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Copy pathNpgsqlTsVector.cs
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556 lines (481 loc) · 17.6 KB
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using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
// ReSharper disable once CheckNamespace
namespace NpgsqlTypes;
/// <summary>
/// Represents a PostgreSQL tsvector.
/// </summary>
public sealed class NpgsqlTsVector : IEnumerable<NpgsqlTsVector.Lexeme>, IEquatable<NpgsqlTsVector>
{
/// <summary>
/// Represents an empty tsvector.
/// </summary>
public static readonly NpgsqlTsVector Empty = new NpgsqlTsVector([], noCheck: true);
readonly List<Lexeme> _lexemes;
internal NpgsqlTsVector(List<Lexeme> lexemes, bool noCheck = false)
{
if (noCheck)
{
_lexemes = lexemes;
return;
}
_lexemes = [..lexemes];
if (_lexemes.Count == 0)
return;
// Culture-specific comparisons doesn't really matter for the backend. It's sorting on its own if it detects an unsorted collection.
// Only when a .NET user wants to print the sort order.
_lexemes.Sort((a, b) => string.Compare(a.Text, b.Text, StringComparison.CurrentCulture));
var res = 0;
var pos = 1;
while (pos < _lexemes.Count)
{
if (_lexemes[pos].Text != _lexemes[res].Text)
{
// We're done with this lexeme. First make sure the word pos list is sorted and contains unique elements.
_lexemes[res] = new Lexeme(_lexemes[res].Text, Lexeme.UniquePos(_lexemes[res].WordEntryPositions), true);
res++;
if (res != pos)
_lexemes[res] = _lexemes[pos];
}
else
{
// Just concatenate the word pos lists
var wordEntryPositions = _lexemes[res].WordEntryPositions;
if (wordEntryPositions != null)
{
var lexeme = _lexemes[pos];
if (lexeme.WordEntryPositions != null)
wordEntryPositions.AddRange(lexeme.WordEntryPositions);
}
else
{
_lexemes[res] = _lexemes[pos];
}
}
pos++;
}
// Last element
_lexemes[res] = new Lexeme(_lexemes[res].Text, Lexeme.UniquePos(_lexemes[res].WordEntryPositions), true);
if (res != pos - 1)
{
_lexemes.RemoveRange(res, pos - 1 - res);
}
}
/// <summary>
/// Parses a tsvector in PostgreSQL's text format.
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
[Obsolete("Client-side parsing of NpgsqlTsVector is unreliable and cannot fully duplicate the PostgreSQL logic. Use PG functions instead (e.g. to_tsvector)")]
public static NpgsqlTsVector Parse(string value)
{
ArgumentNullException.ThrowIfNull(value);
var lexemes = new List<Lexeme>();
var pos = 0;
var wordPos = 0;
var sb = new StringBuilder();
List<Lexeme.WordEntryPos> wordEntryPositions;
WaitWord:
if (pos >= value.Length)
goto Finish;
if (char.IsWhiteSpace(value[pos]))
{
pos++;
goto WaitWord;
}
sb.Clear();
if (value[pos] == '\'')
{
pos++;
goto WaitEndComplex;
}
if (value[pos] == '\\')
{
pos++;
goto WaitNextChar;
}
sb.Append(value[pos++]);
goto WaitEndWord;
WaitNextChar:
if (pos >= value.Length)
throw new FormatException("Missing escaped character after \\ at end of value");
sb.Append(value[pos++]);
WaitEndWord:
if (pos >= value.Length || char.IsWhiteSpace(value[pos]))
{
lexemes.Add(new Lexeme(sb.ToString()));
if (pos >= value.Length)
goto Finish;
pos++;
goto WaitWord;
}
if (value[pos] == '\\')
{
pos++;
goto WaitNextChar;
}
if (value[pos] == ':')
{
pos++;
goto StartPosInfo;
}
sb.Append(value[pos++]);
goto WaitEndWord;
WaitEndComplex:
if (pos >= value.Length)
throw new FormatException("Unexpected end of value");
if (value[pos] == '\'')
{
pos++;
goto WaitCharComplex;
}
if (value[pos] == '\\')
{
pos++;
if (pos >= value.Length)
throw new FormatException("Missing escaped character after \\ at end of value");
}
sb.Append(value[pos++]);
goto WaitEndComplex;
WaitCharComplex:
if (pos < value.Length && value[pos] == '\'')
{
sb.Append('\'');
pos++;
goto WaitEndComplex;
}
if (pos < value.Length && value[pos] == ':')
{
pos++;
goto StartPosInfo;
}
lexemes.Add(new Lexeme(sb.ToString()));
goto WaitWord;
StartPosInfo:
wordEntryPositions = [];
InPosInfo:
var digitPos = pos;
while (pos < value.Length && value[pos] >= '0' && value[pos] <= '9')
pos++;
if (digitPos == pos)
throw new FormatException("Missing length after :");
wordPos = int.Parse(value.Substring(digitPos, pos - digitPos));
// Note: PostgreSQL backend parser matches also for example 1DD2A, which is parsed into 1A, but not 1AA2D ...
if (pos < value.Length)
{
if (value[pos] == 'A' || value[pos] == 'a' || value[pos] == '*') // Why * ?
{
wordEntryPositions.Add(new Lexeme.WordEntryPos(wordPos, Lexeme.Weight.A));
pos++;
goto WaitPosDelim;
}
if (value[pos] >= 'B' && value[pos] <= 'D' || value[pos] >= 'b' && value[pos] <= 'd')
{
var weight = value[pos];
if (weight is >= 'b' and <= 'd')
weight = (char)(weight - ('b' - 'B'));
wordEntryPositions.Add(new Lexeme.WordEntryPos(wordPos, Lexeme.Weight.D + ('D' - weight)));
pos++;
goto WaitPosDelim;
}
}
wordEntryPositions.Add(new Lexeme.WordEntryPos(wordPos));
WaitPosDelim:
if (pos >= value.Length || char.IsWhiteSpace(value[pos]))
{
if (pos < value.Length)
pos++;
lexemes.Add(new Lexeme(sb.ToString(), wordEntryPositions));
goto WaitWord;
}
if (value[pos] == ',')
{
pos++;
goto InPosInfo;
}
throw new FormatException("Missing comma, whitespace or end of value after lexeme pos info");
Finish:
return new NpgsqlTsVector(lexemes);
}
/// <summary>
/// Returns the lexeme at a specific index
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
public Lexeme this[int index]
{
get
{
if (index < 0 || index >= _lexemes.Count)
throw new ArgumentException(nameof(index));
return _lexemes[index];
}
}
/// <summary>
/// Gets the number of lexemes.
/// </summary>
public int Count => _lexemes.Count;
/// <summary>
/// Returns an enumerator.
/// </summary>
/// <returns></returns>
public IEnumerator<Lexeme> GetEnumerator() => _lexemes.GetEnumerator();
/// <summary>
/// Returns an enumerator.
/// </summary>
/// <returns></returns>
IEnumerator IEnumerable.GetEnumerator() => _lexemes.GetEnumerator();
/// <summary>
/// Gets a string representation in PostgreSQL's format.
/// </summary>
/// <returns></returns>
public override string ToString() => string.Join(" ", _lexemes);
/// <inheritdoc />
public bool Equals(NpgsqlTsVector? other)
{
if (ReferenceEquals(this, other))
return true;
if (other is null || _lexemes.Count != other._lexemes.Count)
return false;
for (var i = 0; i < _lexemes.Count; i++)
if (!_lexemes[i].Equals(other._lexemes[i]))
return false;
return true;
}
/// <inheritdoc />
public override bool Equals(object? obj)
=> obj is NpgsqlTsVector other && Equals(other);
/// <inheritdoc />
public override int GetHashCode()
{
var hash = new HashCode();
foreach (var lexeme in _lexemes)
hash.Add(lexeme);
return hash.ToHashCode();
}
/// <summary>
/// Represents a lexeme. A lexeme consists of a text string and optional word entry positions.
/// </summary>
public struct Lexeme : IEquatable<Lexeme>
{
/// <summary>
/// Gets or sets the text.
/// </summary>
public string Text { get; set; }
internal readonly List<WordEntryPos>? WordEntryPositions;
/// <summary>
/// Creates a lexeme with no word entry positions.
/// </summary>
/// <param name="text"></param>
public Lexeme(string text)
{
Text = text;
WordEntryPositions = null;
}
/// <summary>
/// Creates a lexeme with word entry positions.
/// </summary>
/// <param name="text"></param>
/// <param name="wordEntryPositions"></param>
public Lexeme(string text, List<WordEntryPos>? wordEntryPositions)
: this(text, wordEntryPositions, false) {}
internal Lexeme(string text, List<WordEntryPos>? wordEntryPositions, bool noCopy)
{
Text = text;
if (wordEntryPositions != null)
WordEntryPositions = noCopy ? wordEntryPositions : [..wordEntryPositions];
else
WordEntryPositions = null;
}
internal static List<WordEntryPos>? UniquePos(List<WordEntryPos>? list)
{
if (list == null)
return null;
var needsProcessing = false;
for (var i = 1; i < list.Count; i++)
{
if (list[i - 1].Pos >= list[i].Pos)
{
needsProcessing = true;
break;
}
}
if (!needsProcessing)
return list;
// Don't change the original list, as the user might inspect it later if he holds a reference to the lexeme's list
list = [..list];
list.Sort((x, y) => x.Pos.CompareTo(y.Pos));
var a = 0;
for (var b = 1; b < list.Count; b++)
{
if (list[a].Pos != list[b].Pos)
{
a++;
if (a != b)
list[a] = list[b];
}
else if (list[b].Weight > list[a].Weight)
list[a] = list[b];
}
if (a != list.Count - 1)
{
list.RemoveRange(a, list.Count - 1 - a);
}
return list;
}
/// <summary>
/// Gets a word entry position.
/// </summary>
/// <param name="index"></param>
/// <returns></returns>
public WordEntryPos this[int index]
{
get
{
if (index < 0 || WordEntryPositions == null || index >= WordEntryPositions.Count)
throw new ArgumentException(nameof(index));
return WordEntryPositions[index];
}
internal set
{
if (index < 0 || WordEntryPositions == null || index >= WordEntryPositions.Count)
throw new ArgumentOutOfRangeException(nameof(index));
WordEntryPositions[index] = value;
}
}
/// <summary>
/// Gets the number of word entry positions.
/// </summary>
public int Count => WordEntryPositions?.Count ?? 0;
/// <summary>
/// Creates a string representation in PostgreSQL's format.
/// </summary>
/// <returns></returns>
public override string ToString()
{
var str = '\'' + (Text ?? "").Replace(@"\", @"\\").Replace("'", "''") + '\'';
if (Count > 0)
str += ":" + string.Join(",", WordEntryPositions!);
return str;
}
/// <summary>
/// Represents a word entry position and an optional weight.
/// </summary>
public struct WordEntryPos : IEquatable<WordEntryPos>
{
internal short Value { get; }
internal WordEntryPos(short value)
=> Value = value;
/// <summary>
/// Creates a WordEntryPos with a given position and weight.
/// </summary>
/// <param name="pos">Position values can range from 1 to 16383; larger numbers are silently set to 16383.</param>
/// <param name="weight">A weight labeled between A and D.</param>
public WordEntryPos(int pos, Weight weight = Weight.D)
{
if (pos == 0)
throw new ArgumentOutOfRangeException(nameof(pos), "Lexeme position is out of range. Min value is 1, max value is 2^14-1. Value was: " + pos);
if (weight < Weight.D || weight > Weight.A)
throw new ArgumentOutOfRangeException(nameof(weight));
// Per documentation: "Position values can range from 1 to 16383; larger numbers are silently set to 16383."
if (pos >> 14 != 0)
pos = (1 << 14) - 1;
Value = (short)(((int)weight << 14) | pos);
}
/// <summary>
/// The weight is labeled from A to D. D is the default, and not printed.
/// </summary>
public Weight Weight => (Weight)((Value >> 14) & 3);
/// <summary>
/// The position is a 14-bit unsigned integer indicating the position in the text this lexeme occurs. Cannot be 0.
/// </summary>
public int Pos => Value & ((1 << 14) - 1);
/// <summary>
/// Prints this lexeme in PostgreSQL's format, i.e. position is followed by weight (weight is only printed if A, B or C).
/// </summary>
/// <returns></returns>
public override string ToString()
{
if (Weight != Weight.D)
return Pos + Weight.ToString();
return Pos.ToString();
}
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public bool Equals(WordEntryPos o) => Value == o.Value;
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public override bool Equals(object? o) => o is WordEntryPos pos && Equals(pos);
/// <summary>
/// Gets a hash code for the current object.
/// </summary>
public override int GetHashCode() => Value.GetHashCode();
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public static bool operator ==(WordEntryPos left, WordEntryPos right) => left.Equals(right);
/// <summary>
/// Determines whether the specified object is unequal to the current object.
/// </summary>
public static bool operator !=(WordEntryPos left, WordEntryPos right) => !left.Equals(right);
}
/// <summary>
/// The weight is labeled from A to D. D is the default, and not printed.
/// </summary>
public enum Weight
{
/// <summary>
/// D, the default
/// </summary>
D = 0,
/// <summary>
/// C
/// </summary>
C = 1,
/// <summary>
/// B
/// </summary>
B = 2,
/// <summary>
/// A
/// </summary>
A = 3
}
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public bool Equals(Lexeme o)
{
if (Text != o.Text)
return false;
if (WordEntryPositions is null)
return o.WordEntryPositions is null;
if (o.WordEntryPositions is null || WordEntryPositions.Count != o.WordEntryPositions.Count)
return false;
for (var i = 0; i < WordEntryPositions.Count; i++)
if (!WordEntryPositions[i].Equals(o.WordEntryPositions[i]))
return false;
return true;
}
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public override bool Equals(object? o) => o is Lexeme lexeme && Equals(lexeme);
/// <summary>
/// Gets a hash code for the current object.
/// </summary>
public override int GetHashCode() => Text.GetHashCode();
/// <summary>
/// Determines whether the specified object is equal to the current object.
/// </summary>
public static bool operator ==(Lexeme left, Lexeme right) => left.Equals(right);
/// <summary>
/// Determines whether the specified object is unequal to the current object.
/// </summary>
public static bool operator !=(Lexeme left, Lexeme right) => !left.Equals(right);
}
}
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