Build Code Syntax Highlighter with PHP
Code syntax highlighter is a tool or library that adds color and formatting to source code, making it easier to read and understand. It highlights different parts of the code based on their syntax, such as keywords, variables, comments, and strings, by applying different colors or styles to each element.It helps programmers quickly identify and differentiate between different language constructs, which can aid in detecting errors and understanding the code structure.You can get the complete code from Github
highlighter.class.php
1 <?php
2 include_once("keywords.php");
3 class Highlighter {
4 private $fileName;
5 private $fileExtension;
6 private $showFileName;
7
8 public function __construct() {
9 $this->fileName = "";
10 $this->fileExtension = "";
11 $this->showFileName = true;
12 }
13
14 public function showfilename($value) {
15 $this->showFileName = $value;
16 }
17
18 public function applycolor($fileLocation = "") {
19 if($fileLocation == "") {
20 return;
21 }
22 else
23 {
24 if(file_exists$fileLocation) {
25 $temp = explode("/",$fileLocation);
26 $this->fileName = trim(end$temp);
27 $temp = explode(".",$this->fileName);
28 $this->fileExtension = trim(end$temp);
29 $fileContent = trim(file_get_contents$fileLocation, true);
30 $fileContent = htmlentities($fileContent,ENT_NOQUOTES);
31 if($fileContent == "") {
32 return;
33 }
34 }
35 else
36 {
37 return;
38 }
39
40 $parenthesisFound = 0;
41 $bracketFound = 0;
42 $foundCharacter = "";
43
44 $line = 1;
45 $counter = 0;
46 $contentSize = strlen($fileContent);
47
48 $content = "<font class='lI'>".$line."</font> ";
49 while($counter < $contentSize) {
50 $character = $fileContent[$counter];
51 $code = intval(ord$character);
52 if($code >= 97 && $code <= 122 || $code >= 65 && $code <= 90) { //Identify only alphabet(Capital/Small) characters
53 $characterBuffer .= $character;
54 }
55 else
56 {
57 if($characterBuffer != "") {
58 $content .= $this->checker($characterBuffer);
59 $characterBuffer = "";
60 }
61
62 if($character == "/" && isset$fileContent[$counter+1] && $fileContent[$counter+1] == "*" || $fileContent[$counter+1] == "/") { //Identify single comment or multiple comments
63 $content .= "<font class='cC'>".$fileContent[$counter].$fileContent[$counter+1];
64 if($fileContent[$counter+1] == "*") {
65 $counter += 2;
66 while($counter < $contentSize) {
67 $character = $fileContent[$counter];
68 $code = intval(ord$character);
69 if($code != 10) { //Identify not '\n' character
70 if($character == "*" && isset$fileContent[$counter+1] && $fileContent[$counter+1] == "/") {
71 $counter++;
72 $content .= $character.$fileContent[$counter]."</font>";
73 break;
74 }
75 else
76 {
77 $content .= $character;
78 }
79 }
80 else
81 {
82 $line++;
83 $content .= "</font>".$character."<font class='lI'>".$line."</font> <font class='cC'>";
84 }
85 $counter++;
86 }
87 }
88 else
89 {
90 $counter += 2;
91 while($counter < $contentSize) {
92 $character = $fileContent[$counter];
93 $code = intval(ord$character);
94 if($code == 10) { //Identify '\n' character
95 $content .= "</font>";
96 $counter--;
97 break;
98 }
99 $content .= $character;
100 $counter++;
101 }
102 }
103 }
104 else if($character == "'" || $character == "\"") { //Identify sigle quote or double quote character
105 $foundCharacter = $character;
106 $content .= "<font class='qC'>".$foundCharacter;
107 $counter++;
108 while($counter < $contentSize) {
109 $character = $fileContent[$counter];
110 $code = intval(ord$character);
111 if($foundCharacter == $character) {
112 if($foundCharacter == "\"") {
113 if($fileContent[$counter-1] != "\\") {
114 $content .= $foundCharacter."</font>";
115 break;
116 }
117 else if($fileContent[$counter-2] == "\\" && $fileContent[$counter-1] == "\\") {
118 $content .= $foundCharacter."</font>";
119 break;
120 }
121 else
122 {
123 $content .= $character;
124 }
125 }
126 else
127 {
128 $content .= $foundCharacter."</font>";
129 break;
130 }
131 }
132 else if($code == 10) { //Identify '\n' character
133 $line++;
134 $content .= $character;
135 $content .= "<font class='lI'>".$line."</font> ";
136 }
137 else
138 {
139 $content .= $character;
140 }
141 $counter++;
142 }
143 }
144 else if($character == "(" || $character == ")") { //Identify parenthesis character
145 if($parenthesisFound == 0) {
146 $content .= "<font class='pC'>".$character."</font><font class='iPC'>";
147 }
148 if($character == "(") {
149 $parenthesisFound++;
150 }
151 else if($character == ")") {
152 $parenthesisFound--;
153 }
154 if($parenthesisFound == 0) {
155 $content .= "</font><font class='pC'>".$character."</font>";
156 }
157 }
158 else if($character == "[" || $character == "]") { //Identify bracket character
159 if($bracketFound == 0) {
160 $content .= "<font class='bC'>".$character."</font><font class='iBC'>";
161 }
162 if($character == "[") {
163 $bracketFound++;
164 }
165 else if($character == "]") {
166 $bracketFound--;
167 }
168 if($bracketFound == 0) {
169 $content .= "</font><font class='bC'>".$character."</font>";
170 }
171 }
172 else if($code == 10) { //Identify '\n' character
173 $line++;
174 $content .= $character;
175 $content .= "<font class='lI'>".$line."</font> ";
176 }
177 else
178 {
179 $content .= $character;
180 }
181 }
182 $counter++;
183 }
184
185 $output = "<div class='codediv'>";
186 if($this->showFileName == true) {
187 $output .= "<div class='fN'>".$this->fileName."</div>";
188 }
189 $output .= "<div class='code'><pre><code>".$content."</code></pre></div>";
190 $output .= "</div>";
191 return $output;
192 }
193 }
194
195 private function checker($value) {
196 global $languageKeywords;
197 $value = trim($value);
198 if(isset$languageKeywords[$this->fileExtension]) { //Identify file type extension
199 if(in_array$value,$languageKeywords[$this->fileExtension]) { //Identify keywords
200 $value = "<font class='kC'>".$value."</font>";
201 }
202 }
203 return $value;
204 }
205 }
206 ?>keywords.php
1 <?php
2 //Programming language keywords
3 $languageKeywords["php"] = array("function","if","else","isset","unset","foreach","for","while","do","new","private","public","protected");
4 $languageKeywords["cpp"] = array("void","char","int","main","static","if","else","for","while","do","cout","cin","struct","unsigned","long","return");
5 $languageKeywords["java"] = array("if","else","for","while","do","return","public","private","static","void","import","class","try","catch","package","main","this","int","null","new");
6 $languageKeywords["js"] = array("var","function");
7 ?>style.css
1 /* Code Highlighter Start */
2
3 /* Code Div */
4 .codediv {
5 font-size:16px;
6 padding:0px;
7 margin-top:5px;
8 margin-bottom:5px;
9 }
10
11 /* File Name Color */
12 .fN {
13 color:#21094e;
14 margin-bottom:5px;
15 }
16
17 /* Code */
18 .code {
19 line-height:normal;
20 padding:15px;
21 overflow:auto;
22 color:#85d9eb;
23 background-color:#191e1e;
24 border-left:5px solid #605a56;
25 }
26
27 /* Paragraph */
28 pre {
29 margin:0px;
30 padding:0px;
31 }
32
33 /* Line Number Color */
34 .lI {
35 color:#ffffff;
36 }
37
38 /* Keyword Color */
39 .kC {
40 color:#56e27a;
41 }
42
43 /* Single Line & Mulitple Lines Comment Color */
44 .cC {
45 color:#b8b0b0;
46 }
47
48 /* Single & Double Quotes Color */
49 .qC {
50 color:#d4f088;
51 }
52
53 /* Parenthesis Color */
54 .pC {
55 color:#ffffff;
56 }
57
58 /* Inner Parenthesis Color */
59 .iPC {
60 color:#d4f088;
61 }
62
63 /* Bracket Color */
64 .bC {
65 color:#ffffff;
66 }
67
68 /* Inner Bracket Color */
69 .iBC {
70 color:#d4f088;
71 }
72
73 /* Code Highlighter End */index.php
1 <link href="style.css" rel="stylesheet" />
2 <?php
3 include_once("highlighter.class.php");
4 $colorObj = new highlighter();
5 $fileContent = $colorObj->applycolor("highlighter.class.php");
6 echo $fileContent;
7 $colorObj->showfilename(false);
8 $fileContent = $colorObj->applycolor("index.php");
9 echo $fileContent;
10 ?>
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