LibJS: Lexer and parser support for "switch" statements

Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/1923051c5bb

Libraries/LibJS/AST.cpp

@@ -871,4 +871,51 @@ Value ThrowStatement::execute(Interpreter& interpreter) const
     return interpreter.throw_exception(value);
 }
 
+Value SwitchStatement::execute(Interpreter& interpreter) const
+{
+    (void)interpreter;
+    return {};
+}
+
+Value SwitchCase::execute(Interpreter& interpreter) const
+{
+    (void)interpreter;
+    return {};
+}
+
+Value BreakStatement::execute(Interpreter& interpreter) const
+{
+    (void)interpreter;
+    return {};
+}
+
+void SwitchStatement::dump(int indent) const
+{
+    ASTNode::dump(indent);
+    m_discriminant->dump(indent + 1);
+    for (auto& switch_case : m_cases) {
+        switch_case.dump(indent + 1);
+    }
+}
+
+void SwitchCase::dump(int indent) const
+{
+    ASTNode::dump(indent);
+    print_indent(indent);
+    if (m_test) {
+        printf("(Test)\n");
+        m_test->dump(indent + 1);
+    } else {
+        printf("(Default)\n");
+    }
+    print_indent(indent);
+    printf("(Consequent)\n");
+    int i = 0;
+    for (auto& statement : m_consequent) {
+        print_indent(indent);
+        printf("[%d]\n", i++);
+        statement.dump(indent + 1);
+    }
+}
+
 }

Libraries/LibJS/AST.h

@@ -496,7 +496,7 @@ public:
     }
 
 private:
-    virtual const char * class_name() const override { return "NewExpression"; }
+    virtual const char* class_name() const override { return "NewExpression"; }
     virtual bool is_new_expression() const override { return true; }
 };
 
@@ -707,4 +707,50 @@ private:
     NonnullRefPtr<Expression> m_argument;
 };
 
+class SwitchCase final : public ASTNode {
+public:
+    SwitchCase(RefPtr<Expression> test, NonnullRefPtrVector<Statement> consequent)
+        : m_test(move(test))
+        , m_consequent(move(consequent))
+    {
+    }
+
+    virtual void dump(int indent) const override;
+    virtual Value execute(Interpreter&) const override;
+
+private:
+    virtual const char* class_name() const override { return "SwitchCase"; }
+
+    RefPtr<Expression> m_test;
+    NonnullRefPtrVector<Statement> m_consequent;
+};
+
+class SwitchStatement final : public Statement {
+public:
+    SwitchStatement(NonnullRefPtr<Expression> discriminant, NonnullRefPtrVector<SwitchCase> cases)
+        : m_discriminant(move(discriminant))
+        , m_cases(move(cases))
+    {
+    }
+
+    virtual void dump(int indent) const override;
+    virtual Value execute(Interpreter&) const override;
+
+private:
+    virtual const char* class_name() const override { return "SwitchStatement"; }
+
+    NonnullRefPtr<Expression> m_discriminant;
+    NonnullRefPtrVector<SwitchCase> m_cases;
+};
+
+class BreakStatement final : public Statement {
+public:
+    BreakStatement() {}
+
+    virtual Value execute(Interpreter&) const override;
+
+private:
+    virtual const char* class_name() const override { return "BreakStatement"; }
+};
+
 }

Libraries/LibJS/Lexer.cpp

@@ -43,9 +43,12 @@ Lexer::Lexer(StringView source)
 {
     if (s_keywords.is_empty()) {
         s_keywords.set("await", TokenType::Await);
+        s_keywords.set("break", TokenType::Break);
+        s_keywords.set("case", TokenType::Case);
         s_keywords.set("catch", TokenType::Catch);
         s_keywords.set("class", TokenType::Class);
         s_keywords.set("const", TokenType::Const);
+        s_keywords.set("default", TokenType::Default);
         s_keywords.set("delete", TokenType::Delete);
         s_keywords.set("do", TokenType::Do);
         s_keywords.set("else", TokenType::Else);
@@ -60,12 +63,13 @@ Lexer::Lexer(StringView source)
         s_keywords.set("let", TokenType::Let);
         s_keywords.set("new", TokenType::New);
         s_keywords.set("null", TokenType::NullLiteral);
-        s_keywords.set("undefined", TokenType::UndefinedLiteral);
         s_keywords.set("return", TokenType::Return);
+        s_keywords.set("switch", TokenType::Switch);
         s_keywords.set("throw", TokenType::Throw);
         s_keywords.set("true", TokenType::BoolLiteral);
         s_keywords.set("try", TokenType::Try);
         s_keywords.set("typeof", TokenType::Typeof);
+        s_keywords.set("undefined", TokenType::UndefinedLiteral);
         s_keywords.set("var", TokenType::Var);
         s_keywords.set("void", TokenType::Void);
         s_keywords.set("while", TokenType::While);

Libraries/LibJS/Parser.cpp

@@ -202,6 +202,10 @@ NonnullRefPtr<Statement> Parser::parse_statement()
         return parse_throw_statement();
     case TokenType::Try:
         return parse_try_statement();
+    case TokenType::Break:
+        return parse_break_statement();
+    case TokenType::Switch:
+        return parse_switch_statement();
     default:
         if (match_expression())
             return adopt(*new ExpressionStatement(parse_expression(0)));
@@ -559,6 +563,13 @@ NonnullRefPtr<ThrowStatement> Parser::parse_throw_statement()
     return create_ast_node<ThrowStatement>(parse_expression(0));
 }
 
+NonnullRefPtr<BreakStatement> Parser::parse_break_statement()
+{
+    consume(TokenType::Break);
+    // FIXME: Handle labels.
+    return create_ast_node<BreakStatement>();
+}
+
 NonnullRefPtr<TryStatement> Parser::parse_try_statement()
 {
     consume(TokenType::Try);
@@ -578,6 +589,43 @@ NonnullRefPtr<TryStatement> Parser::parse_try_statement()
     return create_ast_node<TryStatement>(move(block), move(handler), move(finalizer));
 }
 
+NonnullRefPtr<SwitchStatement> Parser::parse_switch_statement()
+{
+    consume(TokenType::Switch);
+
+    consume(TokenType::ParenOpen);
+    auto determinant = parse_expression(0);
+    consume(TokenType::ParenClose);
+
+    consume(TokenType::CurlyOpen);
+
+    NonnullRefPtrVector<SwitchCase> cases;
+
+    while (match(TokenType::Case) || match(TokenType::Default))
+        cases.append(parse_switch_case());
+
+    consume(TokenType::CurlyClose);
+
+    return create_ast_node<SwitchStatement>(move(determinant), move(cases));
+}
+
+NonnullRefPtr<SwitchCase> Parser::parse_switch_case()
+{
+    RefPtr<Expression> test;
+
+    if (consume().type() == TokenType::Case) {
+        test = parse_expression(0);
+    }
+
+    consume(TokenType::Colon);
+
+    NonnullRefPtrVector<Statement> consequent;
+    while (match_statement())
+        consequent.append(parse_statement());
+
+    return create_ast_node<SwitchCase>(move(test), move(consequent));
+}
+
 NonnullRefPtr<CatchClause> Parser::parse_catch_clause()
 {
     consume(TokenType::Catch);
@@ -746,6 +794,8 @@ bool Parser::match_statement() const
         || type == TokenType::For
         || type == TokenType::Const
         || type == TokenType::CurlyOpen
+        || type == TokenType::Switch
+        || type == TokenType::Break
         || type == TokenType::Var;
 }
 

Libraries/LibJS/Parser.h

@@ -55,6 +55,9 @@ public:
     NonnullRefPtr<ThrowStatement> parse_throw_statement();
     NonnullRefPtr<TryStatement> parse_try_statement();
     NonnullRefPtr<CatchClause> parse_catch_clause();
+    NonnullRefPtr<SwitchStatement> parse_switch_statement();
+    NonnullRefPtr<SwitchCase> parse_switch_case();
+    NonnullRefPtr<BreakStatement> parse_break_statement();
 
     NonnullRefPtr<Expression> parse_expression(int min_precedence, Associativity associate = Associativity::Right);
     NonnullRefPtr<Expression> parse_primary_expression();

Libraries/LibJS/Token.cpp

@@ -51,8 +51,12 @@ const char* Token::name(TokenType type)
         return "BracketOpen";
     case TokenType::BracketClose:
         return "BracketClose";
+    case TokenType::Break:
+        return "Break";
     case TokenType::Caret:
         return "Caret";
+    case TokenType::Case:
+        return "Case";
     case TokenType::Catch:
         return "Catch";
     case TokenType::Class:
@@ -67,6 +71,8 @@ const char* Token::name(TokenType type)
         return "CurlyClose";
     case TokenType::CurlyOpen:
         return "CurlyOpen";
+    case TokenType::Default:
+        return "Default";
     case TokenType::Delete:
         return "Delete";
     case TokenType::Do:
@@ -179,6 +185,8 @@ const char* Token::name(TokenType type)
         return "SlashEquals";
     case TokenType::StringLiteral:
         return "StringLiteral";
+    case TokenType::Switch:
+        return "Switch";
     case TokenType::Tilde:
         return "Tilde";
     case TokenType::Try:

Libraries/LibJS/Token.h

@@ -41,7 +41,9 @@ enum class TokenType {
     BoolLiteral,
     BracketClose,
     BracketOpen,
+    Break,
     Caret,
+    Case,
     Catch,
     Class,
     Colon,
@@ -49,6 +51,7 @@ enum class TokenType {
     Const,
     CurlyClose,
     CurlyOpen,
+    Default,
     Delete,
     Do,
     DoubleAmpersand,
@@ -105,6 +108,7 @@ enum class TokenType {
     Slash,
     SlashEquals,
     StringLiteral,
+    Switch,
     Throw,
     Tilde,
     Try,