public void ToString_OfForNext_Converts()
{
var forNext = new ForNext(new ScalarVariable("I"),
new Constant("1"),
new Constant("5"),
new Constant("1"),
new PrintLine(new[] { new ScalarVariable("I") }));
var actual = forNext.ToString();
Assert.AreEqual("FOR I = 1 TO 5 STEP 1 PRINT I NEXT", actual);
}
public void Execute_OfForNext_RepeatsInnerStatement()
{
var rte = MakeRunTimeEnvironment();
var i = new ScalarVariable("I");
var from = new Constant(1);
var to = new Constant(10);
var step = new Constant(1);
var shoudBeEqualTo50 = 0;
var forNext = new ForNext(i, from, to, step, MakeStatement(() => { shoudBeEqualTo50 += 5; }));
forNext.Execute(rte);
Assert.AreEqual(50, shoudBeEqualTo50);
}
public static bool TryReadFor(this Scanner scanner, out IStatement result)
{
if (scanner.TryReadToken(Token.For))
{
ILValue loopVariable = scanner.ReadLValue();
scanner.ReadToken(Token.Eq);
IExpression from = scanner.ReadExpression();
scanner.ReadToken(Token.To);
IExpression to = scanner.ReadExpression();
IExpression step = null;
if (scanner.TryReadToken(Token.Step))
{
step = scanner.ReadExpression();
}
if (scanner.CurrentToken == Token.Next)
{
throw new ParserException(ErrorMessages.MissingStatement);
}
IStatement statement;
if (scanner.TryReadStatementExcludingNext(out statement))
{
scanner.ReadToken(Token.Next);
result = new ForNext(loopVariable, from, to, step, statement);
}
else
{
result = new For(loopVariable, from, to, step);
}
return(true);
}
result = null;
return(false);
}
private Stmt ParseStmt()
{
Stmt result;
if (this.index == this.tokens.Count)
{
throw new System.Exception("expected statement, got EOF");
}
// <stmt> := print <expr>
// <expr> := <string>
// | <int>
// | <arith_expr>
// | <ident>
if (this.tokens[this.index].Equals("print"))
{
this.index++;
Print print = new Print();
//Если есть текстовое описание
if (this.index < this.tokens.Count &&
this.tokens[this.index] is Text.StringBuilder)
{
print.Expression = this.ParseExpr();
}
if (this.index < this.tokens.Count &&
this.tokens[this.index] is string)
{
print.VarExpression = this.ParseExpr();
}
result = print;
}
else if (this.tokens[this.index].Equals("var"))
{
this.index++;
DeclareVar declareVar = new DeclareVar();
if (this.index < this.tokens.Count &&
this.tokens[this.index] is string)
{
declareVar.Ident = (string)this.tokens[this.index];
}
else
{
throw new System.Exception("expected variable name after 'var'");
}
this.index++;
if (this.index == this.tokens.Count ||
this.tokens[this.index] != Scanner.Equal)
{
throw new System.Exception("expected = after 'var ident'");
}
this.index++;
declareVar.Expression = this.ParseExpr();
result = declareVar;
}
else if (this.tokens[this.index].Equals("input"))
{
this.index++;
ReadValue readValue = new ReadValue();
//Если есть текстовое описание
if (this.index < this.tokens.Count &&
this.tokens[this.index] is Text.StringBuilder)
{
readValue.Exp = this.ParseExpr();
}
if (this.index < this.tokens.Count &&
this.tokens[this.index] is string)
{
readValue.Ident = (string)this.tokens[this.index++];
result = readValue;
}
else
{
throw new System.Exception("expected variable name after 'input'");
}
}
/*else if (this.tokens[this.index].Equals("read_int"))
* {
* this.index++;
* ReadValue readValue = new ReadValue();
*
* if (this.index < this.tokens.Count &&
* this.tokens[this.index] is string)
* {
* readValue.Ident = (string)this.tokens[this.index++];
* result = readValue;
* }
* else
* {
* throw new System.Exception("expected variable name after 'read_int'");
* }
* }*/
else if (this.tokens[this.index].Equals("for"))
{
this.index++;
ForNext forNext = new ForNext();
if (this.index < this.tokens.Count &&
this.tokens[this.index] is string)
{
forNext.Ident = (string)this.tokens[this.index];
}
else
{
throw new System.Exception("expected identifier after 'for'");
}
this.index++;
if (this.index == this.tokens.Count ||
this.tokens[this.index] != Scanner.Equal)
{
throw new System.Exception("for missing '='");
}
this.index++;
forNext.From = this.ParseExpr();
if (this.index == this.tokens.Count ||
!this.tokens[this.index].Equals("to"))
{
throw new System.Exception("expected 'to' after for");
}
this.index++;
forNext.To = this.ParseExpr();
/*if (this.index == this.tokens.Count ||
* !this.tokens[this.index].Equals("do"))
* {
* throw new System.Exception("expected 'do' after from expression in for next");
* }*/
this.index++;
forNext.Body = this.ParseStmt();
result = forNext;
if (this.index == this.tokens.Count ||
!this.tokens[this.index].Equals("next"))
{
throw new System.Exception("unterminated 'for' loop body");
}
this.index++;
}
else if (this.tokens[this.index].Equals("if"))
{
this.index++;
IfElse ifthen = new IfElse();
ifthen.Condition = new ConExpression();
//Запишем первый операнд в условии
if (this.index < this.tokens.Count &&
this.tokens[this.index] is string)
{
ifthen.Condition.Left = this.ParseExpr();
}
else
{
throw new System.Exception("expected identifier after 'if'");
}
// Запишем условный оператор
if (this.tokens[this.index] == Scanner.More) //Больше
{
ifthen.Condition.Operation = ConOperation.More;
}
else if (this.tokens[this.index] == Scanner.MoreEqual) //Больше-равно
{
ifthen.Condition.Operation = ConOperation.MoreEqual;
}
else if (this.tokens[this.index] == Scanner.Less) //Меньше
{
ifthen.Condition.Operation = ConOperation.Less;
}
else if (this.tokens[this.index] == Scanner.LessEqual) //Меньше-равно
{
ifthen.Condition.Operation = ConOperation.LessEqual;
}
else if (this.tokens[this.index] == Scanner.Equal) //Равенство
{
ifthen.Condition.Operation = ConOperation.Equal;
}
else
{
throw new System.Exception("missing condition operator");
}
//Запишем второй операнд в условии
this.index++;
ifthen.Condition.Right = this.ParseExpr();
if (this.index == this.tokens.Count ||
!this.tokens[this.index].Equals("then"))
{
throw new System.Exception("expected 'then' after if");
}
this.index++;
ifthen.BodyThen = this.ParseStmt();
if (this.index < this.tokens.Count && this.tokens[this.index].Equals("else"))
{
this.index++;
ifthen.BodyElse = this.ParseStmt();
}
result = ifthen;
if (this.index == this.tokens.Count ||
!this.tokens[this.index].Equals("endif"))
{
throw new System.Exception("unterminated 'if' body");
}
this.index++;
}
else if (this.tokens[this.index] is string)
{
//---------------------------------------------------------
// assignment
Assign assign = new Assign();
assign.Ident = (string)this.tokens[this.index++];
if (this.index == this.tokens.Count ||
this.tokens[this.index] != Scanner.Equal)
{
throw new System.Exception("expected '='");
}
this.index++;
assign.Expression = this.ParseExpr();
//Проверим наличие операции
if (this.tokens[this.index] != Scanner.Semi)
{
assign.Expression = this.ParseBinExpr(assign.Expression);
}
result = assign;
}
else
{
throw new System.Exception("parse error at token " + this.index + ": " + this.tokens[this.index]);
}
if (this.index < this.tokens.Count && this.tokens[this.index] == Scanner.Semi)
{
this.index++;
if (this.index < this.tokens.Count &&
!this.tokens[this.index].Equals("next") && !this.tokens[this.index].Equals("endif") && !this.tokens[this.index].Equals("else"))
{
Sequence sequence = new Sequence();
sequence.First = result;
sequence.Second = this.ParseStmt();
result = sequence;
}
}
return(result);
}
private void GenStmt(Stmt stmt)
{
//Обработка элемента последовательности дерева
if (stmt is Sequence)
{
Sequence seq = (Sequence)stmt;
//Выполним обработку левой части дерева
this.GenStmt(seq.First);
//Выполним обработку правой части дерева
this.GenStmt(seq.Second);
}
//Обработка элемента дерева - "Объявление"
else if (stmt is DeclareVar)
{
// Добавим переменную в список переменных
DeclareVar declare = (DeclareVar)stmt;
this.varTable[declare.Ident] = this.TypeOfExpr(declare.Expression);
//Приведем элемент типа "Объевление" к типу "Присвоение"
Assign assign = new Assign();
assign.Ident = declare.Ident;
assign.Expression = declare.Expression;
//Запишем тип переменной
accum.Append(string.Format("\n{0} ", this.TypeOfExpr(declare.Expression).Name));
//Запустим на обработку
this.GenStmt(assign);
}
//Обработка элемента дерева - "Присвоение"
else if (stmt is Assign)
{
Assign assign = (Assign)stmt;
accum.Append(string.Format("{0}=", assign.Ident));
//Обработка правой части элемента
this.GenAssign(assign.Expression);
accum.Append(";");
}
//Обработка элемента дерева - "Вывод данных"
else if (stmt is Print)
{
Print print = (Print)stmt;
accum.Append(print.VarExpression != null
? string.Format("\nConsole.WriteLine(\"{0}\", {1});", this.GetExprValue(print.Expression),
this.GetExprValue(print.VarExpression))
: string.Format("\nConsole.WriteLine(\"{0}\");", this.GetExprValue(print.Expression)));
}
//Обработка элемента дерева - "Ввод данных"
else if (stmt is ReadValue)
{
ReadValue readValue = (ReadValue)stmt;
accum.Append(readValue.Exp != null
? string.Format("\n{0} = Console.ReadLine(\"{1}\");", readValue.Ident, this.GetExprValue(readValue.Exp))
: string.Format("\n{0} = Console.ReadLine();", readValue.Ident));
//Проверка, что переменная объявлена ранее
//CheckVariable
}
else if (stmt is IfElse)
{
IfElse ifElse = (IfElse)stmt;
string operation = string.Empty;
switch (ifElse.Condition.Operation)
{
case ConOperation.Equal: operation = "="; break;
case ConOperation.Less: operation = "<"; break;
case ConOperation.LessEqual: operation = "<="; break;
case ConOperation.More: operation = ">"; break;
case ConOperation.MoreEqual: operation = ">="; break;
}
accum.Append(string.Format("\nif ({0}{1}{2})", this.GetExprValue(ifElse.Condition.Left), operation, this.GetExprValue(ifElse.Condition.Right)));
if (ifElse.BodyThen != null)
{
accum.Append("\n{\n");
this.GenStmt(ifElse.BodyThen);
accum.Append("\n}");
}
if (ifElse.BodyElse != null)
{
if (ifElse.BodyThen == null)
{
throw new System.Exception("error if - else");
}
accum.Append("\nelse\n{\n");
this.GenStmt(ifElse.BodyElse);
accum.Append("\n}");
}
}
else if (stmt is ForNext)
{
ForNext forNext = (ForNext)stmt;
accum.Append(string.Format("\nfor("));
Assign assign = new Assign();
assign.Ident = forNext.Ident;
assign.Expression = forNext.From;
this.GenStmt(assign);
accum.Append(string.Format("{0}<{1};{2}++)", forNext.Ident, this.GetExprValue(forNext.To), forNext.Ident));
this.varTable[forNext.Ident] = typeof(int);
if (forNext.Body != null)
{
accum.Append("\n{");
this.GenStmt(forNext.Body);
accum.Append("\n}");
}
}
else
{
throw new System.Exception("Отсутствует инструкция для генерирования операции: " + stmt.GetType().Name);
}
}