bunch of changes

internal/ast/ast.go

@@ -38,13 +38,13 @@ func (p *Program) TokenLiteral() string {
 }
 
 func (p *Program) String() string {
-	var out bytes.Buffer
+	var s strings.Builder
 
-	for _, s := range p.Statements {
-		out.WriteString(s.String())
+	for _, stmt := range p.Statements {
+		s.WriteString(fmt.Sprintf("%s\n", stmt.String()))
 	}
 
-	return out.String()
+	return s.String()
 }
 
 type ReturnStatement struct {

internal/object/state.go

@@ -6,7 +6,7 @@ import (
 )
 
 var (
-	Args         []string  = os.Args
+	Args         []string  = os.Args[1:] // Skip the monkey binary itself
 	Stdin        io.Reader = os.Stdin
 	Stdout       io.Writer = os.Stdout
 	Stderr       io.Writer = os.Stderr

internal/vm/cache.go

@@ -1,270 +0,0 @@
-package vm
-
-import (
-	"container/list"
-	"fmt"
-	"sync"
-)
-
-type cachedFrame struct {
-	Key       uint   // pointer to key
-	Value     *Frame // pointer to value
-	Frequency uint   // frequency of access
-}
-
-type frequencyNode struct {
-	count      uint          // frequency count - never decreases
-	valuesList *list.List    // valuesList contains pointer to the head of values linked list
-	inner      *list.Element // actual content of the next element
-}
-
-// creates a new frequency list node with the given count
-func newFrequencyNode(count uint) *frequencyNode {
-	return &frequencyNode{
-		count:      count,
-		valuesList: list.New(),
-		inner:      nil,
-	}
-}
-
-type keyRefNode struct {
-	inner          *list.Element // contains the actual value wrapped by a list element
-	parentFreqNode *list.Element // contains reference to the frequency node element
-	keyRef         uint          // contains pointer to the key
-	valueRef       *Frame        // value
-}
-
-// creates a new KeyRef node which is used to represent the value in linked list
-func newKeyRefNode(keyRef uint, valueRef *Frame, parent *list.Element) *keyRefNode {
-	return &keyRefNode{
-		inner:          nil,
-		parentFreqNode: parent,
-		keyRef:         keyRef,
-		valueRef:       valueRef,
-	}
-}
-
-// FrameCache implements all the methods and data-structures required for a LFU cache for caching frames.
-type FrameCache struct {
-	rwLock      sync.RWMutex         // rwLock is a read-write mutex which provides concurrent reads but exclusive writes
-	lookupTable map[uint]*keyRefNode // a hash table of <KeyType, *ValueType> for quick reference of values based on keys
-	frequencies *list.List           // internal linked list that contains frequency mapping
-	maxSize     uint                 // maxSize represents the maximum number of elements that can be in the cache before eviction
-}
-
-// MaxSize returns the maximum size of the cache at that point in time
-func (lfu *FrameCache) MaxSize() uint {
-	lfu.rwLock.RLock()
-	defer lfu.rwLock.RUnlock()
-
-	return lfu.maxSize
-}
-
-// CurrentSize returns the number of elements in that cache
-func (lfu *FrameCache) CurrentSize() uint {
-	lfu.rwLock.RLock()
-	defer lfu.rwLock.RUnlock()
-
-	return uint(len(lfu.lookupTable))
-}
-
-// IsFull checks if the LFU cache is full
-func (lfu *FrameCache) IsFull() bool {
-	lfu.rwLock.RLock()
-	defer lfu.rwLock.RUnlock()
-
-	return uint(len(lfu.lookupTable)) == lfu.maxSize
-}
-
-// SetMaxSize updates the max size of the LFU cache
-func (lfu *FrameCache) SetMaxSize(size uint) {
-	lfu.rwLock.Lock()
-	defer lfu.rwLock.Unlock()
-
-	lfu.maxSize = size
-}
-
-// evict the least recently used element from the cache, this function is unsafe to be called externally
-// because it doesn't provide locking mechanism.
-func (lfu *FrameCache) unsafeEvict() error {
-	// WARNING: This function assumes that a write lock has been held by the caller already
-
-	// get the head node of the list
-	headFreq := lfu.frequencies.Front()
-	if headFreq == nil {
-		// list is empty, this is a very unusual condition
-		return fmt.Errorf("internal error: failed to evict, empty frequency list")
-	}
-
-	headFreqInner := (headFreq.Value).(*frequencyNode)
-
-	if headFreqInner.valuesList.Len() == 0 {
-		// again this is a very unusual condition
-		return fmt.Errorf("internal error: failed to evict, empty values list")
-	}
-
-	headValuesList := headFreqInner.valuesList
-	// pop the head of this this values list
-	headValueNode := headValuesList.Front()
-	removeResult := headValuesList.Remove(headValueNode).(*keyRefNode)
-
-	// update the values list
-	headFreqInner.valuesList = headValuesList
-
-	if headFreqInner.valuesList.Len() == 0 && headFreqInner.count > 1 {
-		// this node can be removed from the frequency list
-		freqList := lfu.frequencies
-		freqList.Remove(headFreq)
-		lfu.frequencies = freqList
-	}
-
-	// remove the key from lookup table
-	key := removeResult.keyRef
-	delete(lfu.lookupTable, key)
-	return nil
-}
-
-// Put method inserts a `<KeyType, ValueType>` to the LFU cache and updates internal
-// data structures to keep track of access frequencies, if the cache is full, it evicts the
-// least frequently used value from the cache.
-func (lfu *FrameCache) Put(key uint, value *Frame) error {
-	// get write lock
-	lfu.rwLock.Lock()
-	defer lfu.rwLock.Unlock()
-
-	if _, ok := lfu.lookupTable[key]; ok {
-		// update the cache value
-		lfu.lookupTable[key].valueRef = value
-		return nil
-	}
-
-	if lfu.maxSize == uint(len(lfu.lookupTable)) {
-		lfu.unsafeEvict()
-	}
-
-	valueNode := newKeyRefNode(key, value, nil)
-
-	head := lfu.frequencies.Front()
-	if head == nil {
-		// fresh linked list
-		freqNode := newFrequencyNode(1)
-		head = lfu.frequencies.PushFront(freqNode)
-		freqNode.inner = head
-
-	} else {
-		node := head.Value.(*frequencyNode)
-		if node.count != 1 {
-			freqNode := newFrequencyNode(1)
-			head = lfu.frequencies.PushFront(freqNode)
-			freqNode.inner = head
-		}
-	}
-
-	valueNode.parentFreqNode = head
-	node := head.Value.(*frequencyNode)
-	head = node.valuesList.PushBack(valueNode)
-	valueNode.inner = head
-
-	lfu.lookupTable[key] = valueNode
-	return nil
-}
-
-// Evict can be called to manually perform eviction
-func (lfu *FrameCache) Evict() error {
-	lfu.rwLock.Lock()
-	defer lfu.rwLock.Unlock()
-
-	return lfu.unsafeEvict()
-}
-
-func (lfu *FrameCache) unsafeUpdateFrequency(valueNode *keyRefNode) {
-	parentFreqNode := valueNode.parentFreqNode
-	currentNode := parentFreqNode.Value.(*frequencyNode)
-	nextParentFreqNode := parentFreqNode.Next()
-
-	var newParent *list.Element = nil
-
-	if nextParentFreqNode == nil {
-		// this is the last node
-		// create a new node with frequency + 1
-		newFreqNode := newFrequencyNode(currentNode.count + 1)
-		lfu.frequencies.PushBack(newFreqNode)
-		newParent = parentFreqNode.Next()
-
-	} else {
-		nextNode := nextParentFreqNode.Value.(*frequencyNode)
-		if nextNode.count == (currentNode.count + 1) {
-			newParent = nextParentFreqNode
-		} else {
-			// insert a node in between
-			newFreqNode := newFrequencyNode(currentNode.count + 1)
-
-			lfu.frequencies.InsertAfter(newFreqNode, parentFreqNode)
-			newParent = parentFreqNode.Next()
-		}
-	}
-
-	// remove from the existing list
-	currentNode.valuesList.Remove(valueNode.inner)
-
-	newParentNode := newParent.Value.(*frequencyNode)
-	valueNode.parentFreqNode = newParent
-	newValueNode := newParentNode.valuesList.PushBack(valueNode)
-	valueNode.inner = newValueNode
-
-	// check if the current node is empty
-	if currentNode.valuesList.Len() == 0 {
-		// remove the current node
-		lfu.frequencies.Remove(parentFreqNode)
-	}
-}
-
-// Get can be called to obtain the value for given key
-func (lfu *FrameCache) Get(key uint) (*Frame, bool) {
-	lfu.rwLock.Lock()
-	defer lfu.rwLock.Unlock()
-
-	// check if data is in the map
-	valueNode, found := lfu.lookupTable[key]
-	if !found {
-		return nil, false
-	}
-
-	lfu.unsafeUpdateFrequency(valueNode)
-
-	return valueNode.valueRef, true
-}
-
-// Delete removes the specified entry from LFU cache
-func (lfu *FrameCache) Delete(key uint) error {
-	lfu.rwLock.Lock()
-	defer lfu.rwLock.Unlock()
-
-	// check if the key is in the map
-	valueNode, found := lfu.lookupTable[key]
-	if !found {
-		return fmt.Errorf("key %v not found", key)
-	}
-
-	parentFreqNode := valueNode.parentFreqNode
-
-	currentNode := (parentFreqNode.Value).(*frequencyNode)
-	currentNode.valuesList.Remove(valueNode.inner)
-
-	if currentNode.valuesList.Len() == 0 {
-		lfu.frequencies.Remove(parentFreqNode)
-	}
-
-	delete(lfu.lookupTable, key)
-	return nil
-}
-
-// NewFrameCache ...
-func NewFrameCache(maxSize uint) *FrameCache {
-	return &FrameCache{
-		rwLock:      sync.RWMutex{},
-		lookupTable: make(map[uint]*keyRefNode),
-		maxSize:     maxSize,
-		frequencies: list.New(),
-	}
-}

internal/vm/frame.go

@@ -3,11 +3,8 @@ package vm
 import (
 	"monkey/internal/code"
 	"monkey/internal/object"
-	"unsafe"
 )
 
-var cache = NewFrameCache(32)
-
 type Frame struct {
 	cl          *object.Closure
 	ip          int
@@ -15,21 +12,11 @@ type Frame struct {
 }
 
 func NewFrame(cl *object.Closure, basePointer int) *Frame {
-	key := uint(uintptr(unsafe.Pointer(cl))) + uint(basePointer)
-	if frame, ok := cache.Get(key); ok {
-		frame.Reset()
-		return frame
-	}
-
-	frame := &Frame{
+	return &Frame{
 		cl:          cl,
 		ip:          -1,
 		basePointer: basePointer,
 	}
-
-	cache.Put(key, frame)
-
-	return frame
 }
 
 // NextOp ...

internal/vm/vm.go

@@ -13,6 +13,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 	"unicode"
 )
 
@@ -201,22 +202,16 @@ func (vm *VM) LastPoppedStackElem() object.Object {
 }
 
 func (vm *VM) Run() error {
+	var n int
 	var ip int
 	var ins code.Instructions
 	var op code.Opcode
 
 	if vm.Debug {
-		log.Printf(
-			"%-25s %-20s\n",
-			fmt.Sprintf(
-				"%04d %s", ip,
-				strings.Split(ins[ip:].String(), "\n")[0][4:],
-			),
-			fmt.Sprintf(
-				"[ip=%02d fp=%02d, sp=%02d]",
-				ip, vm.fp-1, vm.sp,
-			),
-		)
+		start := time.Now()
+		defer func() {
+			log.Printf("%d instructions executed in %s", n, time.Now().Sub(start))
+		}()
 	}
 
 	for vm.frame.ip < len(vm.frame.Instructions())-1 {
@@ -487,6 +482,7 @@ func (vm *VM) Run() error {
 		}
 
 		if vm.Debug {
+			n++
 			log.Printf(
 				"%-25s [ip=%02d fp=%02d, sp=%02d]",
 				"", ip, vm.fp-1, vm.sp,