Add Painless language support (#521)

Author: Mpdreamz

docs/testing/custom-highlighters.md

@@ -112,3 +112,40 @@ FROM books
 | SORT book_no
 | LIMIT 5;
 ```
+
+## Painless
+
+```painless
+int i = (int)5L;
+Map m = new HashMap();
+HashMap hm = (HashMap)m;
+```
+
+```painless
+ZonedDateTime zdt1 =
+        ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
+ZonedDateTime zdt2 =
+        ZonedDateTime.of(1983, 10, 17, 22, 15, 35, 0, ZoneId.of('Z'));
+
+if (zdt1.isAfter(zdt2)) {
+    // handle condition
+}
+```
+
+```painless
+if (doc.containsKey('start') && doc.containsKey('end')) {
+
+    if (doc['start'].size() > 0 && doc['end'].size() > 0) {
+
+        ZonedDateTime start = doc['start'].value;
+        ZonedDateTime end = doc['end'].value;
+        long differenceInMillis = ChronoUnit.MILLIS.between(start, end);
+
+        // handle difference in times
+    } else {
+        // handle fields without values
+    }
+} else {
+    // handle index with missing fields
+}
+```

src/Elastic.Markdown/Assets/hljs.ts

@@ -68,6 +68,32 @@ hljs.registerLanguage('eql', function() {
 	}
 })
 
+hljs.registerLanguage('painless', function() {
+	return {
+		case_insensitive: true, // language is case-insensitive
+		keywords: {
+			keyword: 'where sequence sample untill and or not in in~',
+			literal: ['false','true','null'],
+			'subst': 'add between cidrMatch concat divide endsWith indexOf length modulo multiply number startsWith string stringContains substring subtract'
+		},
+		contains: [
+			hljs.QUOTE_STRING_MODE,
+			hljs.C_LINE_COMMENT_MODE,
+			{
+				scope: "operator", // (pathname: path1/path2/dothis) color #ab5656
+				match: /(?:<|<=|==|:|!=|>=|>|like~?|regex~?)/,
+			},
+			{
+				scope: "punctuation", // (pathname: path1/path2/dothis) color #ab5656
+				match: /(?:!?\[|\]|\|)/,
+			},
+			NUMBER,
+
+		]
+	}
+})
+
+
 hljs.registerLanguage('esql', function() {
 	return {
 		case_insensitive: true, // language is case-insensitive

src/Elastic.Markdown/Assets/markdown/code.css

@@ -118,16 +118,21 @@
 
 	.hljs-meta,
 	.hljs-name,
-	.hljs-type,
-	.hljs-symbol,
 	.hljs-bullet,
 	.hljs-addition,
-	.hljs-variable,
 	.hljs-template-tag,
 	.hljs-template-variable {
 		color: var(--color-yellow-50)
 	}
 
+	.hljs-type,
+	.hljs-symbol {
+		color: var(--color-teal-50)
+	}
+	.hljs-variable {
+		color: var(--color-purple-50)
+	}
+
 	.hljs-comment,
 	.hljs-quote,
 	.hljs-deletion {
@@ -155,7 +160,7 @@
 		color: var(--color-pink-50)
 	}
 	.hljs-number {
-		color: var(--color-teal-50)
+		color: var(--color-red-50)
 	}
 
 	.hljs-emphasis {

src/Elastic.Markdown/Myst/CodeBlocks/EnhancedCodeBlockParser.cs

@@ -85,6 +85,7 @@ public override bool Close(BlockProcessor processor, Block block)
 			"console-response" => "json",
 			"console-result" => "json",
 			"terminal" => "bash",
+			"painless" => "java",
 			_ => codeBlock.Language
 		};
 		if (!string.IsNullOrEmpty(codeBlock.Language) && !CodeBlock.Languages.Contains(codeBlock.Language))