/// <summary>
/// Reads an identifier token.
/// </summary>
/// <param name="firstChar"> The first character of the identifier. </param>
/// <returns> An identifier token, literal token or a keyword token. </returns>
private Token ReadIdentifier(int firstChar)
{
// Process the first character.
var name = new StringBuilder();
if (firstChar == '\\')
{
// Unicode escape sequence.
if (ReadNextChar() != 'u')
{
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid escape sequence in identifier.", this.lineNumber, this.Source.Path);
}
firstChar = ReadHexEscapeSequence(4);
if (IsIdentifierChar(firstChar) == false)
{
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid character in identifier.", this.lineNumber, this.Source.Path);
}
}
name.Append((char)firstChar);
// Read characters until we hit the first non-identifier character.
while (true)
{
int c = this.reader.Peek();
if (IsIdentifierChar(c) == false || c == -1)
{
break;
}
if (c == '\\')
{
// Unicode escape sequence.
ReadNextChar();
if (ReadNextChar() != 'u')
{
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid escape sequence in identifier.", this.lineNumber, this.Source.Path);
}
c = ReadHexEscapeSequence(4);
if (IsIdentifierChar(c) == false)
{
throw new JavaScriptException(this.engine, "SyntaxError", "Invalid character in identifier.", this.lineNumber, this.Source.Path);
}
name.Append((char)c);
}
else
{
// Add the character we peeked at to the identifier name.
name.Append((char)c);
// Advance the input stream.
ReadNextChar();
}
}
// Check if the identifier is actually a keyword, boolean literal, or null literal.
return(KeywordToken.FromString(name.ToString(), this.engine.CompatibilityMode, this.StrictMode));
}
/// <summary>
/// Declares a variable or function in this scope. This will be initialized with the value
/// of the given expression.
/// </summary>
/// <param name="keyword"> The keyword that was used to declare the variable (var, let or
/// const). </param>
/// <param name="name"> The name of the variable. </param>
/// <param name="hoistedFunction"> The function value to hoist to the top of the scope.
/// Should be <c>null</c> for everything except function declarations. </param>
/// <returns> A reference to the variable that was declared. </returns>
internal void DeclareVariable(KeywordToken keyword, string name, FunctionExpression hoistedFunction = null)
{
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
// If variables cannot be declared in the scope, try the parent scope instead.
var declarationScope = this;
if (keyword == KeywordToken.Var)
{
while (declarationScope != null && (declarationScope.Type == ScopeType.Block || declarationScope.Type == ScopeType.With))
{
declarationScope = declarationScope.ParentScope;
}
}
if (declarationScope != null && !declarationScope.variables.ContainsKey(name))
{
// This is a local variable that has not been declared before.
var variable = new DeclaredVariable()
{
Scope = declarationScope,
Index = declarationScope.variables.Count,
Keyword = keyword,
Name = name,
};
declarationScope.variables.Add(name, variable);
}
if (hoistedFunction != null)
{
var hoistedScope = this;
while (hoistedScope != null && hoistedScope.Type == ScopeType.Block)
{
hoistedScope = hoistedScope.ParentScope;
}
if (hoistedScope.hoistedFunctions == null)
{
hoistedScope.hoistedFunctions = new Dictionary <string, FunctionExpression>();
}
hoistedScope.hoistedFunctions[name] = hoistedFunction;
}
}
/// <summary>
/// Parses a var, let or const statement.
/// </summary>
/// <param name="keyword"> Indicates which type of statement is being parsed. Must be var,
/// let or const. </param>
/// <returns> A variable declaration statement. </returns>
private VarStatement ParseVarLetOrConst(KeywordToken keyword)
{
var result = new VarStatement(this.labelsForCurrentStatement, keyword == KeywordToken.Var ? this.currentVarScope : this.currentLetScope);
// Read past the first token (var, let or const).
this.Expect(keyword);
// Keep track of the start of the statement so that source debugging works correctly.
var start = this.PositionAfterWhitespace;
// There can be multiple declarations.
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.currentVarScope.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 or a comma.
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);
}
// Add the declaration to the result.
result.Declarations.Add(declaration);
// Check if we are at the end of the statement.
if (this.AtValidEndOfStatement() == true && this.nextToken != PunctuatorToken.Comma)
break;
// 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;
}
// Consume the end of the statement.
this.ExpectEndOfStatement();
return result;
}
public VariableDeclaration(KeywordToken keyword, string name)
{
Keyword = keyword;
VariableName = name;
}