Expr {
x.lhs.is_pure() && x.rhs.is_pure()
}
Self::Stmt(x, _) => x.is_pure(),
Self::Stmt(x, _) => x.iter().all(Stmt::is_pure),
Self::Variable(_) => true,

53
src/engine.rs
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@ -1579,7 +1579,9 @@ impl Engine {
Expr::Property(_) => unreachable!(),
// Statement block
Expr::Stmt(x, _) => self.eval_stmt(scope, mods, state, lib, this_ptr, x, level),
Expr::Stmt(x, _) => {
self.eval_statements(scope, mods, state, lib, this_ptr, x.as_ref(), level)
}
// lhs[idx_expr]
#[cfg(not(feature = "no_index"))]
@ -1706,6 +1708,37 @@ impl Engine {
.map_err(|err| err.fill_position(expr.position()))
}
pub(crate) fn eval_statements<'a>(
&self,
scope: &mut Scope,
mods: &mut Imports,
state: &mut State,
lib: &[&Module],
this_ptr: &mut Option<&mut Dynamic>,
statements: impl IntoIterator<Item = &'a Stmt>,
level: usize,
) -> Result<Dynamic, Box<EvalAltResult>> {
let prev_scope_len = scope.len();
let prev_mods_len = mods.len();
state.scope_level += 1;
let result = statements
.into_iter()
.try_fold(Default::default(), |_, stmt| {
self.eval_stmt(scope, mods, state, lib, this_ptr, stmt, level)
});
scope.rewind(prev_scope_len);
mods.truncate(prev_mods_len);
state.scope_level -= 1;
// The impact of an eval statement goes away at the end of a block
// because any new variables introduced will go out of scope
state.always_search = false;
result
}
/// Evaluate a statement
///
///
@ -1886,23 +1919,7 @@ impl Engine {
// Block scope
Stmt::Block(statements, _) => {
let prev_scope_len = scope.len();
let prev_mods_len = mods.len();
state.scope_level += 1;
let result = statements.iter().try_fold(Default::default(), |_, stmt| {
self.eval_stmt(scope, mods, state, lib, this_ptr, stmt, level)
});
scope.rewind(prev_scope_len);
mods.truncate(prev_mods_len);
state.scope_level -= 1;
// The impact of an eval statement goes away at the end of a block
// because any new variables introduced will go out of scope
state.always_search = false;
result
self.eval_statements(scope, mods, state, lib, this_ptr, statements, level)
}
// If-else statement

4
src/engine_api.rs
View File

@ -1405,7 +1405,7 @@ impl Engine {
mods: &mut Imports,
ast: &'a AST,
) -> Result<(Dynamic, u64), Box<EvalAltResult>> {
self.eval_statements(scope, mods, ast.statements(), &[ast.lib()])
self.eval_statements_raw(scope, mods, ast.statements(), &[ast.lib()])
}
/// Evaluate a file, but throw away the result and only return error (if any).
@ -1467,7 +1467,7 @@ impl Engine {
ast: &AST,
) -> Result<(), Box<EvalAltResult>> {
let mut mods = Default::default();
self.eval_statements(scope, &mut mods, ast.statements(), &[ast.lib()])
self.eval_statements_raw(scope, &mut mods, ast.statements(), &[ast.lib()])
.map(|_| ())
}

7
src/fn_call.rs
View File

@ -604,9 +604,10 @@ impl Engine {
}
}
/// Evaluate a list of statements.
/// Evaluate a list of statements with an empty state and no `this` pointer.
/// This is commonly used to evaluate a list of statements in an `AST` or a script function body.
#[inline]
pub(crate) fn eval_statements<'a>(
pub(crate) fn eval_statements_raw<'a>(
&self,
scope: &mut Scope,
mods: &mut Imports,
@ -667,7 +668,7 @@ impl Engine {
}
// Evaluate the AST
let (result, operations) = self.eval_statements(scope, mods, ast.statements(), lib)?;
let (result, operations) = self.eval_statements_raw(scope, mods, ast.statements(), lib)?;
state.operations += operations;
self.inc_operations(state)?;

24
src/optimize.rs
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@ -409,9 +409,14 @@ fn optimize_stmt(stmt: Stmt, state: &mut State, preserve_result: bool) -> Stmt {
)))
}
// expr;
Stmt::Expr(Expr::Stmt(x, _)) if matches!(*x, Stmt::Expr(_)) => {
Stmt::Expr(Expr::Stmt(x, pos)) if x.is_empty() => {
state.set_dirty();
optimize_stmt(*x, state, preserve_result)
Stmt::Noop(pos)
}
// expr;
Stmt::Expr(Expr::Stmt(mut x, _)) if x.len() == 1 => {
state.set_dirty();
optimize_stmt(x.remove(0), state, preserve_result)
}
// expr;
Stmt::Expr(expr) => Stmt::Expr(optimize_expr(expr, state)),
@ -438,8 +443,13 @@ fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
match expr {
// expr - do not promote because there is a reason it is wrapped in an `Expr::Expr`
Expr::Expr(x) => Expr::Expr(Box::new(optimize_expr(*x, state))),
// {}
Expr::Stmt(x, pos) if x.is_empty() => {
state.set_dirty();
Expr::Unit(pos)
}
// { stmt }
Expr::Stmt(x, pos) => match *x {
Expr::Stmt(mut x, pos) if x.len() == 1 => match x.remove(0) {
// {} -> ()
Stmt::Noop(_) => {
state.set_dirty();
@ -451,8 +461,12 @@ fn optimize_expr(expr: Expr, state: &mut State) -> Expr {
optimize_expr(expr, state)
}
// { stmt }
stmt => Expr::Stmt(Box::new(optimize_stmt(stmt, state, true)), pos),
},
stmt => Expr::Stmt(Box::new(vec![optimize_stmt(stmt, state, true)].into()), pos)
}
// { stmt; ... }
Expr::Stmt(x, pos) => Expr::Stmt(Box::new(
x.into_iter().map(|stmt| optimize_stmt(stmt, state, true)).collect(),
), pos),
// lhs.rhs
#[cfg(not(feature = "no_object"))]

28
src/parser.rs
View File

@ -765,8 +765,10 @@ fn parse_primary(
let (token, _) = match token {
// { - block statement as expression
Token::LeftBrace if settings.allow_stmt_expr => {
return parse_block(input, state, lib, settings.level_up())
.map(|block| Expr::Stmt(Box::new(block), settings.pos))
return parse_block(input, state, lib, settings.level_up()).map(|block| match block {
Stmt::Block(statements, pos) => Expr::Stmt(Box::new(statements.into()), pos),
_ => unreachable!(),
})
}
Token::EOF => return Err(PERR::UnexpectedEOF.into_err(settings.pos)),
_ => input.next().unwrap(),
@ -962,10 +964,11 @@ fn parse_unary(
match token {
// If statement is allowed to act as expressions
Token::If if settings.allow_if_expr => Ok(Expr::Stmt(
Box::new(parse_if(input, state, lib, settings.level_up())?),
settings.pos,
)),
Token::If if settings.allow_if_expr => {
let mut block: StaticVec<_> = Default::default();
block.push(parse_if(input, state, lib, settings.level_up())?);
Ok(Expr::Stmt(Box::new(block), settings.pos))
}
// -expr
Token::UnaryMinus => {
let pos = eat_token(input, Token::UnaryMinus);
@ -1657,12 +1660,13 @@ fn parse_custom_syntax(
exprs.push(parse_expr(input, state, lib, settings)?);
segments.push(MARKER_EXPR.into());
}
MARKER_BLOCK => {
let stmt = parse_block(input, state, lib, settings)?;
let pos = stmt.position();
exprs.push(Expr::Stmt(Box::new(stmt), pos));
MARKER_BLOCK => match parse_block(input, state, lib, settings)? {
Stmt::Block(statements, pos) => {
exprs.push(Expr::Stmt(Box::new(statements.into()), pos));
segments.push(MARKER_BLOCK.into());
}
_ => unreachable!(),
},
s => match input.next().unwrap() {
(Token::LexError(err), pos) => return Err(err.into_err(pos)),
(t, _) if t.syntax().as_ref() == s => {
@ -2525,12 +2529,12 @@ fn make_curry_from_externals(fn_expr: Expr, externals: StaticVec<Ident>, pos: Po
#[cfg(not(feature = "no_closure"))]
{
// Statement block
let mut statements: Vec<_> = Default::default();
let mut statements: StaticVec<_> = Default::default();
// Insert `Share` statements
statements.extend(externals.into_iter().map(|x| Stmt::Share(Box::new(x))));
// Final expression
statements.push(Stmt::Expr(expr));
Expr::Stmt(Box::new(Stmt::Block(statements, pos)), pos)
Expr::Stmt(Box::new(statements), pos)
}
#[cfg(feature = "no_closure")]