/// <summary>
/// 解析一条赋值或者调用指令
/// </summary>
/// <param name="Lex">词法分析器</param>
/// <returns>解析结果</returns>
private static ASTNode_Statement ParseAssignmentOrCall(Lexer Lex)
{
string tIdentifier = MatchIdentifier(Lex);
if (TryMatchToken(Lex, Lexer.Token.LeftBracket)) // call
{
ASTNode_Call tCall = new ASTNode_Call(Lex.Line, tIdentifier, ParseArgList(Lex));
MatchToken(Lex, Lexer.Token.RightBracket); // ')'
MatchToken(Lex, Lexer.Token.Semico); // ';'
return(tCall);
}
else if (TryMatchToken(Lex, Lexer.Token.Is)) // assignment
{
// 读取表达式
ASTNode_Assignment tAssign = new ASTNode_Assignment(Lex.Line, tIdentifier, ParseExpression(Lex));
MatchToken(Lex, Lexer.Token.Semico); // ';'
return(tAssign);
}
else
{
throw new SyntaxException(Lex.Position, Lex.Line, Lex.Row,
String.Format("unexpected token {0}.", Lex.FormatCurrentToken()));
}
}
/// <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.");
}
}
}
