internal static IList <Expression> ParseQueryParameters(ref Utf8JsonReader reader, Stack <Expression> stack, JsonLogicOptions options)
{
if (!reader.Read())
{
throw new JsonException();
}
var l = new List <Expression>(2);
if (reader.TokenType != JsonTokenType.EndArray)
{
var arrayExpr = Parse(ref reader, stack);
if (!arrayExpr.Type.IsArray)
{
throw new JsonLogicException($"Querie's first parameter MUST be an array.");
}
l.Add(arrayExpr);
var etype = arrayExpr.Type.GetElementType();
if (!reader.Read())
{
throw new JsonException();
}
var predicateParameter = Expression.Parameter(etype, "p");
stack.Push(predicateParameter);
var predicateExpr = Parse(ref reader, stack);
stack.Pop();
l.Add(predicateExpr);
if (!reader.Read())
{
throw new JsonException();
}
if (reader.TokenType != JsonTokenType.EndArray)
{
reader.Skip();
}
}
return(l);
}
internal static IList <Expression> ParseOpParameters(ref Utf8JsonReader reader, Stack <Expression> parameters, JsonLogicOptions options)
{
if (!reader.Read())
{
throw new JsonException();
}
var l = new List <Expression>(2);
while (reader.TokenType != JsonTokenType.EndArray)
{
l.Add(Parse(ref reader, parameters));
if (!reader.Read())
{
throw new JsonException();
}
}
return(l);
}
internal static Expression Parse(ref Utf8JsonReader reader, Stack <Expression> stack, JsonLogicOptions options = null)
{
Expression exp = default;
switch (reader.TokenType)
{
case JsonTokenType.StartObject:
{
if (!reader.Read() || reader.TokenType != JsonTokenType.PropertyName)
{
throw new JsonException();
}
var opName = reader.GetString()?.Trim()?.ToLower();
if (options?.Aliases != null && options.Aliases.TryGetValue(opName, out string alias))
{
opName = alias;
}
if (!reader.Read())
{
throw new JsonException();
}
switch (reader.TokenType)
{
case JsonTokenType.StartArray:
{
// this migh be an expression of type { operation : [params...] }
// 1 - try to get a standard operations
if (KnownOpFactories.TryGetValue(opName, out OpFactory factory))
{
var values = ParseOpParameters(ref reader, stack, options);
exp = factory?.Invoke(values, stack, options);
break;
}
// 2 - Else it's operations on Array. We must parse it in different way, because
// underlying predicate need ExpressionParameter to be passed instead as
// data.
if (KnownQueryFactories.TryGetValue(opName, out factory))
{
var values = ParseQueryParameters(ref reader, stack, options);
exp = factory?.Invoke(values, stack, options);
break;
}
throw new JsonLogicException($"Unknown operation {opName}");
}
case JsonTokenType.String:
{
// using Syntactic sugar such "var"="xxx" instead as "var" = ["xxx"]
switch (opName)
{
case TerminalVocabulary.Var:
{
exp = GetProperty(reader.GetString(), stack, options);
break;
}
default: throw new JsonLogicException($"Syntax error.");
}
break;
}
case JsonTokenType.Number:
{
// using Syntactic sugar such "var"=n instead as "var" = [n]
switch (opName)
{
case TerminalVocabulary.Var:
{
exp = Expression.ArrayAccess(stack.Peek(), Expression.Constant(reader.GetInt32()));
break;
}
default: throw new JsonLogicException($"Syntax error.");
}
break;
}
default: throw new JsonException();
}
if (!reader.Read() || reader.TokenType != JsonTokenType.EndObject)
{
throw new JsonException();
}
break;
}
case JsonTokenType.String:
{
var value = reader.GetString();
exp = Expression.Constant((object)value);
break;
}
case JsonTokenType.Number:
{
var value = reader.GetDouble();
exp = Expression.Constant((object)value);
break;
}
case JsonTokenType.StartArray:
{
exp = ParseArray(ref reader);
break;
}
default: throw new JsonException();
}
return(exp);
}
public static Expression LessThanOrEqual(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
if (values.Count == 2)
{
return(Expression.LessThanOrEqual(values[0].EnsureJsonNumber(), values[1].EnsureJsonNumber()));
}
// special case to test between
var v0 = values[0].EnsureJsonNumber();
var v1 = values[1].EnsureJsonNumber();
var v2 = values[2].EnsureJsonNumber();
var a = Expression.LessThanOrEqual(v0, v1);
var b = Expression.LessThanOrEqual(v1, v2);
return(Expression.And(a, b));
}
public static Expression And(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
Expression exp = Expression.AndAlso(values[0], values[1]);
for (int i = 2; i != values.Count; i++)
{
exp = Expression.AndAlso(exp, values[i]);
}
return(exp);
}
private static Expression MinMax(IList <Expression> values, JsonLogicOptions options, bool op)
{
Expression array = default;
Type etype = default;
switch (values.Count)
{
case 0: throw new JsonLogicException();
case 1:
{
if (values[0].Type.IsArray)
{
array = values[0];
etype = array.Type.GetElementType();
break;
}
return(values[0]);
}
case 2:
{
// fast track..
var a = values[0].EnsureJsonNumber();
var b = values[1].EnsureJsonNumber();
var p = Expression.Variable(a.Type);
return(Expression.Block(a.Type,
new[] { p },
Expression.IfThenElse(Expression.LessThan(a, b),
Expression.Assign(p, op ? b : a),
Expression.Assign(p, op ? a : b)),
p));
}
default:
{
if (!values.All(v => v is ConstantExpression ce && ce.Type.IsNumericType()))
{
throw new JsonLogicException("Array must be of Number");
}
array = Expression.Constant(values.Cast <ConstantExpression>().Select <ConstantExpression, double>(v => (double)Convert.ChangeType(v.Value, typeof(double))).ToArray());
etype = typeof(double);
break;
}
}
var indexVariable = Expression.Variable(typeof(int), "index");
var arrayValue = Expression.Variable(etype, "value");
var result = Expression.Variable(etype, "result");
var lengthExp = Expression.Property(array, typeof(Array).GetPublicInstanceDeclaredOnlyReadProperty(nameof(Array.Length)) !);
return(Expression.Block(
new[] { indexVariable, arrayValue, result },
Expression.Assign(result, Expression.ArrayIndex(array, Expression.Constant(0))),
ExpressionHelpers.For(
Expression.Assign(indexVariable, Expression.Constant(0)),
Expression.LessThan(indexVariable, lengthExp),
Expression.PostIncrementAssign(indexVariable),
Expression.Block(
Expression.Assign(arrayValue, Expression.ArrayIndex(array, indexVariable)),
Expression.IfThenElse(Expression.LessThan(result, arrayValue),
Expression.Assign(result, op ? arrayValue : result),
Expression.Assign(result, op ? result : arrayValue))
)
),
result));
}
public static Expression NotEqual(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
if (values[0].Type.IsNumericType())
{
return(Expression.Equal(values[0].EnsureJsonNumber(), values[1].EnsureJsonNumber()));
}
return(Expression.NotEqual(values[0], values[1]));
}
public static Expression Some(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
if (!values[0].Type.IsArray)
{
throw new JsonLogicException();
}
Expression arrayExpr = values[0];
Type etype = arrayExpr.Type.GetElementType();
var indexVariable = Expression.Variable(typeof(int), "index");
var lengthExp = Expression.Property(arrayExpr, typeof(Array).GetPublicInstanceDeclaredOnlyReadProperty(nameof(Array.Length)) !);
var result = Expression.Variable(typeof(bool), "result");
var label = Expression.Label();
// note we have to replace all parameters into the underlying expression to reflect the item
var itemParameter = Expression.Parameter(etype, "item");
ParameterReplacer replacer = new ParameterReplacer(itemParameter);
var predicate = replacer.Visit(values[1]);
// Parameter for the catch block
var exception = Expression.Parameter(typeof(Exception));
var expr = Expression.Block(
new[] { indexVariable, itemParameter, result },
Expression.TryCatch(
Expression.Block(
Expression.Assign(result, Expression.Constant(false)),
Expression.Assign(indexVariable, Expression.Constant(0)),
#if DEBUG
ExpressionHelpers.DebugExpression(lengthExp),
#endif
Expression.Loop(
Expression.IfThenElse(
Expression.LessThan(indexVariable, lengthExp),
Expression.Block(
Expression.Assign(itemParameter, Expression.ArrayIndex(arrayExpr, indexVariable)),
#if DEBUG
ExpressionHelpers.DebugExpression(predicate),
#endif
Expression.IfThen(
predicate,
Expression.Block(
Expression.Assign(result, Expression.Constant(true)),
Expression.Break(label)
)
),
Expression.PostIncrementAssign(indexVariable)
),
Expression.Break(label)),
label)
),
Expression.Catch(
exception,
#if DEBUG
ExpressionHelpers.DebugExpression(exception)
#else
Expression.Throw(exception)
#endif
)
),
result);
return(expr);
}
public static Expression Var(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 1)
{
throw new JsonLogicException();
}
var a = values[0];
if (a is ConstantExpression ce)
{
if (ce.Value is string str)
{
try
{
return(JsonLogic.GetProperty(str, stack, options));
}
catch (JsonLogicException)
{
if (values.Count > 1)
{
return(values[1]);
}
throw;
}
}
if (ce.Type.IsNumericType())
{
var array = stack?.FirstOrDefault(e => e.Type.IsArray);
if (array != default)
{
return(Expression.ArrayAccess(array, ce.EnsureIndexNumber()));
}
}
}
throw new JsonLogicException();
}
public static Expression Max(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
return(MinMax(values, options, true));
}
public static Expression Modulo(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
return(Expression.Modulo(values[0].EnsureJsonNumber(), values[1].EnsureJsonNumber()));
}
public static Expression GreaterThan(IList <Expression> values, Stack <Expression> stack = null, JsonLogicOptions options = null)
{
if (values.Count < 2)
{
throw new JsonLogicException();
}
return(Expression.GreaterThan(values[0], values[1]));
}