Libraries.Data.Formats.SeparatedValueFileReader Documentation
Inherits from: Libraries.System.FileReader, Libraries.System.Blueprints.FileReaderBlueprint, Libraries.Language.Object
Summary
Actions Summary Table
Actions | Description |
---|---|
Close() | When we open a file for reading, it is marked by the operating system as being in use by our application. |
Compare(Libraries.Language.Object object) | This action compares two object hash codes and returns a CompareResult. |
Equals(Libraries.Language.Object object) | This action determines if two objects are equal based on their hash code values. |
GetHashCode() | This action gets the hash code for an object. |
IsAtEndOfFile() | |
OpenForRead(Libraries.System.File file) | Open a file for sequential reading. |
Read(integer numberOfBytes) | This action reads the specified number of bytes after our current position. |
Read() | This action reads all of the contents of our file from the current position. |
ReadLine() | |
ReadLines() |
Actions Documentation
Close()
When we open a file for reading, it is marked by the operating system as being in use by our application. To make it possible for other files to use this file at a later point in time, it is necessary to tell the operating system when we are done with this file. To do this, we use the Close() action. We should call Close() as soon as we know that a file is no longer needed. If no file is open, Close() will do nothing. After Close() is called, a FileReader object is considered invalid, and no actions should be called on it, other than OpenForRead(), to open the same (or different) file.
Example Code
use Libraries.System.File
use Libraries.System.FileReader
// Open a file, read all the contents and close it.
File f
f:SetPath("To Do List.txt")
FileReader reader
reader:OpenForRead(f)
output "Tim, your to do list says:"
output reader:Read()
// Close the file, as we no longer need it.
reader:Close()
Compare(Libraries.Language.Object object)
This action compares two object hash codes and returns a CompareResult. The compare result is either larger if this hash code is larger than the object passed as a parameter, smaller, or equal.
Example Code
use Libraries.Language.Support.CompareResult
Object o
Object t
CompareResult result = o:Compare(t)
Parameters
- Libraries.Language.Object: The object to compare to.
Return
Libraries.Language.Support.CompareResult: The Compare result, Smaller, Equal, or Larger.
Equals(Libraries.Language.Object object)
This action determines if two objects are equal based on their hash code values.
Example Code
use Libraries.Language.Object
use Libraries.Language.Types.Text
Object o
Text t
boolean result = o:Equals(t)
Parameters
- Libraries.Language.Object: The to be compared.
Return
boolean: True if the hash codes are equal and false if they are not equal.
GetHashCode()
This action gets the hash code for an object.
Example Code
Object o
integer hash = o:GetHashCode()
Return
integer: The integer hash code of the object.
IsAtEndOfFile()
Return
boolean
OpenForRead(Libraries.System.File file)
Open a file for sequential reading. By "sequential reading," it is meant that it is impossible to go backwards in the file--we must make progress toward the end of the file with each successive read. This is extremely useful for reading plain text documents, but is much less useful for reading binary files. Binary files should use the FileRandomAccess class.
Example Code
use Libraries.System.File
use Libraries.System.FileReader
// Open the file for reading.
File f
f:SetPath("homework.txt")
// Read the first two lines and then be done.
FileReader reader
reader:OpenForRead(f)
output reader:ReadLine()
output reader:ReadLine()
// Always close the file.
reader:Close()
Parameters
Read(integer numberOfBytes)
This action reads the specified number of bytes after our current position. When we open a file, we start at the beginning--calling this action with a parameter of, for example, 2, would read the first two bytes of the file. If we perform some other reading action such as ReadLine(), and then call this action, the specified number of bytes will be read after our current position. If the number of bytes specified exceeds the end of the file, content up to the end of the file will be returned. If the end of the file has been reached before this action is called, an EndOfFileError will be raised.
Example Code
use Libraries.System.File
use Libraries.System.FileReader
// Open a file, output the first four bytes.
File f
f:SetPath("Settings.dat")
FileReader reader
reader:OpenForRead(f)
output "The first four bytes are " + reader:Read(4)
reader:Close()
Parameters
- integer numberOfBytes: the number of bytes we wish to read after our current location in the file. This must be a positive number; if it is not, an InvalidArgumentError is raised.
Return
text: the file contents we have read
Read()
This action reads all of the contents of our file from the current position. When we open a file, we start at the beginning--so calling this action immediately after opening a file will read the entire file. If we perform some other reading action, such as ReadLine(), and then call this action, we will receive all file contents after the point where we have read. If the end of file has already been reached before calling this action, an EndOfFileError will be raised.
Example Code
use Libraries.System.File
use Libraries.System.FileReader
// Open a file, read all of its contents to a text value and then output the text value.
File f
f:SetPath("Settings.dat")
FileReader reader
reader:OpenForRead(f)
text settings = reader:Read()
output "The settings are:"
output settings
reader:Close()
Return
text: the file contents from our current position to the end of the file.
ReadLine()
Return
text