private Stmt ParseStmt()
{
Stmt resultado;
if (this.indice == this.tokens.Count)
{
throw new System.Exception("se esperaban sentencias, se llego al final del archivo");
}
// <stmt> := print <expr>
// <expr> := <string>
// | <int>
// | <arith_expr>
// | <ident>
if (this.tokens[this.indice].Equals("print"))
{
this.indice++;
Print print = new Print();
print.Expr = this.ParseExpr();
resultado = print;
}
else if (this.tokens[this.indice].Equals("var"))
{
this.indice++;
DeclareVar declareVar = new DeclareVar();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
declareVar.Ident = (string)this.tokens[this.indice];
}
else
{
throw new System.Exception("Se esperaba nombre de variable despues de 'var'");
}
this.indice++;
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("se esperaba = despues de 'var ident'");
}
this.indice++;
declareVar.Expr = this.ParseExpr();
resultado = declareVar;
}
else if (this.tokens[this.indice].Equals("read_int"))
{
this.indice++;
ReadInt readInt = new ReadInt();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
readInt.Ident = (string)this.tokens[this.indice++];
resultado = readInt;
}
else
{
throw new System.Exception("Se esperaba el nombre de la variable 'read_int'");
}
}
//*******************
else if (this.tokens[this.indice].Equals("if"))
{
this.indice++;
mcIf mcif = new mcIf();
Expr temp = ParseExpr();
if (this.tokens[this.indice] == Scanner.Eq || this.tokens[this.indice] == Scanner.Neq ||
this.tokens[this.indice] == Scanner.Gt || this.tokens[this.indice] == Scanner.Gte ||
this.tokens[this.indice] == Scanner.Lt || this.tokens[this.indice] == Scanner.Lte)
{
CompExpr compExpr = new CompExpr();
compExpr.Left = temp;
object op = this.tokens[this.indice++];
if (op == Scanner.Eq)
compExpr.Op = CompOp.Eq;
else if (op == Scanner.Neq)
compExpr.Op = CompOp.Neq;
else if (op == Scanner.Gt)
compExpr.Op = CompOp.Gt;
else if (op == Scanner.Gte)
compExpr.Op = CompOp.Gte;
else if (op == Scanner.Lt)
compExpr.Op = CompOp.Lt;
else if (op == Scanner.Lte)
compExpr.Op = CompOp.Lte;
compExpr.Rigth = ParseExpr();
temp = compExpr;
}
mcif.compExpr = temp;
if (this.indice == this.tokens.Count || !this.tokens[this.indice].Equals("then"))
{
throw new System.Exception("Se esperaba el identificador 'then' despues de 'if'");
}
this.indice++;
mcif.Then = ParseStmt();
if (this.tokens[this.indice].Equals("else"))
{
this.indice++;
mcif.Else = ParseStmt();
}
resultado = mcif;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("Sentencia if inconclusa");
}
this.indice++;
}
else if (this.tokens[this.indice].Equals("while"))
{
this.indice++;
WhileLoop whileLoop = new WhileLoop();
Expr temp = ParseExpr();
if (this.tokens[this.indice] == Scanner.Eq || this.tokens[this.indice] == Scanner.Neq ||
this.tokens[this.indice] == Scanner.Gt || this.tokens[this.indice] == Scanner.Gte ||
this.tokens[this.indice] == Scanner.Lt || this.tokens[this.indice] == Scanner.Lte)
{
CompExpr compExpr = new CompExpr();
compExpr.Left = temp;
object op = this.tokens[this.indice++];
if (op == Scanner.Eq)
compExpr.Op = CompOp.Eq;
else if (op == Scanner.Neq)
compExpr.Op = CompOp.Neq;
else if (op == Scanner.Gt)
compExpr.Op = CompOp.Gt;
else if (op == Scanner.Gte)
compExpr.Op = CompOp.Gte;
else if (op == Scanner.Lt)
compExpr.Op = CompOp.Lt;
else if (op == Scanner.Lte)
compExpr.Op = CompOp.Lte;
compExpr.Rigth = ParseExpr();
temp = compExpr;
}
whileLoop.Cond = temp;
if (this.indice == this.tokens.Count || !this.tokens[this.indice].Equals("do"))
{
throw new System.Exception("Se esperaba el identificador 'do' despues de 'while'");
}
this.indice++;
whileLoop.Body = ParseStmt();
resultado = whileLoop;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("sentencia while inconclusa");
}
this.indice++;
}
//*******************
else if (this.tokens[this.indice].Equals("for"))
{
this.indice++;
ForLoop forLoop = new ForLoop();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
forLoop.Ident = (string)this.tokens[this.indice];
}
else
{
throw new System.Exception("se esperaba un indentificador despues de 'for'");
}
this.indice++;
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("no se encontro en la sentencia for '='");
}
this.indice++;
forLoop.From = this.ParseExpr();
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("to"))
{
throw new System.Exception("se epsaraba 'to' despues de for");
}
this.indice++;
forLoop.To = this.ParseExpr();
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("do"))
{
throw new System.Exception("se esperaba 'do' despues de la expresion en el ciclo for");
}
this.indice++;
forLoop.Body = this.ParseStmt();
resultado = forLoop;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("setencia for inconclusa");
}
this.indice++;
}
else if (this.tokens[this.indice] is string)
{
// assignment
Assign assign = new Assign();
assign.Ident = (string)this.tokens[this.indice++];
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("se esperaba '='");
}
this.indice++;
assign.Expr = this.ParseExpr();
resultado = assign;
}
else
{
throw new System.Exception("Error en el token " + this.indice + ": " + this.tokens[this.indice]);
}
if (this.indice < this.tokens.Count && this.tokens[this.indice] == Scanner.PyC)
{
this.indice++;
if (this.indice < this.tokens.Count &&
!this.tokens[this.indice].Equals("end") && !this.tokens[this.indice].Equals("else"))
{
Sequence sequence = new Sequence();
sequence.First = resultado;
sequence.Second = this.ParseStmt();
resultado = sequence;
}
}
return resultado;
}
private void GenStmt(Stmt stmt)
{
if (stmt is Sequence)
{
Sequence seq = (Sequence)stmt;
this.GenStmt(seq.First);
this.GenStmt(seq.Second);
}
else if (stmt is DeclareVar)
{
// declare a local
DeclareVar declare = (DeclareVar)stmt;
this.symbolTable[declare.Ident] = this.il.DeclareLocal(this.TypeOfExpr(declare.Expr));
// set the initial value
Assign assign = new Assign();
assign.Ident = declare.Ident;
assign.Expr = declare.Expr;
this.GenStmt(assign);
}
else if (stmt is Assign)
{
Assign assign = (Assign)stmt;
this.GenExpr(assign.Expr, this.TypeOfExpr(assign.Expr));
this.Store(assign.Ident, this.TypeOfExpr(assign.Expr));
}
else if (stmt is Print)
{
// the "print" statement is an alias for System.Console.WriteLine.
// it uses the string case
this.GenExpr(((Print)stmt).Expr, typeof(string));
this.il.Emit(Emit.OpCodes.Call, typeof(System.Console).GetMethod("WriteLine", new System.Type[] { typeof(string) }));
}
else if (stmt is ReadInt)
{
this.il.Emit(Emit.OpCodes.Call, typeof(System.Console).GetMethod("ReadLine", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static, null, new System.Type[] { }, null));
this.il.Emit(Emit.OpCodes.Call, typeof(int).GetMethod("Parse", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static, null, new System.Type[] { typeof(string) }, null));
this.Store(((ReadInt)stmt).Ident, typeof(int));
}
//*******************
else if (stmt is mcIf)
{
mcIf mcif = (mcIf)stmt;
//this.GenExpr(mcif.compExpr, typeof(int));
Emit.Label Else = this.il.DefineLabel();
Emit.Label Then = this.il.DefineLabel();
Emit.Label Salida = this.il.DefineLabel();
if (mcif.compExpr is CompExpr)
{
CompExpr compExpr = (CompExpr)mcif.compExpr;
this.GenExpr(compExpr.Left, typeof(int));
this.GenExpr(compExpr.Rigth, typeof(int));
genCodComp(compExpr.Op, Then);
}
else
{
GenExpr(mcif.compExpr, typeof(string));
this.il.Emit(Emit.OpCodes.Ldc_I4, 0);
this.il.Emit(Emit.OpCodes.Bne_Un, Then);
}
if (mcif.Else != null)
{
this.il.Emit(Emit.OpCodes.Br, Else);
}
else
{
this.il.Emit(Emit.OpCodes.Br, Salida);
}
this.il.MarkLabel(Then);
GenStmt(mcif.Then);
this.il.Emit(Emit.OpCodes.Br, Salida);
this.il.MarkLabel(Else);
if (mcif.Else != null)
{
GenStmt(mcif.Else);
}
this.il.MarkLabel(Salida);
}
else if (stmt is WhileLoop)
{
WhileLoop whileLoop = (WhileLoop)stmt;
Emit.Label Body = this.il.DefineLabel();
Emit.Label Salida = this.il.DefineLabel();
Emit.Label Cond = this.il.DefineLabel();
this.il.MarkLabel(Cond);
if (whileLoop.Cond is CompExpr)
{
CompExpr compExpr = (CompExpr)whileLoop.Cond;
this.GenExpr(compExpr.Left, typeof(int));
this.GenExpr(compExpr.Rigth, typeof(int));
genCodComp(compExpr.Op, Body);
}
else
{
GenExpr(whileLoop.Cond, typeof(string));
this.il.Emit(Emit.OpCodes.Ldc_I4, 0);
this.il.Emit(Emit.OpCodes.Bne_Un, Body);
}
this.il.Emit(Emit.OpCodes.Br, Salida);
this.il.MarkLabel(Body);
GenStmt(whileLoop.Body);
this.il.Emit(Emit.OpCodes.Br, Cond);
this.il.MarkLabel(Salida);
}
//*******************
else if (stmt is ForLoop)
{
// example:
// for x = 0 to 100 do
// print "hello";
// end;
// x = 0
ForLoop forLoop = (ForLoop)stmt;
Assign assign = new Assign();
assign.Ident = forLoop.Ident;
assign.Expr = forLoop.From;
this.GenStmt(assign);
// jump to the test
Emit.Label test = this.il.DefineLabel();
this.il.Emit(Emit.OpCodes.Br, test);
// statements in the body of the for loop
Emit.Label body = this.il.DefineLabel();
this.il.MarkLabel(body);
this.GenStmt(forLoop.Body);
// to (increment the value of x)
this.il.Emit(Emit.OpCodes.Ldloc, this.symbolTable[forLoop.Ident]);
this.il.Emit(Emit.OpCodes.Ldc_I4, 1);
this.il.Emit(Emit.OpCodes.Add);
this.Store(forLoop.Ident, typeof(int));
// **test** does x equal 100? (do the test)
this.il.MarkLabel(test);
this.il.Emit(Emit.OpCodes.Ldloc, this.symbolTable[forLoop.Ident]);
this.GenExpr(forLoop.To, typeof(int));
this.il.Emit(Emit.OpCodes.Blt, body);
}
else
{
throw new System.Exception("imposible generar: " + stmt.GetType().Name);
}
}
private Stmt ParseStmt()
{
Stmt resultado;
if (this.indice == this.tokens.Count)
{
throw new System.Exception("se esperaban sentencias, se llego al final del archivo");
}
// <stmt> := print <expr>
// <expr> := <string>
// | <int>
// | <arith_expr>
// | <ident>
if (this.tokens[this.indice].Equals("print"))
{
this.indice++;
Print print = new Print();
print.Expr = this.ParseExpr();
resultado = print;
}
else if (this.tokens[this.indice].Equals("var"))
{
this.indice++;
DeclareVar declareVar = new DeclareVar();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
declareVar.Ident = (string)this.tokens[this.indice];
}
else
{
throw new System.Exception("Se esperaba nombre de variable despues de 'var'");
}
this.indice++;
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("se esperaba = despues de 'var ident'");
}
this.indice++;
declareVar.Expr = this.ParseExpr();
resultado = declareVar;
}
else if (this.tokens[this.indice].Equals("read_int"))
{
this.indice++;
ReadInt readInt = new ReadInt();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
readInt.Ident = (string)this.tokens[this.indice++];
resultado = readInt;
}
else
{
throw new System.Exception("Se esperaba el nombre de la variable 'read_int'");
}
}
//*******************
else if (this.tokens[this.indice].Equals("if"))
{
this.indice++;
mcIf mcif = new mcIf();
Expr temp = ParseExpr();
if (this.tokens[this.indice] == Scanner.Eq || this.tokens[this.indice] == Scanner.Neq ||
this.tokens[this.indice] == Scanner.Gt || this.tokens[this.indice] == Scanner.Gte ||
this.tokens[this.indice] == Scanner.Lt || this.tokens[this.indice] == Scanner.Lte)
{
CompExpr compExpr = new CompExpr();
compExpr.Left = temp;
object op = this.tokens[this.indice++];
if (op == Scanner.Eq)
{
compExpr.Op = CompOp.Eq;
}
else if (op == Scanner.Neq)
{
compExpr.Op = CompOp.Neq;
}
else if (op == Scanner.Gt)
{
compExpr.Op = CompOp.Gt;
}
else if (op == Scanner.Gte)
{
compExpr.Op = CompOp.Gte;
}
else if (op == Scanner.Lt)
{
compExpr.Op = CompOp.Lt;
}
else if (op == Scanner.Lte)
{
compExpr.Op = CompOp.Lte;
}
compExpr.Rigth = ParseExpr();
temp = compExpr;
}
mcif.compExpr = temp;
if (this.indice == this.tokens.Count || !this.tokens[this.indice].Equals("then"))
{
throw new System.Exception("Se esperaba el identificador 'then' despues de 'if'");
}
this.indice++;
mcif.Then = ParseStmt();
if (this.tokens[this.indice].Equals("else"))
{
this.indice++;
mcif.Else = ParseStmt();
}
resultado = mcif;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("Sentencia if inconclusa");
}
this.indice++;
}
else if (this.tokens[this.indice].Equals("while"))
{
this.indice++;
WhileLoop whileLoop = new WhileLoop();
Expr temp = ParseExpr();
if (this.tokens[this.indice] == Scanner.Eq || this.tokens[this.indice] == Scanner.Neq ||
this.tokens[this.indice] == Scanner.Gt || this.tokens[this.indice] == Scanner.Gte ||
this.tokens[this.indice] == Scanner.Lt || this.tokens[this.indice] == Scanner.Lte)
{
CompExpr compExpr = new CompExpr();
compExpr.Left = temp;
object op = this.tokens[this.indice++];
if (op == Scanner.Eq)
{
compExpr.Op = CompOp.Eq;
}
else if (op == Scanner.Neq)
{
compExpr.Op = CompOp.Neq;
}
else if (op == Scanner.Gt)
{
compExpr.Op = CompOp.Gt;
}
else if (op == Scanner.Gte)
{
compExpr.Op = CompOp.Gte;
}
else if (op == Scanner.Lt)
{
compExpr.Op = CompOp.Lt;
}
else if (op == Scanner.Lte)
{
compExpr.Op = CompOp.Lte;
}
compExpr.Rigth = ParseExpr();
temp = compExpr;
}
whileLoop.Cond = temp;
if (this.indice == this.tokens.Count || !this.tokens[this.indice].Equals("do"))
{
throw new System.Exception("Se esperaba el identificador 'do' despues de 'while'");
}
this.indice++;
whileLoop.Body = ParseStmt();
resultado = whileLoop;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("sentencia while inconclusa");
}
this.indice++;
}
//*******************
else if (this.tokens[this.indice].Equals("for"))
{
this.indice++;
ForLoop forLoop = new ForLoop();
if (this.indice < this.tokens.Count &&
this.tokens[this.indice] is string)
{
forLoop.Ident = (string)this.tokens[this.indice];
}
else
{
throw new System.Exception("se esperaba un indentificador despues de 'for'");
}
this.indice++;
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("no se encontro en la sentencia for '='");
}
this.indice++;
forLoop.From = this.ParseExpr();
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("to"))
{
throw new System.Exception("se epsaraba 'to' despues de for");
}
this.indice++;
forLoop.To = this.ParseExpr();
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("do"))
{
throw new System.Exception("se esperaba 'do' despues de la expresion en el ciclo for");
}
this.indice++;
forLoop.Body = this.ParseStmt();
resultado = forLoop;
if (this.indice == this.tokens.Count ||
!this.tokens[this.indice].Equals("end"))
{
throw new System.Exception("setencia for inconclusa");
}
this.indice++;
}
else if (this.tokens[this.indice] is string)
{
// assignment
Assign assign = new Assign();
assign.Ident = (string)this.tokens[this.indice++];
if (this.indice == this.tokens.Count ||
this.tokens[this.indice] != Scanner.Igual)
{
throw new System.Exception("se esperaba '='");
}
this.indice++;
assign.Expr = this.ParseExpr();
resultado = assign;
}
else
{
throw new System.Exception("Error en el token " + this.indice + ": " + this.tokens[this.indice]);
}
if (this.indice < this.tokens.Count && this.tokens[this.indice] == Scanner.PyC)
{
this.indice++;
if (this.indice < this.tokens.Count &&
!this.tokens[this.indice].Equals("end") && !this.tokens[this.indice].Equals("else"))
{
Sequence sequence = new Sequence();
sequence.First = resultado;
sequence.Second = this.ParseStmt();
resultado = sequence;
}
}
return(resultado);
}
