/// <summary>
/// 执行一个区块
/// </summary>
/// <param name="StatementList">语句列表语法树</param>
public void ExecBlock(ASTNode_StatementList StatementList)
{
foreach (ASTNode_Statement s in StatementList.Statements)
{
switch (s.Type)
{
case ASTNode.ASTType.Assignment:
{
ASTNode_Assignment tAssignment = (ASTNode_Assignment)s;
object tResult = ExecExpression(tAssignment.Expression);
if (!_Environment.ContainsKey(tAssignment.IdentifierLower))
{
_Environment.Add(tAssignment.IdentifierLower, tResult);
}
else
{
_Environment[tAssignment.IdentifierLower] = tResult;
}
}
break;
case ASTNode.ASTType.Call:
{
ASTNode_Call tCall = (ASTNode_Call)s;
applyCallOperator(tCall.Identifier, tCall.IdentifierLower, tCall.ArgList, s.LineNumber);
}
break;
case ASTNode.ASTType.ForStatement:
{
ASTNode_ForStatement tForStatement = (ASTNode_ForStatement)s;
object tFromResult = ExecExpression(tForStatement.FromExpression);
object tToResult = ExecExpression(tForStatement.ToExpression);
object tStepResult = tForStatement.StepExpression == null ? null : ExecExpression(tForStatement.StepExpression);
doForLoop(
tForStatement.Identifier,
tForStatement.IdentifierLower,
tFromResult,
tToResult,
tStepResult,
tForStatement.ExecBlock,
s.LineNumber
);
}
break;
default:
throw new RuntimeException(s.LineNumber, "internal error.");
}
}
}
/// <summary>
/// 解析For语句
/// </summary>
/// <param name="Lex">词法分析器</param>
/// <returns>解析结果</returns>
private static ASTNode_ForStatement ParseForStatement(Lexer Lex)
{
ASTNode_ForStatement tRet = new ASTNode_ForStatement(Lex.Line);
// for <identifier> from <expression> to <expression> {step <expression>} <block>
MatchToken(Lex, Lexer.Token.For);
tRet.Identifier = MatchIdentifier(Lex);
MatchToken(Lex, Lexer.Token.From);
tRet.FromExpression = ParseExpression(Lex);
MatchToken(Lex, Lexer.Token.To);
tRet.ToExpression = ParseExpression(Lex);
if (TryMatchToken(Lex, Lexer.Token.Step))
{
tRet.StepExpression = ParseExpression(Lex);
}
tRet.ExecBlock = ParseBlock(Lex);
return(tRet);
}