|FBB::TableSupport(3bobcat)||Table Support Base class||FBB::TableSupport(3bobcat)|
FBB::TableSupport - Defines protocols for Table-support classes
Linking option: -lbobcat
FBB::TableSupport is used by FBB::Table and FBB::TableBuf objects, handling some of their functionality. Users may derive classes from TableSupport, overriding its virtual members to determine the actual layout of tables. By default the virtual members of TableSupport do not separate the columns of the table from each other.
The Bobcat library offers the specialized class TableLines extending the basic facilities of TableSupport, offering facilities to separate rows by (partial) horizontal lines (cf. tablelines(3bobcat) for details).
More specialized handling can be realized by deriving new classes from FBB::TableSupport, overriding members so that they implement the programmer’s intentions. An object of this derived class may be presented to a FBB::Table or FBB::TableBuf constructor, to activate the special handling.
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.
The enum ColumnType defines the following values (see also the description of the struct HLine, below):
a section of a row-separating line should remain empty. This value is normally not used by applications;
a section of a row-separating line should be used (e.g., by writing a (horizontal) line);
a (horizontal) line should be written over the total width of the separator to the left of a series of columns
a (horizontal) line should be written over the total width of the separator to the right of a series of columns;
a (horizontal) line should be written over the right-half part of the width of the separator to the left of a series of columns; the left-hand part remains blank;
a (horizontal) line should be written over the left-half part of the width of the separator to the right of a series of columns; the right-hand part remains blank;
The value SKIP should always be used by itself; remaining values of the enum may be combined using the binary or (|) operator.
- struct HLine:
This struct has the following fields:
It offers two constructors:
- HLine(size_t row, size_t begin, size_t end):
- HLine(ColumnType type, size_t row, size_t begin, size_t end):
Objects of type TableSupport::HLine may be inserted into a TableSupport object to specify section(s) of a horizontal separator between table rows that should be displayed or skipped.
- E.g., to specify that a separator should be written
- in row 1,
- from column 2 up to (not including) column 5,
- extending the separator to the left by half of the width of the separator between columns 1 and 2, and to the right by the full width of the separator between columns 4 and 5
- the following HLine object should be inserted into the
TableSupport ts object:
ts << HLine(LEFT_MID | RIGHT_FULL, 1, 2, 5);Multiple HLine objects may be inserted, in any order, into TableSupport objecta. When column ranges overlap then their ColumTypes are merged.
The const_iterator is defined in the class’s protected section. It is an input-iterator returning iterators to struct Field (see below) objects
- for table columns and column separators (see below at the begin and end members)
- struct Field:
A Field has two data members: width and type, representing, respectively, the width and ColumnType of a column or separating column. The type values of Field objects returned by TableSupport members only contain single values (like SKIP or LEFT_MID) (note that column types can be combined when inserted into Table objects using HLine objects).
The default, copy and move constructors as well as the copy and move assignment operators are available.
The following overloaded operators define separators between columns. The first value inserted into a TableSupport object defines the separator before column 0, the next one defines the separator before column 1, etc, until inserting separator nColumns + 1, defining the separator to the right of the table’s last column. Inserting additional separators are ignored.
- TableSupport &operator<<(TableSupport &support, size_t
This operator defines a column-separator of width space characters. Width may be zero, in which case no visible separator is used;
- TableSupport &operator<<(TableSupport &support,
std::string const &text):
This operator defines a separator through text. The length of the text defines the width of the separator. No separator is used when text is empty;
- TableSupport &operator<<(TableSupport &support, HLine
This operator defines how a horizontal separator of a specified row should be displayed (see the above description of HLine).
- void hline(size_t row) const:
When inserting a table into a std::ostream Table and TableBuf objects call this member just before the indicated row (offset) is inserted into a std::ostream. It calls the virtual member v_hline, passing it row. By default v_hline performs no actions;
- void hline() const:
When inserting a table into a std::ostream Table and TableBuf objects call this member just after inserting the table’s final row. It calls the virtual member v_hline without arguments, which by default calls hline(nRows);
- void setParam(std::ostream &ostr, size_t nRows, size_t
nColumns, std::vector<Align> const &align):
This member provides the TableSupport object with values that are essential for its proper functioning. It is called by the Table and TableBuf’s def member (and manipulator) to configure the TableSupport with alignment specifications, where
ostr is a reference to the std::ostream to receive the table,
nRows specifies the table’s number of rows,
nColumns specifies the table’s number of columns,
align is a reference to a constant vector of (column) alignment specifications;
- void vline(size_t col) const:
When inserting the data elements of the rows of a table into a std::ostream Table and TableBuf objects call this member just before inserting the data elements of column col. Its task is to write a column separator just before the data elements themselves. It calls the virtual member v_vline passing it its col parameter. By default v_vline inserts the column separator of column col;
- virtual void vline() const:
When inserting a table into a std::ostream Table and TableBuf objects call this member after inserting the data elements of the rows of the table. It is called at the end of each row. It calls the virtual member v_vline without arguments, by default calling vline(nColumns) and inserting a newline into the ostream;
- size_t width() const:
Returns the width of the table in number of characters. It may be called before actually inserting the table into a stream.
The following members are available to classes derived from TableSupport. Except for sep and sepWidth their values are only defined after calling setParam which is called from the def member or manipulator of Table or TableBuf objects.
- std::vector<Align> const &align() const:
A reference to a vector of Align objects, defining the alignments and widths of the table’s columns is returned.
- const_iterator begin(size_t row) const:
An iterator is returned containing information about the first column element when displaying the horizontal separator before line row. Use argument nRows() to obtain the information about the separator beyond the last row. The `column elements’ of the table consist of its separators and data columns.
Dereferencing the returned const_iterator returns a Field struct containing information about the width and type of a column element. Dereferencing the iterator returned by begin provides information about the leftmost column separator. By incrementing the iterator all subsequent column elements are visited. Dereferencing the iterator is defined until the iterator has reached the value returned by end (see below);
- size_t colWidth(size_t col) const:
The width of the indicated column is returned;
- const_iterator end(size_t row) const:
An iterator indicating the end of the iterator range starting at begin(row) is returned;
- size_t nColumns() const:
The table’s number of columns is returned;
- size_t nRows() const:
The table’s number of rows is returned;
- std::ostream &out() const:
A reference to the stream into which the table is inserted is returned;
- std::vector<std::string> const &sep():
A reference to the separators defined for the table’s columns is returned. Element col refers to the separator to the left of the table’s column col, element nColumns() refers to the separator to the right of the rightmost column;
- size_t sepWidth(size_t col) const:
The width of the indicated separator is returned. Element col refers to the separator to the left of the table column col, element nColumns() refers to the separator to the right of the rightmost table column.
The following member functions can be overridden by derived classes to redefine the way horizontal and vertical separators are displayed.
- virtual void v_hline(size_t row) const:
This member is called from hline(size_t row), receiving its row parameter. Its task is to write a horizonal separator before row row. By default nothing is inserted. It may insert the horizontal separator by iterating over the range defined by the begin and end members, deciding what to do on the basis of the Field objects made available by dereferencing the iterators. Alternatively, to let v_hline insert a horizontal line spanning the full width of the table row the following implementation can be used:
void Derived::v_hline(size_t row) const
out() << setfill(’-’) << setw(width()) << "-" <<
- virtual void v_hline() const:
This member is called from hline(). Its task is to write a (partial) horizontal line beyond the table’s last line. By default it calls hline(nRows);
- virtual void v_vline(size_t col) const:
This member is called from vline(size_t col), receiving its col parameter. Its task is to write a separator before data column col. By default it inserts separator[col] if available (if that separator is not available then no separator is inserted before column col);
- virtual void v_vline() const:
This member is called from vline() at the end of each of the table’s rows. Its task is to write a column separator, and to terminate the table’s line for which it is called. By default it inserts the final column separator (if defined) and a newline (\n) character.
See the example in the table(3bobcat) man-page.
bobcat/tableSupport - defines the class interface
bobcat(7), align(3bobcat), csvtable(3bobcat), table(3bobcat), tablebuf(3bobcat), tablelines(3bobcat)
- https://fbb-git.gitlab.io/bobcat/: gitlab project page;
- bobcat_6.02.02-x.dsc: detached signature;
- bobcat_6.02.02-x.tar.gz: source archive;
- bobcat_6.02.02-x_i386.changes: change log;
- libbobcat1_6.02.02-x_*.deb: debian package containing the libraries;
- libbobcat1-dev_6.02.02-x_*.deb: debian package containing the libraries, headers and manual pages;
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
This is free software, distributed under the terms of the GNU General Public License (GPL).
Frank B. Brokken (firstname.lastname@example.org).