feat(2020-day-08): execute commands from the language

Author: developher-net

2020/day-08/runProgram.js

@@ -19,12 +19,51 @@ const program = [
   'acc +6'
 ]
 
+let accumulator = 0
+let position = 1
+
+/**
+ * API of commands this language supports
+ */
+const api = {
+  nop: (a, b) => {
+    console.debug(`doing a nop ${b}`)
+    return a + 1
+  },
+  acc: (a, b) => {
+    console.debug(`adding ${b} to accumulator`)
+    accumulator += api[b.substr(0, 1)](
+      0,
+      Number(b.substr((1)))
+    )
+    return a + 1
+  },
+  jmp: (a, b) => {
+    console.debug(`jumping from ${a} ${b} `)
+    return a + api[b.substr(0, 1)](
+      0,
+      Number(b.substr((1)))
+    )
+  },
+  '+': (x, y) => x + y,
+  '-': (x, y) => x - y
+}
+
 const parseCommand = (inst) => {
   console.debug('Parsing ', inst)
   const [cmd, arg] = inst.split(' ')
   return { cmd, arg }
 }
 
+const execInstruction = (inst, instKey = 0, evKey = 0) => {
+  const { cmd, arg } = parseCommand(inst)
+  // Run the command
+  // Support jumping by passing back next
+  position = api[cmd](instKey, arg)
+  logEvent({ instKey, evKey })
+  return position
+}
+
 const formatLogRow = (command, idx, program) => {
   let countStr
   if (!log[idx]) {
@@ -73,7 +112,9 @@ const logEvent = ({ instKey, evKey }) => {
 
 module.exports = {
   run: console.log('run'),
-  executeStep: console.log('executeStep'),
+  getAccumulator: () => accumulator,
+  getPosition: () => position,
+  execInstruction,
   parseCommand,
   logEvent,
   displayLog

2020/day-08/runProgram.test.js

@@ -1,6 +1,6 @@
 /* eslint-env mocha */
 const { expect } = require('chai')
-const { run, parseCommand, logEvent, displayLog } = require('./runProgram')
+const { run, getPosition, getAccumulator, execInstruction, parseCommand, logEvent, displayLog } = require('./runProgram')
 
 const exampleLog = `
 nop +0  | 1
@@ -21,28 +21,36 @@ describe('--- Day 8: Handheld Halting ---', () => {
         expect(false).to.equal(true)
       })
     })
-    // xdescribe('execInstruction()', () => {
-    //   it('executes a specified command', () => {
-    //     execInstruction()
-    //     expect(false).to.equal(true)
-    //   })
-    //   it('steps to the next sequential command', () => {
-    //     logEvent()
-    //     expect(false).to.equal(true)
-    //   })
-    //   it('can execute a `nop` command which does nothing', () => {
-    //     execInstruction('nop')
-    //     expect(false).to.equal(true)
-    //   })
-    //   it('can execute a `acc` command which increments the accumulator', () => {
-    //     execInstruction('acc')
-    //     expect(false).to.equal(true)
-    //   })
-    //   it('can execute a `jmp` command which jumps to a different command in the instruction set', () => {
-    //     execInstruction('jmp')
-    //     expect(false).to.equal(true)
-    //   })
-    // })
+    describe('execInstruction()', () => {
+      it('executes a specified command', () => {
+        expect(getPosition()).to.equal(1)
+        expect(execInstruction('acc +3', 300, 600)).to.equal(301)
+        expect(getAccumulator()).to.equal(3)
+        expect(getPosition()).to.equal(301)
+      })
+      xit('steps to the next sequential command', () => {
+      //     logEvent()
+      //     expect(false).to.equal(true)
+      })
+      it('can execute a `nop` command which does nothing', () => {
+        const acc = getAccumulator()
+        expect(execInstruction('nop +3', 999, 600)).to.equal(1000)
+        expect(getPosition()).to.equal(1000)
+        expect(getAccumulator()).to.equal(acc)
+      })
+      it('can execute a `acc` command which increments the accumulator', () => {
+        const acc = getAccumulator()
+        expect(execInstruction('acc +100', 1234, 600)).to.equal(1235)
+        expect(getPosition()).to.equal(1235)
+        expect(getAccumulator()).to.equal(acc + 100)
+      })
+      it('can execute a `jmp` command which jumps to a different command in the instruction set', () => {
+        const acc = getAccumulator()
+        expect(execInstruction('jmp -23', 400, 600)).to.equal(377)
+        expect(getPosition()).to.equal(377)
+        expect(getAccumulator()).to.equal(acc)
+      })
+    })
     describe('parseCommand()', () => {
       it('parses an instruction string into a structured command object', () => {
         const instructions = [