feat: allow strip filter with specified char, closes #390

src/builtin/filters/string.ts

@@ -3,7 +3,7 @@
  *
  * * prefer stringify() to String() since `undefined`, `null` should eval ''
  */
-import { stringify } from '../../util/underscore'
+import { escapeRegExp, stringify } from '../../util/underscore'
 import { assert } from '../../util/assert'
 
 export function append (v: string, arg: string) {
@@ -16,7 +16,11 @@ export function prepend (v: string, arg: string) {
   return stringify(arg) + stringify(v)
 }
 
-export function lstrip (v: string) {
+export function lstrip (v: string, chars?: string) {
+  if (chars) {
+    chars = escapeRegExp(stringify(chars))
+    return stringify(v).replace(new RegExp(`^[${chars}]+`, 'g'), '')
+  }
   return stringify(v).replace(/^\s+/, '')
 }
 
@@ -36,7 +40,11 @@ export function removeFirst (v: string, l: string) {
   return stringify(v).replace(String(l), '')
 }
 
-export function rstrip (str: string) {
+export function rstrip (str: string, chars?: string) {
+  if (chars) {
+    chars = escapeRegExp(stringify(chars))
+    return stringify(str).replace(new RegExp(`[${chars}]+$`, 'g'), '')
+  }
   return stringify(str).replace(/\s+$/, '')
 }
 
@@ -48,7 +56,13 @@ export function split (v: string, arg: string) {
   return arr
 }
 
-export function strip (v: string) {
+export function strip (v: string, chars?: string) {
+  if (chars) {
+    chars = escapeRegExp(stringify(chars))
+    return stringify(v)
+      .replace(new RegExp(`^[${chars}]+`, 'g'), '')
+      .replace(new RegExp(`[${chars}]+$`, 'g'), '')
+  }
   return stringify(v).trim()
 }
 

src/util/underscore.ts

@@ -156,3 +156,7 @@ export function caseInsensitiveCompare (a: any, b: any) {
 export function argumentsToValue<F extends (...args: any) => any> (fn: F) {
   return (...args: Parameters<F>) => fn(...args.map(toValue))
 }
+
+export function escapeRegExp (text: string) {
+  return text.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&')
+}

test/integration/builtin/filters/string.ts

@@ -86,9 +86,10 @@ describe('filters/string', function () {
     it('should support upcase', () => test('{{ "Parker Moore" | upcase }}', 'PARKER MOORE'))
     it('should return empty for undefined', () => test('{{ foo | upcase }}', ''))
   })
-  it('should support lstrip', function () {
+  it('should support lstrip', async () => {
     const src = '{{ "          So much room for activities!          " | lstrip }}'
-    return test(src, 'So much room for activities!          ')
+    await test(src, 'So much room for activities!          ')
+    await test('{{ "foobarcoo" | lstrip: "fo" }}', 'barcoo')
   })
   it('should support prepend', function () {
     return test('{% assign url = "liquidmarkup.com" %}' +
@@ -115,9 +116,10 @@ describe('filters/string', function () {
             '{{ my_string | replace_first: "my", "your" }}',
     '\nTake your protein pills and put my helmet on')
   })
-  it('should support rstrip', function () {
+  it('should support rstrip', async () => {
-    return test('{{ "          So much room for activities!          " | rstrip }}',
+    await test('{{ "          So much room for activities!          " | rstrip }}',
       '          So much room for activities!')
+    await test('{{ "foobarcoo" | rstrip: "fco" }}', 'foobar')
   })
   it('should support split', function () {
     return test('{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
@@ -126,9 +128,12 @@ describe('filters/string', function () {
             '{% endfor %}',
     'John Paul George Ringo ')
   })
-  it('should support strip', function () {
+  it('should support strip', async () => {
-    return test('{{ "          So much room for activities!          " | strip }}',
+    await test('{{ "          So much room for activities!          " | strip }}',
       'So much room for activities!')
+    await test('{{ "          So much room for activities!          " | strip: "So " }}',
+      'much room for activities!')
+    await test('{{ "&[]{}" | strip: "&[]{}" }}', '')
   })
   it('should support strip_newlines', function () {
     return test('{% capture string_with_newlines %}\n' +