Train Data Structure Implementation

A sophisticated implementation of a doubly circular linked list with sentinel node, designed for efficient data manipulation and management.

Project Overview

This implementation represents a train system using a doubly circular linked list with a sentinel node. Each cell in the structure represents a train car, with a mechanic pointer indicating the current position for operations.

Core Data Structures

typedef struct TrCell2 {
    char data;              // Content of the train car
    struct TrCell2 *next;   // Pointer to next car
    struct TrCell2 *prev;   // Pointer to previous car
} TRCell2, *TRL2;

typedef struct Train {
    TRL2 head;             // Sentinel node
    TRL2 mechanic;         // Current position pointer
} *TTrain;

Implemented Operations

Navigation Operations

Operation	Description
MOVE_LEFT/RIGHT	Moves the mechanic cursor to adjacent positions
SEARCH_LEFT/RIGHT	Searches for a character from current position to sentinel
SEARCH	Performs circular search from current position

Modification Operations

Operation	Description
INSERT_LEFT/RIGHT	Adds new cell adjacent to mechanic position
WRITE	Overwrites current cell content
CLEAR_CELL	Removes current cell
CLEAR_ALL	Resets structure to initial state
SWITCH	Reverses queue content up to current position

Display Operations

Operation	Description
SHOW	Displays entire list (mechanic position marked with |character|)
SHOW_CURRENT	Displays mechanic's cell content

Important Notes

1. Insert operations will display an error if mechanic is in first car
2. All commands except SHOW, SHOW_CURRENT, and SWITCH are processed through a priority queue
3. The mechanic position always indicates the active cell for operations

Implementation Details

Each operation is carefully implemented to maintain list integrity while providing efficient data manipulation:

• Circular Nature: The list maintains its circular property through all operations
• Sentinel Node: Provides simplified edge case handling
• Bidirectional Links: Enable efficient traversal in both directions
• Priority Queue: Ensures ordered command execution

Usage Example

// Example structure visualization
[S]-[A]-[B]-[|C|]-[D]-[E]
// Where S is sentinel node and |C| is mechanic position

Licence

This project is licensed under the MIT Licence. See the LICENCE file for further details.