static void WriteStatement(StreamWriter writer, AST.Statement statement)
{
if (statement is AST.Return)
{
WriteReturn(writer, (AST.Return)statement);
}
}
private AST.Statement ParseIfStatement(Lexer lexer)
{
var expr = ParseExpression(lexer);
var text = string.Empty;
var token = lexer.InputToken(out text);
if (token == Token.辅助标点)
{
token = lexer.InputToken(out text);
}
if (token != Token.则)
{
throw new Exception($"语法错误，不是预期的输入:{text}。 在 {lexer.Line} 行，{lexer.Column}列");
}
token = lexer.InputToken(out text);
if (token != Token.冒号)
{
lexer.ReturnToken(token, text);
}
var trueBlock = ParseBlockStatement(lexer);
AST.Statement falseBlock = null;
token = lexer.InputToken(out text);
if (token == Token.否则)
{
token = lexer.InputToken(out text);
if (token != Token.冒号)
{
lexer.ReturnToken(token, text);
}
falseBlock = ParseBlockStatement(lexer);
}
else
{
lexer.ReturnToken(token, text);
}
return(new AST.IfStatement(expr, trueBlock, falseBlock));
}
/// <summary>
/// Renders a single statement with the given indentation
/// </summary>
/// <returns>The VHDL lines in the statement.</returns>
/// <param name="method">The method the statement belongs to.</param>
/// <param name="statement">The statement to render.</param>
/// <param name="indentation">The indentation to use.</param>
private IEnumerable <string> RenderStatement(AST.Method method, AST.Statement statement, int indentation)
{
if (statement is AST.ForStatement)
{
return(RenderStatement(method, statement as AST.ForStatement, indentation));
}
else if (statement is AST.ReturnStatement)
{
return(RenderStatement(method, statement as AST.ReturnStatement, indentation));
}
else if (statement is AST.BlockStatement)
{
return(RenderStatement(method, statement as AST.BlockStatement, indentation));
}
else if (statement is AST.SwitchStatement)
{
return(RenderStatement(method, statement as AST.SwitchStatement, indentation));
}
else if (statement is AST.IfElseStatement)
{
return(RenderStatement(method, statement as AST.IfElseStatement, indentation));
}
else if (statement is AST.ExpressionStatement)
{
return(RenderStatement(method, statement as AST.ExpressionStatement, indentation));
}
else if (statement is AST.CommentStatement)
{
return(RenderStatement(method, statement as AST.CommentStatement, indentation));
}
else if (statement is AST.EmptyStatement)
{
return(new string[0]);
}
else
{
throw new Exception($"Unuspported statement type: {statement.GetType().FullName}");
}
}
private AST.BlockStatement ParseBlockStatement(Lexer lexer)
{
var block = new AST.BlockStatement();
var exitLoop = false;
while (!exitLoop)
{
var text = string.Empty;
var token = lexer.InputToken(out text);
AST.Statement steatement = null;
switch (token)
{
case Token.一个数字:
steatement = ParseNumberVariableStatement(lexer);
break;
case Token.一句话:
steatement = ParseStringVariableStatement(lexer);
break;
case Token.一个逻辑量:
steatement = ParseBooleanVariableStatement(lexer);
break;
case Token.一个阵列:
steatement = ParseArrayVariableStatement(lexer);
break;
case Token.一种方法:
steatement = ParseFunctionStatement(lexer);
break;
case Token.设:
steatement = ParseSetVariableStatement(lexer);
break;
case Token.如果:
steatement = ParseIfStatement(lexer);
break;
case Token.当:
steatement = ParseWhileStatement(lexer);
break;
case Token.列操作:
steatement = ParseLoopCountStatement(lexer);
break;
case Token.跳出循环:
steatement = ParseBreakStatement(lexer);
break;
case Token.返回:
steatement = ParseReturnStatement(lexer);
break;
case Token.方法调用:
steatement = ParseCallExpression(lexer, ParseName(text), true);
break;
case Token.行结束符号:
continue;
case Token.段结束符号:
exitLoop = true;
continue;
case Token.V程序结束:
lexer.ReturnToken(token, text);
exitLoop = true;
continue;
default:
throw new Exception($"语法错误，不是预期的输入:{text}。 在 {lexer.Line} 行，{lexer.Column}列");
}
block.AddStatement(steatement);
}
return(block);
}
virtual public void visit(AST.Statement statement)
{
statement.body.accept(this);
}
