old data

StgSharp.Model/Step/Reader/StepReader.cs

@@ -0,0 +1,158 @@
+//-----------------------------------------------------------------------
+//-----------------------------------------------------------------------
+//     file="StepReader.cs"
+//     Project: StgSharp
+//     AuthorGroup: Nitload Space
+//     Copyright (c) Nitload Space. All rights reserved.
+//     
+//     Permission is hereby granted, free of charge, to any person 
+//     obtaining a copy of this software and associated documentation 
+//     files (the “Software”), to deal in the Software without restriction, 
+//     including without limitation the rights to use, copy, modify, merge,
+//     publish, distribute, sublicense, and/or sell copies of the Software, 
+//     and to permit persons to whom the Software is furnished to do so, 
+//     subject to the following conditions:
+//     
+//     The above copyright notice and 
+//     this permission notice shall be included in all copies 
+//     or substantial portions of the Software.
+//     
+//     THE SOFTWARE IS PROVIDED “AS IS”, 
+//     WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, 
+//     INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+//     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
+//     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
+//     DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 
+//     ARISING FROM, OUT OF OR IN CONNECTION WITH 
+//     THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//     
+//-----------------------------------------------------------------------
+//-----------------------------------------------------------------------
+using StgSharp;
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.MemoryMappedFiles;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace StgSharp.Modeling.STEP
+{
+    public partial class StepReader : IDisposable
+    {
+
+        private const string fileLabel = "ISO-10303-21;";
+
+        private bool disposedValue;
+        private FileStream _fileStream;
+        private long _headStart = -1, _headEnd = -1, _dataStart = -1, _size;
+        private MemoryMappedFile _memoryFile;
+
+        private StepReader() { }
+
+        private StepReader( FileStream stream, long size )
+        {
+            _fileStream = stream;
+            _size = size;
+            _memoryFile = MemoryMappedFile.CreateFromFile(
+                stream, mapName: null, size, MemoryMappedFileAccess.Read,
+                HandleInheritability.None, leaveOpen: true );
+        }
+
+        // ~StepReader()
+        // {
+        //     Dispose(disposing: false);
+        // }
+
+        public void Dispose()
+        {
+            Dispose( disposing: true );
+            GC.SuppressFinalize( this );
+        }
+
+        public static bool FromFile( string path, out StepReader reader )
+        {
+            FileInfo info = new FileInfo( path );
+            if( !info.Exists ) {
+                reader = null!;
+                return false;
+            }
+            FileStream stream = new FileStream(
+                path, FileMode.Open, FileAccess.Read, FileShare.Read,
+                bufferSize: 4096, useAsync: true );
+            byte[] fileHead = new byte[40];
+            stream.Read( fileHead, 0, fileLabel.Length );
+            if( !Encoding.UTF8.GetString( fileHead ).Contains( fileLabel ) ) {
+                throw new InvalidDataException(
+                    "The given file is not a STEP file" );
+            }
+            reader = new StepReader( stream, info.Length );
+            reader.LocateSection();
+            return  reader != null;
+        }
+
+        private void LocateSection()
+        {
+            long startPos = 0;
+            byte[] buffer = new byte[1024];
+            Span<byte> bufferSpan = buffer, 
+                headerSec = Encoding.UTF8.GetBytes( "HEADER;" ),
+                endsecSec = Encoding.UTF8.GetBytes( "ENDSEC;" ),
+                dataSec = Encoding.UTF8.GetBytes( "DATA;" );
+            _fileStream.Position = 0;
+            for( ; startPos < _size; startPos += 1000 ) {
+                _fileStream.Read( buffer );
+                if( _headStart == -1 ) {
+                    long pos = bufferSpan.IndexOf( headerSec );
+                    if( pos >= 0 ) {
+                        _headStart = startPos + pos;
+                    }
+                }
+                if( _headEnd == -1 ) {
+                    long pos = bufferSpan.IndexOf( endsecSec );
+                    if( pos >= 0 ) {
+                        _headEnd = startPos + pos;
+                    }
+                }
+                if( _dataStart == -1 ) {
+                    long pos = bufferSpan.IndexOf( dataSec );
+                    if( pos >= 0 ) {
+                        _dataStart = startPos + pos;
+                    }
+                } else {
+                    break;
+                }
+                _fileStream.Seek( 1000, SeekOrigin.Current );
+            }
+        }
+
+        private string ReadToken( StreamReader reader, ref long posCache )
+        {
+            StringBuilder token = new StringBuilder( 100 );
+            while( token.Length == 0 || token[ token.Length - 1 ] != ';' ) {
+                string subString = reader.ReadLine();
+                if( subString == null ) {
+                    break;
+                }
+                token.Append( subString.TrimStart() );
+            }
+            posCache += token.Length;
+            return token.ToString();
+        }
+
+        private protected virtual void Dispose( bool disposing )
+        {
+            if( !disposedValue ) {
+                if( disposing ) {
+                    _fileStream.Dispose();
+                    _memoryFile.Dispose();
+                }
+
+                disposedValue = true;
+            }
+        }
+
+    }
+}