private ScopedProgram Block()
{
if (!Accept(Symbol.Begin))
{
return(null);
}
ScopedProgram block = new ScopedProgram();
while (true)
{
IStatement stm = Statement();
if (stm == null)
{
throw new SyntaxException("beginning of a statement", current);
}
block.Add(stm);
if (!Accept(Symbol.SemiColon))
{
Require(Symbol.End);
break;
}
if (Accept(Symbol.End))
{
break;
}
}
return(block);
}
public Procedure(Identifier Identifier, Parameters Parameters, ScopedProgram Block, MiniPascalType Type)
{
identifier = Identifier;
this.Parameters = Parameters;
block = Block;
ReturnType = Type;
}
private Procedure ProcedureStatement()
{
if (Accept(Symbol.Procedure))
{
Identifier ident = Identifier();
Require(Symbol.ClosureOpen);
Parameters parameters = ReadParameters();
Require(Symbol.ClosureClose);
Require(Symbol.SemiColon);
ScopedProgram block = Block();
block.AddParameters(parameters);
return(new Procedure(ident, parameters, block, null));
}
return(null);
}
private AbstractSyntaxTree Program()
{
Require(Symbol.Program);
Identifier ident = Identifier();
if (ident == null)
{
throw new SyntaxException("Program must have a name");
}
Require(Symbol.SemiColon);
ScopedProgram block = Block();
if (block == null)
{
throw new SyntaxException("Program must start with a block");
}
Require(Symbol.Period);
return(new AbstractSyntaxTree(block, ident));
}
private Procedure ReadFunction()
{
if (Accept(Symbol.Function))
{
Identifier ident = Identifier();
Require(Symbol.ClosureOpen);
Parameters parameters = ReadParameters();
Require(Symbol.ClosureClose);
Require(Symbol.Colon);
MiniPascalType type = ReadType();
if (type == null)
{
throw new SyntaxException(expType, current);
}
Require(Symbol.SemiColon);
ScopedProgram block = Block();
block.AddParameters(parameters);
return(new Procedure(ident, parameters, block, type));
}
return(null);
}
private IStatement StructuredStatement()
{
ScopedProgram block = Block();
if (block != null)
{
return(block);
}
If ifStm = IfStatement();
if (ifStm != null)
{
return(ifStm);
}
While whileStm = ReadWhile();
if (whileStm != null)
{
return(whileStm);
}
return(null);
}