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LibJS: Add basic support for (scoped) variables

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It's now possible to assign expressions to variables. The variables are
put into the current scope of the interpreter.

Variable lookup follows the scope chain, ending in the global object.
This commit is contained in:
Andreas Kling 2020-03-09 21:13:55 +01:00
parent ac3c19b91c
commit 1382dbc5e1
5 changed files with 224 additions and 19 deletions
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70
Libraries/LibJS/AST.h
View file

@ -40,6 +40,7 @@ public:
virtual const char* class_name() const = 0;
virtual Value execute(Interpreter&) const = 0;
virtual void dump(int indent) const;
virtual bool is_identifier() const { return false; }
protected:
ASTNode() {}
@ -188,7 +189,7 @@ enum class BinaryOp {
class BinaryExpression : public Expression {
public:
BinaryExpression(BinaryOp op, NonnullOwnPtr<Expression> lhs, NonnullOwnPtr<Expression> rhs)
BinaryExpression(BinaryOp op, NonnullOwnPtr<ASTNode> lhs, NonnullOwnPtr<ASTNode> rhs)
: m_op(op)
, m_lhs(move(lhs))
, m_rhs(move(rhs))
@ -202,8 +203,8 @@ private:
virtual const char* class_name() const override { return "BinaryExpression"; }
BinaryOp m_op;
NonnullOwnPtr<Expression> m_lhs;
NonnullOwnPtr<Expression> m_rhs;
NonnullOwnPtr<ASTNode> m_lhs;
NonnullOwnPtr<ASTNode> m_rhs;
};
enum class LogicalOp {
@ -270,6 +271,25 @@ private:
Value m_value;
};
class Identifier final : public ASTNode {
public:
explicit Identifier(String string)
: m_string(move(string))
{
}
const String& string() const { return m_string; }
virtual Value execute(Interpreter&) const override;
virtual void dump(int indent) const override;
virtual bool is_identifier() const override { return true; }
private:
virtual const char* class_name() const override { return "Identifier"; }
String m_string;
};
class CallExpression : public Expression {
public:
explicit CallExpression(String name)
@ -288,4 +308,48 @@ private:
String m_name;
};
enum class AssignmentOp {
Assign,
};
class AssignmentExpression : public Expression {
public:
AssignmentExpression(AssignmentOp op, NonnullOwnPtr<ASTNode> lhs, NonnullOwnPtr<ASTNode> rhs)
: m_op(op)
, m_lhs(move(lhs))
, m_rhs(move(rhs))
{
}
virtual Value execute(Interpreter&) const override;
virtual void dump(int indent) const override;
private:
virtual const char* class_name() const override { return "AssignmentExpression"; }
AssignmentOp m_op;
NonnullOwnPtr<ASTNode> m_lhs;
NonnullOwnPtr<ASTNode> m_rhs;
};
class VariableDeclaration : public ASTNode {
public:
VariableDeclaration(NonnullOwnPtr<Identifier> name, OwnPtr<ASTNode> initializer)
: m_name(move(name))
, m_initializer(move(initializer))
{
}
const Identifier& name() const { return *m_name; }
virtual Value execute(Interpreter&) const override;
virtual void dump(int indent) const override;
private:
virtual const char* class_name() const override { return "VariableDeclaration"; }
NonnullOwnPtr<Identifier> m_name;
OwnPtr<ASTNode> m_initializer;
};
}