/// <summary>
/// Execute the actions encapsulated by this executor within the context of a
/// particular
/// <see cref="Antlr4.Runtime.Lexer"/>
/// .
/// <p>This method calls
/// <see cref="Antlr4.Runtime.IIntStream.Seek(int)"/>
/// to set the position of the
/// <paramref name="input"/>
///
/// <see cref="Antlr4.Runtime.ICharStream"/>
/// prior to calling
/// <see cref="ILexerAction.Execute(Antlr4.Runtime.Lexer)"/>
/// on a position-dependent action. Before the
/// method returns, the input position will be restored to the same position
/// it was in when the method was invoked.</p>
/// </summary>
/// <param name="lexer">The lexer instance.</param>
/// <param name="input">
/// The input stream which is the source for the current token.
/// When this method is called, the current
/// <see cref="Antlr4.Runtime.IIntStream.Index()"/>
/// for
/// <paramref name="input"/>
/// should be the start of the following token, i.e. 1
/// character past the end of the current token.
/// </param>
/// <param name="startIndex">
/// The token start index. This value may be passed to
/// <see cref="Antlr4.Runtime.IIntStream.Seek(int)"/>
/// to set the
/// <paramref name="input"/>
/// position to the beginning
/// of the token.
/// </param>
public virtual void Execute(Lexer lexer, ICharStream input, int startIndex)
{
bool requiresSeek = false;
int stopIndex = input.Index;
try
{
foreach (ILexerAction lexerAction in lexerActions)
{
ILexerAction action = lexerAction;
if (action is LexerIndexedCustomAction)
{
int offset = ((LexerIndexedCustomAction)action).Offset;
input.Seek(startIndex + offset);
action = ((LexerIndexedCustomAction)action).Action;
requiresSeek = (startIndex + offset) != stopIndex;
}
else
{
if (action.IsPositionDependent)
{
input.Seek(stopIndex);
requiresSeek = false;
}
}
action.Execute(lexer);
}
}
finally
{
if (requiresSeek)
{
input.Seek(stopIndex);
}
}
}
/// <summary>
/// <inheritDoc/>
/// <p>This method calls
/// <see cref="Execute(Antlr4.Runtime.Lexer)"/>
/// on the result of
/// <see cref="Action()"/>
/// using the provided
/// <code>lexer</code>
/// .</p>
/// </summary>
public void Execute(Lexer lexer)
{
// assume the input stream position was properly set by the calling code
action.Execute(lexer);
}
