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LibJS: Add missing undefined fallback to IfStatement completions

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Also add spec comments.
This commit is contained in:
Linus Groh 2021-12-31 15:38:38 +01:00
parent a6476ad61f
commit d7f6635d55
2 changed files with 23 additions and 4 deletions
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23
Userland/Libraries/LibJS/AST.cpp
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@ -424,20 +424,35 @@ Value ReturnStatement::execute(Interpreter& interpreter, GlobalObject& global_ob
return value;
}
// 14.6.2 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-if-statement-runtime-semantics-evaluation
Value IfStatement::execute(Interpreter& interpreter, GlobalObject& global_object) const
{
InterpreterNodeScope node_scope { interpreter, *this };
// IfStatement : if ( Expression ) Statement else Statement
// 1. Let exprRef be the result of evaluating Expression.
// 2. Let exprValue be ! ToBoolean(? GetValue(exprRef)).
auto predicate_result = m_predicate->execute(interpreter, global_object);
if (interpreter.exception())
return {};
if (predicate_result.to_boolean())
return m_consequent->execute(interpreter, global_object);
// 3. If exprValue is true, then
if (predicate_result.to_boolean()) {
// a. Let stmtCompletion be the result of evaluating the second Statement.
// 5. Return Completion(UpdateEmpty(stmtCompletion, undefined)).
return m_consequent->execute(interpreter, global_object).value_or(js_undefined());
}
if (m_alternate)
return m_alternate->execute(interpreter, global_object);
// 4. Else,
if (m_alternate) {
// a. Let stmtCompletion be the result of evaluating the second Statement.
// 5. Return Completion(UpdateEmpty(stmtCompletion, undefined)).
return m_alternate->execute(interpreter, global_object).value_or(js_undefined());
}
// IfStatement : if ( Expression ) Statement
// 3. If exprValue is false, then
// a. Return NormalCompletion(undefined).
return js_undefined();
}