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Copy pathvars.go
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433 lines (405 lo
8000
c) · 11.3 KB
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package js
import (
"bytes"
"sort"
"github.com/tdewolff/parse/v2/js"
)
type renamer struct {
identStart []byte
identContinue []byte
reserved map[string]struct{}
rename bool
}
func newRenamer(rename, useCharFreq bool) *renamer {
reserved := make(map[string]struct{}, len(js.Keywords))
for name := range js.Keywords {
reserved[name] = struct{}{}
}
identStart := []byte("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$")
identContinue := []byte("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_$0123456789")
if useCharFreq {
// sorted based on character frequency of a collection of JS samples (incl. the var names!)
identStart = []byte("etnsoiarclduhmfpgvbjy_wOxCEkASMFTzDNLRPHIBV$WUKqYGXQZJ")
identContinue = []byte("etnsoiarcldu14023hm8f6pg57v9bjy_wOxCEkASMFTzDNLRPHIBV$WUKqYGXQZJ")
}
return &renamer{
identStart: identStart,
identContinue: identContinue,
reserved: reserved,
rename: rename,
}
}
func (r *renamer) renameScope(scope js.Scope) {
if !r.rename {
return
}
i := 0
sort.Sort(js.VarsByUses(scope.Declared))
for _, v := range scope.Declared {
v.Data = r.getName(v.Data, i)
i++
for r.isReserved(v.Data, scope.Undeclared) {
v.Data = r.getName(v.Data, i)
i++
}
}
}
func (r *renamer) isReserved(name []byte, undeclared js.VarArray) bool {
if 1 < len(name) { // there are no keywords or known globa
8000
ls that are one character long
if _, ok := r.reserved[string(name)]; ok {
return true
}
}
for _, v := range undeclared {
for v.Link != nil {
v = v.Link
}
if bytes.Equal(v.Data, name) {
return true
}
}
return false
}
func (r *renamer) getIndex(name []byte) int {
index := 0
NameLoop:
for i, b := range name {
chars := r.identContinue
if i == 0 {
chars = r.identStart
} else {
index *= len(r.identContinue)
}
for j, c := range chars {
if b == c {
index += j
continue NameLoop
}
}
return -1
}
for n := 0; n < len(name)-1; n++ {
offset := len(r.identStart)
for i := 0; i < n; i++ {
offset *= len(r.identContinue)
}
index += offset
}
return index
}
func (r *renamer) getName(name []byte, index int) []byte {
// Generate new names for variables where the last character is (a-zA-Z$_) and others are (a-zA-Z).
// Thus we can have 54 one-character names and 52*54=2808 two-character names for every branch leaf.
// That is sufficient for virtually all input.
if index < len(r.identStart) {
name[0] = r.identStart[index]
return name[:1]
}
index -= len(r.identStart)
n := 2
for {
offset := len(r.identStart)
for i := 0; i < n-1; i++ {
offset *= len(r.identContinue)
}
if index < offset {
break
}
index -= offset
n++
}
if cap(name) < n {
name = make([]byte, n)
} else {
name = name[:n]
}
for j := n - 1; 0 < j; j-- {
name[j] = r.identContinue[index%len(r.identContinue)]
index /= len(r.identContinue)
}
name[0] = r.identStart[index]
return name
}
////////////////////////////////////////////////////////////////
func hasDefines(v *js.VarDecl) bool {
for _, item := range v.List {
if item.Default != nil {
return true
}
}
return false
}
func bindingVars(ibinding js.IBinding) (vs []*js.Var) {
switch binding := ibinding.(type) {
case *js.Var:
vs = append(vs, binding)
case *js.BindingArray:
for _, item := range binding.List {
if item.Binding != nil {
vs = append(vs, bindingVars(item.Binding)...)
}
}
if binding.Rest != nil {
vs = append(vs, bindingVars(binding.Rest)...)
}
case *js.BindingObject:
for _, item := range binding.List {
if item.Value.Binding != nil {
vs = append(vs, bindingVars(item.Value.Binding)...)
}
}
if binding.Rest != nil {
vs = append(vs, binding.Rest)
}
}
return
}
func addDefinition(decl *js.VarDecl, binding js.IBinding, value js.IExpr, forward bool) bool {
// see if not already defined in variable declaration list
// if forward is set, binding=value comes before decl, otherwise the reverse holds true
if vbind, ok := binding.(*js.Var); ok {
for i := 0; i < len(decl.List); i++ {
idx := i
if forward {
// reverse lookup order in destinations
idx = len(decl.List) - i - 1
}
item := decl.List[idx]
if v, ok := item.Binding.(*js.Var); ok && v == vbind {
if decl.List[idx].Default != nil {
return false
}
decl.List[idx].Default = value
decl.List = append(decl.List, decl.List[idx])
decl.List = append(decl.List[:idx], decl.List[idx+1:]...)
return true
}
}
return false
}
return false
//vars := bindingRefs(binding)
//if len(vars) == 0 {
// return false
//}
//locs := make([]int, len(vars))
//for i, vdef := range vars {
// locs[i] = -1
// for loc, item := range decl.List {
// if v, ok := item.Binding.(*js.Var); ok && v == vdef {
// locs[i] = loc
// break
// }
// }
// if locs[i] == -1 {
// return false // cannot (probably) happen if we hoist variables
// }
//}
//sort.Ints(locs)
//if locs[0] != 0 {
// decl.List[0], decl.List[locs[0]] = decl.List[locs[0]], decl.List[0]
//}
//decl.List[0].Binding = binding
//decl.List[0].Default = value
//for i := len(locs) - 1; 1 <= i; i-- {
// if locs[i] != locs[i-1] { // ignore duplicates, otherwise remove items from hoisted var declaration
// decl.List = append(decl.List[:locs[i]], decl.List[locs[i]+1:]...)
// }
//}
//return true
}
func mergeVarDecls(dst, src *js.VarDecl) bool {
// this is the second VarDecl, so we are hoisting var declarations, which means the forInit variables are already in 'left'
merge := true
for j := 0; j < len(src.List); j++ {
if src.List[j].Default != nil {
if addDefinition(dst, src.List[j].Binding, src.List[j].Default, false) {
src.List = append(src.List[:j], src.List[j+1:]...)
j--
} else {
merge = false
}
} else {
src.List = append(src.List[:j], src.List[j+1:]...)
j--
}
}
return merge
}
func mergeVarDeclExprStmt(decl *js.VarDecl, exprStmt *js.ExprStmt, swapped bool) bool {
if src, ok := exprStmt.Value.(*js.VarDecl); ok {
// this happens when a variable declarations is converted to an expression
return mergeVarDecls(decl, src)
} else if commaExpr, ok := exprStmt.Value.(*js.CommaExpr); ok {
n := 0
for i := 0; i < len(commaExpr.List); i++ {
item := commaExpr.List[i]
if swapped {
item = commaExpr.List[len(commaExpr.List)-i-1]
}
if binaryExpr, ok := item.(*js.BinaryExpr); ok && binaryExpr.Op == js.EqToken {
if v, ok := binaryExpr.X.(*js.Var); ok && v.Decl == js.VariableDecl {
if addDefinition(decl, v, binaryExpr.Y, swapped) {
n++
continue
}
}
}
break
}
merge := n == len(commaExpr.List)
if !swapped {
commaExpr.List = commaExpr.List[n:]
} else {
commaExpr.List = commaExpr.List[:len(commaExpr.List)-n]
}
return merge
} else if binaryExpr, ok := exprStmt.Value.(*js.BinaryExpr); ok && binaryExpr.Op == js.EqToken {
if v, ok := binaryExpr.X.(*js.Var); ok && v.Decl == js.VariableDecl {
if addDefinition(decl, v, binaryExpr.Y, swapped) {
return true
}
}
}
return false
}
func (m *jsMinifier) countHoistLength(ibinding js.IBinding) int {
if !m.o.KeepVarNames {
return len(bindingVars(ibinding)) * 2 // assume that var name will be of length one, +1 for the comma
}
n := 0
for _, v := range bindingVars(ibinding) {
n += len(v.Data) + 1 // +1 for the comma
}
return n
}
func (m *jsMinifier) hoistVars(body *js.BlockStmt) {
// Hoist all variable declarations in the current module/function scope to the top.
// If the first statement is a var declaration, expand it. Otherwise prepend a new var declaration.
// Except for the first var declaration, all others are converted to expressions. This is possible because an ArrayBindingPattern and ObjectBindingPattern can be converted to an ArrayLiteral or ObjectLiteral respectively, as they are supersets of the BindingPatterns.
if 1 < len(body.Scope.VarDecls) {
// Select which variable declarations will be hoisted (convert to expression) and which not
best := 0
score := make([]int, len(body.Scope.VarDecls)) // savings if hoisted
hoist := make([]bool, len(body.Scope.VarDecls))
for i, varDecl := range body.Scope.VarDecls {
hoist[i] = true
score[i] = 4 // "var "
if !varDecl.InForInOf {
n := 0
nArrays := 0
nObjects := 0
hasDefinitions := false
for j, item := range varDecl.List {
if item.Default != nil {
if _, ok := item.Binding.(*js.BindingObject); ok {
if j != 0 && nArrays == 0 && nObjects == 0 {
varDecl.List[0], varDecl.List[j] = varDecl.List[j], varDecl.List[0]
}
nObjects++
} else if _, ok := item.Binding.(*js.BindingArray); ok {
if j != 0 && nArrays == 0 && nObjects == 0 {
varDecl.List[0], varDecl.List[j] = varDecl.List[j], varDecl.List[0]
}
nArrays++
}
score[i] -= m.countHoistLength(item.Binding) // var names and commas
hasDefinitions = true
n++
}
}
if !hasDefinitions {
score[i] = 5 - 1 // 1 for a comma
if varDecl.InFor {
score[i]-- // semicolon can be reused
}
}
if nObjects != 0 && !varDecl.InFor && nObjects == n {
score[i] -= 2 // required parenthesis around braces
}
if nArrays != 0 || nObjects != 0 {
score[i]-- // space after var disappears
}
if score[i] < score[best] || body.Scope.VarDecls[best].InForInOf {
// select var decl with the least savings if hoisted
best = i
}
if score[i] < 0 {
hoist[i] = false
}
}
}
if body.Scope.VarDecls[best].InForInOf {
// no savings possible
return
}
decl := body.Scope.VarDecls[best]
hoist[best] = false
// get original declarations
orig := []*js.Var{}
for _, item := range decl.List {
orig = append(orig, bindingVars(item.Binding)...)
}
// hoist other variable declarations in this function scope but don't initialize yet
j := 0
for i, varDecl := range body.Scope.VarDecls {
if hoist[i] {
varDecl.TokenType = js.ErrorToken
for _, item := range varDecl.List {
refs := bindingVars(item.Binding)
bindingElements := make([]js.BindingElement, 0, len(refs))
DeclaredLoop:
for _, ref := range refs {
for _, v := range orig {
if ref == v {
continue DeclaredLoop
}
}
bindingElements = append(bindingElements, js.BindingElement{Binding: ref, Default: nil})
orig = append(orig, ref)
s := decl.Scope
for s != nil && s != s.Func {
s.AddUndeclared(ref)
s = s.Parent
}
}
if i < best {
// prepend
decl.List = append(decl.List[:j], append(bindingElements, decl.List[j:]...)...)
j += len(bindingElements)
} else {
// append
decl.List = append(decl.List, bindingElements...)
}
}
}
}
// rearrange to put array/object first
var prevRefs []*js.Var
BeginArrayObject:
for i, item := range decl.List {
refs := bindingVars(item.Binding)
if _, ok := item.Binding.(*js.Var); !ok {
if i != 0 {
interferes := false
InterferenceLoop:
for _, ref := range refs {
for _, v := range prevRefs {
if ref == v {
interferes = true
break InterferenceLoop
}
}
}
if !interferes {
decl.List[0], decl.List[i] = decl.List[i], decl.List[0]
break BeginArrayObject
}
} else {
break BeginArrayObject
}
}
prevRefs = append(prevRefs, refs...)
}
}
}