concatenate any number of scripts

classes/script.js

@@ -8,6 +8,7 @@ const isBuffer = require('../functions/is-buffer')
 const encodeASM = require('../functions/encode-asm')
 const decodeASM = require('../functions/decode-asm')
 const Address = require('./address')
+const BufferWriter = require('./buffer-writer')
 
 // These WeakMap caches allow the objects themselves to maintain their immutability
 const SCRIPT_TO_CHUNKS_CACHE = new WeakMap()
@@ -76,6 +77,17 @@ class Script {
     throw new Error('unsupported type')
   }
 
+  static concat (...scripts) {
+    const writer = new BufferWriter()
+
+    for (const script of scripts) {
+      if (!(script instanceof Script)) throw new Error('all arguments need to be scripts')
+      writer.write(script.buffer)
+    }
+
+    return new Script(writer.toBuffer())
+  }
+
   toString () {
     return this.toHex()
   }

test/classes/script.js

@@ -215,6 +215,27 @@ describe('Script', () => {
     })
   })
 
+  describe('concat', () => {
+    it('concatenates scripts', () => {
+      const emptyScript = new Script()
+      const script = new Script([1, 2])
+      const script2 = new Script([4, 5])
+      expect(Array.from(Script.concat().buffer)).to.deep.equal([])
+      expect(Array.from(Script.concat(emptyScript).buffer)).to.deep.equal([])
+      expect(Array.from(Script.concat(script).buffer)).to.deep.equal([1, 2])
+      expect(Array.from(Script.concat(emptyScript, script).buffer)).to.deep.equal([1, 2])
+      expect(Array.from(Script.concat(script, emptyScript).buffer)).to.deep.equal([1, 2])
+      expect(Array.from(Script.concat(script, script2).buffer)).to.deep.equal([1, 2, 4, 5])
+      expect(Array.from(Script.concat(script, script2, script).buffer)).to.deep.equal([1, 2, 4, 5, 1, 2])
+    })
+
+    it('thows if any argument is not a scripts', () => {
+      const script = new Script([1, 2])
+      expect(() => Script.concat('not a script')).to.throw('all arguments need to be scripts')
+      expect(() => Script.concat(script, 'not a script')).to.throw('all arguments need to be scripts')
+    })
+  })
+
   describe('P2PKHLockScript', () => {
     describe('fromAddress', () => {
       it('creates', () => {