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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/ast/ast.h"
#include "src/message-template.h"
#include "src/objects-inl.h"
#include "src/parsing/expression-scope-reparenter.h"
#include "src/parsing/parser.h"
namespace v8 {
namespace internal {
// An AST visitor which performs declaration and assignment related tasks,
// particularly for destructuring patterns:
//
// 1. Declares variables from variable proxies (particularly for destructuring
// declarations),
// 2. Marks destructuring-assigned variable proxies as assigned, and
// 3. Rewrites scopes for parameters containing a sloppy eval.
//
// Historically this also rewrote destructuring assignments/declarations as a
// block of multiple assignments, hence the named, however this is now done
// during bytecode generation.
//
// TODO(leszeks): Rename or remove this class
class PatternRewriter final : public AstVisitor<PatternRewriter> {
public:
typedef Parser::DeclarationDescriptor DeclarationDescriptor;
static void InitializeVariables(
Parser* parser, VariableKind kind,
const Parser::DeclarationParsingResult::Declaration* declaration);
private:
PatternRewriter(Parser* parser, VariableKind kind, int initializer_position,
bool declares_parameter_containing_sloppy_eval)
: parser_(parser),
initializer_position_(initializer_position),
declares_parameter_containing_sloppy_eval_(
declares_parameter_containing_sloppy_eval) {}
#define DECLARE_VISIT(type) void Visit##type(v8::internal::type* node);
// Visiting functions for AST nodes make this an AstVisitor.
AST_NODE_LIST(DECLARE_VISIT)
#undef DECLARE_VISIT
Expression* Visit(Assignment* assign) {
if (parser_->has_error()) return parser_->FailureExpression();
DCHECK_EQ(Token::ASSIGN, assign->op());
Expression* pattern = assign->target();
if (pattern->IsObjectLiteral()) {
VisitObjectLiteral(pattern->AsObjectLiteral());
} else {
DCHECK(pattern->IsArrayLiteral());
VisitArrayLiteral(pattern->AsArrayLiteral());
}
return assign;
}
void RewriteParameterScopes(Expression* expr);
Scope* scope() const { return parser_->scope(); }
Parser* const parser_;
const int initializer_position_;
const bool declares_parameter_containing_sloppy_eval_;
DEFINE_AST_VISITOR_MEMBERS_WITHOUT_STACKOVERFLOW()
};
void Parser::InitializeVariables(
ScopedPtrList<Statement>* statements, VariableKind kind,
const DeclarationParsingResult::Declaration* declaration) {
if (has_error()) return;
if (!declaration->initializer) {
// The parameter scope is only a block scope if the initializer calls sloppy
// eval. Since there is no initializer, we can't be calling sloppy eval.
DCHECK_IMPLIES(kind == PARAMETER_VARIABLE, scope()->is_function_scope());
return;
}
PatternRewriter::InitializeVariables(this, kind, declaration);
int pos = declaration->value_beg_position;
if (pos == kNoSourcePosition) {
pos = declaration->initializer_position;
}
Assignment* assignment = factory()->NewAssignment(
Token::INIT, declaration->pattern, declaration->initializer, pos);
statements->Add(factory()->NewExpressionStatement(assignment, pos));
}
void PatternRewriter::InitializeVariables(
Parser* parser, VariableKind kind,
const Parser::DeclarationParsingResult::Declaration* declaration) {
PatternRewriter rewriter(
parser, kind, declaration->initializer_position,
kind == PARAMETER_VARIABLE && parser->scope()->is_block_scope());
rewriter.Visit(declaration->pattern);
}
void PatternRewriter::VisitVariableProxy(VariableProxy* proxy) {
DCHECK(!parser_->has_error());
Variable* var =
proxy->is_resolved()
? proxy->var()
: scope()->GetDeclarationScope()->LookupLocal(proxy->raw_name());
DCHECK_NOT_NULL(var);
DCHECK_NE(initializer_position_, kNoSourcePosition);
var->set_initializer_position(initializer_position_);
}
// When an extra declaration scope needs to be inserted to account for
// a sloppy eval in a default parameter or function body, the expressions
// needs to be in that new inner scope which was added after initial
// parsing.
void PatternRewriter::RewriteParameterScopes(Expression* expr) {
if (declares_parameter_containing_sloppy_eval_) {
ReparentExpressionScope(parser_->stack_limit(), expr, scope());
}
}
void PatternRewriter::VisitObjectLiteral(ObjectLiteral* pattern) {
for (ObjectLiteralProperty* property : *pattern->properties()) {
Expression* key = property->key();
if (!key->IsLiteral()) {
// Computed property names contain expressions which might require
// scope rewriting.
RewriteParameterScopes(key);
}
Visit(property->value());
}
}
void PatternRewriter::VisitArrayLiteral(ArrayLiteral* node) {
for (Expression* value : *node->values()) {
if (value->IsTheHoleLiteral()) continue;
Visit(value);
}
}
void PatternRewriter::VisitAssignment(Assignment* node) {
DCHECK_EQ(Token::ASSIGN, node->op());
// Initializer may have been parsed in the wrong scope.
RewriteParameterScopes(node->value());
Visit(node->target());
}
void PatternRewriter::VisitSpread(Spread* node) { Visit(node->expression()); }
// =============== UNREACHABLE =============================
#define NOT_A_PATTERN(Node) \
void PatternRewriter::Visit##Node(v8::internal::Node*) { UNREACHABLE(); }
NOT_A_PATTERN(BinaryOperation)
NOT_A_PATTERN(NaryOperation)
NOT_A_PATTERN(Block)
NOT_A_PATTERN(BreakStatement)
NOT_A_PATTERN(Call)
NOT_A_PATTERN(CallNew)
NOT_A_PATTERN(CallRuntime)
NOT_A_PATTERN(ClassLiteral)
NOT_A_PATTERN(CompareOperation)
NOT_A_PATTERN(CompoundAssignment)
NOT_A_PATTERN(Conditional)
NOT_A_PATTERN(ContinueStatement)
NOT_A_PATTERN(CountOperation)
NOT_A_PATTERN(DebuggerStatement)
NOT_A_PATTERN(DoExpression)
NOT_A_PATTERN(DoWhileStatement)
NOT_A_PATTERN(EmptyStatement)
NOT_A_PATTERN(EmptyParentheses)
NOT_A_PATTERN(ExpressionStatement)
NOT_A_PATTERN(ForInStatement)
NOT_A_PATTERN(ForOfStatement)
NOT_A_PATTERN(ForStatement)
NOT_A_PATTERN(FunctionDeclaration)
NOT_A_PATTERN(FunctionLiteral)
NOT_A_PATTERN(GetTemplateObject)
NOT_A_PATTERN(IfStatement)
NOT_A_PATTERN(ImportCallExpression)
NOT_A_PATTERN(Literal)
NOT_A_PATTERN(NativeFunctionLiteral)
NOT_A_PATTERN(Property)
NOT_A_PATTERN(RegExpLiteral)
NOT_A_PATTERN(ResolvedProperty)
NOT_A_PATTERN(ReturnStatement)
NOT_A_PATTERN(SloppyBlockFunctionStatement)
NOT_A_PATTERN(StoreInArrayLiteral)
NOT_A_PATTERN(SuperPropertyReference)
NOT_A_PATTERN(SuperCallReference)
NOT_A_PATTERN(SwitchStatement)
NOT_A_PATTERN(TemplateLiteral)
NOT_A_PATTERN(ThisFunction)
NOT_A_PATTERN(Throw)
NOT_A_PATTERN(TryCatchStatement)
NOT_A_PATTERN(TryFinallyStatement)
NOT_A_PATTERN(UnaryOperation)
NOT_A_PATTERN(VariableDeclaration)
NOT_A_PATTERN(WhileStatement)
NOT_A_PATTERN(WithStatement)
NOT_A_PATTERN(Yield)
NOT_A_PATTERN(YieldStar)
NOT_A_PATTERN(Await)
NOT_A_PATTERN(InitializeClassMembersStatement)
#undef NOT_A_PATTERN
} // namespace internal
} // namespace v8
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