PathParser.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Data / PathParser.cs / 1305600 / PathParser.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: Parser for the Path of a (CLR) binding 
// 
//---------------------------------------------------------------------------
 
using System;
using System.Collections;
using System.Text;          // StringBuilder
using System.Windows; 
using MS.Utility;           // FrugalList
 
namespace MS.Internal.Data 
{
    internal enum SourceValueType { Property, Indexer, Direct }; 
    internal enum DrillIn { Never, IfNeeded, Always };

    internal struct SourceValueInfo
    { 
        public SourceValueType type;
        public DrillIn drillIn; 
        public string name;                 // the name the user supplied - could be "(0)" 
        public FrugalObjectList paramList;    // params for indexer
        public string propertyName;         // the real name - could be "Width" 

        public SourceValueInfo(SourceValueType t, DrillIn d, string n)
        {
            type = t; 
            drillIn = d;
            name = n; 
            paramList = null; 
            propertyName = null;
        } 

        public SourceValueInfo(SourceValueType t, DrillIn d, FrugalObjectList list)
        {
            type = t; 
            drillIn = d;
            name = null; 
            paramList = list; 
            propertyName = null;
        } 
    }

    internal struct IndexerParamInfo
    { 
        // parse each indexer param "(abc)xyz" into two pieces - either can be empty
        public string parenString; 
        public string valueString; 

        public IndexerParamInfo(string paren, string value) 
        {
            parenString = paren;
            valueString = value;
        } 
    }
 
    internal class PathParser 
    {
        string _error; 
        public String Error { get { return _error; } }
        void SetError(string id, params object[] args) { _error = SR.Get(id, args); }

        enum State { Init, DrillIn, Prop, Done }; 

        // Each level of the path consists of 
        //      a property or indexer: 
        //                  .propname
        //                  /propname 
        //                  [index]
        //                  /[index]
        //          (The . or / is optional in the very first level.)
        // The parser is a finite-state machine with two states corresponding 
        // to the two-character lookahead above, plus two more states for the begining
        // and end.  The state transistions are done explicitly in the code below. 
        // 
        // The parser returns a 0-length array if it finds a syntax error.
        // It sets the Error property, so the caller can find out what happened. 

        public SourceValueInfo[] Parse(string path)
        {
            _path = (path != null) ? path.Trim() : String.Empty; 
            _n = _path.Length;
 
            if (_n == 0) 
            {
                // When no path string is specified, use value directly and do not drill-in. (same as Path=".") 
                // ClrBindingWorker needs this information to tell XmlBindingWorker about collectionMode.
                return new SourceValueInfo[] { new SourceValueInfo(SourceValueType.Direct, DrillIn.Never, (string)null) };
            }
 
            _index = 0;
            _drillIn = DrillIn.IfNeeded; 
 
            _al.Clear();
            _error = null; 
            _state = State.Init;

            while (_state != State.Done)
            { 
                char c = (_index<_n) ? _path[_index] : NullChar;
                if (Char.IsWhiteSpace(c)) 
                { 
                    ++ _index;
                    continue; 
                }

                switch (_state)
                { 
                case State.Init:
                    switch (c) 
                    { 
                    case '/':
                    case '.': 
                    case NullChar:
                        _state = State.DrillIn;
                        break;
                    default: 
                        _state = State.Prop;
                        break; 
                    } 
                    break;
 
                case State.DrillIn:
                    switch (c)
                    {
                    case '/': 
                        _drillIn = DrillIn.Always;
                        ++ _index; 
                        break; 
                    case '.':
                        _drillIn = DrillIn.Never; 
                        ++ _index;
                        break;
                    case '[':
                    case NullChar: 
                        break;
                    default: 
                        SetError(SRID.PathSyntax, _path.Substring(0, _index), _path.Substring(_index)); 
                        return EmptyInfo;
                    } 
                    _state = State.Prop;
                    break;

                case State.Prop: 
                    bool isIndexer = false;
                    switch (c) 
                    { 
                    case '[':
                        isIndexer = true; 
                        break;
                    default:
                        break;
                    } 

                    if (isIndexer) 
                        AddIndexer(); 
                    else
                        AddProperty(); 

                    break;
                }
            } 

 
            SourceValueInfo[] result; 

            if (_error == null) 
            {
                result = new SourceValueInfo[_al.Count];
                _al.CopyTo(result);
            } 
            else
            { 
                result = EmptyInfo; 
            }
 
            return result;
        }

        void AddProperty() 
        {
            int start = _index; 
            int level = 0; 

            // include leading dots in the path (for XLinq) 
            while (_index < _n && _path[_index] == '.')
                ++ _index;

            while (_index < _n && (level > 0 || SpecialChars.IndexOf(_path[_index]) < 0)) 
            {
                if (_path[_index] == '(') 
                    ++ level; 
                else if (_path[_index] == ')')
                    -- level; 

                ++ _index;
            }
 
            if (level > 0)
            { 
                SetError(SRID.UnmatchedParen, _path.Substring(start)); 
                return;
            } 

            if (level < 0)
            {
                SetError(SRID.UnmatchedParen, _path.Substring(0, _index)); 
                return;
            } 
 
            string name = _path.Substring(start, _index - start).Trim();
 
            SourceValueInfo info = (name.Length > 0)
                ? new SourceValueInfo(SourceValueType.Property, _drillIn, name)
                : new SourceValueInfo(SourceValueType.Direct, _drillIn, (string)null);
 
            _al.Add(info);
 
            StartNewLevel(); 
        }
 

        enum IndexerState { BeginParam, ParenString, ValueString, Done }

        void AddIndexer() 
        {
            // indexer args are parsed by a (sub-) state machine with four 
            // states.  The string is a comma-separated list of params, each 
            // of which has two parts:  a "paren string" and a "value string"
            // (both parts are optional).  The character ^ can be used to 
            // escape any of the special characters:  comma, parens, ], ^,
            // and white space.

            int start = ++_index;       // skip over initial [ 
            int level = 1;              // level of nested []
 
            bool escaped = false;       // true if current char is escaped 
            bool trimRight = false;     // true if value string has trailing white space
 
            StringBuilder parenStringBuilder = new StringBuilder();
            StringBuilder valueStringBuilder = new StringBuilder();

            FrugalObjectList paramList = new FrugalObjectList(); 

            IndexerState state = IndexerState.BeginParam; 
            while (state != IndexerState.Done) 
            {
                if (_index >= _n) 
                {
                    SetError(SRID.UnmatchedBracket, _path.Substring(start - 1));
                    return;
                } 

                Char c = _path[_index++]; 
 
                // handle the escape character - set the flag for the next character
                if (c == EscapeChar && !escaped) 
                {
                    escaped = true;
                    continue;
                } 

                switch (state) 
                { 
                    case IndexerState.BeginParam:   // look for optional (...)
                        if (escaped) 
                        {
                            // no '(', go parse the value
                            state = IndexerState.ValueString;
                            goto case IndexerState.ValueString; 
                        }
                        else if (c == '(') 
                        { 
                            // '(' introduces optional paren string
                            state = IndexerState.ParenString; 
                        }
                        else if (Char.IsWhiteSpace(c))
                        {
                            // ignore leading white space 
                        }
                        else 
                        { 
                            // no '(', go parse the value
                            state = IndexerState.ValueString; 
                            goto case IndexerState.ValueString;
                        }
                        break;
 
                    case IndexerState.ParenString:  // parse (...)
                        if (escaped) 
                        { 
                            // add an escaped character without question
                            parenStringBuilder.Append(c); 
                        }
                        else if (c == ')')
                        {
                            // end of (...), start to parse value 
                            state = IndexerState.ValueString;
                        } 
                        else 
                        {
                            // add normal characters inside (...) 
                            parenStringBuilder.Append(c);
                        }
                        break;
 
                    case IndexerState.ValueString:  // parse value
                        if (escaped) 
                        { 
                            // add an escaped character without question
                            valueStringBuilder.Append(c); 
                            trimRight = false;
                        }
                        else if (level > 1)
                        { 
                            // inside nested [], add characters without question
                            valueStringBuilder.Append(c); 
                            trimRight = false; 

                            if (c == ']') 
                            {
                                --level;
                            }
                        } 
                        else if (Char.IsWhiteSpace(c))
                        { 
                            // add white space, but trim it later if it's trailing 
                            valueStringBuilder.Append(c);
                            trimRight = true; 
                        }
                        else if (c == ',' || c == ']')
                        {
                            // end of current paramater - assemble the two parts 
                            string parenString = parenStringBuilder.ToString();
                            string valueString = valueStringBuilder.ToString(); 
                            if (trimRight) 
                            {
                                valueString = valueString.TrimEnd(); 
                            }

                            // add the parts to the final result
                            paramList.Add(new IndexerParamInfo(parenString, valueString)); 

                            // reset for the next parameter 
                            parenStringBuilder.Length = 0; 
                            valueStringBuilder.Length = 0;
                            trimRight = false; 

                            // after ',' parse next parameter;  after ']' we're done
                            state = (c == ']') ? IndexerState.Done : IndexerState.BeginParam;
                        } 
                        else
                        { 
                            // add normal characters 
                            valueStringBuilder.Append(c);
                            trimRight = false; 

                            // keep track of nested []
                            if (c == '[')
                            { 
                                ++level;
                            } 
                        } 
                        break;
                } 

                // after processing each character, clear the escape flag
                escaped = false;
            } 

            // assemble the final result 
            SourceValueInfo info = new SourceValueInfo( 
                                        SourceValueType.Indexer,
                                        _drillIn, paramList); 
            _al.Add(info);

            StartNewLevel();
        } 

        void StartNewLevel() 
        { 
            _state = (_index < _n) ? State.DrillIn : State.Done;
            _drillIn = DrillIn.Never; 
        }

        State _state;
        string _path; 
        int _index;
        int _n; 
        DrillIn _drillIn; 
        ArrayList _al = new ArrayList();
        const char NullChar = Char.MinValue; 
        const char EscapeChar = '^';
        static SourceValueInfo[] EmptyInfo = new SourceValueInfo[0];
        static string SpecialChars = @"./[]";
    } 
}
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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PathParser.cs source code in C# .NET

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