/** <summary>
* To write out the value of a condition expr, invoke the evaluator in eval.g
* to walk the condition tree computing the boolean value. If result
* is true, then write subtemplate.
* </summary>
*/
public override int Write(StringTemplate self, IStringTemplateWriter @out)
{
if (AST == null || self == null || @out == null)
{
return(0);
}
//System.Console.Out.WriteLine( "evaluating conditional tree: " + AST.ToStringTree() );
#if !COMPILE_EXPRESSIONS
ActionEvaluator eval = null;
#endif
int n = 0;
try
{
bool testedTrue = false;
// get conditional from tree and compute result
#if COMPILE_EXPRESSIONS
if (EvaluateCondition == null)
{
EvaluateCondition = GetEvaluator(this, AST.GetChild(0));
}
bool includeSubtemplate = EvaluateCondition(self, @out); // eval and write out tree
#else
ITree cond = AST.GetChild(0);
eval = new ActionEvaluator(self, this, @out, cond);
// eval and write out trees
bool includeSubtemplate = eval.ifCondition();
#endif
//System.Console.Out.WriteLine( "subtemplate " + _subtemplate );
// IF
if (includeSubtemplate)
{
n = WriteSubTemplate(self, @out, _subtemplate);
testedTrue = true;
}
// ELSEIF
else if (_elseIfSubtemplates != null && _elseIfSubtemplates.Count > 0)
{
for (int i = 0; i < _elseIfSubtemplates.Count; i++)
{
ElseIfClauseData elseIfClause = _elseIfSubtemplates[i];
#if COMPILE_EXPRESSIONS
if (elseIfClause.EvaluateCondition == null)
{
elseIfClause.EvaluateCondition = GetEvaluator(this, elseIfClause.expr.AST);
}
includeSubtemplate = elseIfClause.EvaluateCondition(self, @out);
#else
eval = new ActionEvaluator(self, this, @out, elseIfClause.expr.AST);
includeSubtemplate = eval.ifCondition();
#endif
if (includeSubtemplate)
{
WriteSubTemplate(self, @out, elseIfClause.st);
testedTrue = true;
break;
}
}
}
// ELSE
if (!testedTrue && _elseSubtemplate != null)
{
// evaluate ELSE clause if present and IF condition failed
StringTemplate s = _elseSubtemplate.GetInstanceOf();
s.EnclosingInstance = self;
s.Group = self.Group;
s.NativeGroup = self.NativeGroup;
n = s.Write(@out);
}
// cond==false and no else => Missing output not empty
if (!testedTrue && _elseSubtemplate == null)
{
n = Missing;
}
}
catch (RecognitionException re)
{
self.Error("can't evaluate tree: " + AST.ToStringTree(), re);
}
return(n);
}
static System.Func <StringTemplate, IStringTemplateWriter, bool> GetEvaluator(ASTExpr chunk, ITree condition)
{
if (EnableDynamicMethods)
{
try
{
DynamicMethod method = null;
#if CACHE_FUNCTORS
if (!_methods.TryGetValue(condition, out method))
#endif
{
Type[] parameterTypes = { typeof(ASTExpr), typeof(StringTemplate), typeof(IStringTemplateWriter) };
method = new DynamicMethod("ConditionEvaluator" + _evaluatorNumber, typeof(bool), parameterTypes, typeof(ConditionalExpr), true);
#if !NETSTANDARD2_0
method.DefineParameter(1, ParameterAttributes.None, "chunk");
method.DefineParameter(2, ParameterAttributes.None, "self");
method.DefineParameter(3, ParameterAttributes.None, "writer");
#endif
_evaluatorNumber++;
var gen = method.GetILGenerator();
ActionEvaluator evalCompiled = new ActionEvaluator(null, chunk, null, condition);
evalCompiled.ifConditionCompiled(gen);
gen.Emit(OpCodes.Ret);
#if CACHE_FUNCTORS
_methods[condition] = method;
#endif
}
var dynamicEvaluator = (System.Func <StringTemplate, IStringTemplateWriter, bool>)method.CreateDelegate(typeof(System.Func <StringTemplate, IStringTemplateWriter, bool>), chunk);
return(dynamicEvaluator);
}
catch
{
// fall back to functional (or interpreted) version
}
}
if (EnableFunctionalMethods)
{
try
{
ActionEvaluator evalFunctional = new ActionEvaluator(null, chunk, null, condition);
var functionalEvaluator = evalFunctional.ifConditionFunctional();
HoldsConditionFuncAndChunk holder = new HoldsConditionFuncAndChunk()
{
func = functionalEvaluator,
chunk = chunk
};
return((System.Func <StringTemplate, IStringTemplateWriter, bool>)System.Delegate.CreateDelegate(typeof(System.Func <StringTemplate, IStringTemplateWriter, bool>), holder, typeof(ConditionalExpr).GetMethod("CallFunctionalConditionEvaluator")));
}
catch
{
// fall back to interpreted version
}
}
return(new System.Func <StringTemplate, IStringTemplateWriter, bool>((self, @out) =>
{
ActionEvaluator eval = new ActionEvaluator(self, chunk, @out, condition);
return eval.ifCondition();
}));
}