public ContextVariable FreeVariable(string name)
{
ContextVariable var = GetVariable(name);
if (var == null)
{
return(null);
}
Variables.Remove(var);
return(var);
}
public ContextVariable AllocVariable(string name)
{
ContextVariable var = GetVariable(name);
if (var != null)
{
return(var);
}
var = new ContextVariable(name);
Variables.Add(var);
return(var);
}
/// <summary>
/// Evaluate one instruction. Change the state in the (parent) context depending on its current state.
/// Names are resolved for each instruction. Alternatively, we could first resolve all names in all instructions in a separate pass and then execute without resolution.
/// </summary>
public virtual object Execute()
{
// Context stores the current state which is read and then written as a result of the operation execution
ScriptContext ctx = GetContext();
Schema.Schema top = ctx.Schemas[0];
string name, type;
switch (OpType)
{
case ScriptOpType.NOP:
break;
case ScriptOpType.CONTEXT: // Not possible: it is overloaded and processed by a subclass
break;
case ScriptOpType.ALLOC:
ctx.AllocVariable(Name);
// TODO: process the type of the variable
break;
case ScriptOpType.FREE:
ctx.FreeVariable(Name);
break;
case ScriptOpType.VALUE:
if (Children.Count != 0) // Expression (not value/literal), e.g., a variable
{
foreach (ScriptOp op in Children)
{
op.Execute();
}
Result.Value = GetChild(Children.Count - 1).Result.Value;
}
break;
case ScriptOpType.DOT:
case ScriptOpType.CALL:
// Check if it is a variable
if (OpType == ScriptOpType.CALL && Children.Count == 0)
{
ContextVariable var = ctx.GetVariable(Name);
if (var != null)
{
Result.Value = var.Value;
break;
}
}
// Process all parameters so that they have values that can be used in this run-time call
foreach (ScriptOp op in Children)
{
op.Execute();
}
// Try to find a run-time procedure/method from our API corresponding to this instruction and its parameters (resolution, binding)
if (Name == "OpenOledb")
{
// Find parameter 'connection' among children
ScriptOp child = GetChild("connection");
string connection = null;
if (child != null)
{
connection = (string)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
//SchemaOledb dbTop = new SchemaOledb("");
//dbTop.ConnectionString = connection;
//dbTop.Open();
//dbTop.ImportSchema();
//Result.Value = dbTop;
}
else if (Name == "Load")
{
ScriptOp child = GetChild("this");
Schema.Schema db = null;
if (child != null)
{
db = (Schema.Schema)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
// Find parameter 'table' among children
child = GetChild("table");
string table = null;
if (child != null)
{
table = (string)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
Table set = null; // Mapper.ImportSet(db.FindSubset(table), top);
Result.Value = set;
}
else if (Name == "AddFunction")
{
ScriptOp child = GetChild("this");
Table set = null;
if (child != null)
{
set = (Table)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
// Find parameter 'name' among children
child = GetChild("name");
name = null;
if (child != null)
{
name = (string)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
// Find parameter 'type' among children
child = GetChild("type");
type = null;
if (child != null)
{
type = (string)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
// Find parameter 'formula' among children
child = GetChild("formula");
AstNode formula = null;
if (child != null)
{
formula = (AstNode)child.Result.Value;
}
else
{
break;
} // ERROR: parameter wrong or not found
// TOD: Really add a new function with this definition
Table typeSet = (Table)top.GetSubTable(type);
Column dim = (Column)((DcSchema)top).Space.CreateColumn(name, set, typeSet, false);
//dim.FormulaAst = formula;
Result.Value = dim;
}
break;
case ScriptOpType.WRITE: // ASSIGN
{
ContextVariable var = ctx.GetVariable(Name);
GetChild(0).Execute();
var.Value = GetChild(0).Result.Value;
break;
}
}
return(null); // TODO: Return content of the 'return' variable
}
public ScriptOp()
{
OpType = ScriptOpType.NOP;
Result = new ContextVariable("return");
}