Buffer tree: Manage ordered collections of data items

Buffer tree

Two PHP classes for creating and manipulating a hierarchy of output buffers.

The class buffer represents a single buffer, it has a name, a list of content and an optional separator. The list of content consists of other buffers and data. The following methods are defined:

append($data)   -- append data (including buffer or array) to this buffer
clear()         -- clear this buffer
replace($data)  -- replace this buffer with new data
find($name)     -- find a named buffer within this buffer
dump()          -- make visual output of this buffer (for debugging)
__toString()    -- output buffer content as a string

The second class buffer_manager has methods for managing a stack of buffers.

current()       -- return current buffer instance
enter($name)    -- activate named buffer, if it does not exist: create and append to current buffer
leave()         -- leave current buffer, activate previous active buffer
out($data)      -- write data (string, buffer or array) to current active buffer
undo()          -- remove current (newly created) buffer
find($name)     -- find named buffer within root buffer

There are two demo files provided for each class, showing examples of how these classes can be used.

• buffer_demo_1: Creating and manipulating a table of integers, using different separators
• buffer_demo_2: Creating HTML output, using buffers as templates
• buffer_manager_demo_1: Using the buffer manager for better control of HTML output
• buffer_manager_demo_2: More advanced examples of HTML template usage

Note that the first example is very different from the others. The buffer class is very generic, it does not need to contain strings as values. However the __toString() method will automatically cast each content member to a string. This means you can use any scalars and even objects as data items, as long as they can be cast to strings, i.e. they have a __toString() method.