/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals() { NonDefaultSourceSpanBehavior = true };
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
generator.BeginExceptionBlock();
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
if (this.CatchBlock != null)
{
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(JavaScriptException));
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
var branches = new List<ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
switchLabels[i] = generator.CreateLabel();
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Parses a for statement or a for-in statement.
/// </summary>
/// <returns> A for statement or a for-in statement. </returns>
private Statement ParseFor()
{
// Consume the for keyword.
this.Expect(KeywordToken.For);
// Read the left parenthesis.
this.Expect(PunctuatorToken.LeftParenthesis);
// The initialization statement.
Statement initializationStatement = null;
// The for-in expression needs a variable to assign to. Is null for a regular for statement.
IReferenceExpression forInReference = null;
// Keep track of the start of the statement so that source debugging works correctly.
var start = this.PositionAfterWhitespace;
if (this.nextToken == KeywordToken.Var)
{
// Read past the var token.
this.Expect(KeywordToken.Var);
// There can be multiple initializers (but not for for-in statements).
var varStatement = new VarStatement(this.labelsForCurrentStatement, this.currentScope);
initializationStatement = varStatement;
// Only a simple variable name is allowed for for-in statements.
bool cannotBeForIn = false;
while (true)
{
var declaration = new VariableDeclaration();
// The next token must be a variable name.
declaration.VariableName = this.ExpectIdentifier();
ValidateVariableName(declaration.VariableName);
// Add the variable to the current function's list of local variables.
this.currentScope.DeclareVariable(declaration.VariableName,
this.context == CodeContext.Function ? null : new LiteralExpression(Undefined.Value),
writable: true, deletable: this.context == CodeContext.Eval);
// The next token is either an equals sign (=), a semi-colon, a comma, or the "in" keyword.
if (this.nextToken == PunctuatorToken.Assignment)
{
// Read past the equals token (=).
this.Expect(PunctuatorToken.Assignment);
// Read the setter expression.
declaration.InitExpression = ParseExpression(PunctuatorToken.Semicolon, PunctuatorToken.Comma);
// Record the portion of the source document that will be highlighted when debugging.
declaration.SourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
// This is a regular for statement.
cannotBeForIn = true;
}
// Add the declaration to the initialization statement.
varStatement.Declarations.Add(declaration);
if (this.nextToken == PunctuatorToken.Semicolon)
{
// This is a regular for statement.
break;
}
else if (this.nextToken == KeywordToken.In && cannotBeForIn == false)
{
// This is a for-in statement.
forInReference = new NameExpression(this.currentScope, declaration.VariableName);
break;
}
else if (this.nextToken != PunctuatorToken.Comma)
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Unexpected token {0}", Token.ToText(this.nextToken)), this.LineNumber, this.SourcePath);
// Read past the comma token.
this.Expect(PunctuatorToken.Comma);
// Keep track of the start of the statement so that source debugging works correctly.
start = this.PositionAfterWhitespace;
// Multiple initializers are not allowed in for-in statements.
cannotBeForIn = true;
}
// Record the portion of the source document that will be highlighted when debugging.
varStatement.SourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
}
else
{
// Not a var initializer - can be a simple variable name then "in" or any expression ending with a semi-colon.
// The expression can be empty.
if (this.nextToken != PunctuatorToken.Semicolon)
{
// Parse an expression.
var initializationExpression = ParseExpression(PunctuatorToken.Semicolon, KeywordToken.In);
// Record debug info for the expression.
initializationStatement = new ExpressionStatement(initializationExpression);
initializationStatement.SourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
if (this.nextToken == KeywordToken.In)
{
// This is a for-in statement.
if ((initializationExpression is IReferenceExpression) == false)
throw new JavaScriptException(this.engine, "ReferenceError", "Invalid left-hand side in for-in", this.LineNumber, this.SourcePath);
forInReference = (IReferenceExpression)initializationExpression;
}
}
}
if (forInReference != null)
{
// for (x in y)
// for (var x in y)
var result = new ForInStatement(this.labelsForCurrentStatement);
result.Variable = forInReference;
result.VariableSourceSpan = initializationStatement.SourceSpan;
// Consume the "in".
this.Expect(KeywordToken.In);
// Parse the right-hand-side expression.
start = this.PositionAfterWhitespace;
result.TargetObject = ParseExpression(PunctuatorToken.RightParenthesis);
result.TargetObjectSourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
// Read the right parenthesis.
this.Expect(PunctuatorToken.RightParenthesis);
// Read the statements that will be executed in the loop body.
result.Body = ParseStatement();
return result;
}
else
{
var result = new ForStatement(this.labelsForCurrentStatement);
// Set the initialization statement.
if (initializationStatement != null)
result.InitStatement = initializationStatement;
// Read the semicolon.
this.Expect(PunctuatorToken.Semicolon);
// Parse the optional condition expression.
// Note: if the condition is omitted then it is considered to always be true.
if (this.nextToken != PunctuatorToken.Semicolon)
{
start = this.PositionAfterWhitespace;
result.ConditionStatement = new ExpressionStatement(ParseExpression(PunctuatorToken.Semicolon));
result.ConditionStatement.SourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
}
// Read the semicolon.
// Note: automatic semicolon insertion never inserts a semicolon in the header of a
// for statement.
this.Expect(PunctuatorToken.Semicolon);
// Parse the optional increment expression.
if (this.nextToken != PunctuatorToken.RightParenthesis)
{
start = this.PositionAfterWhitespace;
result.IncrementStatement = new ExpressionStatement(ParseExpression(PunctuatorToken.RightParenthesis));
result.IncrementStatement.SourceSpan = new SourceCodeSpan(start, this.PositionBeforeWhitespace);
}
// Read the right parenthesis.
this.Expect(PunctuatorToken.RightParenthesis);
// Read the statements that will be executed in the loop body.
result.Body = ParseStatement();
return result;
}
}
/// <summary>
/// Generates IL for the script.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
protected override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Method signature: object FunctionDelegate(Compiler.Scope scope, object thisObject, Library.FunctionInstance functionObject, object[] arguments)
// Initialize the scope (note: the initial scope for a function is always declarative).
this.InitialScope.GenerateScopeCreation(generator, optimizationInfo);
// Verify the scope is correct.
VerifyScope(generator);
// In ES3 the "this" value must be an object. See 10.4.3 in the spec.
if (this.StrictMode == false && this.MethodOptimizationHints.HasThis == true)
{
// if (thisObject == null || thisObject == Null.Value || thisObject == Undefined.Value)
EmitHelpers.LoadThis(generator);
generator.LoadNull();
generator.CompareEqual();
EmitHelpers.LoadThis(generator);
EmitHelpers.EmitNull(generator);
generator.CompareEqual();
generator.BitwiseOr();
EmitHelpers.LoadThis(generator);
EmitHelpers.EmitUndefined(generator);
generator.CompareEqual();
generator.BitwiseOr();
// {
var startOfFalse = generator.CreateLabel();
generator.BranchIfFalse(startOfFalse);
// thisObject = engine.Global;
EmitHelpers.LoadScriptEngine(generator);
generator.Call(ReflectionHelpers.ScriptEngine_Global);
// } else {
var endOfIf = generator.CreateLabel();
generator.Branch(endOfIf);
generator.DefineLabelPosition(startOfFalse);
// thisObject = TypeConverter.ToObject(thisObject);
EmitHelpers.LoadThis(generator);
EmitConversion.ToObject(generator, PrimitiveType.Any);
// }
generator.DefineLabelPosition(endOfIf);
EmitHelpers.StoreThis(generator);
}
// Transfer the function name into the scope.
if (string.IsNullOrEmpty(this.Name) == false &&
this.ArgumentNames.Contains(this.Name) == false &&
optimizationInfo.MethodOptimizationHints.HasVariable(this.Name))
{
EmitHelpers.LoadFunction(generator);
var functionName = new NameExpression(this.InitialScope, this.Name);
functionName.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
// Transfer the arguments object into the scope.
if (this.MethodOptimizationHints.HasArguments == true && this.ArgumentNames.Contains("arguments") == false)
{
// prototype
EmitHelpers.LoadScriptEngine(generator);
generator.Call(ReflectionHelpers.ScriptEngine_Object);
generator.Call(ReflectionHelpers.FunctionInstance_InstancePrototype);
// callee
EmitHelpers.LoadFunction(generator);
generator.CastClass(typeof(Library.UserDefinedFunction));
// scope
EmitHelpers.LoadScope(generator);
generator.CastClass(typeof(DeclarativeScope));
// argumentValues
EmitHelpers.LoadArgumentsArray(generator);
generator.NewObject(ReflectionHelpers.Arguments_Constructor);
var arguments = new NameExpression(this.InitialScope, "arguments");
arguments.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
// Transfer the argument values into the scope.
// Note: the arguments array can be smaller than expected.
if (this.ArgumentNames.Count > 0)
{
var endOfArguments = generator.CreateLabel();
for (int i = 0; i < this.ArgumentNames.Count; i++)
{
// Check if a duplicate argument name exists.
bool duplicate = false;
for (int j = i + 1; j < this.ArgumentNames.Count; j++)
if (this.ArgumentNames[i] == this.ArgumentNames[j])
{
duplicate = true;
break;
}
if (duplicate == true)
continue;
// Check if an array element exists.
EmitHelpers.LoadArgumentsArray(generator);
generator.LoadArrayLength();
generator.LoadInt32(i);
generator.BranchIfLessThanOrEqual(endOfArguments);
// Store the array element in the scope.
EmitHelpers.LoadArgumentsArray(generator);
generator.LoadInt32(i);
generator.LoadArrayElement(typeof(object));
var argument = new NameExpression(this.InitialScope, this.ArgumentNames[i]);
argument.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
generator.DefineLabelPosition(endOfArguments);
}
// Initialize any declarations.
this.InitialScope.GenerateDeclarations(generator, optimizationInfo);
//EmitHelpers.LoadScope(generator);
//EmitConversion.ToObject(generator, PrimitiveType.Any);
//generator.Pop();
// Generate code for the body of the function.
this.AbstractSyntaxTree.GenerateCode(generator, optimizationInfo);
// Define the return target - this is where the return statement jumps to.
// ReturnTarget can be null if there were no return statements.
if (optimizationInfo.ReturnTarget != null)
generator.DefineLabelPosition(optimizationInfo.ReturnTarget);
// Load the return value. If the variable is null, there were no return statements.
if (optimizationInfo.ReturnVariable != null)
// Return the value stored in the variable. Will be null if execution hits the end
// of the function without encountering any return statements.
generator.LoadVariable(optimizationInfo.ReturnVariable);
else
// There were no return statements - return null.
generator.LoadNull();
}
/// <summary>
/// Generates code that initializes the variable and function declarations.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
internal virtual void GenerateDeclarations(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Initialize the declared variables and functions.
foreach (var variable in this.variables.Values)
{
// When a scope is reused, i.e. with an eval(), do not reinitialize the variables.
if (variable.Initialized == true)
continue;
if (variable.ValueAtTopOfScope != null)
{
// Emit the initialization code.
if (this is ObjectScope)
{
// Determine the property attributes.
var attributes = Library.PropertyAttributes.Enumerable;
if (variable.Writable == true)
attributes |= Library.PropertyAttributes.Writable;
if (variable.Deletable == true)
attributes |= Library.PropertyAttributes.Configurable;
// bool DefineProperty(string propertyName, PropertyDescriptor descriptor, bool throwOnError)
EmitHelpers.LoadScope(generator);
generator.CastClass(typeof(ObjectScope));
generator.Call(ReflectionHelpers.ObjectScope_ScopeObject);
generator.LoadString(variable.Name);
variable.ValueAtTopOfScope.GenerateCode(generator, optimizationInfo);
EmitConversion.Convert(generator, variable.ValueAtTopOfScope.ResultType, PrimitiveType.Any, optimizationInfo);
generator.LoadInt32((int)attributes);
generator.NewObject(ReflectionHelpers.PropertyDescriptor_Constructor2);
generator.LoadBoolean(false);
generator.Call(ReflectionHelpers.ObjectInstance_DefineProperty);
generator.Pop();
}
else
{
variable.ValueAtTopOfScope.GenerateCode(generator, optimizationInfo);
var name = new NameExpression(this, variable.Name);
name.GenerateSet(generator, optimizationInfo, variable.ValueAtTopOfScope.ResultType, false);
}
// Mark the variable as having been initialized.
variable.Initialized = true;
}
}
}
/// <summary>
/// Parses a javascript expression.
/// </summary>
/// <param name="endToken"> A token that indicates the end of the expression. </param>
/// <returns> An expression tree that represents the expression. </returns>
private Expression ParseExpression(params Token[] endTokens)
{
// The root of the expression tree.
Expression root = null;
// The active operator, i.e. the one last encountered.
OperatorExpression unboundOperator = null;
while (this.nextToken != null)
{
if (this.nextToken is LiteralToken ||
this.nextToken is IdentifierToken ||
this.nextToken == KeywordToken.Function ||
this.nextToken == KeywordToken.This ||
this.nextToken == PunctuatorToken.LeftBrace ||
(this.nextToken == PunctuatorToken.LeftBracket && this.expressionState == ParserExpressionState.Literal) ||
(this.nextToken is KeywordToken && unboundOperator != null && unboundOperator.OperatorType == OperatorType.MemberAccess && this.expressionState == ParserExpressionState.Literal))
{
// If a literal was found where an operator was expected, insert a semi-colon
// automatically (if this would fix the error and a line terminator was
// encountered) or throw an error.
if (this.expressionState != ParserExpressionState.Literal)
{
// Check for automatic semi-colon insertion.
if (Array.IndexOf(endTokens, PunctuatorToken.Semicolon) >= 0 && this.consumedLineTerminator == true)
break;
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Expected operator but found {0}", Token.ToText(this.nextToken)), this.LineNumber, this.SourcePath);
}
// New in ECMAScript 5 is the ability to use keywords as property names.
if ((this.nextToken is KeywordToken || (this.nextToken is LiteralToken && ((LiteralToken)this.nextToken).IsKeyword == true)) &&
unboundOperator != null &&
unboundOperator.OperatorType == OperatorType.MemberAccess &&
this.expressionState == ParserExpressionState.Literal)
{
this.nextToken = new IdentifierToken(this.nextToken.Text);
}
Expression terminal;
if (this.nextToken is LiteralToken)
// If the token is a literal, convert it to a literal expression.
terminal = new LiteralExpression(((LiteralToken)this.nextToken).Value);
else if (this.nextToken is IdentifierToken)
{
// If the token is an identifier, convert it to a NameExpression.
var identifierName = ((IdentifierToken)this.nextToken).Name;
terminal = new NameExpression(this.currentScope, identifierName);
// Record each occurance of a variable name.
if (unboundOperator == null || unboundOperator.OperatorType != OperatorType.MemberAccess)
this.methodOptimizationHints.EncounteredVariable(identifierName);
}
else if (this.nextToken == KeywordToken.This)
{
// Convert "this" to an expression.
terminal = new ThisExpression();
// Add method optimization info.
this.methodOptimizationHints.HasThis = true;
}
else if (this.nextToken == PunctuatorToken.LeftBracket)
// Array literal.
terminal = ParseArrayLiteral();
else if (this.nextToken == PunctuatorToken.LeftBrace)
// Object literal.
terminal = ParseObjectLiteral();
else if (this.nextToken == KeywordToken.Function)
terminal = ParseFunctionExpression();
else
throw new InvalidOperationException("Unsupported literal type.");
// Push the literal to the most recent unbound operator, or, if there is none, to
// the root of the tree.
if (root == null)
{
// This is the first term in an expression.
root = terminal;
}
else
{
Debug.Assert(unboundOperator != null && unboundOperator.AcceptingOperands == true);
unboundOperator.Push(terminal);
}
}
else if (this.nextToken is PunctuatorToken || this.nextToken is KeywordToken)
{
// The token is an operator (o1).
Operator newOperator = OperatorFromToken(this.nextToken, postfixOrInfix: this.expressionState == ParserExpressionState.Operator);
// Make sure the token is actually an operator and not just a random keyword.
if (newOperator == null)
{
// Check if the token is an end token, for example a semi-colon.
if (Array.IndexOf(endTokens, this.nextToken) >= 0)
break;
// Check for automatic semi-colon insertion.
if (Array.IndexOf(endTokens, PunctuatorToken.Semicolon) >= 0 && (this.consumedLineTerminator == true || this.nextToken == PunctuatorToken.RightBrace))
break;
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Unexpected token {0} in expression.", Token.ToText(this.nextToken)), this.LineNumber, this.SourcePath);
}
// Post-fix increment and decrement cannot have a line terminator in between
// the operator and the operand.
if (this.consumedLineTerminator == true && (newOperator == Operator.PostIncrement || newOperator == Operator.PostDecrement))
break;
// There are four possibilities:
// 1. The token is the second of a two-part operator (for example, the ':' in a
// conditional operator. In this case, we need to go up the tree until we find
// an instance of the operator and make that the active unbound operator.
if (this.nextToken == newOperator.SecondaryToken)
{
// Traverse down the tree looking for the parent operator that corresponds to
// this token.
OperatorExpression parentExpression = null;
var node = root as OperatorExpression;
while (node != null)
{
if (node.Operator.Token == newOperator.Token && node.SecondTokenEncountered == false)
parentExpression = node;
if (node == unboundOperator)
break;
node = node.RightBranch;
}
// If the operator was not found, then this is a mismatched token, unless
// it is the end token. For example, if an unbalanced right parenthesis is
// found in an if statement then it is merely the end of the test expression.
if (parentExpression == null)
{
// Check if the token is an end token, for example a right parenthesis.
if (Array.IndexOf(endTokens, this.nextToken) >= 0)
break;
// Check for automatic semi-colon insertion.
if (Array.IndexOf(endTokens, PunctuatorToken.Semicolon) >= 0 && this.consumedLineTerminator == true)
break;
throw new JavaScriptException(this.engine, "SyntaxError", "Mismatched closing token in expression.", this.LineNumber, this.SourcePath);
}
// Mark that we have seen the closing token.
unboundOperator = parentExpression;
unboundOperator.SecondTokenEncountered = true;
}
else
{
// Check if the token is an end token, for example the comma in a variable
// declaration.
if (Array.IndexOf(endTokens, this.nextToken) >= 0)
{
// But make sure the token isn't inside an operator.
// For example, in the expression "var x = f(a, b)" the comma does not
// indicate the start of a new variable clause because it is inside the
// function call operator.
bool insideOperator = false;
var node = root as OperatorExpression;
while (node != null)
{
if (node.Operator.SecondaryToken != null && node.SecondTokenEncountered == false)
insideOperator = true;
if (node == unboundOperator)
break;
node = node.RightBranch;
}
if (insideOperator == false)
break;
}
// All the other situations involve the creation of a new operator.
var newExpression = OperatorExpression.FromOperator(newOperator);
// 2. The new operator is a prefix operator. The new operator becomes an operand
// of the previous operator.
if (newOperator.HasLHSOperand == false)
{
if (root == null)
// "!"
root = newExpression;
else if (unboundOperator != null && unboundOperator.AcceptingOperands == true)
{
// "5 + !"
unboundOperator.Push(newExpression);
}
else
{
// "5 !" or "5 + 5 !"
// Check for automatic semi-colon insertion.
if (Array.IndexOf(endTokens, PunctuatorToken.Semicolon) >= 0 && this.consumedLineTerminator == true)
break;
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid use of prefix operator.", this.LineNumber, this.SourcePath);
}
}
else
{
// Search up the tree for an operator that has a lower precedence.
// Because we don't store the parent link, we have to traverse down the
// tree and take the last one we find instead.
OperatorExpression lowPrecedenceOperator = null;
if (unboundOperator == null ||
(newOperator.Associativity == OperatorAssociativity.LeftToRight && unboundOperator.Precedence < newOperator.Precedence) ||
(newOperator.Associativity == OperatorAssociativity.RightToLeft && unboundOperator.Precedence <= newOperator.Precedence))
{
// Performance optimization: look at the previous operator first.
lowPrecedenceOperator = unboundOperator;
}
else
{
// Search for a lower precedence operator by traversing the tree.
var node = root as OperatorExpression;
while (node != null && node != unboundOperator)
{
if ((newOperator.Associativity == OperatorAssociativity.LeftToRight && node.Precedence < newOperator.Precedence) ||
(newOperator.Associativity == OperatorAssociativity.RightToLeft && node.Precedence <= newOperator.Precedence))
lowPrecedenceOperator = node;
node = node.RightBranch;
}
}
if (lowPrecedenceOperator == null)
{
// 3. The new operator has a lower precedence (or if the associativity is left to
// right, a lower or equal precedence) than all the parent operators. The new
// operator goes to the root of the tree and the previous operator becomes the
// first operand for the new operator.
if (root != null)
newExpression.Push(root);
root = newExpression;
}
else
{
// 4. Otherwise, the new operator can steal the last operand from the previous
// operator and then put itself in the place of that last operand.
if (lowPrecedenceOperator.OperandCount == 0)
{
// "! ++"
// Check for automatic semi-colon insertion.
if (Array.IndexOf(endTokens, PunctuatorToken.Semicolon) >= 0 && this.consumedLineTerminator == true)
break;
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid use of prefix operator.", this.LineNumber, this.SourcePath);
}
newExpression.Push(lowPrecedenceOperator.Pop());
lowPrecedenceOperator.Push(newExpression);
}
}
unboundOperator = newExpression;
}
}
else
{
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Unexpected token {0} in expression", Token.ToText(this.nextToken)), this.LineNumber, this.SourcePath);
}
// Read the next token.
this.Consume(root != null && (unboundOperator == null || unboundOperator.AcceptingOperands == false) ? ParserExpressionState.Operator : ParserExpressionState.Literal);
}
// Empty expressions are invalid.
if (root == null)
throw new JavaScriptException(this.engine, "SyntaxError", string.Format("Expected an expression but found {0} instead", Token.ToText(this.nextToken)), this.LineNumber, this.SourcePath);
// Check the AST is valid.
CheckASTValidity(root);
// A literal is the next valid expression token.
this.expressionState = ParserExpressionState.Literal;
this.lexer.ParserExpressionState = expressionState;
// Resolve all the unbound operators into real operators.
return root;
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals() { NonDefaultBreakStatementBehavior = true, NonDefaultSourceSpanBehavior = true };
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// <initializer>
// if (<condition>)
// {
// <loop body>
// <increment>
// while (true) {
// if (<condition> == false)
// break;
//
// <body statements>
//
// continue-target:
// <increment>
// }
// }
// break-target:
// Set up some labels.
var continueTarget = generator.CreateLabel();
var breakTarget1 = generator.CreateLabel();
var breakTarget2 = generator.CreateLabel();
// Emit the initialization statement.
if (this.InitStatement != null)
this.InitStatement.GenerateCode(generator, optimizationInfo);
// Check the condition and jump to the end if it is false.
if (this.CheckConditionAtEnd == false && this.ConditionStatement != null)
{
optimizationInfo.MarkSequencePoint(generator, this.ConditionStatement.SourceSpan);
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget1);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget1, continueTarget, false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// Increment the loop variable.
if (this.IncrementStatement != null)
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
// Strengthen the variable types.
List<KeyValuePair<Scope.DeclaredVariable, RevertInfo>> previousVariableTypes = null;
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
if (optimizationInfo.OptimizeInferredTypes == true)
{
// Keep a record of the variable types before strengthening.
previousVariableTypes = new List<KeyValuePair<Scope.DeclaredVariable, RevertInfo>>();
var typedVariables = FindTypedVariables();
foreach (var variableAndType in typedVariables)
{
var variable = variableAndType.Key;
var variableInfo = variableAndType.Value;
if (variableInfo.Conditional == false && variableInfo.Type != variable.Type)
{
// Save the previous type so we can restore it later.
var previousType = variable.Type;
previousVariableTypes.Add(new KeyValuePair<Scope.DeclaredVariable, RevertInfo>(variable, new RevertInfo() { Type = previousType, Variable = variable.Store }));
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
variable.Store = generator.DeclareVariable(variableInfo.Type);
variable.Type = variableInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
}
// The variables must be reverted even in the presence of exceptions.
if (previousVariableTypes.Count > 0)
{
generator.BeginExceptionBlock();
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
optimizationInfo.InsideTryCatchOrFinally = true;
}
}
// The inner loop starts here.
var startOfLoop = generator.DefineLabelPosition();
// Check the condition and jump to the end if it is false.
if (this.ConditionStatement != null)
{
optimizationInfo.MarkSequencePoint(generator, this.ConditionStatement.SourceSpan);
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget2);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget2, continueTarget, labelledOnly: false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// The continue statement jumps here.
generator.DefineLabelPosition(continueTarget);
// Increment the loop variable.
if (this.IncrementStatement != null)
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
// Unconditionally branch back to the start of the loop.
generator.Branch(startOfLoop);
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget2);
// Revert the variable types.
if (previousVariableTypes != null && previousVariableTypes.Count > 0)
{
// Revert the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Revert the variable types within a finally block.
generator.BeginFinallyBlock();
foreach (var previousVariableAndType in previousVariableTypes)
{
var variable = previousVariableAndType.Key;
var variableRevertInfo = previousVariableAndType.Value;
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
var previousType = variable.Type;
variable.Store = variableRevertInfo.Variable;
variable.Type = variableRevertInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
// End the exception block.
generator.EndExceptionBlock();
}
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget1);
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals()
{
NonDefaultSourceSpanBehavior = true
};
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
{
generator.BeginExceptionBlock();
}
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
ILLocalVariable skipFinallyBlock = null;
if (this.CatchBlock != null)
{
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(Exception));
// Check the exception is catchable by calling CanCatchException(ex).
// We need to handle the case where JS code calls into .NET code which then throws
// a JavaScriptException from a different ScriptEngine.
var endOfIfLabel = generator.CreateLabel();
generator.Duplicate(); // ex
var exceptionTemporary = generator.CreateTemporaryVariable(typeof(Exception));
generator.StoreVariable(exceptionTemporary);
EmitHelpers.LoadScriptEngine(generator);
generator.LoadVariable(exceptionTemporary);
generator.ReleaseTemporaryVariable(exceptionTemporary);
generator.Call(ReflectionHelpers.ScriptEngine_CanCatchException);
generator.BranchIfTrue(endOfIfLabel);
generator.LoadBoolean(true);
if (this.FinallyBlock != null)
{
skipFinallyBlock = generator.DeclareVariable(typeof(bool), "skipFinallyBlock");
generator.StoreVariable(skipFinallyBlock);
}
generator.Rethrow();
generator.DefineLabelPosition(endOfIfLabel);
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
// If an exception was thrown that wasn't handled by the catch block, then don't
// run the finally block either. This prevents user code from being run when a
// ThreadAbortException is thrown.
var endOfFinallyBlock = generator.CreateLabel();
if (skipFinallyBlock != null)
{
var endOfSkipFinallyBlockLabel = generator.CreateLabel();
generator.LoadVariable(skipFinallyBlock);
generator.BranchIfTrue(endOfFinallyBlock);
}
var branches = new List <ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// Define the position at the end of the finally block.
generator.DefineLabelPosition(endOfFinallyBlock);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
{
switchLabels[i] = generator.CreateLabel();
}
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals();
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// Unlike in .NET, in javascript there are no restrictions on what can appear inside
// try, catch and finally blocks. The one restriction which causes problems is the
// inability to jump out of .NET finally blocks. This is required when break, continue
// or return statements appear inside of a finally block. To work around this, when
// inside a finally block these instructions throw an exception instead.
// Setting the InsideTryCatchOrFinally flag converts BR instructions into LEAVE
// instructions so that the finally block is executed correctly.
var previousInsideTryCatchOrFinally = optimizationInfo.InsideTryCatchOrFinally;
optimizationInfo.InsideTryCatchOrFinally = true;
// Finally requires two exception nested blocks.
if (this.FinallyBlock != null)
{
generator.BeginExceptionBlock();
}
// Begin the exception block.
generator.BeginExceptionBlock();
// Generate code for the try block.
this.TryBlock.GenerateCode(generator, optimizationInfo);
// Generate code for the catch block.
if (this.CatchBlock != null)
{
// Begin a catch block. The exception is on the top of the stack.
generator.BeginCatchBlock(typeof(JavaScriptException));
// Create a new DeclarativeScope.
this.CatchScope.GenerateScopeCreation(generator, optimizationInfo);
// Store the error object in the variable provided.
generator.Call(ReflectionHelpers.JavaScriptException_ErrorObject);
var catchVariable = new NameExpression(this.CatchScope, this.CatchVariableName);
catchVariable.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
// Make sure the scope is reverted even if an exception is thrown.
generator.BeginExceptionBlock();
// Emit code for the statements within the catch block.
this.CatchBlock.GenerateCode(generator, optimizationInfo);
// Revert the scope.
generator.BeginFinallyBlock();
this.CatchScope.GenerateScopeDestruction(generator, optimizationInfo);
generator.EndExceptionBlock();
}
// Generate code for the finally block.
if (this.FinallyBlock != null)
{
generator.BeginFinallyBlock();
var branches = new List <ILLabel>();
var previousStackSize = optimizationInfo.LongJumpStackSizeThreshold;
optimizationInfo.LongJumpStackSizeThreshold = optimizationInfo.BreakOrContinueStackSize;
var previousCallback = optimizationInfo.LongJumpCallback;
optimizationInfo.LongJumpCallback = (generator2, label) =>
{
// It is not possible to branch out of a finally block - therefore instead of
// generating LEAVE instructions we throw an exception then catch it to transfer
// control out of the finally block.
generator2.LoadInt32(branches.Count);
generator2.NewObject(ReflectionHelpers.LongJumpException_Constructor);
generator2.Throw();
// Record any branches that are made within the finally code.
branches.Add(label);
};
// Emit code for the finally block.
this.FinallyBlock.GenerateCode(generator, optimizationInfo);
// End the main exception block.
generator.EndExceptionBlock();
// Begin a catch block to catch any LongJumpExceptions. The exception object is on
// the top of the stack.
generator.BeginCatchBlock(typeof(LongJumpException));
if (branches.Count > 0)
{
// switch (exception.RouteID)
// {
// case 0: goto label1;
// case 1: goto label2;
// }
ILLabel[] switchLabels = new ILLabel[branches.Count];
for (int i = 0; i < branches.Count; i++)
{
switchLabels[i] = generator.CreateLabel();
}
generator.Call(ReflectionHelpers.LongJumpException_RouteID);
generator.Switch(switchLabels);
for (int i = 0; i < branches.Count; i++)
{
generator.DefineLabelPosition(switchLabels[i]);
generator.Leave(branches[i]);
}
}
// Reset the state we clobbered.
optimizationInfo.LongJumpStackSizeThreshold = previousStackSize;
optimizationInfo.LongJumpCallback = previousCallback;
}
// End the exception block.
generator.EndExceptionBlock();
// Reset the InsideTryCatchOrFinally flag.
optimizationInfo.InsideTryCatchOrFinally = previousInsideTryCatchOrFinally;
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
/// <summary>
/// Generates IL for the script.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
protected override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Method signature: object FunctionDelegate(Compiler.Scope scope, object thisObject, Library.FunctionInstance functionObject, object[] arguments)
// Initialize the scope (note: the initial scope for a function is always declarative).
this.InitialScope.GenerateScopeCreation(generator, optimizationInfo);
// In ES3 the "this" value must be an object. See 10.4.3 in the spec.
if (this.StrictMode == false && this.MethodOptimizationHints.HasThis == true)
{
// if (thisObject == null || thisObject == Null.Value || thisObject == Undefined.Value)
EmitHelpers.LoadThis(generator);
generator.LoadNull();
generator.CompareEqual();
EmitHelpers.LoadThis(generator);
EmitHelpers.EmitNull(generator);
generator.CompareEqual();
generator.BitwiseOr();
EmitHelpers.LoadThis(generator);
EmitHelpers.EmitUndefined(generator);
generator.CompareEqual();
generator.BitwiseOr();
// {
var startOfFalse = generator.CreateLabel();
generator.BranchIfFalse(startOfFalse);
// thisObject = engine.Global;
EmitHelpers.LoadScriptEngine(generator);
generator.Call(ReflectionHelpers.ScriptEngine_Global);
// } else {
var endOfIf = generator.CreateLabel();
generator.Branch(endOfIf);
generator.DefineLabelPosition(startOfFalse);
// thisObject = TypeConverter.ToObject(thisObject);
EmitHelpers.LoadThis(generator);
EmitConversion.ToObject(generator, PrimitiveType.Any, optimizationInfo);
// }
generator.DefineLabelPosition(endOfIf);
EmitHelpers.StoreThis(generator);
}
// Transfer the function name into the scope.
if (string.IsNullOrEmpty(this.Name) == false &&
(this.DeclarationType != FunctionDeclarationType.Getter && this.DeclarationType != FunctionDeclarationType.Setter) &&
this.Arguments.Any(a => a.Name == this.Name) == false &&
optimizationInfo.MethodOptimizationHints.HasVariable(this.Name))
{
EmitHelpers.LoadFunction(generator);
var functionName = new NameExpression(this.InitialScope, this.Name);
functionName.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
// Transfer the arguments object into the scope.
if (this.MethodOptimizationHints.HasArguments == true && this.Arguments.Any(a => a.Name == "arguments") == false)
{
// prototype
EmitHelpers.LoadScriptEngine(generator);
generator.Call(ReflectionHelpers.ScriptEngine_Object);
generator.Call(ReflectionHelpers.FunctionInstance_InstancePrototype);
// callee
EmitHelpers.LoadFunction(generator);
generator.CastClass(typeof(Library.UserDefinedFunction));
// scope
EmitHelpers.LoadScope(generator);
generator.CastClass(typeof(DeclarativeScope));
// argumentValues
EmitHelpers.LoadArgumentsArray(generator);
generator.NewObject(ReflectionHelpers.Arguments_Constructor);
var arguments = new NameExpression(this.InitialScope, "arguments");
arguments.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
// Transfer the argument values into the scope.
// Note: the arguments array can be smaller than expected.
if (this.Arguments.Count > 0)
{
for (int i = 0; i < this.Arguments.Count; i++)
{
// Check if a duplicate argument name exists.
bool duplicate = false;
for (int j = i + 1; j < this.Arguments.Count; j++)
{
if (this.Arguments[i].Name == this.Arguments[j].Name)
{
duplicate = true;
break;
}
}
if (duplicate == true)
{
continue;
}
var loadDefaultValue = generator.CreateLabel();
var storeValue = generator.CreateLabel();
// Check if an array element exists.
EmitHelpers.LoadArgumentsArray(generator);
generator.LoadArrayLength();
generator.LoadInt32(i);
generator.BranchIfLessThanOrEqual(loadDefaultValue);
// Load the parameter value from the parameters array.
EmitHelpers.LoadArgumentsArray(generator);
generator.LoadInt32(i);
generator.LoadArrayElement(typeof(object));
if (this.Arguments[i].DefaultValue == null)
{
// Branch to the part where it stores the value.
generator.Branch(storeValue);
// Load undefined.
generator.DefineLabelPosition(loadDefaultValue);
EmitHelpers.EmitUndefined(generator);
}
else
{
// Check if it's undefined.
generator.Duplicate();
EmitHelpers.EmitUndefined(generator);
generator.BranchIfNotEqual(storeValue);
generator.Pop();
// Load the default value.
generator.DefineLabelPosition(loadDefaultValue);
this.Arguments[i].DefaultValue.GenerateCode(generator, optimizationInfo);
EmitConversion.ToAny(generator, this.Arguments[i].DefaultValue.ResultType);
}
// Store the value in the scope.
generator.DefineLabelPosition(storeValue);
var argument = new NameExpression(this.InitialScope, this.Arguments[i].Name);
argument.GenerateSet(generator, optimizationInfo, PrimitiveType.Any, false);
}
}
// Initialize any declarations.
this.InitialScope.GenerateDeclarations(generator, optimizationInfo);
// Generate code for the body of the function.
this.AbstractSyntaxTree.GenerateCode(generator, optimizationInfo);
// Define the return target - this is where the return statement jumps to.
// ReturnTarget can be null if there were no return statements.
if (optimizationInfo.ReturnTarget != null)
{
generator.DefineLabelPosition(optimizationInfo.ReturnTarget);
}
// Load the return value. If the variable is null, there were no return statements.
if (optimizationInfo.ReturnVariable != null)
{
// Return the value stored in the variable. Will be null if execution hits the end
// of the function without encountering any return statements.
generator.LoadVariable(optimizationInfo.ReturnVariable);
}
else
{
// There were no return statements - return null.
generator.LoadNull();
}
}
/// <summary>
/// Generates CIL for the statement.
/// </summary>
/// <param name="generator"> The generator to output the CIL to. </param>
/// <param name="optimizationInfo"> Information about any optimizations that should be performed. </param>
public override void GenerateCode(ILGenerator generator, OptimizationInfo optimizationInfo)
{
// Generate code for the start of the statement.
var statementLocals = new StatementLocals()
{
NonDefaultBreakStatementBehavior = true, NonDefaultDebugInfoBehavior = true
};
GenerateStartOfStatement(generator, optimizationInfo, statementLocals);
// <initializer>
// if (<condition>)
// {
// <loop body>
// <increment>
// while (true) {
// if (<condition> == false)
// break;
//
// <body statements>
//
// continue-target:
// <increment>
// }
// }
// break-target:
// Set up some labels.
var continueTarget = generator.CreateLabel();
var breakTarget1 = generator.CreateLabel();
var breakTarget2 = generator.CreateLabel();
// Emit the initialization statement.
if (this.InitStatement != null)
{
this.InitStatement.GenerateCode(generator, optimizationInfo);
}
// Check the condition and jump to the end if it is false.
if (this.CheckConditionAtEnd == false && this.ConditionStatement != null)
{
if (optimizationInfo.DebugDocument != null)
{
generator.MarkSequencePoint(optimizationInfo.DebugDocument, this.ConditionStatement.DebugInfo);
}
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget1);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget1, continueTarget, false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// Increment the loop variable.
if (this.IncrementStatement != null)
{
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
}
// Strengthen the variable types.
List <KeyValuePair <Scope.DeclaredVariable, RevertInfo> > previousVariableTypes = null;
if (optimizationInfo.OptimizeInferredTypes == true)
{
// Keep a record of the variable types before strengthening.
previousVariableTypes = new List <KeyValuePair <Scope.DeclaredVariable, RevertInfo> >();
var typedVariables = FindTypedVariables();
foreach (var variableAndType in typedVariables)
{
var variable = variableAndType.Key;
var variableInfo = variableAndType.Value;
if (variableInfo.Conditional == false && variableInfo.Type != variable.Type)
{
// Save the previous type so we can restore it later.
var previousType = variable.Type;
previousVariableTypes.Add(new KeyValuePair <Scope.DeclaredVariable, RevertInfo>(variable, new RevertInfo()
{
Type = previousType, Variable = variable.Store
}));
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
variable.Store = generator.DeclareVariable(variableInfo.Type);
variable.Type = variableInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
}
// The variables must be reverted even in the presence of exceptions.
if (previousVariableTypes.Count > 0)
{
generator.BeginExceptionBlock();
}
}
// The inner loop starts here.
var startOfLoop = generator.DefineLabelPosition();
// Check the condition and jump to the end if it is false.
if (this.ConditionStatement != null)
{
if (optimizationInfo.DebugDocument != null)
{
generator.MarkSequencePoint(optimizationInfo.DebugDocument, this.ConditionStatement.DebugInfo);
}
this.Condition.GenerateCode(generator, optimizationInfo);
EmitConversion.ToBool(generator, this.Condition.ResultType);
generator.BranchIfFalse(breakTarget2);
}
// Emit the loop body.
optimizationInfo.PushBreakOrContinueInfo(this.Labels, breakTarget2, continueTarget, labelledOnly: false);
this.Body.GenerateCode(generator, optimizationInfo);
optimizationInfo.PopBreakOrContinueInfo();
// The continue statement jumps here.
generator.DefineLabelPosition(continueTarget);
// Increment the loop variable.
if (this.IncrementStatement != null)
{
this.IncrementStatement.GenerateCode(generator, optimizationInfo);
}
// Unconditionally branch back to the start of the loop.
generator.Branch(startOfLoop);
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget2);
// Revert the variable types.
if (previousVariableTypes != null && previousVariableTypes.Count > 0)
{
// Revert the variable types within a finally block.
generator.BeginFinallyBlock();
foreach (var previousVariableAndType in previousVariableTypes)
{
var variable = previousVariableAndType.Key;
var variableRevertInfo = previousVariableAndType.Value;
// Load the existing value.
var nameExpression = new NameExpression(variable.Scope, variable.Name);
nameExpression.GenerateGet(generator, optimizationInfo, false);
// Store the typed value.
var previousType = variable.Type;
variable.Store = variableRevertInfo.Variable;
variable.Type = variableRevertInfo.Type;
nameExpression.GenerateSet(generator, optimizationInfo, previousType, false);
}
// End the exception block.
generator.EndExceptionBlock();
}
// Define the end of the loop (actually just after).
generator.DefineLabelPosition(breakTarget1);
// Generate code for the end of the statement.
GenerateEndOfStatement(generator, optimizationInfo, statementLocals);
}
