mirror of
https://github.com/RGBCube/serenity
synced 2025-05-30 17:48:12 +00:00
LibJS: Add operator precedence parsing
Obey precedence and associativity rules when parsing expressions with chained operators.
This commit is contained in:
Stephan Unverwerth
Andreas Kling
parent
f347dd5c5e
commit
15d5b2d29e
8 changed files with 281 additions and 53 deletions
|
|
@ -25,14 +25,142 @@
|
|||
*/
|
||||
|
||||
#include "Parser.h"
|
||||
#include <AK/HashMap.h>
|
||||
#include <AK/StdLibExtras.h>
|
||||
#include <stdio.h>
|
||||
|
||||
namespace JS {
|
||||
|
||||
static HashMap<TokenType, int> g_operator_precedence;
|
||||
|
||||
Parser::Parser(Lexer lexer)
|
||||
: m_lexer(move(lexer))
|
||||
, m_current_token(m_lexer.next())
|
||||
{
|
||||
if (g_operator_precedence.is_empty()) {
|
||||
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Operator_Precedence
|
||||
g_operator_precedence.set(TokenType::Period, 20);
|
||||
g_operator_precedence.set(TokenType::BracketOpen, 20);
|
||||
g_operator_precedence.set(TokenType::ParenOpen, 20);
|
||||
g_operator_precedence.set(TokenType::QuestionMarkPeriod, 20);
|
||||
|
||||
g_operator_precedence.set(TokenType::New, 19);
|
||||
|
||||
g_operator_precedence.set(TokenType::PlusPlus, 18);
|
||||
g_operator_precedence.set(TokenType::MinusMinus, 18);
|
||||
|
||||
g_operator_precedence.set(TokenType::ExclamationMark, 17);
|
||||
g_operator_precedence.set(TokenType::Tilde, 17);
|
||||
g_operator_precedence.set(TokenType::Typeof, 17);
|
||||
g_operator_precedence.set(TokenType::Void, 17);
|
||||
g_operator_precedence.set(TokenType::Delete, 17);
|
||||
g_operator_precedence.set(TokenType::Await, 17);
|
||||
|
||||
g_operator_precedence.set(TokenType::DoubleAsterisk, 16);
|
||||
|
||||
g_operator_precedence.set(TokenType::Asterisk, 15);
|
||||
g_operator_precedence.set(TokenType::Slash, 15);
|
||||
g_operator_precedence.set(TokenType::Percent, 15);
|
||||
|
||||
g_operator_precedence.set(TokenType::Plus, 14);
|
||||
g_operator_precedence.set(TokenType::Minus, 14);
|
||||
|
||||
g_operator_precedence.set(TokenType::ShiftLeft, 13);
|
||||
g_operator_precedence.set(TokenType::ShiftRight, 13);
|
||||
g_operator_precedence.set(TokenType::UnsignedShiftRight, 13);
|
||||
|
||||
g_operator_precedence.set(TokenType::LessThan, 12);
|
||||
g_operator_precedence.set(TokenType::LessThanEquals, 12);
|
||||
g_operator_precedence.set(TokenType::GreaterThan, 12);
|
||||
g_operator_precedence.set(TokenType::GreaterThanEquals, 12);
|
||||
g_operator_precedence.set(TokenType::In, 12);
|
||||
g_operator_precedence.set(TokenType::Instanceof, 12);
|
||||
|
||||
g_operator_precedence.set(TokenType::EqualsEquals, 11);
|
||||
g_operator_precedence.set(TokenType::ExclamationMarkEquals, 11);
|
||||
g_operator_precedence.set(TokenType::EqualsEqualsEquals, 11);
|
||||
g_operator_precedence.set(TokenType::ExclamationMarkEqualsEquals, 11);
|
||||
|
||||
g_operator_precedence.set(TokenType::Ampersand, 10);
|
||||
|
||||
g_operator_precedence.set(TokenType::Caret, 9);
|
||||
|
||||
g_operator_precedence.set(TokenType::Pipe, 8);
|
||||
|
||||
g_operator_precedence.set(TokenType::DoubleQuestionMark, 7);
|
||||
|
||||
g_operator_precedence.set(TokenType::DoubleAmpersand, 6);
|
||||
|
||||
g_operator_precedence.set(TokenType::DoublePipe, 5);
|
||||
|
||||
g_operator_precedence.set(TokenType::QuestionMark, 4);
|
||||
|
||||
g_operator_precedence.set(TokenType::Equals, 3);
|
||||
g_operator_precedence.set(TokenType::PlusEquals, 3);
|
||||
g_operator_precedence.set(TokenType::MinusEquals, 3);
|
||||
g_operator_precedence.set(TokenType::AsteriskAsteriskEquals, 3);
|
||||
g_operator_precedence.set(TokenType::AsteriskEquals, 3);
|
||||
g_operator_precedence.set(TokenType::SlashEquals, 3);
|
||||
g_operator_precedence.set(TokenType::PercentEquals, 3);
|
||||
g_operator_precedence.set(TokenType::ShiftLeftEquals, 3);
|
||||
g_operator_precedence.set(TokenType::ShiftRightEquals, 3);
|
||||
g_operator_precedence.set(TokenType::UnsignedShiftRightEquals, 3);
|
||||
g_operator_precedence.set(TokenType::PipeEquals, 3);
|
||||
|
||||
g_operator_precedence.set(TokenType::Yield, 2);
|
||||
|
||||
g_operator_precedence.set(TokenType::Comma, 1);
|
||||
}
|
||||
}
|
||||
|
||||
int Parser::operator_precedence(TokenType type) const
|
||||
{
|
||||
auto it = g_operator_precedence.find(type);
|
||||
if (it == g_operator_precedence.end()) {
|
||||
fprintf(stderr, "No precedence for operator %s\n", Token::name(type));
|
||||
ASSERT_NOT_REACHED();
|
||||
return -1;
|
||||
}
|
||||
|
||||
return it->value;
|
||||
}
|
||||
|
||||
Associativity Parser::operator_associativity(TokenType type) const
|
||||
{
|
||||
switch (type) {
|
||||
case TokenType::Period:
|
||||
case TokenType::BracketOpen:
|
||||
case TokenType::ParenOpen:
|
||||
case TokenType::QuestionMarkPeriod:
|
||||
case TokenType::Asterisk:
|
||||
case TokenType::Slash:
|
||||
case TokenType::Percent:
|
||||
case TokenType::Plus:
|
||||
case TokenType::Minus:
|
||||
case TokenType::ShiftLeft:
|
||||
case TokenType::ShiftRight:
|
||||
case TokenType::UnsignedShiftRight:
|
||||
case TokenType::LessThan:
|
||||
case TokenType::LessThanEquals:
|
||||
case TokenType::GreaterThan:
|
||||
case TokenType::GreaterThanEquals:
|
||||
case TokenType::In:
|
||||
case TokenType::Instanceof:
|
||||
case TokenType::EqualsEquals:
|
||||
case TokenType::ExclamationMarkEquals:
|
||||
case TokenType::EqualsEqualsEquals:
|
||||
case TokenType::ExclamationMarkEqualsEquals:
|
||||
case TokenType::Ampersand:
|
||||
case TokenType::Caret:
|
||||
case TokenType::Pipe:
|
||||
case TokenType::DoubleQuestionMark:
|
||||
case TokenType::DoubleAmpersand:
|
||||
case TokenType::DoublePipe:
|
||||
case TokenType::Comma:
|
||||
return Associativity::Left;
|
||||
default:
|
||||
return Associativity::Right;
|
||||
}
|
||||
}
|
||||
|
||||
NonnullOwnPtr<Program> Parser::parse_program()
|
||||
|
|
@ -54,7 +182,7 @@ NonnullOwnPtr<Program> Parser::parse_program()
|
|||
NonnullOwnPtr<Statement> Parser::parse_statement()
|
||||
{
|
||||
if (match_expression()) {
|
||||
return make<JS::ExpressionStatement>(parse_expression());
|
||||
return make<JS::ExpressionStatement>(parse_expression(0));
|
||||
}
|
||||
|
||||
switch (m_current_token.type()) {
|
||||
|
|
@ -83,7 +211,7 @@ NonnullOwnPtr<Expression> Parser::parse_primary_expression()
|
|||
switch (m_current_token.type()) {
|
||||
case TokenType::ParenOpen: {
|
||||
consume(TokenType::ParenOpen);
|
||||
auto expression = parse_expression();
|
||||
auto expression = parse_expression(0);
|
||||
consume(TokenType::ParenClose);
|
||||
return expression;
|
||||
}
|
||||
|
|
@ -113,68 +241,75 @@ NonnullOwnPtr<ObjectExpression> Parser::parse_object_expression()
|
|||
return make<ObjectExpression>();
|
||||
}
|
||||
|
||||
NonnullOwnPtr<Expression> Parser::parse_expression()
|
||||
NonnullOwnPtr<Expression> Parser::parse_expression(int min_precedence, Associativity associativity)
|
||||
{
|
||||
auto expression = parse_primary_expression();
|
||||
while (match_secondary_expression()) {
|
||||
expression = parse_secondary_expression(move(expression));
|
||||
int new_precedence = operator_precedence(m_current_token.type());
|
||||
if (new_precedence < min_precedence)
|
||||
break;
|
||||
if (new_precedence == min_precedence && associativity == Associativity::Left)
|
||||
break;
|
||||
|
||||
Associativity new_associativity = operator_associativity(m_current_token.type());
|
||||
expression = parse_secondary_expression(move(expression), new_precedence, new_associativity);
|
||||
}
|
||||
return expression;
|
||||
}
|
||||
|
||||
NonnullOwnPtr<Expression> Parser::parse_secondary_expression(NonnullOwnPtr<Expression> lhs)
|
||||
NonnullOwnPtr<Expression> Parser::parse_secondary_expression(NonnullOwnPtr<Expression> lhs, int min_precedence, Associativity associativity)
|
||||
{
|
||||
switch (m_current_token.type()) {
|
||||
case TokenType::Plus:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::Plus, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::Plus, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::PlusEquals:
|
||||
consume();
|
||||
return make<AssignmentExpression>(AssignmentOp::AdditionAssignment, move(lhs), parse_expression());
|
||||
return make<AssignmentExpression>(AssignmentOp::AdditionAssignment, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::Minus:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::Minus, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::Minus, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::MinusEquals:
|
||||
consume();
|
||||
return make<AssignmentExpression>(AssignmentOp::SubtractionAssignment, move(lhs), parse_expression());
|
||||
return make<AssignmentExpression>(AssignmentOp::SubtractionAssignment, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::Asterisk:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::Asterisk, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::Asterisk, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::AsteriskEquals:
|
||||
consume();
|
||||
return make<AssignmentExpression>(AssignmentOp::MultiplicationAssignment, move(lhs), parse_expression());
|
||||
return make<AssignmentExpression>(AssignmentOp::MultiplicationAssignment, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::Slash:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::Slash, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::Slash, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::SlashEquals:
|
||||
consume();
|
||||
return make<AssignmentExpression>(AssignmentOp::DivisionAssignment, move(lhs), parse_expression());
|
||||
return make<AssignmentExpression>(AssignmentOp::DivisionAssignment, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::GreaterThan:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::GreaterThan, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::GreaterThan, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::GreaterThanEquals:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::GreaterThanEquals, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::GreaterThanEquals, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::LessThan:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::LessThan, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::LessThan, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::LessThanEquals:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::LessThanEquals, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::LessThanEquals, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::EqualsEqualsEquals:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::TypedEquals, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::TypedEquals, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::ExclamationMarkEqualsEquals:
|
||||
consume();
|
||||
return make<BinaryExpression>(BinaryOp::TypedInequals, move(lhs), parse_expression());
|
||||
return make<BinaryExpression>(BinaryOp::TypedInequals, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::ParenOpen:
|
||||
return parse_call_expression(move(lhs));
|
||||
case TokenType::Equals:
|
||||
consume();
|
||||
return make<AssignmentExpression>(AssignmentOp::Assignment, move(lhs), parse_expression());
|
||||
return make<AssignmentExpression>(AssignmentOp::Assignment, move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::Period:
|
||||
consume();
|
||||
return make<MemberExpression>(move(lhs), parse_expression());
|
||||
return make<MemberExpression>(move(lhs), parse_expression(min_precedence, associativity));
|
||||
case TokenType::PlusPlus:
|
||||
consume();
|
||||
return make<UpdateExpression>(UpdateOp::Increment, move(lhs));
|
||||
|
|
@ -196,7 +331,7 @@ NonnullOwnPtr<CallExpression> Parser::parse_call_expression(NonnullOwnPtr<Expres
|
|||
NonnullOwnPtrVector<Expression> arguments;
|
||||
|
||||
while (match_expression()) {
|
||||
arguments.append(parse_expression());
|
||||
arguments.append(parse_expression(0));
|
||||
if (!match(TokenType::Comma))
|
||||
break;
|
||||
consume();
|
||||
|
|
@ -204,20 +339,14 @@ NonnullOwnPtr<CallExpression> Parser::parse_call_expression(NonnullOwnPtr<Expres
|
|||
|
||||
consume(TokenType::ParenClose);
|
||||
|
||||
// FIXME: Allow lhs expression instead of just a string
|
||||
if (lhs->is_identifier()) {
|
||||
return make<CallExpression>(static_cast<Identifier*>(lhs.ptr())->string(), move(arguments));
|
||||
}
|
||||
|
||||
m_has_errors = true;
|
||||
return make<CallExpression>("***ERROR***");
|
||||
return make<CallExpression>(move(lhs), move(arguments));
|
||||
}
|
||||
|
||||
NonnullOwnPtr<ReturnStatement> Parser::parse_return_statement()
|
||||
{
|
||||
consume(TokenType::Return);
|
||||
if (match_expression()) {
|
||||
return make<ReturnStatement>(parse_expression());
|
||||
return make<ReturnStatement>(parse_expression(0));
|
||||
}
|
||||
return make<ReturnStatement>(nullptr);
|
||||
}
|
||||
|
|
@ -283,7 +412,7 @@ NonnullOwnPtr<VariableDeclaration> Parser::parse_variable_declaration()
|
|||
OwnPtr<Expression> initializer;
|
||||
if (match(TokenType::Equals)) {
|
||||
consume();
|
||||
initializer = parse_expression();
|
||||
initializer = parse_expression(0);
|
||||
}
|
||||
return make<VariableDeclaration>(make<Identifier>(name), move(initializer), declaration_type);
|
||||
}
|
||||
|
|
@ -313,7 +442,7 @@ NonnullOwnPtr<ForStatement> Parser::parse_for_statement()
|
|||
case TokenType::Semicolon:
|
||||
break;
|
||||
default:
|
||||
test = parse_expression();
|
||||
test = parse_expression(0);
|
||||
break;
|
||||
}
|
||||
|
||||
|
|
@ -324,7 +453,7 @@ NonnullOwnPtr<ForStatement> Parser::parse_for_statement()
|
|||
case TokenType::Semicolon:
|
||||
break;
|
||||
default:
|
||||
update = parse_expression();
|
||||
update = parse_expression(0);
|
||||
break;
|
||||
}
|
||||
|
||||
|
|
@ -405,9 +534,9 @@ bool Parser::done() const
|
|||
|
||||
Token Parser::consume()
|
||||
{
|
||||
auto oldToken = m_current_token;
|
||||
auto old_token = m_current_token;
|
||||
m_current_token = m_lexer.next();
|
||||
return oldToken;
|
||||
return old_token;
|
||||
}
|
||||
|
||||
Token Parser::consume(TokenType type)
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue