object IVisitor <object> .visit(ForConditionNode node)
{
Node left = node.getLeft();
Node right = node.getRight();
left.accept(this);
right.accept(this);
// Only allow integers in range
if (!(left != null & right != null)) // Cannot proceed if there has been an error
{
if (!left.type.Equals(Token.INT))
{
new SemanticError(left, "Semantic Error: Expected integer, got " + left.type);
}
if (!right.type.Equals(Token.INT))
{
new SemanticError(right, "Semantic Error: Expected integer, got " + right.type);
}
}
return(null);
}
private Node stmt()
{
Node statement = new StatementNode();
if (currentToken.type == Token.KW)
{
// For loop detected
if (currentToken.value == "for")
{
Node forLoop = new ForLoopNode();
match_keyword("for");
// Control node
Node control = new ForControlNode();
// Condition
Node condition = new ForConditionNode();
// Control node assignment
Node assignment = new AssignmentNode();
Node id = new IdNode(currentToken);
assignment.addChild(id);
condition.addChild(id);
match(Token.ID);
match_keyword("in");
assignment.addChild(expr());
match(Token.RANGE);
condition.addChild(expr());
match_keyword("do");
control.addChild(assignment);
control.addChild(condition);
forLoop.addChild(control);
statement.addChild(forLoop);
// Add block
Node block = new BlockNode();
while (!accept_keyword("end"))
{
block.addChild(stmt());
}
forLoop.addChild(block);
match_keyword("end");
match_keyword("for");
}
// Read detected
else if (currentToken.value == "read")
{
Node read = new ReadNode();
statement.addChild(read);
match_keyword("read");
read.addChild(new IdNode(currentToken));
match(Token.ID);
}
// Print detected
else if (currentToken.value == "print")
{
Node print = new PrintNode();
statement.addChild(print);
match_keyword("print");
print.addChild(expr());
}
// Assert detected
else if (currentToken.value == "assert")
{
Node assert = new AssertNode();
match_keyword("assert");
match(Token.LPAR);
assert.addChild(expr());
match(Token.RPAR);
statement.addChild(assert);
}
// Variable declaration detected
else if (currentToken.value == "var")
{
Node declaration = new DeclarationNode();
match_keyword("var");
Node id = new IdNode(currentToken);
declaration.addChild(id);
match(Token.ID);
match(Token.COL);
if (accept_keyword("int"))
{
id.type = Token.INT;
match_keyword("int");
}
else if (accept_keyword("string"))
{
id.type = Token.STRING;
match_keyword("string");
}
else if (accept_keyword("bool"))
{
id.type = Token.BOOL;
match_keyword("bool");
}
else
{
new SyntaxError(currentToken, "Syntax Error: Expected type int, string or bool, got '" + currentToken.value + "'");
nextStatement();
return(null);
}
statement.addChild(declaration);
// Optional assignment
if (accept(Token.ASS))
{
Node assignment = new AssignmentNode();
assignment.addChild(id);
match(Token.ASS);
assignment.addChild(expr());
statement.addChild(assignment);
}
}
else
{
new SyntaxError(currentToken, "Syntax Error: Expected keyword var, for, read, print or assert, got " + currentToken.value);
statement = new StatementNode();
return(null);
}
// End of statement
match(Token.SCOL);
}
// Assignment detected
else if (currentToken.type == Token.ID)
{
Node id = new IdNode(currentToken);
match(Token.ID);
Node assignment = new AssignmentNode();
assignment.addChild(id);
match(Token.ASS);
assignment.addChild(expr());
statement.addChild(assignment);
match(Token.SCOL);
}
return(statement);
}
object IVisitor <object> .visit(ForConditionNode node)
{
return(null);
}