/// <summary>
/// Parses a block of statements.
/// </summary>
/// <returns> A BlockStatement containing the statements. </returns>
/// <remarks> The value of a block statement is the value of the last statement in the block,
/// or undefined if there are no statements in the block. </remarks>
private BlockStatement ParseBlock()
{
// Consume the start brace ({).
this.Expect(PunctuatorToken.LeftBrace);
// Read zero or more statements.
var result = new BlockStatement(this.labelsForCurrentStatement);
while (true)
{
// Check for the end brace (}).
if (this.nextToken == PunctuatorToken.RightBrace)
break;
// Parse a single statement.
result.Statements.Add(ParseStatement());
}
// Consume the end brace.
this.Expect(PunctuatorToken.RightBrace);
return result;
}
// PARSE METHODS
//_________________________________________________________________________________________
/// <summary>
/// Parses javascript source code.
/// </summary>
/// <returns> An expression that can be executed to run the program represented by the
/// source code. </returns>
public Statement Parse()
{
// Read the directive prologue.
var result = new BlockStatement(new string[0]);
while (true)
{
// Check if we should stop parsing.
if (this.nextToken == this.endToken)
break;
// A directive must start with a string literal token. Record it now so that the
// escape sequence and line continuation information is not lost.
var directiveToken = this.nextToken as StringLiteralToken;
if (directiveToken == null)
break;
// Directives cannot have escape sequences or line continuations.
if (directiveToken.EscapeSequenceCount != 0 || directiveToken.LineContinuationCount != 0)
break;
// If the statement starts with a string literal, it must be an expression.
var beforeInitialToken = this.PositionAfterWhitespace;
var expression = ParseExpression(PunctuatorToken.Semicolon);
// The statement must be added to the AST so that eval("'test'") works.
var initialStatement = new ExpressionStatement(this.labelsForCurrentStatement, expression);
initialStatement.SourceSpan = new SourceCodeSpan(beforeInitialToken, this.PositionBeforeWhitespace);
result.Statements.Add(initialStatement);
// In order for the expression to be part of the directive prologue, it must
// consist solely of a string literal.
if ((expression is LiteralExpression) == false)
break;
// Strict mode directive.
if (directiveToken.Value == "use strict")
this.StrictMode = true;
// Read the end of the statement. This must happen last so that the lexer has a
// chance to act on the strict mode flag.
ExpectEndOfStatement();
}
// Call the directive prologue callback.
if (this.DirectivePrologueProcessedCallback != null)
this.DirectivePrologueProcessedCallback(this);
// Read zero or more regular statements.
while (true)
{
// Check if we should stop parsing.
if (this.nextToken == this.endToken)
break;
// Parse a single statement.
result.Statements.Add(ParseStatement());
}
return result;
}