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Make LongRational immutable

pull/506/head
Jason Nelson 8 years ago
parent
d7bcffa286
commit
26e678282f
3 changed files with 98 additions and 209 deletions
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  1. 271
      src/ImageSharp/Primitives/LongRational.cs
  2. 18
      src/ImageSharp/Primitives/Rational.cs
  3. 18
      src/ImageSharp/Primitives/SignedRational.cs

271
src/ImageSharp/Primitives/LongRational.cs
View File

@ -13,7 +13,7 @@ namespace SixLabors.ImageSharp.Primitives
/// <remarks>
/// This is a very simplified implementation of a rational number designed for use with metadata only.
/// </remarks>
internal struct LongRational : IEquatable<LongRational>
internal readonly struct LongRational : IEquatable<LongRational>
{
/// <summary>
/// Initializes a new instance of the <see cref="LongRational"/> struct.
@ -26,126 +26,25 @@ namespace SixLabors.ImageSharp.Primitives
/// The number below the line in a vulgar fraction; a divisor.
/// </param>
public LongRational(long numerator, long denominator)
: this(numerator, denominator, false)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="LongRational"/> struct.
/// </summary>
/// <param name="numerator">
/// The number above the line in a vulgar fraction showing how many of the parts
/// indicated by the denominator are taken.
/// </param>
/// <param name="denominator">
/// The number below the line in a vulgar fraction; a divisor.
/// </param>
/// <param name="simplify">
/// Whether to attempt to simplify the fractional parts.
/// </param>
public LongRational(long numerator, long denominator, bool simplify)
: this()
{
this.Numerator = numerator;
this.Denominator = denominator;
if (simplify)
{
this.Simplify();
}
}
/// <summary>
/// Initializes a new instance of the <see cref="LongRational"/> struct.
/// </summary>
/// <param name="value">The <see cref="double"/> to create the instance from.</param>
/// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
public LongRational(double value, bool bestPrecision)
: this()
{
if (double.IsNaN(value))
{
this.Numerator = this.Denominator = 0;
return;
}
if (double.IsPositiveInfinity(value))
{
this.Numerator = 1;
this.Denominator = 0;
return;
}
if (double.IsNegativeInfinity(value))
{
this.Numerator = -1;
this.Denominator = 0;
return;
}
this.Numerator = 1;
this.Denominator = 1;
double val = Math.Abs(value);
double df = this.Numerator / (double)this.Denominator;
double epsilon = bestPrecision ? double.Epsilon : .000001;
while (Math.Abs(df - val) > epsilon)
{
if (df < val)
{
this.Numerator++;
}
else
{
this.Denominator++;
this.Numerator = (int)(val * this.Denominator);
}
df = this.Numerator / (double)this.Denominator;
}
if (value < 0.0)
{
this.Numerator *= -1;
}
this.Simplify();
}
/// <summary>
/// Gets the numerator of a number.
/// </summary>
public long Numerator
{
get;
private set;
}
public long Numerator { get; }
/// <summary>
/// Gets the denominator of a number.
/// </summary>
public long Denominator
{
get;
private set;
}
public long Denominator { get; }
/// <summary>
/// Gets a value indicating whether this instance is indeterminate.
/// </summary>
public bool IsIndeterminate
{
get
{
if (this.Denominator != 0)
{
return false;
}
return this.Numerator == 0;
}
}
public bool IsIndeterminate => this.Denominator == 0 && this.Numerator == 0;
/// <summary>
/// Gets a value indicating whether this instance is an integer (n, 1)
@ -155,76 +54,28 @@ namespace SixLabors.ImageSharp.Primitives
/// <summary>
/// Gets a value indicating whether this instance is equal to negative infinity (-1, 0)
/// </summary>
public bool IsNegativeInfinity
{
get
{
if (this.Denominator != 0)
{
return false;
}
return this.Numerator == -1;
}
}
public bool IsNegativeInfinity => this.Denominator == 0 && this.Numerator == -1;
/// <summary>
/// Gets a value indicating whether this instance is equal to positive infinity (1, 0)
/// </summary>
public bool IsPositiveInfinity
{
get
{
if (this.Denominator != 0)
{
return false;
}
return this.Numerator == 1;
}
}
public bool IsPositiveInfinity => this.Denominator == 0 && this.Numerator == 1;
/// <summary>
/// Gets a value indicating whether this instance is equal to 0 (0, 1)
/// </summary>
public bool IsZero
{
get
{
if (this.Denominator != 1)
{
return false;
}
return this.Numerator == 0;
}
}
public bool IsZero => this.Denominator == 1 && this.Numerator == 0;
/// <inheritdoc/>
public bool Equals(LongRational other)
{
if (this.Denominator == other.Denominator)
{
return this.Numerator == other.Numerator;
}
if (this.Numerator == 0 && this.Denominator == 0)
{
return other.Numerator == 0 && other.Denominator == 0;
}
if (other.Numerator == 0 && other.Denominator == 0)
{
return this.Numerator == 0 && this.Denominator == 0;
}
return (this.Numerator * other.Denominator) == (this.Denominator * other.Numerator);
return this.Numerator == other.Numerator && this.Denominator == other.Denominator;
}
/// <inheritdoc/>
public override int GetHashCode()
{
return this.GetHashCode(this);
return ((this.Numerator * 397) ^ this.Denominator).GetHashCode();
}
/// <inheritdoc/>
@ -276,78 +127,100 @@ namespace SixLabors.ImageSharp.Primitives
}
/// <summary>
/// Finds the greatest common divisor of two <see cref="long"/> values.
/// Create a new instance of the <see cref="LongRational"/> struct from a double value.
/// </summary>
/// <param name="left">The first value</param>
/// <param name="right">The second value</param>
/// <returns>The <see cref="long"/></returns>
private static long GreatestCommonDivisor(long left, long right)
/// <param name="value">The <see cref="double"/> to create the instance from.</param>
/// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
public static LongRational FromDouble(double value, bool bestPrecision)
{
return right == 0 ? left : GreatestCommonDivisor(right, left % right);
}
if (double.IsNaN(value))
{
return new LongRational(0, 0);
}
/// <summary>
/// Simplifies the <see cref="LongRational"/>
/// </summary>
private void Simplify()
{
if (this.IsIndeterminate)
if (double.IsPositiveInfinity(value))
{
return;
return new LongRational(1, 0);
}
if (this.IsNegativeInfinity)
if (double.IsNegativeInfinity(value))
{
return;
return new LongRational(-1, 0);
}
if (this.IsPositiveInfinity)
long numerator = 1;
long denominator = 1;
double val = Math.Abs(value);
double df = numerator / (double)denominator;
double epsilon = bestPrecision ? double.Epsilon : .000001;
while (Math.Abs(df - val) > epsilon)
{
return;
if (df < val)
{
numerator++;
}
else
{
denominator++;
numerator = (int)(val * denominator);
}
df = numerator / (double)denominator;
}
if (this.IsInteger)
if (value < 0.0)
{
return;
numerator *= -1;
}
if (this.IsZero)
return new LongRational(numerator, denominator).Simplify();
}
/// <summary>
/// Finds the greatest common divisor of two <see cref="long"/> values.
/// </summary>
/// <param name="left">The first value</param>
/// <param name="right">The second value</param>
/// <returns>The <see cref="long"/></returns>
private static long GreatestCommonDivisor(long left, long right)
{
return right == 0 ? left : GreatestCommonDivisor(right, left % right);
}
/// <summary>
/// Simplifies the <see cref="LongRational"/>
/// </summary>
public LongRational Simplify()
{
if (this.IsIndeterminate ||
this.IsNegativeInfinity ||
this.IsPositiveInfinity ||
this.IsInteger ||
this.IsZero)
{
return;
return this;
}
if (this.Numerator == 0)
{
this.Denominator = 0;
return;
return new LongRational(0, 0);
}
if (this.Numerator == this.Denominator)
{
this.Numerator = 1;
this.Denominator = 1;
return new LongRational(1, 1);
}
long gcd = GreatestCommonDivisor(Math.Abs(this.Numerator), Math.Abs(this.Denominator));
if (gcd > 1)
{
this.Numerator = this.Numerator / gcd;
this.Denominator = this.Denominator / gcd;
return new LongRational(this.Numerator / gcd, this.Denominator / gcd);
}
}
/// <summary>
/// Returns the hash code for this instance.
/// </summary>
/// <param name="rational">
/// The instance of <see cref="LongRational"/> to return the hash code for.
/// </param>
/// <returns>
/// A 32-bit signed integer that is the hash code for this instance.
/// </returns>
private int GetHashCode(LongRational rational)
{
return ((rational.Numerator * 397) ^ rational.Denominator).GetHashCode();
return this;
}
}
}

18
src/ImageSharp/Primitives/Rational.cs
View File

@ -41,10 +41,18 @@ namespace SixLabors.ImageSharp.Primitives
/// <param name="simplify">Specified if the rational should be simplified.</param>
public Rational(uint numerator, uint denominator, bool simplify)
{
var rational = new LongRational(numerator, denominator, simplify);
this.Numerator = (uint)rational.Numerator;
this.Denominator = (uint)rational.Denominator;
if (simplify)
{
LongRational rational = new LongRational(numerator, denominator).Simplify();
this.Numerator = (uint)rational.Numerator;
this.Denominator = (uint)rational.Denominator;
}
else
{
this.Numerator = numerator;
this.Denominator = denominator;
}
}
/// <summary>
@ -63,7 +71,7 @@ namespace SixLabors.ImageSharp.Primitives
/// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
public Rational(double value, bool bestPrecision)
{
var rational = new LongRational(Math.Abs(value), bestPrecision);
var rational = LongRational.FromDouble(Math.Abs(value), bestPrecision);
this.Numerator = (uint)rational.Numerator;
this.Denominator = (uint)rational.Denominator;

18
src/ImageSharp/Primitives/SignedRational.cs
View File

@ -41,10 +41,18 @@ namespace SixLabors.ImageSharp.Primitives
/// <param name="simplify">Specified if the rational should be simplified.</param>
public SignedRational(int numerator, int denominator, bool simplify)
{
var rational = new LongRational(numerator, denominator, simplify);
this.Numerator = (int)rational.Numerator;
this.Denominator = (int)rational.Denominator;
if (simplify)
{
LongRational rational = new LongRational(numerator, denominator).Simplify();
this.Numerator = (int)rational.Numerator;
this.Denominator = (int)rational.Denominator;
}
else
{
this.Numerator = numerator;
this.Denominator = denominator;
}
}
/// <summary>
@ -63,7 +71,7 @@ namespace SixLabors.ImageSharp.Primitives
/// <param name="bestPrecision">Whether to use the best possible precision when parsing the value.</param>
public SignedRational(double value, bool bestPrecision)
{
var rational = new LongRational(value, bestPrecision);
var rational = LongRational.FromDouble(value, bestPrecision);
this.Numerator = (int)rational.Numerator;
this.Denominator = (int)rational.Denominator;

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