refactor and cleanup

Fix defect in previous version (math wrong on temps)

Author: lawson89

entries/rlawson/src/parser.pas

@@ -5,7 +5,7 @@
 interface
 
 uses
-  Classes, SysUtils, bufstream, Contnrs, Math;
+  Classes, SysUtils, bufstream, Contnrs, Math, util;
 
 procedure ReadMeasurements(inputFile: string);
 
@@ -20,13 +20,16 @@   TCityTemp = record
     numReadings: integer;
   end;
 
+
 implementation
 
 const
   READ_SIZE = 65536;
   // read size plus enough to hold one record if we split it
   BUFFER_SIZE = READ_SIZE + 1024;
   REC_SEP: char = ';';
+  LF: char = chr(10);
+  ANSI_ZERO: integer = 48;
   DECIMAL_POINT: char = '.';
   NEGATIVE_SIGN: char = '-';
 
@@ -41,11 +44,12 @@ procedure ProcessMeasurements(var buffer: array of char; bufferLength: integer;
 begin
   while idx < (bufferLength - 1) do
   begin
-    // read the city until separator
+    // read the city by looking for semicolon
+    city := '';
     cityStart := idx;
     while buffer[idx] <> REC_SEP do Inc(idx);
     SetString(city, @buffer[cityStart], (idx - cityStart));
-    // increment through temp reading and calculate integer temp (*100)
+    // parse the temp reading
     Inc(idx); // move pointer past the ;
     currentTempSign := 1;
     // check for negative sign, if so flag the multiplier and then move past neg sign
@@ -55,21 +59,16 @@ procedure ProcessMeasurements(var buffer: array of char; bufferLength: integer;
       Inc(idx);
     end;
     // look ahead - is decimal point 2 spaces away then we have two digits
+    temp := 0;
     if buffer[idx + 2] = DECIMAL_POINT then
     begin
-      // this is the math that results from subtracting the byte value of ansi zero from each character
-      temp := currentTempSign * (100 * byte(buffer[idx]) + 10 *
-        byte(buffer[idx + 1]) + byte(buffer[idx + 2]) - 5328);
-      // move past digits and CRLF and position pointer to first character of next record
-      idx := idx + 6;
-    end
-    else
-    begin
-      temp := currentTempSign * (10 * byte(buffer[idx + 1]) +
-        byte(buffer[idx + 2]) - 528);
-      // move past digits and CRLF and position pointer to first character of next record
-      idx := idx + 5;
+      temp := 100 * (byte(buffer[idx]) - ANSI_ZERO);
+      Inc(idx);
     end;
+    temp := temp + 10 * (byte(buffer[idx]) - ANSI_ZERO);
+    idx := idx + 2;
+    temp := currentTempSign * (temp + (byte(buffer[idx]) - ANSI_ZERO));
+    idx := idx + 3;
     reading := results.Find(city);
     if reading = nil then
     begin
@@ -91,51 +90,6 @@ procedure ProcessMeasurements(var buffer: array of char; bufferLength: integer;
   end;
 end;
 
-function PascalRound(x: double): double;
-var
-  t: double;
-begin
-  //round towards positive infinity
-  t := Trunc(x);
-  if (x < 0.0) and (t - x = 0.5) then
-  begin
-    // Do nothing
-  end
-  else if Abs(x - t) >= 0.5 then
-  begin
-    t := t + Math.Sign(x);
-  end;
-
-  if t = 0.0 then
-    Result := 0.0
-  else
-    Result := t;
-end;
-
-
-function RoundEx(x: double): double;
-begin
-  Result := PascalRound(x * 10.0) / 10.0;
-end;
-
-function Compare(AList: TStringList; AIndex1, AIndex2: integer): integer;
-var
-  Pos1, Pos2: integer;
-  Str1, Str2: string;
-begin
-  Result := 0;
-  Str1 := AList.Strings[AIndex1];
-  Str2 := AList.Strings[AIndex2];
-  Pos1 := Pos('=', Str1);
-  Pos2 := Pos('=', Str2);
-  if (Pos1 > 0) and (Pos2 > 0) then
-  begin
-    Str1 := Copy(Str1, 1, Pos1 - 1);
-    Str2 := Copy(Str2, 1, Pos2 - 1);
-    Result := CompareStr(Str1, Str2);
-  end;
-end;
-
 procedure DumpMeasurements(results: TFPHashList);
 var
   i: integer;
@@ -147,6 +101,7 @@ procedure DumpMeasurements(results: TFPHashList);
   weatherStationList: TStringList;
   isFirstKey: boolean = True;
 begin
+  //WriteLn(results.Count);
   weatherStationList := TStringList.Create;
   for i := 0 to results.Count - 1 do
   begin
@@ -163,21 +118,23 @@ procedure DumpMeasurements(results: TFPHashList);
   Write('{');
   for ws in weatherStationList do
   begin
+    // If it's not the first key, print a comma
     if not isFirstKey then
       Write(', ');
+    // Print the weather station and the temp stat
     Write(ws);
+    // Set isFirstKey to False after printing the first key
     isFirstKey := False;
   end;
   WriteLn('}');
 end;
 
 procedure ReadMeasurements(inputFile: string);
-type
-  TCharArray = array of char;
 var
-  BytesRead: int64;
-  buffer: TCharArray;
+  totalBytesRead, BytesRead: int64;
+  Buffer: array [0..BUFFER_SIZE] of char;
   FileStream: TFileStream;
+  fileSize: int64;
   ReadBufferStream: TReadBufStream;
   results: TFPHashList;
   idx: integer;
@@ -186,29 +143,32 @@ procedure ReadMeasurements(inputFile: string);
   bufferLength: integer = 0;
 begin
   try
-    buffer := Default(TCharArray);
-    SetLength(buffer, BUFFER_SIZE);
     FileStream := TFileStream.Create(inputFile, fmOpenRead);
-    FileStream.Position := 0;
+    FileStream.Position := 0;  // Ensure you are at the start of the file
     ReadBufferStream := TReadBufStream.Create(FileStream);
+    fileSize := FileStream.size;
+    totalBytesRead := 0;
     results := TFPHashList.Create;
     startOfNextRecord := '';
-    while True do
+    while totalBytesRead <= fileSize do
+      // While the amount of data read is less than or equal to the size of the stream do
     begin
       startOfNextRecordLength := Length(startOfNextRecord);
       // if we have leftover from previous read then prepend it to this buffer
       if startOfNextRecordLength > 0 then
-        Move(PChar(startOfNextRecord)^, buffer[0], startOfNextRecordLength);
-      BytesRead := ReadBufferStream.Read(buffer[startOfNextRecordLength], READ_SIZE);
+        Move(PChar(startOfNextRecord)^, Buffer[0], startOfNextRecordLength);
+      BytesRead := ReadBufferStream.Read(Buffer[startOfNextRecordLength], READ_SIZE);
       if BytesRead < 1 then break;
       // now look in buffer backwards until we find the first LF
       bufferLength := startOfNextRecordLength + BytesRead;
       idx := bufferLength - 1;
-      while (buffer[idx] <> REC_SEP) do Inc(idx);
-      ProcessMeasurements(buffer, idx + 1, results);
+      while (buffer[idx] <> LF) do Dec(idx);
+      ProcessMeasurements(Buffer, idx + 1, results);
+      startOfNextRecord := '';
       startOfNextRecordLength := bufferLength - idx - 1;
       if startOfNextRecordLength > 0 then
         SetString(startOfNextRecord, @buffer[idx + 1], startOfNextRecordLength);
+      Inc(totalBytesRead, BytesRead);
     end;
     DumpMeasurements(results);
     ReadBufferStream.Free;
@@ -218,6 +178,7 @@ procedure ReadMeasurements(inputFile: string);
     on E: Exception do
     begin
       writeln('File ', inputFile, ' could not be read or written because: ', E.ToString);
+      DumpExceptionCallStack(E);
     end;
   end;
 end;

entries/rlawson/src/util.pas

@@ -0,0 +1,82 @@
+unit util;
+
+{$mode ObjFPC}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, Math;
+
+procedure DumpExceptionCallStack(E: Exception);
+function RoundEx(x: double): double;
+function Compare(AList: TStringList; AIndex1, AIndex2: integer): integer;
+
+implementation
+
+procedure DumpExceptionCallStack(E: Exception);
+var
+  I: integer;
+  Frames: PPointer;
+  Report: string;
+begin
+  Report := 'Program exception! ' + LineEnding + 'Stacktrace:' +
+    LineEnding + LineEnding;
+  if E <> nil then
+  begin
+    Report := Report + 'Exception class: ' + E.ClassName + LineEnding +
+      'Message: ' + E.Message + LineEnding;
+  end;
+  Report := Report + BackTraceStrFunc(ExceptAddr);
+  Frames := ExceptFrames;
+  for I := 0 to ExceptFrameCount - 1 do
+    Report := Report + LineEnding + BackTraceStrFunc(Frames[I]);
+  WriteLn(Report);
+  Halt; // End of program execution
+end;
+
+function PascalRound(x: double): double;
+var
+  t: double;
+begin
+  //round towards positive infinity
+  t := Trunc(x);
+  if (x < 0.0) and (t - x = 0.5) then
+  begin
+    // Do nothing
+  end
+  else if Abs(x - t) >= 0.5 then
+  begin
+    t := t + Math.Sign(x);
+  end;
+
+  if t = 0.0 then
+    Result := 0.0
+  else
+    Result := t;
+end;
+
+
+function RoundEx(x: double): double;
+begin
+  Result := PascalRound(x * 10.0) / 10.0;
+end;
+
+function Compare(AList: TStringList; AIndex1, AIndex2: integer): integer;
+var
+  Pos1, Pos2: integer;
+  Str1, Str2: string;
+begin
+  Result := 0;
+  Str1 := AList.Strings[AIndex1];
+  Str2 := AList.Strings[AIndex2];
+  Pos1 := Pos('=', Str1);
+  Pos2 := Pos('=', Str2);
+  if (Pos1 > 0) and (Pos2 > 0) then
+  begin
+    Str1 := Copy(Str1, 1, Pos1 - 1);
+    Str2 := Copy(Str2, 1, Pos2 - 1);
+    Result := CompareStr(Str1, Str2);
+  end;
+end;
+
+end.

entries/rlawson/src/weather.lpi

@@ -83,7 +83,7 @@
     <RunParams>
       <FormatVersion Value="2"/>
     </RunParams>
-    <Units Count="2">
+    <Units Count="3">
       <Unit0>
         <Filename Value="weather.lpr"/>
         <IsPartOfProject Value="True"/>
@@ -92,6 +92,10 @@
         <Filename Value="parser.pas"/>
         <IsPartOfProject Value="True"/>
       </Unit1>
+      <Unit2>
+        <Filename Value="util.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit2>
     </Units>
   </ProjectOptions>
   <CompilerOptions>

entries/rlawson/src/weather.lpr

@@ -4,11 +4,12 @@
 
 uses
   {$IFDEF UNIX}
-  cthreads,
+  cthreads, cmem,
   {$ENDIF}
   Classes,
   SysUtils,
-  CustApp, parser;
+  CustApp,
+  parser;
 
 type