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LibJS: Add Javascript lexer and parser

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This adds a basic Javascript lexer and parser. It can parse the
currently existing demo programs. More work needs to be done to
turn it into a complete parser than can parse arbitrary JS Code.

The lexer outputs tokens with preceeding whitespace and comments
in the trivia member. This should allow us to generate the exact
source code by concatenating the generated tokens.

The parser is written in a way that it always returns a complete
syntax tree. Error conditions are represented as nodes in the
tree. This simplifies the code and allows it to be used as an
early stage parser, e.g for parsing JS documents in an IDE while
editing the source code.:
This commit is contained in:
Stephan Unverwerth 2020-03-11 19:27:43 +01:00 • committed by Andreas Kling
parent 17705d23fb
commit f3a9eba987
11 changed files with 1069 additions and 36 deletions
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16
Libraries/LibJS/AST.cpp
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@ -44,6 +44,11 @@ Value FunctionDeclaration::execute(Interpreter& interpreter) const
return Value(function);
}
Value ExpressionStatement::execute(Interpreter& interpreter) const
{
return m_expression->execute(interpreter);
}
Value CallExpression::execute(Interpreter& interpreter) const
{
if (name() == "$gc") {
@ -61,7 +66,7 @@ Value CallExpression::execute(Interpreter& interpreter) const
Value ReturnStatement::execute(Interpreter& interpreter) const
{
auto value = argument().execute(interpreter);
auto value = argument() ? argument()->execute(interpreter) : js_undefined();
interpreter.do_return();
return value;
}
@ -310,7 +315,8 @@ void FunctionDeclaration::dump(int indent) const
void ReturnStatement::dump(int indent) const
{
ASTNode::dump(indent);
argument().dump(indent + 1);
if (argument())
argument()->dump(indent + 1);
}
void IfStatement::dump(int indent) const
@ -413,6 +419,12 @@ void ObjectExpression::dump(int indent) const
ASTNode::dump(indent);
}
void ExpressionStatement::dump(int indent) const
{
ASTNode::dump(indent);
m_expression->dump(indent + 1);
}
Value ObjectExpression::execute(Interpreter& interpreter) const
{
return Value(interpreter.heap().allocate<Object>());