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using System;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Text;
// ReSharper disable once CheckNamespace
namespace NpgsqlTypes;
/// <summary>
/// Represents a PostgreSQL range type.
/// </summary>
/// <typeparam name="T">The element type of the values in the range.</typeparam>
/// <remarks>
/// See: https://www.postgresql.org/docs/current/static/rangetypes.html
/// </remarks>
public readonly struct NpgsqlRange<T> : IEquatable<NpgsqlRange<T>>
{
// -----------------------------------------------------------------------------------------------
// Regarding bitwise flag checks via @roji:
//
// > Note that Flags.HasFlag() used to be very inefficient compared to simply doing the
// > bit operation - this is why I've always avoided it. .NET Core 2.1 adds JIT intrinstics
// > for this, making Enum.HasFlag() fast, but I honestly don't see the value over just doing
// > a bitwise and operation, which would also be fast under .NET Core 2.0 and .NET Framework.
//
// See:
// - https://github.com/npgsql/npgsql/pull/1939#pullrequestreview-121308396
// - https://blogs.msdn.microsoft.com/dotnet/2018/04/18/performance-improvements-in-net-core-2-1
// -----------------------------------------------------------------------------------------------
/// <summary>
/// Defined by PostgreSQL to represent an empty range.
/// </summary>
const string EmptyLiteral = "empty";
/// <summary>
/// Defined by PostgreSQL to represent an infinite lower bound.
/// Some element types may have specific handling for this value distinct from a missing or null value.
/// </summary>
const string LowerInfinityLiteral = "-infinity";
/// <summary>
/// Defined by PostgreSQL to represent an infinite upper bound.
/// Some element types may have specific handling for this value distinct from a missing or null value.
/// </summary>
const string UpperInfinityLiteral = "infinity";
/// <summary>
/// Defined by PostgreSQL to represent an null bound.
/// Some element types may have specific handling for this value distinct from an infinite or missing value.
/// </summary>
const string NullLiteral = "null";
/// <summary>
/// Defined by PostgreSQL to represent a lower inclusive bound.
/// </summary>
const char LowerInclusiveBound = '[';
/// <summary>
/// Defined by PostgreSQL to represent a lower exclusive bound.
/// </summary>
const char LowerExclusiveBound = '(';
/// <summary>
/// Defined by PostgreSQL to represent an upper inclusive bound.
/// </summary>
const char UpperInclusiveBound = ']';
/// <summary>
/// Defined by PostgreSQL to represent an upper exclusive bound.
/// </summary>
const char UpperExclusiveBound = ')';
/// <summary>
/// Defined by PostgreSQL to separate the values for the upper and lower bounds.
/// </summary>
const char BoundSeparator = ',';
/// <summary>
/// The <see cref="TypeConverter"/> used by <see cref="Parse"/> to convert <see cref="string"/> bounds into <typeparamref name="T"/>.
/// </summary>
static TypeConverter? BoundConverter;
/// <summary>
/// True if <typeparamref name="T"/> implements <see cref="IEquatable{T}"/>; otherwise, false.
/// </summary>
static readonly bool HasEquatableBounds = typeof(IEquatable<T>).IsAssignableFrom(typeof(T));
/// <summary>
/// Represents the empty range. This field is read-only.
/// </summary>
public static readonly NpgsqlRange<T> Empty = new(default, default, RangeFlags.Empty);
/// <summary>
/// The lower bound of the range. Only valid when <see cref="LowerBoundInfinite"/> is false (i.e. the range is non-empty with a finite lower bound).
/// </summary>
public T? LowerBound { get; }
/// <summary>
/// The upper bound of the range. Only valid when <see cref="UpperBoundInfinite"/> is false (i.e. the range is non-empty with a finite upper bound).
/// </summary>
public T? UpperBound { get; }
/// <summary>
/// The characteristics of the boundaries.
/// </summary>
internal readonly RangeFlags Flags;
/// <summary>
/// True if the lower bound is part of the range (i.e. inclusive); otherwise, false.
/// </summary>
public bool LowerBoundIsInclusive => (Flags & RangeFlags.LowerBoundInclusive) != 0;
/// <summary>
/// True if the upper bound is part of the range (i.e. inclusive); otherwise, false.
/// </summary>
public bool UpperBoundIsInclusive => (Flags & RangeFlags.UpperBoundInclusive) != 0;
/// <summary>
/// True if the lower bound is indefinite (i.e. infinite or unbounded); otherwise, false.
/// </summary>
[MemberNotNullWhen(false, nameof(LowerBound))]
public bool LowerBoundInfinite => (Flags & RangeFlags.LowerBoundInfinite) != 0;
/// <summary>
/// True if the upper bound is indefinite (i.e. infinite or unbounded); otherwise, false.
/// </summary>
[MemberNotNullWhen(false, nameof(UpperBound))]
public bool UpperBoundInfinite => (Flags & RangeFlags.UpperBoundInfinite) != 0;
/// <summary>
/// True if the range is empty; otherwise, false.
/// </summary>
public bool IsEmpty => (Flags & RangeFlags.Empty) != 0;
/// <summary>
/// Constructs an <see cref="NpgsqlRange{T}"/> with inclusive and definite bounds.
/// </summary>
/// <param name="lowerBound">The lower bound of the range.</param>
/// <param name="upperBound">The upper bound of the range.</param>
public NpgsqlRange(T lowerBound, T upperBound)
: this(lowerBound, lowerBoundIsInclusive: true, lowerBoundInfinite: false, upperBound, upperBoundIsInclusive: true, upperBoundInfinite: false) { }
/// <summary>
/// Constructs an <see cref="NpgsqlRange{T}"/> with definite bounds.
/// </summary>
/// <param name="lowerBound">The lower bound of the range.</param>
/// <param name="lowerBoundIsInclusive">True if the lower bound is is part of the range (i.e. inclusive); otherwise, false.</param>
/// <param name="upperBound">The upper bound of the range.</param>
/// <param name="upperBoundIsInclusive">True if the upper bound is part of the range (i.e. inclusive); otherwise, false.</param>
public NpgsqlRange(T lowerBound, bool lowerBoundIsInclusive, T upperBound, bool upperBoundIsInclusive)
: this(lowerBound, lowerBoundIsInclusive, lowerBoundInfinite: false, upperBound, upperBoundIsInclusive, upperBoundInfinite: false) { }
/// <summary>
/// Constructs an <see cref="NpgsqlRange{T}"/>.
/// </summary>
/// <param name="lowerBound">The lower bound of the range.</param>
/// <param name="lowerBoundIsInclusive">True if the lower bound is is part of the range (i.e. inclusive); otherwise, false.</param>
/// <param name="lowerBoundInfinite">True if the lower bound is indefinite (i.e. infinite or unbounded); otherwise, false.</param>
/// <param name="upperBound">The upper bound of the range.</param>
/// <param name="upperBoundIsInclusive">True if the upper bound is part of the range (i.e. inclusive); otherwise, false.</param>
/// <param name="upperBoundInfinite">True if the upper bound is indefinite (i.e. infinite or unbounded); otherwise, false.</param>
public NpgsqlRange(T? lowerBound, bool lowerBoundIsInclusive, bool lowerBoundInfinite, T? upperBound, bool upperBoundIsInclusive, bool upperBoundInfinite)
: this(
lowerBound,
upperBound,
EvaluateBoundaryFlags(
lowerBoundIsInclusive,
upperBoundIsInclusive,
lowerBoundInfinite,
upperBoundInfinite)) { }
/// <summary>
/// Constructs an <see cref="NpgsqlRange{T}"/>.
/// </summary>
/// <param name="lowerBound">The lower bound of the range.</param>
/// <param name="upperBound">The upper bound of the range.</param>
/// <param name="flags">The characteristics of the range boundaries.</param>
internal NpgsqlRange(T? lowerBound, T? upperBound, RangeFlags flags) : this()
{
// TODO: We need to check if the bounds are implicitly empty. E.g. '(1,1)' or '(0,0]'.
// See: https://github.com/npgsql/npgsql/issues/1943.
LowerBound = (flags & RangeFlags.LowerBoundInfinite) != 0 ? default : lowerBound;
UpperBound = (flags & RangeFlags.UpperBoundInfinite) != 0 ? default : upperBound;
Flags = flags;
if (IsEmptyRange(LowerBound, UpperBound, Flags))
{
LowerBound = default!;
UpperBound = default!;
Flags = RangeFlags.Empty;
}
}
/// <summary>
/// Attempts to determine if the range is malformed or implicitly empty.
/// </summary>
/// <param name="lowerBound">The lower bound of the range.</param>
/// <param name="upperBound">The upper bound of the range.</param>
/// <param name="flags">The characteristics of the range boundaries.</param>
/// <returns>
/// True if the range is implicitly empty; otherwise, false.
/// </returns>
static bool IsEmptyRange(T? lowerBound, T? upperBound, RangeFlags flags)
{
// ---------------------------------------------------------------------------------
// We only want to check for those conditions that are unambiguously erroneous:
// 1. The bounds must not be default values (including null).
// 2. The bounds must be definite (non-infinite).
// 3. The bounds must be inclusive.
// 4. The bounds must be considered equal.
//
// See:
// - https://github.com/npgsql/npgsql/pull/1939
// - https://github.com/npgsql/npgsql/issues/1943
// ---------------------------------------------------------------------------------
if ((flags & RangeFlags.Empty) == RangeFlags.Empty)
return true;
if ((flags & RangeFlags.Infinite) == RangeFlags.Infinite)
return false;
if ((flags & RangeFlags.Inclusive) == RangeFlags.Inclusive)
return false;
if (lowerBound is null || upperBound is null)
return false;
if (!HasEquatableBounds)
return lowerBound.Equals(upperBound);
var lower = (IEquatable<T>)lowerBound;
var upper = (IEquatable<T>)upperBound;
return !lower.Equals(default!) && !upper.Equals(default!) && lower.Equals(upperBound);
}
/// <summary>
/// Evaluates the boundary flags.
/// </summary>
/// <param name="lowerBoundIsInclusive">True if the lower bound is is part of the range (i.e. inclusive); otherwise, false.</param>
/// <param name="lowerBoundInfinite">True if the lower bound is indefinite (i.e. infinite or unbounded); otherwise, false.</param>
/// <param name="upperBoundIsInclusive">True if the upper bound is part of the range (i.e. inclusive); otherwise, false.</param>
/// <param name="upperBoundInfinite">True if the upper bound is indefinite (i.e. infinite or unbounded); otherwise, false.</param>
/// <returns>
/// The boundary characteristics.
/// </returns>
static RangeFlags EvaluateBoundaryFlags(bool lowerBoundIsInclusive, bool upperBoundIsInclusive, bool lowerBoundInfinite, bool upperBoundInfinite)
{
var result = RangeFlags.None;
// This is the only place flags are calculated.
if (lowerBoundIsInclusive)
result |= RangeFlags.LowerBoundInclusive;
if (upperBoundIsInclusive)
result |= RangeFlags.UpperBoundInclusive;
if (lowerBoundInfinite)
result |= RangeFlags.LowerBoundInfinite;
if (upperBoundInfinite)
result |= RangeFlags.UpperBoundInfinite;
// PostgreSQL automatically converts inclusive-infinities.
// See: https://www.postgresql.org/docs/current/static/rangetypes.html#RANGETYPES-INFINITE
if ((result & RangeFlags.LowerInclusiveInfinite) == RangeFlags.LowerInclusiveInfinite)
result &= ~RangeFlags.LowerBoundInclusive;
if ((result & RangeFlags.UpperInclusiveInfinite) == RangeFlags.UpperInclusiveInfinite)
result &= ~RangeFlags.UpperBoundInclusive;
return result;
}
/// <summary>
/// Indicates whether the <see cref="NpgsqlRange{T}"/> on the left is equal to the <see cref="NpgsqlRange{T}"/> on the right.
/// </summary>
/// <param name="x">The <see cref="NpgsqlRange{T}"/> on the left.</param>
/// <param name="y">The <see cref="NpgsqlRange{T}"/> on the right.</param>
/// <returns>
/// True if the <see cref="NpgsqlRange{T}"/> on the left is equal to the <see cref="NpgsqlRange{T}"/> on the right; otherwise, false.
/// </returns>
public static bool operator ==(NpgsqlRange<T> x, NpgsqlRange<T> y) => x.Equals(y);
/// <summary>
/// Indicates whether the <see cref="NpgsqlRange{T}"/> on the left is not equal to the <see cref="NpgsqlRange{T}"/> on the right.
/// </summary>
/// <param name="x">The <see cref="NpgsqlRange{T}"/> on the left.</param>
/// <param name="y">The <see cref="NpgsqlRange{T}"/> on the right.</param>
/// <returns>
/// True if the <see cref="NpgsqlRange{T}"/> on the left is not equal to the <see cref="NpgsqlRange{T}"/> on the right; otherwise, false.
/// </returns>
public static bool operator !=(NpgsqlRange<T> x, NpgsqlRange<T> y) => !x.Equals(y);
/// <inheritdoc />
public override bool Equals(object? o) => o is NpgsqlRange<T> range && Equals(range);
/// <inheritdoc />
public bool Equals(NpgsqlRange<T> other)
{
if (Flags != other.Flags)
return false;
if (HasEquatableBounds)
{
var lowerEqual = LowerBound is null
? other.LowerBound is null
: !(other.LowerBound is null) && ((IEquatable<T>)LowerBound).Equals(other.LowerBound);
if (!lowerEqual)
return false;
return UpperBound is null
? other.UpperBound is null
: !(other.UpperBound is null) && ((IEquatable<T>)UpperBound).Equals(other.UpperBound);
}
return
(LowerBound?.Equals(other.LowerBound) ?? other.LowerBound is null) &&
(UpperBound?.Equals(other.UpperBound) ?? other.UpperBound is null);
}
/// <inheritdoc />
public override int GetHashCode()
=> unchecked((397 * (int)Flags) ^ (397 * (LowerBound?.GetHashCode() ?? 0)) ^ (397 * (UpperBound?.GetHashCode() ?? 0)));
/// <inheritdoc />
public override string ToString()
{
if (IsEmpty)
return EmptyLiteral;
var sb = new StringBuilder();
sb.Append(LowerBoundIsInclusive ? LowerInclusiveBound : LowerExclusiveBound);
if (!LowerBoundInfinite)
sb.Append(LowerBound);
sb.Append(BoundSeparator);
if (!UpperBoundInfinite)
sb.Append(UpperBound);
sb.Append(UpperBoundIsInclusive ? UpperInclusiveBound : UpperExclusiveBound);
return sb.ToString();
}
// TODO: rewrite this to use ReadOnlySpan<char> for the 4.1 release
/// <summary>
/// Parses the well-known text representation of a PostgreSQL range type into a <see cref="NpgsqlRange{T}"/>.
/// </summary>
/// <param name="value">A PosgreSQL range type in a well-known text format.</param>
/// <returns>
/// The <see cref="NpgsqlRange{T}"/> represented by the <paramref name="value"/>.
/// </returns>
/// <exception cref="FormatException">
/// Malformed range literal.
/// </exception>
/// <exception cref="FormatException">
/// Malformed range literal. Missing left parenthesis or bracket.
/// </exception>
/// <exception cref="FormatException">
/// Malformed range literal. Missing right parenthesis or bracket.
/// </exception>
/// <exception cref="FormatException">
/// Malformed range literal. Missing comma after lower bound.
/// </exception>
/// <remarks>
/// See: https://www.postgresql.org/docs/current/static/rangetypes.html
/// </remarks>
[RequiresUnreferencedCode("Parse implementations for certain types of T may require members that have been trimmed.")]
public static NpgsqlRange<T> Parse(string value)
{
ArgumentNullException.ThrowIfNull(value);
value = value.Trim();
if (value.Length < 3)
throw new FormatException("Malformed range literal.");
if (string.Equals(value, EmptyLiteral, StringComparison.OrdinalIgnoreCase))
return Empty;
var lowerInclusive = value[0] == LowerInclusiveBound;
var lowerExclusive = value[0] == LowerExclusiveBound;
if (!lowerInclusive && !lowerExclusive)
throw new FormatException("Malformed range literal. Missing left parenthesis or bracket.");
var upperInclusive = value[^1] == UpperInclusiveBound;
var upperExclusive = value[^1] == UpperExclusiveBound;
if (!upperInclusive && !upperExclusive)
throw new FormatException("Malformed range literal. Missing right parenthesis or bracket.");
var separator = value.IndexOf(BoundSeparator);
if (separator == -1)
throw new FormatException("Malformed range literal. Missing comma after lower bound.");
if (separator != value.LastIndexOf(BoundSeparator))
// TODO: this should be replaced to handle quoted commas.
throw new NotSupportedException("Ranges with embedded commas are not currently supported.");
// Skip the opening bracket and stop short of the separator.
var lowerSegment = value.Substring(1, separator - 1).Trim();
// Skip past the separator and stop short of the closing bracket.
var upperSegment = value.Substring(separator + 1, value.Length - separator - 2).Trim();
// TODO: infinity literals have special meaning to some types (e.g. daterange), we should consider a flag to track them.
var lowerInfinite =
lowerSegment.Length == 0 ||
string.Equals(lowerSegment, string.Empty, StringComparison.OrdinalIgnoreCase) ||
string.Equals(lowerSegment, NullLiteral, StringComparison.OrdinalIgnoreCase) ||
string.Equals(lowerSegment, LowerInfinityLiteral, StringComparison.OrdinalIgnoreCase);
var upperInfinite =
upperSegment.Length == 0 ||
string.Equals(upperSegment, string.Empty, StringComparison.OrdinalIgnoreCase) ||
string.Equals(upperSegment, NullLiteral, StringComparison.OrdinalIgnoreCase) ||
string.Equals(upperSegment, UpperInfinityLiteral, StringComparison.OrdinalIgnoreCase);
BoundConverter ??= TypeDescriptor.GetConverter(typeof(T));
var lower = lowerInfinite ? default : (T?)BoundConverter.ConvertFromString(lowerSegment);
var upper = upperInfinite ? default : (T?)BoundConverter.ConvertFromString(upperSegment);
return new NpgsqlRange<T>(lower, lowerInclusive, lowerInfinite, upper, upperInclusive, upperInfinite);
}
/// <summary>
/// Represents a type converter for <see cref="NpgsqlRange{T}" />.
/// </summary>
[RequiresUnreferencedCode("ConvertFrom implementations for certain types of T may require members that have been trimmed.")]
public class RangeTypeConverter : TypeConverter
{
/// <summary>
/// Adds a <see cref="TypeConverterAttribute"/> to the closed form <see cref="NpgsqlRange{T}"/>.
/// </summary>
public static void Register() =>
TypeDescriptor.AddAttributes(
typeof(NpgsqlRange<T>),
new TypeConverterAttribute(typeof(RangeTypeConverter)));
/// <inheritdoc />
public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
=> sourceType == typeof(string);
/// <inheritdoc />
public override bool CanConvertTo(ITypeDescriptorContext? context, Type? destinationType)
=> destinationType == typeof(string);
/// <inheritdoc />
public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
=> value is string s ? Parse(s) : base.ConvertFrom(context, culture, value);
/// <inheritdoc />
public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
=> value is null ? string.Empty : value.ToString();
}
}
/// <summary>
/// Represents characteristics of range type boundaries.
/// </summary>
/// <remarks>
/// See: https://www.postgresql.org/docs/current/static/rangetypes.html
/// </remarks>
[Flags]
enum RangeFlags : byte
{
/// <summary>
/// The default flag. The range is not empty and has boundaries that are definite and exclusive.
/// </summary>
None = 0,
/// <summary>
/// The range is empty. E.g. '(0,0)', 'empty'.
/// </summary>
Empty = 1,
/// <summary>
/// The lower bound is inclusive. E.g. '[0,5]', '[0,5)', '[0,)'.
/// </summary>
LowerBoundInclusive = 2,
/// <summary>
/// The upper bound is inclusive. E.g. '[0,5]', '(0,5]', '(,5]'.
/// </summary>
UpperBoundInclusive = 4,
/// <summary>
/// The lower bound is infinite or indefinite. E.g. '(null,5]', '(-infinity,5]', '(,5]'.
/// </summary>
LowerBoundInfinite = 8,
/// <summary>
/// The upper bound is infinite or indefinite. E.g. '[0,null)', '[0,infinity)', '[0,)'.
/// </summary>
UpperBoundInfinite = 16,
/// <summary>
/// Both the lower and upper bounds are inclusive.
/// </summary>
Inclusive = LowerBoundInclusive | UpperBoundInclusive,
/// <summary>
/// Both the lower and upper bounds are indefinite.
/// </summary>
Infinite = LowerBoundInfinite | UpperBoundInfinite,
/// <summary>
/// The lower bound is both inclusive and indefinite. This represents an error condition.
/// </summary>
LowerInclusiveInfinite = LowerBoundInclusive | LowerBoundInfinite,
/// <summary>
/// The upper bound is both inclusive and indefinite. This represents an error condition.
/// </summary>
UpperInclusiveInfinite = UpperBoundInclusive | UpperBoundInfinite
}
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