3.7. State¶

1<?php
2
3/**
4 * The WritingStateInterface defines the interface for all writing states.
5 */
6interface WritingStateInterface
7{
8    public function write(string $words);
9}

 1<?php
 2
 3/**
 4 * The UpperCase class represents a writing state where all text is converted to uppercase.
 5 */
 6class UpperCase implements WritingStateInterface
 7{
 8    public function write(string $words)
 9    {
10        echo strtoupper($words) . "\n";
11    }
12}
13
14/**
15 * The LowerCase class represents a writing state where all text is converted to lowercase.
16 */
17class LowerCase implements WritingStateInterface
18{
19    public function write(string $words)
20    {
21        echo strtolower($words) . "\n";
22    }
23}
24
25/**
26 * The DefaultText class represents the default writing state where text is output as is.
27 */
28class DefaultText implements WritingStateInterface
29{
30    public function write(string $words)
31    {
32        echo $words . "\n";
33    }
34}

 1<?php
 2
 3/**
 4 * The TextEditor class maintains a reference to a writing state and allows changing it at runtime.
 5 */
 6class TextEditor
 7{
 8    private WritingStateInterface $state;
 9
10    public function __construct()
11    {
12        $this->state = new DefaultText();
13    }
14
15    public function setState(WritingStateInterface $state): void
16    {
17        $this->state = $state;
18    }
19
20    public function type(string $words): void
21    {
22        $this->state->write($words);
23    }
24}

 1<?php
 2
 3// Example usage
 4$editor = new TextEditor();
 5
 6$editor->type("First line");
 7
 8$editor->setState(new UpperCase());
 9
10$editor->type("Second Line");
11$editor->type("Third Line");
12
13$editor->setState(new LowerCase());
14
15$editor->type("Fourth Line");
16$editor->type("Fifth Line");
17
18// Output:
19// First line
20// SECOND LINE
21// THIRD LINE
22// fourth line
23// fifth line