Add Svelte syntax highlighting

This commit adds support for syntax highlighting of Svelte code

components/prism-svelte.js

@@ -0,0 +1,153 @@
+// Define a regular expression pattern for specific blocks
+const blocks = '(if|else if|await|then|catch|each|html|debug)';
+
+// Extend the Prism markup language to support Svelte syntax
+Prism.languages.svelte = Prism.languages.extend('markup', {
+    // Define syntax highlighting for Svelte each block
+    each: {
+        pattern: new RegExp(
+            '{[#/]each' + '(?:(?:\\{(?:(?:\\{(?:[^{}])*\\})|(?:[^{}]))*\\})|(?:[^{}]))*}'
+        ),
+        inside: {
+            'language-javascript': [
+                // Define patterns for 'as' keyword followed by JavaScript content inside parentheses
+                {
+                    pattern: /(as[\s\S]*)\([\s\S]*\)(?=\s*\})/,
+                    lookbehind: true,
+                    inside: Prism.languages['javascript']
+                },
+                // Define patterns for 'as' keyword followed by JavaScript content without parentheses
+                {
+                    pattern: /(as[\s]*)[\s\S]*(?=\s*)/,
+                    lookbehind: true,
+                    inside: Prism.languages['javascript']
+                },
+                // Define patterns for '#each' followed by JavaScript content until 'as' keyword
+                {
+                    pattern: /(#each[\s]*)[\s\S]*(?=as)/,
+                    lookbehind: true,
+                    inside: Prism.languages['javascript']
+                }
+            ],
+            keyword: /[#/]each|as/, // Define keyword patterns
+            punctuation: /{|}/ // Define punctuation patterns
+        }
+    },
+    // Define syntax highlighting for Svelte block elements
+    block: {
+        pattern: new RegExp(
+            '{[#:/@]/s' + blocks + '(?:(?:\\{(?:(?:\\{(?:[^{}])*\\})|(?:[^{}]))*\\})|(?:[^{}]))*}'
+        ),
+        inside: {
+            punctuation: /^{|}$/, // Define punctuation patterns
+            keyword: [new RegExp('[#:/@]' + blocks + '( )*'), /as/, /then/], // Define keyword patterns
+            'language-javascript': { // Define JavaScript language patterns
+                pattern: /[\s\S]*/, // Match any JavaScript content
+                inside: Prism.languages['javascript']
+            }
+        }
+    },
+    // Define syntax highlighting for Svelte HTML tags and attributes
+    tag: {
+        pattern:
+            /<\/?(?!\d)[^\s>\/=$<%]+(?:\s(?:\s*[^\s>\/=]+(?:\s*=\s*(?:(?:"[^"]*"|'[^']*'|[^\s'">=]+(?=[\s>]))|(?:"[^"]*"|'[^']*'|{[\s\S]+?}(?=[\s/>])))|(?=[\s/>])))+)?\s*\/?>/i,
+        greedy: true,
+        inside: {
+            tag: {
+                pattern: /^<\/?[^\s>\/]+/i,
+                inside: {
+                    punctuation: /^<\/?/,
+                    namespace: /^[^\s>\/:]+:/
+                }
+            },
+            'language-javascript': { // Define JavaScript language patterns within tags
+                pattern: /\{(?:(?:\{(?:(?:\{(?:[^{}])*\})|(?:[^{}]))*\})|(?:[^{}]))*\}/,
+                inside: Prism.languages['javascript']
+            },
+            'attr-value': { // Define attribute value patterns
+                pattern: /=\s*(?:"[^"]*"|'[^']*'|[^\s'">=]+)/i,
+                inside: {
+                    punctuation: [
+                        /^=/,
+                        {
+                            pattern: /^(\s*)["']|["']$/,
+                            lookbehind: true
+                        }
+                    ],
+                    'language-javascript': { // Define JavaScript language patterns within attribute values
+                        pattern: /{[\s\S]+}/,
+                        inside: Prism.languages['javascript']
+                    }
+                }
+            },
+            punctuation: /\/?>/, // Define punctuation patterns for tags
+            'attr-name': { // Define attribute name patterns
+                pattern: /[^\s>\/]+/,
+                inside: {
+                    namespace: /^[^\s>\/:]+:/
+                }
+            }
+        }
+    },
+    // Define syntax highlighting for inline JavaScript content
+    'language-javascript': {
+        pattern: /\{(?:(?:\{(?:(?:\{(?:[^{}])*\})|(?:[^{}]))*\})|(?:[^{}]))*\}/,
+        lookbehind: true,
+        inside: Prism.languages['javascript']
+    }
+});
+
+// Add entity highlighting support for Svelte tags
+Prism.languages.svelte['tag'].inside['attr-value'].inside['entity'] =
+    Prism.languages.svelte['entity'];
+
+// Add a hook to wrap entities with additional attributes
+Prism.hooks.add('wrap', (env) => {
+    if (env.type === 'entity') {
+        env.attributes['title'] = env.content.replace(/&amp;/, '&');
+    }
+});
+
+// Define a function to add inline language support for specific tags
+Object.defineProperty(Prism.languages.svelte.tag, 'addInlined', {
+    value: function addInlined(tagName, lang) {
+        const includedCdataInside = {};
+        includedCdataInside['language-' + lang] = {
+            pattern: /(^<!\[CDATA\[)[\s\S]+?(?=\]\]>$)/i,
+            lookbehind: true,
+            inside: Prism.languages[lang]
+        };
+        includedCdataInside['cdata'] = /^<!\[CDATA\[|\]\]>$/i;
+
+        const inside = {
+            'included-cdata': {
+                pattern: /<!\[CDATA\[[\s\S]*?\]\]>/i,
+                inside: includedCdataInside
+            }
+        };
+        inside['language-' + lang] = {
+            pattern: /[\s\S]+/,
+            inside: Prism.languages[lang]
+        };
+
+        const def = {};
+        def[tagName] = {
+            pattern: RegExp(
+                /(<_tagName_[\s\S]*?>)(?:<!\[CDATA\[[\s\S]*?\]\]>\s*|[\s\S])*?(?=<\/_tagName_>)/.source.replace(
+                    /_tagName_/g,
+                    tagName
+                ),
+                'i'
+            ),
+            lookbehind: true,
+            greedy: true,
+            inside
+        };
+
+        Prism.languages.insertBefore('svelte', 'cdata', def);
+    }
+});
+
+// Add inline language support for CSS and JavaScript within style and script tags
+Prism.languages.svelte.tag.addInlined('style', 'css');
+Prism.languages.svelte.tag.addInlined('script', 'javascript');