MulAvailable

StgSharp.Model/Step/StepReader.cs

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+//-----------------------------------------------------------------------
+// -----------------------------------------------------------------------
+// file="StepReader"
+// 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 StgSharp.Script;
+using StgSharp.Script.Express;
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.IO;
+using System.IO.MemoryMappedFiles;
+using System.Linq;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace StgSharp.Model.Step
+{
+    public partial class StepReader : IDisposable
+    {
+
+        private const string fileLabel = "ISO-10303-21;";
+
+        private bool disposedValue;
+        private FileStream _fileStream;
+        private int _dataBeginLine;
+        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;
+            }
+        }
+
+    }
+}