✨ feat(Seq): Add insert, remove, slice, and splice methods.

Author: make-github-pseudonymous-again

src/seq.js

@@ -76,6 +76,52 @@ Seq.prototype.get = function ( index ) {
 
 } ;
 
+Seq.prototype.insert = function ( index , value ) {
+
+	if ( index < 0 || index >= this.len( ) ) throw new Error( `wrong index '${index}'` ) ;
+
+	const [prefix, rest] = this.tree.split( ( m ) => m > index ) ;
+	return new Seq(prefix.push(value).concat(rest)) ;
+
+} ;
+
+Seq.prototype.remove = function ( index ) {
+
+	if ( index < 0 || index >= this.len( ) ) throw new Error( `wrong index '${index}'` ) ;
+
+	const { left , right } = this.tree.splitTree( ( m ) => m > index , size.zero( ) ) ;
+	return new Seq(left.concat(right)) ;
+
+} ;
+
+Seq.prototype.slice = function ( start = 0 , end = this.len( ) ) {
+
+	if ( start < -this.len( ) || start > this.len( ) ) throw new Error( `wrong start '${start}'` ) ;
+	if ( end < -this.len( ) || end > this.len( ) ) throw new Error( `wrong end '${end}'` ) ;
+
+	if ( start < 0 ) start += this.len( ) ;
+	if ( end < 0 ) end += this.len( ) ;
+
+	const [ prefix , rest ] = this.tree.split( ( m ) => m > start ) ;
+	const [ slice , suffix ] = rest.split( ( m ) => m > end - start ) ;
+	return new Seq(slice);
+
+} ;
+
+Seq.prototype.splice = function ( start , deleteCount , ...items ) {
+
+	const length = this.len( ) ;
+
+	if ( start < -length || start >= length ) throw new Error( `wrong start '${start}'` ) ;
+
+	if ( start < 0 ) start += length ;
+
+	const [ prefix , rest ] = this.tree.split( ( m ) => m > start ) ;
+	const [ deleted , suffix ] = rest.split( ( m ) => m > deleteCount ) ;
+	return [ new Seq(prefix.append(items).concat(suffix)) , new Seq(deleted) ] ;
+
+} ;
+
 
 Seq.prototype[Symbol.iterator] = function ( ) {
 	return this.tree[Symbol.iterator]( ) ;

test/src/seq.js

@@ -75,3 +75,172 @@ test('@aureooms/js-fingertree github issue #73', t => {
 		t.deepEqual(list(s), list('ab'+c+'de'));
 	}
 }) ;
+
+test('Seq#slice', t => {
+
+	const s = Seq.from('abcde');
+	t.deepEqual(list('abcde'), list(s.slice(0,5)));
+	t.deepEqual(list('abcd'), list(s.slice(0,4)));
+	t.deepEqual(list('bcde'), list(s.slice(1,5)));
+	t.deepEqual(list('bcd'), list(s.slice(1,4)));
+	t.deepEqual(list('cde'), list(s.slice(2,5)));
+
+}) ;
+
+// Examples from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice
+test('Seq#slice (MDN Return a portion of an existing array)', t => {
+	const fruits = Seq.from(['Banana', 'Orange', 'Lemon', 'Apple', 'Mango']);
+	const citrus = fruits.slice(1, 3);
+
+	t.deepEqual(['Banana', 'Orange', 'Lemon', 'Apple', 'Mango'], list(fruits));
+	t.deepEqual(['Orange', 'Lemon'], list(citrus));
+});
+
+test('Seq#slice (MDN Using slice)', t => {
+
+	const myHonda = { color: 'red', wheels: 4, engine: { cylinders: 4, size: 2.2 } }
+	const myCar = Seq.from([myHonda, 2, 'cherry condition', 'purchased 1997']);
+	const newCar = myCar.slice(0, 2)
+
+	t.deepEqual([myHonda, 2, 'cherry condition', 'purchased 1997'], list(myCar));
+	t.deepEqual([myHonda, 2], list(newCar));
+
+	t.is('red', myCar.get(0).color);
+	t.is('red', newCar.get(0).color);
+
+	myCar.get(0).color = 'purple';
+	t.is('purple', myCar.get(0).color);
+	t.is('purple', newCar.get(0).color);
+
+	newCar.get(0).color = 'green';
+	t.is('green', myCar.get(0).color);
+	t.is('green', newCar.get(0).color);
+
+});
+
+test('Seq#remove', t => {
+
+	const string = 'abcde' ;
+	const s = Seq.from(string);
+	for (const i of range(0, string.length)) {
+		const result = s.remove(i);
+		t.deepEqual(list(string.slice(0,i)+string.slice(i+1)), list(result));
+	}
+
+}) ;
+
+test('Seq#insert', t => {
+
+	const string = 'abcde' ;
+	const s = Seq.from(string);
+
+	for (const i of range(0, string.length)) {
+		const result = s.insert(i, string[i].toUpperCase());
+		t.deepEqual(list(string.slice(0,i)+string[i].toUpperCase()+string.slice(i)), list(result));
+	}
+
+}) ;
+
+test('Seq#splice', t => {
+
+	const string = 'abcde' ;
+	const s = Seq.from(string);
+	for (const i of range(-string.length, string.length)) {
+		const [result, removed] = s.splice(i,1);
+		const _i = i < 0 ? i + string.length : i;
+		t.deepEqual(list(string.slice(0,_i)+string.slice(_i+1)), list(result));
+		t.deepEqual(list(string[_i]), list(removed));
+	}
+
+	for (const i of range(0, string.length)) {
+		const [result, removed] = s.splice(i,1, ...string.slice(0,i+1).toUpperCase());
+		t.deepEqual(list(string.slice(0,i)+string.slice(0,i+1).toUpperCase()+string.slice(i+1)), list(result));
+		t.deepEqual(list(string[i]), list(removed));
+	}
+
+	for (const i of range(0, string.length)) {
+		const [result, removed] = s.splice(i,0, ...string.slice(0,i+1).toUpperCase());
+		t.deepEqual(list(string.slice(0,i)+string.slice(0,i+1).toUpperCase()+string.slice(i)), list(result));
+		t.deepEqual([], list(removed));
+	}
+
+	for (const i of range(0, string.length)) {
+		const [result, removed] = s.splice(i,undefined, ...string.slice(0,i+1).toUpperCase());
+		t.deepEqual(list(string.slice(0,i)+string.slice(0,i+1).toUpperCase()), list(result));
+		t.deepEqual(list(string.slice(i)), list(removed));
+	}
+
+}) ;
+
+// Examples from https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice
+test('Seq#splice (MDN Remove 0 (zero) elements before index 2, and insert "drum")', t => {
+	const myFish = Seq.from(['angel', 'clown', 'mandarin', 'sturgeon']);
+	const [result, removed] = myFish.splice(2, 0, 'drum');
+
+	t.deepEqual(['angel', 'clown', 'mandarin', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown", "drum", "mandarin", "sturgeon"], list(result));
+	t.deepEqual([], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 0 (zero) elements before index 2, and insert "drum" and "guitar")', t => {
+	const myFish = Seq.from(['angel', 'clown', 'mandarin', 'sturgeon']);
+	const [result, removed] = myFish.splice(2, 0, 'drum', 'guitar');
+
+	t.deepEqual(['angel', 'clown', 'mandarin', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown", "drum", "guitar", "mandarin", "sturgeon"], list(result));
+	t.deepEqual([], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 1 element at index 3)', t => {
+	const myFish = Seq.from(['angel', 'clown', 'drum', 'mandarin', 'sturgeon']);
+	const [result, removed] = myFish.splice(3, 1);
+
+	t.deepEqual(['angel', 'clown', 'drum', 'mandarin', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown", "drum", "sturgeon"], list(result));
+	t.deepEqual(["mandarin"], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 1 element at index 2, and insert "trumpet")', t => {
+	const myFish = Seq.from(['angel', 'clown', 'drum', 'sturgeon']);
+	const [result, removed] = myFish.splice(2, 1, 'trumpet');
+
+	t.deepEqual(['angel', 'clown', 'drum', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown", "trumpet", "sturgeon"], list(result));
+	t.deepEqual(["drum"], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 2 elements from index 0, and insert "parrot", "anemone" and "blue")', t => {
+	const myFish = Seq.from(['angel', 'clown', 'trumpet', 'sturgeon']);
+	const [result, removed] = myFish.splice(0, 2, 'parrot', 'anemone', 'blue');
+
+	t.deepEqual(['angel', 'clown', 'trumpet', 'sturgeon'], list(myFish));
+	t.deepEqual(["parrot", "anemone", "blue", "trumpet", "sturgeon"], list(result));
+	t.deepEqual(["angel", "clown"], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 2 elements from index 2)', t => {
+	const myFish = Seq.from(['parrot', 'anemone', 'blue', 'trumpet', 'sturgeon']);
+	const [result, removed] = myFish.splice(2, 2);
+
+	t.deepEqual(['parrot', 'anemone', 'blue', 'trumpet', 'sturgeon'], list(myFish));
+	t.deepEqual(["parrot", "anemone", "sturgeon"], list(result));
+	t.deepEqual(["blue", "trumpet"], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove 1 element from index -2)', t => {
+	const myFish = Seq.from(['angel', 'clown', 'mandarin', 'sturgeon']);
+	const [result, removed] = myFish.splice(-2, 1);
+
+	t.deepEqual(['angel', 'clown', 'mandarin', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown", "sturgeon"], list(result));
+	t.deepEqual(["mandarin"], list(removed));
+}) ;
+
+test('Seq#splice (MDN Remove all elements after index 2 (incl.))', t => {
+	const myFish = Seq.from(['angel', 'clown', 'mandarin', 'sturgeon']);
+	const [result, removed] = myFish.splice(2);
+
+	t.deepEqual(['angel', 'clown', 'mandarin', 'sturgeon'], list(myFish));
+	t.deepEqual(["angel", "clown"], list(result));
+	t.deepEqual(["mandarin", "sturgeon"], list(removed));
+}) ;