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Improves generated desugared AST.
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Improved generated desugared AST corrresponds to:
```
    let mut iterable = iterator;
    while true {
        let value_opt = iterable.next();
        if value_opt.is_none() {
             break;
        }
        let value = value_opt.unwrap();
        code_block
    }
```
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@esdrubal
esdrubal committed Feb 8, 2024
1 parent f571473 commit c8fae10
Showing 1 changed file with 64 additions and 36 deletions.
100 changes: 64 additions & 36 deletions sway-core/src/transform/to_parsed_lang/convert_parse_tree.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2055,12 +2055,14 @@ fn expr_to_expression(
} => {
// Desugar for loop into:
// let mut iterable = iterator;
// let mut value_opt = iterable.next();
// while value_opt.is_some() {
// let value = value_opt.unwrap();
// value_opt = iterable.next();
// code_block
// }
// while true {
// let value_opt = iterable.next();
// if value_opt.is_none() {
// break;
// }
// let value = value_opt.unwrap();
// code_block
// }
let value_opt_ident = Ident::new_no_span("__for_value_opt".into());
let value_opt_expr = Expression {
kind: ExpressionKind::Variable(value_opt_ident.clone()),
Expand Down Expand Up @@ -2109,7 +2111,7 @@ fn expr_to_expression(
};

// Declare value_opt = iterable.next()
let value_opt_decl = engines.pe().insert(VariableDeclaration {
let value_opt_to_next_decl = engines.pe().insert(VariableDeclaration {
type_ascription: {
let type_id = engines.te().insert(engines, TypeInfo::Unknown, None);
TypeArgument {
Expand All @@ -2124,27 +2126,13 @@ fn expr_to_expression(
body: set_value_opt_to_next_body_expr.clone(),
});

// Set value_opt = iterable.next()
let set_value_opt_to_next_node = AstNode {
content: AstNodeContent::Expression(Expression {
kind: ExpressionKind::Reassignment(ReassignmentExpression {
lhs: ReassignmentTarget::VariableExpression(Box::new(
value_opt_expr.clone(),
)),
rhs: Box::new(set_value_opt_to_next_body_expr),
}),
span: Span::dummy(),
}),
span: Span::dummy(),
};

// Call value_opt.is_some()
let value_opt_is_some = Expression {
// Call value_opt.is_none()
let value_opt_is_none = Expression {
kind: ExpressionKind::MethodApplication(Box::new(MethodApplicationExpression {
arguments: vec![value_opt_expr.clone()],
method_name_binding: TypeBinding {
inner: MethodName::FromModule {
method_name: Ident::new_no_span("is_some".into()),
method_name: Ident::new_no_span("is_none".into()),
},
type_arguments: TypeArgs::Regular(vec![]),
span: Span::dummy(),
Expand Down Expand Up @@ -2185,16 +2173,59 @@ fn expr_to_expression(
braced_code_block_contents_to_code_block(context, handler, engines, block)?;

//At the beginning of while block do:
// let value_pattern = value_opt.unwrap()
// value_opt = iterable.next()
// let value_opt = iterable.next();
// if value_opt.is_none() {
// break;
// }
// let value = value_opt.unwrap();
// Note: Inserting in reverse order
while_body
.contents
.insert(0, set_value_opt_to_next_node.clone());

// let value = value_opt.unwrap();
for node in pattern_ast_nodes.iter().rev() {
while_body.contents.insert(0, node.clone());
}

// if value_opt.is_none() {
// break;
// }
while_body.contents.insert(
0,
AstNode {
content: AstNodeContent::Expression(Expression {
kind: ExpressionKind::If(IfExpression {
condition: Box::new(value_opt_is_none),
then: Box::new(Expression {
kind: ExpressionKind::CodeBlock(CodeBlock {
contents: vec![AstNode {
content: AstNodeContent::Expression(Expression {
kind: ExpressionKind::Break,
span: Span::dummy(),
}),
span: Span::dummy(),
}],
whole_block_span: Span::dummy(),
}),
span: Span::dummy(),
}),
r#else: None,
}),
span: Span::dummy(),
}),
span: Span::dummy(),
},
);

// let value_opt = iterable.next();
while_body.contents.insert(
0,
AstNode {
content: AstNodeContent::Declaration(Declaration::VariableDeclaration(
value_opt_to_next_decl,
)),
span: Span::dummy(),
},
);

let desugared = Expression {
kind: ExpressionKind::CodeBlock(CodeBlock {
contents: vec![
Expand All @@ -2204,16 +2235,13 @@ fn expr_to_expression(
)),
span: Span::dummy(),
},
AstNode {
content: AstNodeContent::Declaration(Declaration::VariableDeclaration(
value_opt_decl,
)),
span: Span::dummy(),
},
AstNode {
content: AstNodeContent::Expression(Expression {
kind: ExpressionKind::WhileLoop(WhileLoopExpression {
condition: Box::new(value_opt_is_some),
condition: Box::new(Expression {
kind: ExpressionKind::Literal(Literal::Boolean(true)),
span: Span::dummy(),
}),
body: while_body,
}),
span: Span::dummy(),
Expand Down

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