/// <summary>
/// Creates a new ExpressionStatement instance. By default, this expression does not
/// contribute to the result of an eval().
/// </summary>
/// <param name="expression"> The underlying expression. </param>
public ExpressionStatement(Expression expression)
: base(null)
{
if (expression == null)
throw new ArgumentNullException("expression");
this.Expression = expression;
}
/// <summary>
/// Creates a new ExpressionStatement instance. By default, this expression does
/// contribute to the result of an eval().
/// </summary>
/// <param name="labels"> The labels that are associated with this statement. </param>
/// <param name="expression"> The underlying expression. </param>
public ExpressionStatement(IList<string> labels, Expression expression)
: base(labels)
{
if (expression == null)
throw new ArgumentNullException("expression");
this.Expression = expression;
this.ContributesToEvalResult = true;
}
/// <summary>
/// Declares a variable or function in this scope. This will be initialized with the value
/// of the given expression.
/// </summary>
/// <param name="name"> The name of the variable. </param>
/// <param name="valueAtTopOfScope"> The value of the variable at the top of the scope. </param>
/// <param name="writable"> <c>true</c> if the variable can be modified; <c>false</c>
/// otherwise. </param>
/// <param name="deletable"> <c>true</c> if the variable can be deleted; <c>false</c>
/// otherwise. </param>
/// <returns> A reference to the variable that was declared. </returns>
internal override DeclaredVariable DeclareVariable(string name, Expression valueAtTopOfScope = null, bool writable = true, bool deletable = false)
{
// Variables can be added to a declarative scope using eval(). When this happens the
// values array needs to be resized. That check happens here.
if (this.values != null && this.DeclaredVariableCount >= this.Values.Length)
Array.Resize(ref this.values, this.DeclaredVariableCount + 10);
// Delegate to the Scope class.
return base.DeclareVariable(name, valueAtTopOfScope, writable, deletable);
}
/// <summary>
/// Checks the given AST is valid.
/// </summary>
/// <param name="root"> The root of the AST. </param>
private void CheckASTValidity(Expression root)
{
// Push the root expression onto a stack.
Stack<Expression> stack = new Stack<Expression>();
stack.Push(root);
while (stack.Count > 0)
{
// Pop the next expression from the stack.
var expression = stack.Pop() as OperatorExpression;
// Only operator expressions are checked for validity.
if (expression == null)
continue;
// Check the operator expression has the right number of operands.
if (expression.Operator.IsValidNumberOfOperands(expression.OperandCount) == false)
throw new JavaScriptException(this.engine, "SyntaxError", "Wrong number of operands", this.LineNumber, this.SourcePath);
// Check the operator expression is closed.
if (expression.Operator.SecondaryToken != null && expression.SecondTokenEncountered == false)
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Missing closing token '{0}'", expression.Operator.SecondaryToken.Text), this.LineNumber, this.SourcePath);
// Check the child nodes.
for (int i = 0; i < expression.OperandCount; i++)
stack.Push(expression.GetRawOperand(i));
}
}
/// <summary>
/// Declares a variable or function in this scope. This will be initialized with the value
/// of the given expression.
/// </summary>
/// <param name="name"> The name of the variable. </param>
/// <param name="valueAtTopOfScope"> The value of the variable at the top of the scope.
/// Can be <c>null</c> to indicate the variable does not need initializing. </param>
/// <param name="writable"> <c>true</c> if the variable can be modified; <c>false</c>
/// otherwise. Defaults to <c>true</c>. </param>
/// <param name="deletable"> <c>true</c> if the variable can be deleted; <c>false</c>
/// otherwise. Defaults to <c>true</c>. </param>
/// <returns> A reference to the variable that was declared. </returns>
internal virtual DeclaredVariable DeclareVariable(string name, Expression valueAtTopOfScope = null, bool writable = true, bool deletable = false)
{
if (name == null)
throw new ArgumentNullException("name");
// If variables cannot be declared in the scope, try the parent scope instead.
if (this.CanDeclareVariables == false)
{
if (this.ParentScope == null)
throw new InvalidOperationException("Invalid scope chain.");
return this.ParentScope.DeclareVariable(name, valueAtTopOfScope, writable, deletable);
}
DeclaredVariable variable;
this.variables.TryGetValue(name, out variable);
if (variable == null)
{
// This is a local variable that has not been declared before.
variable = new DeclaredVariable() { Scope = this, Index = this.variables.Count, Name = name, Writable = writable, Deletable = deletable };
this.variables.Add(name, variable);
}
// Set the initial value, if one was provided.
if (valueAtTopOfScope != null)
{
// Function expressions override literals.
if ((valueAtTopOfScope is LiteralExpression && variable.ValueAtTopOfScope is FunctionExpression) == false)
variable.ValueAtTopOfScope = valueAtTopOfScope;
}
return variable;
}
/// <summary>
/// Creates a simple variable assignment expression.
/// </summary>
/// <param name="scope"> The scope the variable is defined within. </param>
/// <param name="name"> The name of the variable to set. </param>
/// <param name="value"> The value to set the variable to. </param>
public AssignmentExpression(Scope scope, string name, Expression value)
: base(Operator.Assignment)
{
this.Push(new NameExpression(scope, name));
this.Push(value);
}
/// <summary>
/// Creates a new instance of BinaryJSExpression.
/// </summary>
/// <param name="operator"> The binary operator to base this expression on. </param>
/// <param name="left"> The operand on the left side of the operator. </param>
/// <param name="right"> The operand on the right side of the operator. </param>
public BinaryExpression(Operator @operator, Expression left, Expression right)
: base(@operator)
{
this.Push(left);
this.Push(right);
}
/// <summary>
/// Creates a new object scope for use inside a with statement.
/// </summary>
/// <param name="parentScope"> A reference to the parent scope. Can not be <c>null</c>. </param>
/// <param name="scopeObject"> An expression that evaluates to the object to use. </param>
/// <returns> A new ObjectScope instance. </returns>
internal static ObjectScope CreateWithScope(Scope parentScope, Expression scopeObject)
{
if (parentScope == null)
throw new ArgumentException("With scopes must have a parent scope.");
return new ObjectScope(parentScope) { ScopeObjectExpression = scopeObject, ProvidesImplicitThisValue = true, CanDeclareVariables = false };
}
/// <summary>
/// Adds an operand.
/// </summary>
/// <param name="operand"> The expression representing the operand to add. </param>
public void Push(Expression operand)
{
if (this.OperandCount >= this.operands.Length)
throw new InvalidOperationException("Too many operands.");
this.operands[this.OperandCount] = operand;
this.OperandCount ++;
}
