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Fix compilation explosion in OneOf #179

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Dec 1, 2024
Merged

Fix compilation explosion in OneOf #179

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144 changes: 91 additions & 53 deletions src/Parlot/Fluent/OneOf.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -241,76 +241,114 @@ void UseLookup()
var charMapSetMethodInfo = typeof(CharMap<Func<ParseContext, ValueTuple<bool, T>>>).GetMethod("Set")!;
var nullSeekableParser = Expression.Constant(null, typeof(Func<ParseContext, ValueTuple<bool, T>>));

var lambdaCache = new List<(List<Parser<T>> Parsers, Func<ParseContext, ValueTuple<bool, T>> CompiledLambda)>();

foreach (var key in _map!.ExpectedChars)
{
Expression group = Expression.Empty();

var parsers = _map[key];
var lambdaSuccess = Expression.Variable(typeof(bool), $"successL{context.NextNumber}");
var lambdaResult = Expression.Variable(typeof(T), $"resultL{context.NextNumber}");
var parsers = _map[key]!;

// The list is reversed since the parsers are unwrapped
foreach (var parser in parsers!.ToArray().Reverse())
// Search if the same parsers set was already generated and compiled

Func<ParseContext, ValueTuple<bool, T>>? cacheCompiledLambda = null;

for (var i = 0; i < lambdaCache.Count; i++)
{
var groupResult = parser.Build(context);
var cacheEntry = lambdaCache[i];
if (cacheEntry.Parsers.Count != parsers.Count)
{
continue;
}

// lambdaSuccess and lambdaResult will be registered at the top of the method
var match = true;

group = Expression.Block(
groupResult.Variables,
Expression.Block(groupResult.Body),
Expression.IfThenElse(
groupResult.Success,
Expression.Block(
Expression.Assign(lambdaSuccess, Expression.Constant(true, typeof(bool))),
context.DiscardResult
? Expression.Empty()
: Expression.Assign(lambdaResult, groupResult.Value)
),
group
)
);
for (var j = 0; j < parsers.Count; j++)
{
if (cacheEntry.Parsers[j] != parsers[j])
{
match = false;
break;
}
}

if (match)
{
cacheCompiledLambda = cacheEntry.CompiledLambda;
}
}

var resultExpression = Expression.Variable(typeof(ValueTuple<bool, T>), $"result{context.NextNumber}");
var returnTarget = Expression.Label(typeof(ValueTuple<bool, T>));
var returnExpression = Expression.Return(returnTarget, resultExpression, typeof(ValueTuple<bool, T>));
var returnLabel = Expression.Label(returnTarget, defaultValue: Expression.New(typeof(ValueTuple<bool, T>)));

var groupBlock = (BlockExpression)group;

var lambda = Expression.Lambda<Func<ParseContext, ValueTuple<bool, T>>>(
body: Expression.Block(
type: typeof(ValueTuple<bool, T>),
variables: groupBlock.Variables
.Append(resultExpression)
.Append(lambdaSuccess)
.Append(lambdaResult),
group,
Expression.Assign(
resultExpression,
Expression.New(
typeof(ValueTuple<bool, T>).GetConstructor([typeof(bool), typeof(T)])!,
lambdaSuccess,
context.DiscardResult ?
Expression.Constant(default(T), typeof(T)) :
lambdaResult)
),
returnExpression,
returnLabel),
name: $"_map_{key}_{context.NextNumber}",
parameters: [context.ParseContext] // Only the name is used, so it will match the ones inside each compiler
);
if (cacheCompiledLambda == null)
{
var lambdaSuccess = Expression.Variable(typeof(bool), $"successL{context.NextNumber}");
var lambdaResult = Expression.Variable(typeof(T), $"resultL{context.NextNumber}");

context.Lambdas.Add(lambda);
// The list is reversed since the parsers are unwrapped
foreach (var parser in parsers.ToArray().Reverse())
{
var groupResult = parser.Build(context);

// lambdaSuccess and lambdaResult will be registered at the top of the method

group = Expression.Block(
groupResult.Variables,
Expression.Block(groupResult.Body),
Expression.IfThenElse(
groupResult.Success,
Expression.Block(
Expression.Assign(lambdaSuccess, Expression.Constant(true, typeof(bool))),
context.DiscardResult
? Expression.Empty()
: Expression.Assign(lambdaResult, groupResult.Value)
),
group
)
);
}

var resultExpression = Expression.Variable(typeof(ValueTuple<bool, T>), $"result{context.NextNumber}");
var returnTarget = Expression.Label(typeof(ValueTuple<bool, T>));
var returnExpression = Expression.Return(returnTarget, resultExpression, typeof(ValueTuple<bool, T>));
var returnLabel = Expression.Label(returnTarget, defaultValue: Expression.New(typeof(ValueTuple<bool, T>)));

var groupBlock = (BlockExpression)group;

var lambda = Expression.Lambda<Func<ParseContext, ValueTuple<bool, T>>>(
body: Expression.Block(
type: typeof(ValueTuple<bool, T>),
variables: groupBlock.Variables
.Append(resultExpression)
.Append(lambdaSuccess)
.Append(lambdaResult),
group,
Expression.Assign(
resultExpression,
Expression.New(
typeof(ValueTuple<bool, T>).GetConstructor([typeof(bool), typeof(T)])!,
lambdaSuccess,
context.DiscardResult ?
Expression.Constant(default(T), typeof(T)) :
lambdaResult)
),
returnExpression,
returnLabel),
name: $"_map_{key}_{context.NextNumber}",
parameters: [context.ParseContext] // Only the name is used, so it will match the ones inside each compiler
);

cacheCompiledLambda = lambda.Compile();
lambdaCache.Add((parsers, cacheCompiledLambda));

context.Lambdas.Add(lambda);
}

if (key == OtherSeekableChar)
{
_lambdaOtherParsers = lambda.Compile();
_lambdaOtherParsers = cacheCompiledLambda;
}
else
{
_lambdaMap.Set(key, lambda.Compile());
_lambdaMap.Set(key, cacheCompiledLambda!);
}
}

Expand Down