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AngleSharp

, 3 Jul 2013 BSD
Bringing the DOM to C# with a HTML5/CSS3 parser written in C#.
Demo.zip
AngleSharp
Css
Tokens
DOM
Collections
Css
Properties
Rules
Selector
Values
Enums
Exception
Html
Basic
Formatting
Forms
Frames
Head
Lists
Media
Objects
Semantic
Tables
Interfaces
Mathml
Objects
Svg
Various
Xml
Foundation
Attributes
Helpers
Mutations
Html
Tokens
Properties
Stream
Xml
Tokens
packages
ModernUI.WPF.1.0.4
lib
net40
FirstFloor.ModernUI.dll
Microsoft.Windows.Shell.dll
net45
FirstFloor.ModernUI.dll
ModernUI.WPF.1.0.4.nupkg
ModernUI.WPF.1.0.4.nuspec
OxyPlot.Core.2013.1.49.1
lib
portable-net4+sl4+wp71+win8
OxyPlot.dll
OxyPlot.Core.2013.1.49.1.nupkg
OxyPlot.Core.2013.1.49.1.nuspec
OxyPlot.Wpf.2013.1.49.1
lib
NET40
OxyPlot.Wpf.dll
OxyPlot.Xps.dll
NET45
OxyPlot.Wpf.dll
OxyPlot.Xps.dll
OxyPlot.Wpf.2013.1.49.1.nupkg
OxyPlot.Wpf.2013.1.49.1.nuspec
Samples
Logo.ico
Pages
Properties
Settings.settings
ViewModels
Source.zip
Documents
using System;
using System.Text;
using System.Collections;
using System.Collections.Generic;
using AngleSharp.Css;

namespace AngleSharp.DOM.Css
{
    /// <summary>
    /// Represents a complex selector.
    /// One or more compound selectors separated by combinators.
    /// </summary>
    internal class ComplexSelector : Selector
    {
        #region Members

        List<CombinatorSelector> selectors;

        #endregion

        #region ctor

        /// <summary>
        /// Creates a new complex selector.
        /// </summary>
        public ComplexSelector()
        {
            selectors = new List<CombinatorSelector>();
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets the specifity index for this chain of selectors.
        /// </summary>
        public override Int32 Specifity
        {
            get
            {
                int sum = 0;

                for (int i = 0; i < selectors.Count; i++)
                    sum += selectors[i].selector.Specifity;

                return sum;
            }
        }

        /// <summary>
        /// Gets the number of selectors in this group.
        /// </summary>
        public Int32 Length
        {
            get { return selectors.Count; }
        }

        /// <summary>
        /// Gets if the selector has already been finalized.
        /// </summary>
        public Boolean IsReady
        {
            get;
            private set;
        }

        #endregion

        #region Methods

        /// <summary>
        /// Determines if the given object is matched by this selector.
        /// </summary>
        /// <param name="element">The element to be matched.</param>
        /// <returns>True if the selector matches the given element, otherwise false.</returns>
        public override Boolean Match(Element element)
        {
            var last = selectors.Count - 1;

            if (selectors[last].selector.Match(element))
            {
                if (last > 0)
                    return MatchCascade(last - 1, element);
                else
                    return true;
            }

            return false;
        }

        /// <summary>
        /// Appends the LAST selector to the complex of selectors.
        /// </summary>
        /// <param name="selector">The (final) selector to append.</param>
        /// <returns>The current complex selector.</returns>
        public ComplexSelector ConcludeSelector(Selector selector)
        {
            if (!IsReady)
            {
                selectors.Add(new CombinatorSelector { selector = selector, transform = null });
                IsReady = true;
            }

            return this;
        }

        /// <summary>
        /// Appends a selector to the complex of selectors.
        /// </summary>
        /// <param name="selector">The selector to append.</param>
        /// <param name="combinator">The combinator to use.</param>
        /// <returns>The current complex selector.</returns>
        public ComplexSelector AppendSelector(Selector selector, CssCombinator combinator)
        {
            if (IsReady)
                return this;

            Func<Element, IEnumerable<Element>> transform = null;
            char delim;

            switch (combinator)
            {
                case CssCombinator.Child:
                    delim = Specification.GT;
                    transform = el => Single(el.ParentElement);
                    break;

                case CssCombinator.AdjacentSibling:
                    delim = Specification.PLUS;
                    transform = el => Single(el.PreviousElementSibling);
                    break;

                case CssCombinator.Descendent:
                    delim = Specification.SPACE;
                    transform = el =>
                    {
                        var parents = new List<Element>();
                        var parent = el.ParentElement;

                        while(parent != null)
                        {
                            parents.Add(parent);
                            parent = parent.ParentElement;
                        }

                        return parents;
                    };
                    break;

                case CssCombinator.Sibling:
                    delim = Specification.TILDE;
                    transform = el =>
                    {
                        var parent = el.ParentElement;

                        if (parent == null)
                            return new Element[0];

                        var kids = parent.Children;
                        var passed = false;
                        var siblings = new List<Element>();

                        for (int i = kids.Length - 1; i >= 0; i--)
			            {
                            if (kids[i] == el)
                                passed = true;
                            else if (passed)
                                siblings.Add(kids[i]);
			            }

                        return siblings;
                    };
                    break;

                default:
                    return this;
            }

            selectors.Add(new CombinatorSelector { selector = selector, transform = transform, delimiter = delim });
            return this;
        }

        /// <summary>
        /// Clears the list of selectors.
        /// </summary>
        /// <returns>The current complex selector.</returns>
        public ComplexSelector ClearSelectors()
        {
            IsReady = false;
            selectors.Clear();
            return this;
        }

        #endregion

        #region Helpers

        Boolean MatchCascade(int pos, Element element)
        {
            var elements = selectors[pos].transform(element);

            foreach (var e in elements)
            {
                if (selectors[pos].selector.Match(e))
                {
                    if (pos == 0 || MatchCascade(pos - 1, e))
                        return true;
                }
            }

            return false;
        }

        static IEnumerable<Element> Single(Element element)
        {
            if (element == null)
                return System.Linq.Enumerable.Empty<Element>();

            return new Element[1] { element };
        }

        #endregion

        #region Nested

        struct CombinatorSelector
        {
            public Char delimiter;
            public Func<Element, IEnumerable<Element>> transform;
            public Selector selector;
        }

        #endregion

        #region String Representation

        /// <summary>
        /// Returns a valid CSS string representing this selector.
        /// </summary>
        /// <returns>The CSS to create this selector.</returns>
        public override String ToCss()
        {
            var sb = new StringBuilder();

            if (selectors.Count > 0)
            {
                var n = selectors.Count - 1;

                for (int i = 0; i < n; i++)
                    sb.Append(selectors[i].selector.ToCss()).Append(selectors[i].delimiter);

                sb.Append(selectors[n].selector.ToCss());
            }

            return sb.ToString();
        }

        #endregion
    }
}

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License

This article, along with any associated source code and files, is licensed under The BSD License

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About the Author

Florian Rappl
Chief Technology Officer
Germany Germany
Florian is from Regensburg, Germany. He started his programming career with Perl. After programming C/C++ for some years he discovered his favorite programming language C#. He did work at Siemens as a programmer until he decided to study Physics. During his studies he worked as an IT consultant for various companies.
 
Florian is also giving lectures in C#, HTML5 with CSS3 and JavaScript, and other topics. Having graduated from University with a Master's degree in theoretical physics he is currently busy doing his PhD in the field of High Performance Computing.
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