Highlight single-line comments, and refactor highlighting method

src/common/filetype/filetype.ts

@@ -1,4 +1,5 @@
 import { node_path as path } from '../runtime/mod.ts';
+import Option, { None, Some } from '../option.ts';
 
 // ----------------------------------------------------------------------------
 // File-related types
@@ -18,6 +19,7 @@ export interface HighlightingOptions {
 
 interface IFileType {
 	readonly name: FileLang;
+	readonly singleLineComment: Option<string>;
 	readonly hlOptions: HighlightingOptions;
 	get flags(): HighlightingOptions;
 }
@@ -27,6 +29,7 @@ interface IFileType {
  */
 export abstract class AbstractFileType implements IFileType {
 	public readonly name: FileLang = FileLang.Plain;
+	public readonly singleLineComment = None;
 	public readonly hlOptions: HighlightingOptions = {
 		numbers: false,
 		strings: false,
@@ -47,6 +50,7 @@ const defaultHighlightOptions: HighlightingOptions = {
 
 class TypeScriptFile extends AbstractFileType {
 	public readonly name: FileLang = FileLang.TypeScript;
+	public readonly singleLineComment = Some('//');
 	public readonly hlOptions: HighlightingOptions = {
 		...defaultHighlightOptions,
 	};
@@ -54,6 +58,7 @@ class TypeScriptFile extends AbstractFileType {
 
 class JavaScriptFile extends AbstractFileType {
 	public readonly name: FileLang = FileLang.JavaScript;
+	public readonly singleLineComment = Some('//');
 	public readonly hlOptions: HighlightingOptions = {
 		...defaultHighlightOptions,
 	};
@@ -61,6 +66,7 @@ class JavaScriptFile extends AbstractFileType {
 
 class CSSFile extends AbstractFileType {
 	public readonly name: FileLang = FileLang.CSS;
+	public readonly singleLineComment = None;
 	public readonly hlOptions: HighlightingOptions = {
 		...defaultHighlightOptions,
 	};

src/common/highlight.ts

@@ -5,6 +5,7 @@ export enum HighlightType {
 	Number,
 	Match,
 	String,
+	SingleLineComment,
 }
 
 export function highlightToColor(type: HighlightType): string {
@@ -18,6 +19,9 @@ export function highlightToColor(type: HighlightType): string {
 		case HighlightType.String:
 			return Ansi.color256(201);
 
+		case HighlightType.SingleLineComment:
+			return Ansi.color256(45);
+
 		default:
 			return Ansi.ResetFormatting;
 	}

src/common/row.ts

@@ -225,94 +225,141 @@ export class Row {
 	}
 
 	public highlight(word: Option<string>, syntax: FileType): void {
-		const highlighting = [];
+		this.hl = [];
+
+		let i = 0;
+		for (; i < this.rsize;) {
+			const ch = this.rchars[i];
+
+			const maybeNext = this.highlightComment(i, syntax, ch)
+				.orElse(() => this.highlightString(i, syntax, ch))
+				.orElse(() => this.highlightNumber(i, syntax, ch));
+
+			if (maybeNext.isSome()) {
+				const next = maybeNext.unwrap();
+				if (next < this.rsize) {
+					i = maybeNext.unwrap();
+					continue;
+				}
+
+				break;
+			}
+			this.hl.push(HighlightType.None);
+			i += 1;
+		}
+
+		this.highlightMatch(word);
+	}
+
+	protected highlightMatch(word: Option<string>): void {
 		let searchIndex = 0;
-		const matches = [];
 
 		// Find matches for the current search
 		if (word.isSome()) {
 			while (true) {
-				const match = this.find(word.unwrap(), searchIndex);
+				const match = this.find(
+					word.unwrap(),
+					searchIndex,
+					SearchDirection.Forward,
+				);
 				if (match.isNone()) {
 					break;
 				}
 
-				matches.push(match.unwrap());
-				const nextPossible = match.unwrap() + strlen(word.unwrap());
+				const index = match.unwrap();
+				const nextPossible = index + strlen(word.unwrap());
 				if (nextPossible < this.rsize) {
+					let i = index;
+					for (const _ in strChars(word.unwrap())) {
+						this.hl[i] = HighlightType.Match;
+						i += 1;
+					}
+
 					searchIndex = nextPossible;
 				} else {
 					break;
 				}
 			}
 		}
+	}
 
-		let prevIsSeparator = true;
-		let inString: string | boolean = false;
-		let i = 0;
-		for (; i < this.rsize;) {
-			const ch = this.rchars[i];
-			const prevHighlight = (i > 0) ? highlighting[i - 1] : HighlightType.None;
-
-			// Highlight search matches
-			if (word.isSome()) {
-				if (matches.includes(i)) {
-					for (const _ in strChars(word.unwrap())) {
-						i += 1;
-						highlighting.push(HighlightType.Match);
-					}
-
-					continue;
+	protected highlightComment(
+		i: number,
+		syntax: FileType,
+		_ch: string,
+	): Option<number> {
+		// Highlight single-line comments
+		if (syntax.singleLineComment.isSome()) {
+			const commentStart = syntax.singleLineComment.unwrap();
+			if (
+				this.toString().indexOf(commentStart) === this.charIndexToByteIndex(i)
+			) {
+				for (; i < this.rsize; i++) {
+					this.hl.push(HighlightType.SingleLineComment);
 				}
+
+				return Some(i);
 			}
-
-			// Highlight strings
-			if (syntax.flags.strings) {
-				if (inString) {
-					highlighting.push(HighlightType.String);
-
-					// Handle escaped characters in strings
-					if (ch === '\\' && i < this.rsize + 1) {
-						highlighting.push(HighlightType.String);
-						i += 2;
-						continue;
-					}
-
-					if (ch === inString) {
-						inString = false;
-					}
-					i += 1;
-					prevIsSeparator = true;
-					continue;
-				} else if (prevIsSeparator && ch === '"' || ch === "'") {
-					highlighting.push(HighlightType.String);
-					inString = ch;
-					prevIsSeparator = true;
-					i += 1;
-					continue;
-				}
-			}
-
-			// Highlight numbers
-			if (syntax.flags.numbers) {
-				const isNumeric = isAsciiDigit(ch) && (prevIsSeparator ||
-					prevHighlight === HighlightType.Number);
-				const isDecimalNumeric = ch === '.' &&
-					prevHighlight === HighlightType.Number;
-				const isHexNumeric = ch === 'x' &&
-					prevHighlight === HighlightType.Number;
-				if (isNumeric || isDecimalNumeric || isHexNumeric) {
-					highlighting.push(HighlightType.Number);
-				} else {
-					highlighting.push(HighlightType.None);
-				}
-			}
-
-			prevIsSeparator = isSeparator(ch);
-			i += 1;
 		}
 
-		this.hl = highlighting;
+		return None;
+	}
+
+	protected highlightString(
+		i: number,
+		syntax: FileType,
+		ch: string,
+	): Option<number> {
+		// Highlight strings
+		if (syntax.flags.strings && ch === '"' || ch === "'") {
+			while (true) {
+				this.hl.push(HighlightType.String);
+				i += 1;
+				if (i === this.rsize) {
+					break;
+				}
+
+				const nextChar = this.rchars[i];
+				if (nextChar === ch) {
+					break;
+				}
+			}
+			this.hl.push(HighlightType.String);
+			i += 1;
+			return Some(i);
+		}
+
+		return None;
+	}
+
+	protected highlightNumber(
+		i: number,
+		syntax: FileType,
+		ch: string,
+	): Option<number> {
+		// Highlight numbers
+		if (syntax.flags.numbers && isAsciiDigit(ch)) {
+			if (i > 0 && !isSeparator(this.rchars[i - 1])) {
+				return None;
+			}
+
+			while (true) {
+				this.hl.push(HighlightType.Number);
+				i += 1;
+				if (i < this.rsize) {
+					const nextChar = this.rchars[i];
+					if (nextChar !== '.' && nextChar !== 'x' && !isAsciiDigit(nextChar)) {
+						break;
+					}
+				} else {
+					break;
+				}
+			}
+
+			return Some(i);
+		}
+
+		return None;
 	}
 
 	public render(offset: number, len: number): string {