Hash cashing.

expreduce/builtin_comparison.go

@@ -450,8 +450,7 @@ func getComparisonDefinitions() (defs []Definition) {
 				}
 			}
 			i -= 1
-			this.Parts = append([]Ex{this.Parts[0]}, this.Parts[i:]...)
-			return this
+			return NewExpression(append([]Ex{this.Parts[0]}, this.Parts[i:]...))
 		},
 		SimpleExamples: []TestInstruction{
 			&SameTest{"3", "Max[1,2,3]"},

expreduce/builtin_sort.go

@@ -17,6 +17,7 @@ func GetSortDefinitions() (defs []Definition) {
 			exp, ok := this.Parts[1].(*Expression)
 			if ok {
 				sortedExp := exp.DeepCopy().(*Expression)
+				sortedExp.evaledHash = 0
 				sortedExp.cachedHash = 0
 				sort.Sort(sortedExp)
 				return sortedExp

expreduce/builtin_system.go

@@ -8,15 +8,12 @@ import "runtime/pprof"
 import "log"
 import "io/ioutil"
 import "github.com/op/go-logging"
-import "hash/fnv"
 import "flag"
 
 var mymemprofile = flag.String("mymemprofile", "", "write memory profile to this file")
 
 func hashEx(e Ex) uint64 {
-	h := fnv.New64a()
-	e.Hash(&h)
-	return h.Sum64()
+	return e.Hash()
 }
 
 func exprToN(es *EvalState, e Ex) Ex {

expreduce/cas.go

@@ -4,8 +4,6 @@
 
 package expreduce
 
-import "hash"
-
 type ToStringFnType (func(*Expression, string) (bool, string))
 
 // A nasty global to keep track of ToString functions. TODO: Fix this.
@@ -19,5 +17,5 @@ type Ex interface {
 	IsEqual(b Ex, cl *CASLogger) string
 	DeepCopy() Ex
 	NeedsEval() bool
-	Hash(h *hash.Hash64)
+	Hash() uint64
 }

expreduce/ex_expression.go

@@ -4,9 +4,10 @@ import "bytes"
 import "math/big"
 import "sort"
 import "fmt"
+import "encoding/binary"
 import "time"
 import "flag"
-import "hash"
+import "hash/fnv"
 
 var printevals = flag.Bool("printevals", false, "")
 var checkhashes = flag.Bool("checkhashes", false, "")
@@ -15,6 +16,7 @@ type Expression struct {
 	Parts []Ex
 	needsEval bool
 	correctlyInstantiated bool
+	evaledHash uint64
 	cachedHash uint64
 }
 
@@ -103,7 +105,7 @@ func (this *Expression) Eval(es *EvalState) Ex {
 	lastExHash := uint64(0)
 	var lastEx Ex = this
 	currExHash := hashEx(this)
-	if currExHash == this.cachedHash {
+	if currExHash == this.evaledHash {
 		return this
 	}
 	var currEx Ex = this
@@ -112,7 +114,7 @@ func (this *Expression) Eval(es *EvalState) Ex {
 		lastExHash = currExHash
 		curr, isExpr := currEx.(*Expression)
 		if *checkhashes {
-			if isExpr && curr.cachedHash != 0 && currExHash != curr.cachedHash {
+			if isExpr && curr.evaledHash != 0 && currExHash != curr.evaledHash {
 				fmt.Printf("invalid cache: %v. Used to be %v\n", curr, lastEx)
 			}
 			lastEx = currEx
@@ -124,7 +126,7 @@ func (this *Expression) Eval(es *EvalState) Ex {
 				return retVal
 			}
 		}
-		if isExpr && currExHash == curr.cachedHash {
+		if isExpr && currExHash == curr.evaledHash {
 			return curr
 		}
 
@@ -184,7 +186,11 @@ func (this *Expression) Eval(es *EvalState) Ex {
 			if es.trace != nil && !es.IsFrozen() {
 				es.trace = NewExpression([]Ex{&Symbol{"List"}})
 			}
+			oldHash := curr.Parts[i].Hash()
 			curr.Parts[i] = curr.Parts[i].Eval(es)
+			if oldHash != curr.Parts[i].Hash() {
+				curr.cachedHash = 0
+			}
 			if es.trace != nil && !es.IsFrozen() {
 				if len(es.trace.Parts) > 2 {
 					// The DeepCopy here doesn't seem to affect anything, but
@@ -279,7 +285,7 @@ func (this *Expression) Eval(es *EvalState) Ex {
 	curr, isExpr := currEx.(*Expression)
 	if isExpr {
 		curr.needsEval = false
-		curr.cachedHash = currExHash
+		curr.evaledHash = currExHash
 	}
 	return currEx
 }
@@ -421,6 +427,7 @@ func (this *Expression) DeepCopy() Ex {
 	}
 	thiscopy.needsEval = this.needsEval
 	thiscopy.correctlyInstantiated = this.correctlyInstantiated
+	thiscopy.evaledHash = this.evaledHash
 	thiscopy.cachedHash = this.cachedHash
 	return thiscopy
 }
@@ -430,6 +437,7 @@ func (this *Expression) ShallowCopy() *Expression {
 	thiscopy.Parts = append([]Ex{}, this.Parts...)
 	thiscopy.needsEval = this.needsEval
 	thiscopy.correctlyInstantiated = this.correctlyInstantiated
+	thiscopy.evaledHash = this.evaledHash
 	thiscopy.cachedHash = this.cachedHash
 	return thiscopy
 }
@@ -455,11 +463,19 @@ func (this *Expression) NeedsEval() bool {
 	return this.needsEval
 }
 
-func (this *Expression) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{72, 5, 244, 86, 5, 210, 69, 30})
+func (this *Expression) Hash() uint64 {
+	if this.cachedHash > 0 {
+		return this.cachedHash
+	}
+	h := fnv.New64a()
+	h.Write([]byte{72, 5, 244, 86, 5, 210, 69, 30})
 	for _, part := range this.Parts {
-		part.Hash(h)
+		b := make([]byte, 8)
+		binary.LittleEndian.PutUint64(b, part.Hash())
+		h.Write(b)
 	}
+	this.cachedHash = h.Sum64()
+	return h.Sum64()
 }
 
 func NewExpression(parts []Ex) *Expression {

expreduce/ex_integer.go

@@ -2,7 +2,7 @@ package expreduce
 
 import "fmt"
 import "math/big"
-import "hash"
+import "hash/fnv"
 
 // Integer numbers represented by big.Int
 type Integer struct {
@@ -54,10 +54,12 @@ func NewInt(i int64) *Integer {
 	return &Integer{big.NewInt(i)}
 }
 
-func (this *Integer) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{242, 99, 84, 113, 102, 46, 118, 94})
+func (this *Integer) Hash() uint64 {
+	h := fnv.New64a()
+	h.Write([]byte{242, 99, 84, 113, 102, 46, 118, 94})
 	bytes, _ := this.Val.MarshalText()
-	(*h).Write(bytes)
+	h.Write(bytes)
+	return h.Sum64()
 }
 
 func (this *Integer) AsBigFloat() *big.Float {

expreduce/ex_rational.go

@@ -2,7 +2,7 @@ package expreduce
 
 import "fmt"
 import "math/big"
-import "hash"
+import "hash/fnv"
 
 type Rational struct {
 	Num *big.Int
@@ -96,12 +96,14 @@ func NewRational(n *big.Int, d *big.Int) *Rational {
 	return &Rational{n, d, true}
 }
 
-func (this *Rational) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{90, 82, 214, 51, 52, 7, 7, 33})
+func (this *Rational) Hash() uint64 {
+	h := fnv.New64a()
+	h.Write([]byte{90, 82, 214, 51, 52, 7, 7, 33})
 	nBytes, _ := this.Num.MarshalText()
-	(*h).Write(nBytes)
+	h.Write(nBytes)
 	dBytes, _ := this.Den.MarshalText()
-	(*h).Write(dBytes)
+	h.Write(dBytes)
+	return h.Sum64()
 }
 
 func (this *Rational) AsBigFloat() *big.Float {

expreduce/ex_real.go

@@ -3,7 +3,7 @@ package expreduce
 import "fmt"
 import "math/big"
 import "bytes"
-import "hash"
+import "hash/fnv"
 
 // Floating point numbers represented by big.Float
 type Flt struct {
@@ -68,10 +68,12 @@ func (this *Flt) NeedsEval() bool {
 	return false
 }
 
-func (this *Flt) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{195, 244, 76, 249, 227, 115, 88, 251})
+func (this *Flt) Hash() uint64 {
+	h := fnv.New64a()
+	h.Write([]byte{195, 244, 76, 249, 227, 115, 88, 251})
 	bytes, _ := this.Val.MarshalText()
-	(*h).Write(bytes)
+	h.Write(bytes)
+	return h.Sum64()
 }
 
 func (this *Flt) AddI(i *Integer) {

expreduce/ex_string.go

@@ -1,7 +1,7 @@
 package expreduce
 
 import "fmt"
-import "hash"
+import "hash/fnv"
 
 type String struct {
 	Val string
@@ -42,7 +42,9 @@ func (this *String) NeedsEval() bool {
 	return false
 }
 
-func (this *String) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{102, 206, 57, 172, 207, 100, 198, 133})
-	(*h).Write([]byte(this.Val))
+func (this *String) Hash() uint64 {
+	h := fnv.New64a()
+	h.Write([]byte{102, 206, 57, 172, 207, 100, 198, 133})
+	h.Write([]byte(this.Val))
+	return h.Sum64()
 }

expreduce/ex_symbol.go

@@ -2,7 +2,7 @@ package expreduce
 
 import "fmt"
 import "sort"
-import "hash"
+import "hash/fnv"
 
 // Symbols are defined by a string-based name
 type Symbol struct {
@@ -229,9 +229,11 @@ func (this *Symbol) NeedsEval() bool {
 	return false
 }
 
-func (this *Symbol) Hash(h *hash.Hash64) {
-	(*h).Write([]byte{107, 10, 247, 23, 33, 221, 163, 156})
-	(*h).Write([]byte(this.Name))
+func (this *Symbol) Hash() uint64 {
+	h := fnv.New64a()
+	h.Write([]byte{107, 10, 247, 23, 33, 221, 163, 156})
+	h.Write([]byte(this.Name))
+	return h.Sum64()
 }
 
 func ContainsSymbol(e Ex, name string) bool {

expreduce/replace.go

@@ -52,6 +52,7 @@ func ReplacePDInternal(e Ex, pm *PDManager) Ex {
 	}
 	asExpr, isExpr := e.(*Expression)
 	if isExpr {
+		asExpr.evaledHash = 0
 		asExpr.cachedHash = 0
 		for i := range asExpr.Parts {
 			asExpr.Parts[i] = ReplacePDInternal(asExpr.Parts[i], pm)