From 8851e0f19b69ef46947b81250ad64391c1bfe09d Mon Sep 17 00:00:00 2001
From: mrmlnc <mrmlnc@yandex-team.ru>
Date: Fri, 21 Feb 2020 23:17:55 +0300
Subject: [PATCH] refactor(utils): add leading dot segment removal utility

---
 src/utils/path.spec.ts | 19 +++++++++++++++++++
 src/utils/path.ts      | 15 +++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/src/utils/path.spec.ts b/src/utils/path.spec.ts
index 5c290d2c..d8a588e9 100644
--- a/src/utils/path.spec.ts
+++ b/src/utils/path.spec.ts
@@ -54,4 +54,23 @@ describe('Utils → Path', () => {
 			assert.strictEqual(util.escape('abc@'), 'abc@');
 		});
 	});
+
+	describe('.removeLeadingDotCharacters', () => {
+		it('should return path without changes', () => {
+			assert.strictEqual(util.removeLeadingDotSegment('../a/b'), '../a/b');
+			assert.strictEqual(util.removeLeadingDotSegment('~/a/b'), '~/a/b');
+			assert.strictEqual(util.removeLeadingDotSegment('/a/b'), '/a/b');
+			assert.strictEqual(util.removeLeadingDotSegment('a/b'), 'a/b');
+
+			assert.strictEqual(util.removeLeadingDotSegment('..\\a\\b'), '..\\a\\b');
+			assert.strictEqual(util.removeLeadingDotSegment('~\\a\\b'), '~\\a\\b');
+			assert.strictEqual(util.removeLeadingDotSegment('\\a\\b'), '\\a\\b');
+			assert.strictEqual(util.removeLeadingDotSegment('a\\b'), 'a\\b');
+		});
+
+		it('should return path without leading dit characters', () => {
+			assert.strictEqual(util.removeLeadingDotSegment('./a/b'), 'a/b');
+			assert.strictEqual(util.removeLeadingDotSegment('.\\a\\b'), 'a\\b');
+		});
+	});
 });
diff --git a/src/utils/path.ts b/src/utils/path.ts
index 02e33030..3a6e9951 100644
--- a/src/utils/path.ts
+++ b/src/utils/path.ts
@@ -2,6 +2,7 @@ import * as path from 'path';
 
 import { Pattern } from '../types';
 
+const LEADING_DOT_SEGMENT_CHARACTERS_COUNT = 2; // ./ or .\\
 const UNESCAPED_GLOB_SYMBOLS_RE = /(\\?)([()*?[\]{|}]|^!|[!+@](?=\())/g;
 
 /**
@@ -18,3 +19,17 @@ export function makeAbsolute(cwd: string, filepath: string): string {
 export function escape(pattern: Pattern): Pattern {
 	return pattern.replace(UNESCAPED_GLOB_SYMBOLS_RE, '\\$2');
 }
+
+export function removeLeadingDotSegment(entry: string): string {
+	// We do not use `startsWith` because this is 10x slower than current implementation for some cases.
+	// eslint-disable-next-line @typescript-eslint/prefer-string-starts-ends-with
+	if (entry.charAt(0) === '.') {
+		const secondCharactery = entry.charAt(1);
+
+		if (secondCharactery === '/' || secondCharactery === '\\') {
+			return entry.slice(LEADING_DOT_SEGMENT_CHARACTERS_COUNT);
+		}
+	}
+
+	return entry;
+}