Bug fixes and performance improvements

ws-garcia · ws-garcia · commit ede574d85b3a · 2021-06-26T00:15:07.000-04:00
The class was not able to handle lines with more characters than the buffer. Streams ending in line breaks are 2 times faster than the previous version.
diff --git a/src/ECPTextStream.cls b/src/ECPTextStream.cls
@@ -26,6 +26,7 @@ Option Explicit
 Private Const DualLFchar As String = vbLf & vbLf
 Private Const InverseCRLF As String = vbLf & vbCr
 Private Const SizeFactor As Long = 524288
+Private Const WhiteSpace As String = " "
 '////////////////////////////////////////////////////////////////////////////////////////////
 '#
 '////////////////////////////////////////////////////////////////////////////////////////////
@@ -45,10 +46,13 @@ Private P_TEXT As String '-------------------------Holds the current stream's te
 '////////////////////////////////////////////////////////////////////////////////////////////
 ' VARIABLES:
 ' @Common
+Private Last2Chrs As String
+Private LastChr As String
 '////////////////////////////////////////////////////////////////////////////////////////////
 '#
 Private Buffer As String
 Private BufferDelta As Long
+Private BufferEnds As Boolean
 Private BufferMark As Long
 Private CorrectedPos As Long
 Private EndLineMark As EndLineChar
@@ -57,6 +61,7 @@ Private InitialPos As Long
 Private LCS As Long
 Private NullChar As String
 Private NullCharPos As Long
+Private TmpInitialPos As Long
 '////////////////////////////////////////////////////////////////////////////////////////////
 '#
 '////////////////////////////////////////////////////////////////////////////////////////////
@@ -103,9 +108,9 @@ End Property
 Public Property Get isOpenStream() As Boolean
     isOpenStream = P_ISOPENSTREAM
 End Property
-Public Property Get LineBreak() As String
-Attribute LineBreak.VB_Description = "Returns the character used to end the last received stream. The value is vbNullString when the last stream is not forced to end on line break."
-    LineBreak = P_LINEBREAK
+Public Property Get lineBreak() As String
+Attribute lineBreak.VB_Description = "Returns the character used to end the last received stream. The value is vbNullString when the last stream is not forced to end on line break."
+    lineBreak = P_LINEBREAK
 End Property
 Public Property Get pointerPosition() As Long
 Attribute pointerPosition.VB_Description = "Gets the overall pointer position over the current text file."
@@ -120,6 +125,7 @@ Attribute streamLength.VB_Description = "Gets the current opened file
     streamLength = P_STREAMLENGTH
 End Property
 Public Property Get unifiedLFOutput() As Boolean
+Attribute unifiedLFOutput.VB_Description = "Determines whether the buffer string is returned using only the LF character as a linefeed."
     unifiedLFOutput = P_UNIFIEDLFOUTPUT
 End Property
 Public Property Let unifiedLFOutput(value As Boolean)
@@ -136,70 +142,97 @@ Attribute CloseStream.VB_Description = "Closes the current text file stream."
         P_ISOPENSTREAM = False
     End If
 End Sub
+Private Sub DoubleBufferSize()
+    Dim LCSt As Long
+    P_BUFFERSIZE = 2 * P_BUFFERSIZE
+    P_BUFFERLENGTH = CLng(P_BUFFERSIZE * SizeFactor)
+    LCSt = P_STREAMLENGTH - P_BUFFERLENGTH
+    Select Case LCSt
+        Case Is > 0
+            Buffer = SPACE$(P_BUFFERLENGTH)
+        Case Else
+            Buffer = SPACE$(P_STREAMLENGTH)
+    End Select
+End Sub
 Private Sub FindEOLcharacter()
-    Dim LastCrLfPos As Long
-    Dim LastCrPos As Long
-    Dim LastLfPos As Long
-    Dim tmpResultPos As Long
-    Dim bufferReverse As String
+    Dim CrCharInStream As Boolean
+    Dim LfCharInStream  As Boolean
     Dim EOLchr As EndLineChar
     Dim missingEOLchar As Boolean
     Dim EOStream As Boolean
-    Dim tmpBuffer As String
 
     Do
-        bufferReverse = StrReverse(Buffer)
-        LastCrLfPos = InStrB(1, bufferReverse, InverseCRLF)
-        If LastCrLfPos Then LastCrLfPos = LastCrLfPos + 2
-        LastCrPos = InStrB(1, bufferReverse, vbCr)
-        LastLfPos = InStrB(1, bufferReverse, vbLf)
-        missingEOLchar = (LastCrLfPos = 0 And LastCrPos = 0 And LastLfPos = 0)
+        CrCharInStream = InStrB(1, Buffer, vbCr)
+        LfCharInStream = InStrB(1, Buffer, vbLf)
+        missingEOLchar = (Not CrCharInStream) And (Not LfCharInStream)
         If missingEOLchar Then
-            tmpBuffer = Buffer
+            DoubleBufferSize
+            SeekPointer TmpInitialPos
             Get #FileHandled, , Buffer
-            Buffer = tmpBuffer + Buffer
             InitialPos = Seek(FileHandled)
             BufferMark = LenB(Buffer)
-            EOStream = ((P_STREAMLENGTH - InitialPos) <= 0)
-            If EOStream Then
-                NullCharPos = InStrB(Buffer, NullChar)
-                If NullCharPos Then
-                    Buffer = MidB$(Buffer, 1, NullCharPos)
-                End If
-            End If
+            EOStream = (P_STREAMLENGTH <= InitialPos)
         End If
     Loop While missingEOLchar And Not EOStream
     P_ATENDOFSTREAM = EOStream
     If Not EOStream Then
-        tmpResultPos = LastCrLfPos
-        EOLchr = CRLF
-        If tmpResultPos < LastCrPos Then
-            tmpResultPos = LastCrPos
-            EOLchr = CR
-        End If
-        If tmpResultPos < LastLfPos Then
-            tmpResultPos = LastLfPos
-            EOLchr = LF
+        If Not missingEOLchar Then
+            Last2Chrs = MidB$(Buffer, BufferMark - 3, 4)
+            BufferEnds = (Last2Chrs = vbCrLf)
+            Select Case BufferEnds
+                Case False
+                    LastChr = MidB$(Last2Chrs, 3, 2)
+                    BufferEnds = (LastChr = vbCr)
+                    Select Case BufferEnds
+                        Case False
+                            BufferEnds = (LastChr = vbLf)
+                            If BufferEnds Then
+                                P_LINEBREAK = vbLf
+                            Else
+                                GoBackToLineBreak
+                            End If
+                        Case Else
+                            P_LINEBREAK = vbCr
+                    End Select
+                Case Else
+                    P_LINEBREAK = vbCrLf
+            End Select
         End If
-        Select Case EOLchr
-            Case 0
-                BufferDelta = tmpResultPos - 3
-                P_LINEBREAK = vbCrLf
-            Case Else
-                BufferDelta = tmpResultPos - 1
-                If EOLchr = 1 Then
-                    P_LINEBREAK = vbCr
-                Else
-                    P_LINEBREAK = vbLf
-                End If
-        End Select
-        BufferMark = BufferMark - BufferDelta
-        CorrectedPos = InitialPos - (BufferDelta / 2)
+        CorrectedPos = InitialPos - BufferDelta
+        BufferDelta = 0
     Else
-        CorrectedPos = InitialPos
+        NullCharPos = InStrB(Buffer, NullChar)
+        If NullCharPos Then
+            BufferMark = NullCharPos
+        End If
+        CorrectedPos = P_STREAMLENGTH + 1
     End If
     Seek #FileHandled, CorrectedPos
 End Sub
+Private Sub GoBackToLineBreak()
+    Do
+        BufferMark = BufferMark - 2
+        BufferDelta = BufferDelta + 1
+        Last2Chrs = MidB$(Buffer, BufferMark - 3, 4)
+        BufferEnds = (Last2Chrs = vbCrLf)
+        Select Case BufferEnds
+            Case False
+                LastChr = MidB$(Last2Chrs, 3, 2)
+                BufferEnds = (LastChr = vbCr)
+            Select Case BufferEnds
+                Case False
+                    BufferEnds = (LastChr = vbLf)
+                    If BufferEnds Then
+                        P_LINEBREAK = vbLf
+                    End If
+                Case Else
+                    P_LINEBREAK = vbCr
+            End Select
+            Case Else
+                P_LINEBREAK = vbCrLf
+        End Select
+    Loop While Not BufferEnds
+End Sub
 Private Sub NormalizeLineBreaks()
     If InStrB(1, P_TEXT, vbCr, vbBinaryCompare) Then
         P_TEXT = Replace(P_TEXT, vbCr, vbLf, 1)
@@ -209,20 +242,22 @@ Private Sub NormalizeLineBreaks()
     Loop
     P_LINEBREAK = vbLf
 End Sub
-Public Sub OpenStream(filePath As String)
+Public Sub OpenStream(FilePath As String)
 Attribute OpenStream.VB_Description = "Opens a stream over a text file."
     FileHandled = FreeFile
-    Open filePath For Binary As #FileHandled
+    Open FilePath For Binary As #FileHandled
     P_ISOPENSTREAM = True
     P_STREAMLENGTH = LOF(FileHandled)
     StartVariables
 End Sub
 Public Sub ReadText()
 Attribute ReadText.VB_Description = "Reads a number of characters from the stream file and saves the result to the current instance."
     If Not P_ATENDOFSTREAM And P_ISOPENSTREAM Then
+        If InitialPos = 0 Then InitialPos = 1
         Select Case P_BUFFERLENGTH
             Case Is < LCS
                 BufferDelta = 0
+                TmpInitialPos = InitialPos
                 Get #FileHandled, , Buffer
                 InitialPos = Seek(FileHandled)
                 BufferMark = LenB(Buffer)
@@ -278,20 +313,20 @@ End Sub
 Public Sub WriteBlankLines(Lines As Long, Optional EndLineMark As EndLineChar = 0)
 Attribute WriteBlankLines.VB_Description = "Inserts a specified number of blank lines into the current opened text file."
     If P_ISOPENSTREAM Then
-        Dim Idx As Long
+        Dim idx As Long
         Select Case EndLineMark
             Case 0
-                For Idx = 1 To Lines
+                For idx = 1 To Lines
                     Put #FileHandled, , vbCrLf
-                Next Idx
+                Next idx
             Case 1
-                For Idx = 1 To Lines
+                For idx = 1 To Lines
                     Put #FileHandled, , vbCr
-                Next Idx
+                Next idx
             Case 2
-                For Idx = 1 To Lines
+                For idx = 1 To Lines
                     Put #FileHandled, , vbLf
-                Next Idx
+                Next idx
         End Select
         P_STREAMLENGTH = LOF(FileHandled)
     End If
