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Copy pathjs.go
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1329 lines (1276 loc) · 36.8 KB
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// Package js minifies ECMAScript 2021 following the language specification at https://tc39.es/ecma262/.
package js
import (
"bytes"
"io"
"github.com/tdewolff/minify/v2"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/js"
)
type blockType int
const (
defaultBlock blockType = iota
functionBlock
iterationBlock
)
// DefaultMinifier is the default minifier.
var DefaultMinifier = &Minifier{}
// Minifier is a JS minifier.
type Minifier struct {
Precision int // number of significant digits
KeepVarNames bool
useAlphabetVarNames bool
NoNullishOperator bool
}
// Minify minifies JS data, it reads from r and writes to w.
func Minify(m *minify.M, w io.Writer, r io.Reader, params map[string]string) error {
return DefaultMinifier.Minify(m, w, r, params)
}
// Minify minifies JS data, it reads from r and writes to w.
func (o *Minifier) Minify(_ *minify.M, w io.Writer, r io.Reader, _ map[string]string) error {
z := parse.NewInput(r)
ast, err := js.Parse(z, js.Options{WhileToFor: true})
if err != nil {
return err
}
// license comments
for _, comment := range ast.Comments {
if 3 < len(comment) && comment[2] == '!' {
w.Write(comment)
if comment[1] == '/' {
w.Write(newlineBytes)
}
} else if 2 < len(comment) && comment[0] == '#' && comment[1] == '!' {
w.Write(comment)
}
}
m := &jsMinifier{
o: o,
w: w,
renamer: newRenamer(!o.KeepVarNames, !o.useAlphabetVarNames),
}
m.hoistVars(&ast.BlockStmt)
ast.List = m.optimizeStmtList(ast.List, functionBlock)
for _, item := range ast.List {
m.writeSemicolon()
m.minifyStmt(item)
}
if _, err := w.Write(nil); err != nil {
return err
}
return nil
}
type expectExpr int
const (
expectAny expectExpr = iota
expectExprStmt // in statement
expectExprBody // in arrow function body
)
type jsMinifier struct {
o *Minifier
w io.Writer
prev []byte
needsSemicolon bool // write a semicolon if required
needsSpace bool // write a space if next token is an identifier
expectExpr expectExpr // avoid ambiguous syntax such as an expression starting with function
groupedStmt bool // avoid ambiguous syntax by grouping the expression statement
inFor bool
spaceBefore byte
renamer *renamer
}
func (m *jsMinifier) write(b []byte) {
// 0 < len(b)
if m.needsSpace && js.IsIdentifierContinue(b) || m.spaceBefore == b[0] {
m.w.Write(spaceBytes)
}
m.w.Write(b)
m.prev = b
m.needsSpace = false
m.expectExpr = expectAny
m.spaceBefore = 0
}
func (m *jsMinifier) writeSpaceAfterIdent() {
// space after identifier and after regular expression (to prevent confusion with its tag)
if js.IsIdentifierEnd(m.prev) || 1 < len(m.prev) && m.prev[0] == '/' {
m.w.Write(spaceBytes)
}
}
func (m *jsMinifier) writeSpaceBeforeIdent() {
m.needsSpace = true
}
func (m *jsMinifier) writeSpaceBefore(c byte) {
m.spaceBefore = c
}
func (m *jsMinifier) requireSemicolon() {
m.needsSemicolon = true
}
func (m *jsMinifier) writeSemicolon() {
if m.needsSemicolon {
m.w.Write(semicolonBytes)
m.needsSemicolon = false
m.needsSpace = false
}
}
func (m *jsMinifier) minifyStmt(i js.IStmt) {
switch stmt := i.(type) {
case *js.ExprStmt:
m.expectExpr = expectExprStmt
m.minifyExpr(stmt.Value, js.OpExpr)
if m.groupedStmt {
m.write(closeParenBytes)
m.groupedStmt = false
}
m.requireSemicolon()
case *js.VarDecl:
m.minifyVarDecl(stmt, false)
m.requireSemicolon()
case *js.IfStmt:
hasIf := !m.isEmptyStmt(stmt.Body)
hasElse := !m.isEmptyStmt(stmt.Else)
if !hasIf && !hasElse {
break
}
m.write(ifOpenBytes)
m.minifyExpr(stmt.Cond, js.OpExpr)
m.write(closeParenBytes)
if !hasIf && hasElse {
m.requireSemicolon()
} else if hasIf {
if hasElse && endsInIf(stmt.Body) {
// prevent: if(a){if(b)c}else d; => if(a)if(b)c;else d;
m.write(openBraceBytes)
m.minifyStmt(stmt.Body)
m.write(closeBraceBytes)
m.needsSemicolon = false
} else {
m.minifyStmt(stmt.Body)
}
}
if hasElse {
m.writeSemicolon()
m.write(elseBytes)
m.writeSpaceBeforeIdent()
m.minifyStmt(stmt.Else)
}
case *js.BlockStmt:
m.renamer.renameScope(stmt.Scope)
m.minifyBlockStmt(stmt)
case *js.ReturnStmt:
m.write(returnBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(stmt.Value, js.OpExpr)
m.requireSemicolon()
case *js.LabelledStmt:
m.write(stmt.Label)
m.write(colonBytes)
m.minifyStmt(stmt.Value)
case *js.BranchStmt:
m.write(stmt.Type.Bytes())
if stmt.Label != nil {
m.write(spaceBytes)
m.write(stmt.Label)
}
m.requireSemicolon()
case *js.WithStmt:
m.write(withOpenBytes)
m.minifyExpr(stmt.Cond, js.OpExpr)
m.write(closeParenBytes)
m.minifyStmtOrBlock(stmt.Body, defaultBlock)
case *js.DoWhileStmt:
m.write(doBytes)
m.writeSpaceBeforeIdent()
m.minifyStmtOrBlock(stmt.Body, iterationBlock)
m.writeSemicolon()
m.write(whileOpenBytes)
m.minifyExpr(stmt.Cond, js.OpExpr)
m.write(closeParenBytes)
case *js.WhileStmt:
m.write(whileOpenBytes)
m.minifyExpr(stmt.Cond, js.OpExpr)
m.write(closeParenBytes)
m.minifyStmtOrBlock(stmt.Body, iterationBlock)
case *js.ForStmt:
stmt.Body.List = m.optimizeStmtList(stmt.Body.List, iterationBlock)
m.renamer.renameScope(stmt.Body.Scope)
m.write(forOpenBytes)
m.inFor = true
if decl, ok := stmt.Init.(*js.VarDecl); ok {
m.minifyVarDecl(decl, true)
} else {
m.minifyExpr(stmt.Init, js.OpLHS)
}
m.inFor = false
m.write(semicolonBytes)
m.minifyExpr(stmt.Cond, js.OpExpr)
m.write(semicolonBytes)
m.minifyExpr(stmt.Post, js.OpExpr)
m.write(closeParenBytes)
m.minifyBlockAsStmt(stmt.Body, iterationBlock)
case *js.ForInStmt:
stmt.Body.List = m.optimizeStmtList(stmt.Body.List, iterationBlock)
m.renamer.renameScope(stmt.Body.Scope)
m.write(forOpenBytes)
m.inFor = true
if decl, ok := stmt.Init.(*js.VarDecl); ok {
m.minifyVarDecl(decl, false)
} else {
m.minifyExpr(stmt.Init, js.OpLHS)
}
m.inFor = false
m.writeSpaceAfterIdent()
m.write(inBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(stmt.Value, js.OpExpr)
m.write(closeParenBytes)
m.minifyBlockAsStmt(stmt.Body, iterationBlock)
case *js.ForOfStmt:
stmt.Body.List = m.optimizeStmtList(stmt.Body.List, iterationBlock)
m.renamer.renameScope(stmt.Body.Scope)
if stmt.Await {
m.write(forAwaitOpenBytes)
} else {
m.write(forOpenBytes)
}
m.inFor = true
if decl, ok := stmt.Init.(*js.VarDecl); ok {
m.minifyVarDecl(decl, false)
} else {
m.minifyExpr(stmt.Init, js.OpLHS)
}
m.inFor = false
m.writeSpaceAfterIdent()
m.write(ofBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(stmt.Value, js.OpAssign)
m.write(closeParenBytes)
m.minifyBlockAsStmt(stmt.Body, iterationBlock)
case *js.SwitchStmt:
m.write(switchOpenBytes)
m.minifyExpr(stmt.Init, js.OpExpr)
m.write(closeParenOpenBracketBytes)
m.needsSemicolon = false
for i, _ := range stmt.List {
stmt.List[i].List = m.optimizeStmtList(stmt.List[i].List, defaultBlock)
}
m.renamer.renameScope(stmt.Scope)
for _, clause := range stmt.List {
m.writeSemicolon()
m.write(clause.TokenType.Bytes())
if clause.Cond != nil {
m.writeSpaceBeforeIdent()
m.minifyExpr(clause.Cond, js.OpExpr)
}
m.write(colonBytes)
for _, item := range clause.List {
m.writeSemicolon()
m.minifyStmt(item)
}
}
m.write(closeBraceBytes)
m.needsSemicolon = false
case *js.ThrowStmt:
m.write(throwBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(stmt.Value, js.OpExpr)
m.requireSemicolon()
case *js.TryStmt:
m.write(tryBytes)
stmt.Body.List = m.optimizeStmtList(stmt.Body.List, defaultBlock)
m.renamer.renameScope(stmt.Body.Scope)
m.minifyBlockStmt(stmt.Body)
if stmt.Catch != nil {
m.write(catchBytes)
stmt.Catch.List = m.optimizeStmtList(stmt.Catch.List, defaultBlock)
m.renamer.renameScope(stmt.Catch.Scope)
if stmt.Binding != nil {
m.write(openParenBytes)
m.minifyBinding(stmt.Binding)
m.write(closeParenBytes)
}
m.minifyBlockStmt(stmt.Catch)
}
if stmt.Finally != nil {
m.write(finallyBytes)
stmt.Finally.List = m.optimizeStmtList(stmt.Finally.List, defaultBlock)
m.renamer.renameScope(stmt.Finally.Scope)
m.minifyBlockStmt(stmt.Finally)
}
case *js.FuncDecl:
m.minifyFuncDecl(stmt, false)
case *js.ClassDecl:
m.minifyClassDecl(stmt)
case *js.DebuggerStmt:
m.write(debuggerBytes)
m.requireSemicolon()
case *js.EmptyStmt:
case *js.ImportStmt:
m.write(importBytes)
if stmt.Default != nil {
m.write(spaceBytes)
m.write(stmt.Default)
if len(stmt.List) != 0 {
m.write(commaBytes)
} else if stmt.Default != nil || len(stmt.List) != 0 {
m.write(spaceBytes)
}
}
if len(stmt.List) == 1 && len(stmt.List[0].Name) == 1 && stmt.List[0].Name[0] == '*' {
m.writeSpaceBeforeIdent()
m.minifyAlias(stmt.List[0])
if stmt.Default != nil || len(stmt.List) != 0 {
m.write(spaceBytes)
}
} else if 0 < len(stmt.List) {
m.write(openBraceBytes)
for i, item := range stmt.List {
if i != 0 {
m.write(commaBytes)
}
m.minifyAlias(item)
}
m.write(closeBraceBytes)
}
if stmt.Default != nil || len(stmt.List) != 0 {
m.write(fromBytes)
}
m.write(minifyString(stmt.Module))
m.requireSemicolon()
case *js.ExportStmt:
m.write(exportBytes)
if stmt.Decl != nil {
if stmt.Default {
m.write(spaceDefaultBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(stmt.Decl, js.OpAssign)
_, isHoistable := stmt.Decl.(*js.FuncDecl)
_, isClass := stmt.Decl.(*js.ClassDecl)
if !isHoistable && !isClass {
m.requireSemicolon()
}
} else {
m.writeSpaceBeforeIdent()
m.minifyStmt(stmt.Decl.(js.IStmt)) // can only be variable, function, or class decl
}
} else {
if len(stmt.List) == 1 && (len(stmt.List[0].Name) == 1 && stmt.List[0].Name[0] == '*' || stmt.List[0].Name == nil && len(stmt.List[0].Binding) == 1 && stmt.List[0].Binding[0] == '*') {
m.writeSpaceBeforeIdent()
m.minifyAlias(stmt.List[0])
if stmt.Module != nil && stmt.List[0].Name != nil {
m.write(spaceBytes)
}
} else if 0 < len(stmt.List) {
m.write(openBraceBytes)
for i, item := range stmt.List {
if i != 0 {
m.write(commaBytes)
}
m.minifyAlias(item)
}
m.write(closeBraceBytes)
}
if stmt.Module != nil {
m.write(fromBytes)
m.write(minifyString(stmt.Module))
}
m.requireSemicolon()
}
case *js.DirectivePrologueStmt:
m.write(stmt.Value)
m.requireSemicolon()
}
}
func (m *jsMinifier) minifyBlockStmt(stmt *js.BlockStmt) {
m.write(openBraceBytes)
m.needsSemicolon = false
for _, item := range stmt.List {
m.writeSemicolon()
m.minifyStmt(item)
}
m.write(closeBraceBytes)
m.needsSemicolon = false
}
func (m *jsMinifier) minifyBlockAsStmt(blockStmt *js.BlockStmt, blockType blockType) {
// minify block when statement is expected, i.e. semicolon if empty or remove braces for single statement
// assume we already renamed the scope
hasLexicalVars := false
for _, v := range blockStmt.Scope.Declared[blockStmt.Scope.NumForDeclared:] {
if v.Decl == js.LexicalDecl {
hasLexicalVars = true
break
}
}
if 1 < len(blockStmt.List) || hasLexicalVars {
m.minifyBlockStmt(blockStmt)
} else if len(blockStmt.List) == 1 {
m.minifyStmt(blockStmt.List[0])
} else {
m.write(semicolonBytes)
m.needsSemicolon = false
}
}
func (m *jsMinifier) minifyStmtOrBlock(i js.IStmt, blockType blockType) {
// minify stmt or a block
if blockStmt, ok := i.(*js.BlockStmt); ok {
blockStmt.List = m.optimizeStmtList(blockStmt.List, blockType)
m.renamer.renameScope(blockStmt.Scope)
m.minifyBlockAsStmt(blockStmt, blockType)
} else {
// optimizeStmtList can in some cases expand one stmt to two shorter stmts
list := m.optimizeStmtList([]js.IStmt{i}, blockType)
if len(list) == 1 {
m.minifyStmt(list[0])
} else if len(list) == 0 {
m.write(semicolonBytes)
m.needsSemicolon = false
} else {
m.minifyBlockStmt(&js.BlockStmt{List: list, Scope: js.Scope{}})
}
}
}
func (m *jsMinifier) minifyAlias(alias js.Alias) {
if alias.Name != nil {
if alias.Name[0] == '"' || alias.Name[0] == '\'' {
m.write(minifyString(alias.Name))
} else {
m.write(alias.Name)
}
if !bytes.Equal(alias.Name, starBytes) {
m.write(spaceBytes)
}
m.write(asSpaceBytes)
}
if alias.Binding != nil {
if alias.Binding[0] == '"' || alias.Binding[0] == '\'' {
m.write(minifyString(alias.Binding))
} else {
m.write(alias.Binding)
}
}
}
func (m *jsMinifier) minifyParams(params js.Params) {
// remove unused parameters from the end
j := len(params.List)
if params.Rest == nil {
for ; 0 < j; j-- {
if v, ok := params.List[j-1].Binding.(*js.Var); !ok || ok && 1 < v.Uses {
break
}
}
}
m.write(openParenBytes)
for i, item := range params.List[:j] {
if i != 0 {
m.write(commaBytes)
}
m.minifyBindingElement(item)
}
if params.Rest != nil {
if len(params.List) != 0 {
m.write(commaBytes)
}
m.write(ellipsisBytes)
m.minifyBinding(params.Rest)
}
m.write(closeParenBytes)
}
func (m *jsMinifier) minifyArguments(args js.Args) {
m.write(openParenBytes)
for i, item := range args.List {
if i != 0 {
m.write(commaBytes)
}
if item.Rest {
m.write(ellipsisBytes)
}
m.minifyExpr(item.Value, js.OpAssign)
}
m.write(closeParenBytes)
}
func (m *jsMinifier) minifyVarDecl(decl *js.VarDecl, onlyDefines bool) {
if len(decl.List) == 0 {
return
} else if decl.TokenType == js.ErrorToken {
// remove 'var' when hoisting variables
first := true
for _, item := range decl.List {
if item.Default != nil || !onlyDefines {
if !first {
m.write(commaBytes)
}
m.minifyBindingElement(item)
first = false
}
}
} else {
m.write(decl.TokenType.Bytes())
m.writeSpaceBeforeIdent()
for i, item := range decl.List {
if i != 0 {
m.write(commaBytes)
}
m.minifyBindingElement(item)
}
}
}
func (m *jsMinifier) minifyFuncDecl(decl *js.FuncDecl, inExpr bool) {
parentRename := m.renamer.rename
m.renamer.rename = !decl.Body.Scope.HasWith && !m.o.KeepVarNames
m.hoistVars(&decl.Body)
decl.Body.List = m.optimizeStmtList(decl.Body.List, functionBlock)
if decl.Async {
m.write(asyncSpaceBytes)
}
m.write(functionBytes)
if decl.Generator {
m.write(starBytes)
}
if inExpr {
m.renamer.renameScope(decl.Body.Scope)
}
if decl.Name != nil && (!inExpr || 1 < decl.Name.Uses) {
if !decl.Generator {
m.write(spaceBytes)
}
m.write(decl.Name.Data)
}
if !inExpr {
m.renamer.renameScope(decl.Body.Scope)
}
m.minifyParams(decl.Params)
m.minifyBlockStmt(&decl.Body)
m.renamer.rename = parentRename
}
func (m *jsMinifier) minifyMethodDecl(decl *js.MethodDecl) {
parentRename := m.renamer.rename
m.renamer.rename = !decl.Body.Scope.HasWith && !m.o.KeepVarNames
m.hoistVars(&decl.Body)
decl.Body.List = m.optimizeStmtList(decl.Body.List, functionBlock)
if decl.Static {
m.write(staticBytes)
m.writeSpaceBeforeIdent()
}
if decl.Async {
m.write(asyncBytes)
if decl.Generator {
m.write(starBytes)
} else {
m.writeSpaceBeforeIdent()
}
} else if decl.Generator {
m.write(starBytes)
} else if decl.Get {
m.write(getBytes)
m.writeSpaceBeforeIdent()
} else if decl.Set {
m.write(setBytes)
m.writeSpaceBeforeIdent()
}
m.minifyPropertyName(decl.Name)
m.renamer.renameScope(decl.Body.Scope)
m.minifyParams(decl.Params)
m.minifyBlockStmt(&decl.Body)
m.renamer.rename = parentRename
}
func (m *jsMinifier) minifyArrowFunc(decl *js.ArrowFunc) {
parentRename := m.renamer.rename
m.renamer.rename = !decl.Body.Scope.HasWith && !m.o.KeepVarNames
m.hoistVars(&decl.Body)
decl.Body.List = m.optimizeStmtList(decl.Body.List, functionBlock)
m.renamer.renameScope(decl.Body.Scope)
if decl.Async {
m.write(asyncBytes)
}
removeParens := false
if decl.Params.Rest == nil && len(decl.Params.List) == 1 && decl.Params.List[0].Default == nil {
if decl.Params.List[0].Binding == nil {
removeParens = true
} else if _, ok := decl.Params.List[0].Binding.(*js.Var); ok {
removeParens = true
}
}
if removeParens {
if decl.Async && decl.Params.List[0].Binding != nil {
// add space after async in: async a => ...
m.write(spaceBytes)
}
m.minifyBindingElement(decl.Params.List[0])
} else {
parentInFor := m.inFor
m.inFor = false
m.minifyParams(decl.Params)
m.inFor = parentInFor
}
m.write(arrowBytes)
removeBraces := false
if 0 < len(decl.Body.List) {
returnStmt, isReturn := decl.Body.List[len(decl.Body.List)-1].(*js.ReturnStmt)
if isReturn && returnStmt.Value != nil {
// merge expression statements to final return statement, remove function body braces
var list []js.IExpr
removeBraces = true
for _, item := range decl.Body.List[:len(decl.Body.List)-1] {
if expr, isExpr := item.(*js.ExprStmt); isExpr {
list = append(list, expr.Value)
} else {
removeBraces = false
break
}
}
if removeBraces {
list = append(list, returnStmt.Value)
expr := list[0]
if 0 < len(list) {
if 1 < len(list) {
expr = &js.CommaExpr{list}
}
expr = &js.GroupExpr{X: expr}
}
m.expectExpr = expectExprBody
m.minifyExpr(expr, js.OpAssign)
if m.groupedStmt {
m.write(closeParenBytes)
m.groupedStmt = false
}
}
} else if isReturn && returnStmt.Value == nil {
// remove empty return
decl.Body.List = decl.Body.List[:len(decl.Body.List)-1]
}
}
if !removeBraces {
m.minifyBlockStmt(&decl.Body)
}
m.renamer.rename = parentRename
}
func (m *jsMinifier) minifyClassDecl(decl *js.ClassDecl) {
m.write(classBytes)
if decl.Name != nil {
m.write(spaceBytes)
m.write(decl.Name.Data)
}
if decl.Extends != nil {
m.write(spaceExtendsBytes)
m.writeSpaceBeforeIdent()
m.minifyExpr(decl.Extends, js.OpLHS)
}
m.write(openBraceBytes)
m.needsSemicolon = false
for _, item := range decl.Definitions {
m.writeSemicolon()
m.minifyPropertyName(item.Name)
if item.Init != nil {
m.write(equalBytes)
m.minifyExpr(item.Init, js.OpAssign)
}
m.requireSemicolon()
}
if 0 < len(decl.Methods) {
m.writeSemicolon()
for _, item := range decl.Methods {
m.minifyMethodDecl(item)
}
}
m.write(closeBraceBytes)
m.needsSemicolon = false
}
func (m *jsMinifier) minifyPropertyName(name js.PropertyName) {
if name.IsComputed() {
m.write(openBracketBytes)
m.minifyExpr(name.Computed, js.OpAssign)
m.write(closeBracketBytes)
} else {
m.write(name.Literal.Data)
}
}
func (m *jsMinifier) minifyProperty(property js.Property) {
// property.Name is always set in ObjectLiteral
if property.Spread {
m.write(ellipsisBytes)
} else if v, ok := property.Value.(*js.Var); property.Name != nil && (!ok || !property.Name.IsIdent(v.Name())) {
// add 'old-name:' before BindingName as the latter will be renamed
m.minifyPropertyName(*property.Name)
m.write(colonBytes)
}
m.minifyExpr(property.Value, js.OpAssign)
if property.Init != nil {
m.write(equalBytes)
m.minifyExpr(property.Init, js.OpAssign)
}
}
func (m *jsMinifier) minifyBindingElement(element js.BindingElement) {
if element.Binding != nil {
parentInFor := m.inFor
m.inFor = false
m.minifyBinding(element.Binding)
m.inFor = parentInFor
if element.Default != nil {
m.write(equalBytes)
m.minifyExpr(element.Default, js.OpAssign)
}
}
}
func (m *jsMinifier) minifyBinding(ibinding js.IBinding) {
switch binding := ibinding.(type) {
case *js.Var:
m.write(binding.Data)
case *js.BindingArray:
m.write(openBracketBytes)
for i, item := range binding.List {
if i != 0 {
m.write(commaBytes)
}
m.minifyBindingElement(item)
}
if binding.Rest != nil {
if 0 < len(binding.List) {
m.write(commaBytes)
}
m.write(ellipsisBytes)
m.minifyBinding(binding.Rest)
}
m.write(closeBracketBytes)
case *js.BindingObject:
m.write(openBraceBytes)
for i, item := range binding.List {
if i != 0 {
m.write(commaBytes)
}
// item.Key is always set
if item.Key.IsComputed() {
m.minifyPropertyName(*item.Key)
m.write(colonBytes)
} else if v, ok := item.Value.Binding.(*js.Var); !ok || !item.Key.IsIdent(v.Data) {
// add 'old-name:' before BindingName as the latter will be renamed
m.minifyPropertyName(*item.Key)
m.write(colonBytes)
}
m.minifyBindingElement(item.Value)
}
if binding.Rest != nil {
if 0 < len(binding.List) {
m.write(commaBytes)
}
m.write(ellipsisBytes)
m.write(binding.Rest.Data)
}
m.write(closeBraceBytes)
}
}
func (m *jsMinifier) minifyBinaryExpr(expr *js.BinaryExpr) bool {
if lit, ok := expr.Y.(*js.LiteralExpr); ok && lit.TokenType == js.StringToken && expr.Op == js.AddToken {
// merge strings that are added together
n := len(lit.Data) - 2
strings := []*js.LiteralExpr{lit}
left := expr
for {
if 50 < len(strings) {
return false // limit recursion
} else if lit, ok := left.X.(*js.LiteralExpr); ok && lit.TokenType == js.StringToken {
n += len(lit.Data) - 2
strings = append(strings, lit)
break
} else if left, ok = left.X.(*js.BinaryExpr); ok && left.Op == js.AddToken {
if lit, ok := left.Y.(*js.LiteralExpr); ok && lit.TokenType == js.StringToken {
n += len(lit.Data) - 2
strings = append(strings, lit)
continue
}
}
return false
}
b := make([]byte, 0, n+2)
b = append(b, strings[len(strings)-1].Data[:len(strings[len(strings)-1].Data)-1]...)
for i := len(strings) - 2; 0 < i; i-- {
b = append(b, strings[i].Data[1:len(strings[i].Data)-1]...)
}
b = append(b, strings[0].Data[1:]...)
b[len(b)-1] = b[0]
// unescaped quotes will be repaired in minifyString
m.write(minifyString(b))
return true
}
return false
}
func (m *jsMinifier) minifyExpr(i js.IExpr, prec js.OpPrec) {
switch expr := i.(type) {
case *js.Var:
for expr.Link != nil {
expr = expr.Link
}
data := expr.Data
if bytes.Equal(data, undefinedBytes) { // TODO: only if not defined
if js.OpUnary < prec {
m.write(groupedVoidZeroBytes)
} else {
m.write(voidZeroBytes)
}
} else if bytes.Equal(data, infinityBytes) { // TODO: only if not defined
if js.OpMul < prec {
m.write(groupedOneDivZeroBytes)
} else {
m.write(oneDivZeroBytes)
}
} else {
m.write(data)
}
case *js.LiteralExpr:
if expr.TokenType == js.DecimalToken {
m.write(minify.Number(expr.Data, m.o.Precision))
} else if expr.TokenType == js.BinaryToken {
m.write(binaryNumber(expr.Data, m.o.Precision))
} else if expr.TokenType == js.OctalToken {
m.write(octalNumber(expr.Data, m.o.Precision))
} else if expr.TokenType == js.HexadecimalToken {
m.write(hexadecimalNumber(expr.Data, m.o.Precision))
} else if expr.TokenType == js.TrueToken {
if js.OpUnary < prec {
m.write(groupedNotZeroBytes)
} else {
m.write(notZeroBytes)
}
} else if expr.TokenType == js.FalseToken {
if js.OpUnary < prec {
m.write(groupedNotOneBytes)
} else {
m.write(notOneBytes)
}
} else if expr.TokenType == js.StringToken {
m.write(minifyString(expr.Data))
} else if expr.TokenType == js.RegExpToken {
// </script>/ => < /script>/
if 0 < len(m.prev) && m.prev[len(m.prev)-1] == '<' && bytes.HasPrefix(expr.Data, regExpScriptBytes) {
m.write(spaceBytes)
}
m.write(minifyRegExp(expr.Data))
} else {
m.write(expr.Data)
}
case *js.BinaryExpr:
if m.minifyBinaryExpr(expr) {
break
}
precLeft := binaryLeftPrecMap[expr.Op]
// convert (a,b)&&c into a,b&&c but not a=(b,c)&&d into a=(b,c&&d)
if prec <= js.OpExpr {
if group, ok := expr.X.(*js.GroupExpr); ok {
if comma, ok := group.X.(*js.CommaExpr); ok && js.OpAnd <= exprPrec(comma.List[len(comma.List)-1]) {
expr.X = group.X
precLeft = js.OpExpr
}
}
}
if expr.Op == js.InstanceofToken || expr.Op == js.InToken {
group := expr.Op == js.InToken && m.inFor
if group {
m.write(openParenBytes)
}
m.minifyExpr(expr.X, precLeft)
m.writeSpaceAfterIdent()
m.write(expr.Op.Bytes())
m.writeSpaceBeforeIdent()
m.minifyExpr(expr.Y, binaryRightPrecMap[expr.Op])
if group {
m.write(closeParenBytes)
}
} else {
// TODO: has effect on GZIP?
//if expr.Op == js.EqEqToken || expr.Op == js.NotEqToken || expr.Op == js.EqEqEqToken || expr.Op == js.NotEqEqToken {
// // switch a==const for const==a, such as typeof a=="undefined" for "undefined"==typeof a (GZIP improvement)
// if _, ok := expr.Y.(*js.LiteralExpr); ok {
// expr.X, expr.Y = expr.Y, expr.X
// }
//}
m.minifyExpr(expr.X, precLeft)
// 0 < len(m.prev) always
if expr.Op == js.GtToken && m.prev[len(m.prev)-1] == '-' {
m.write(spaceBytes)
} else if expr.Op == js.EqEqEqToken || expr.Op == js.NotEqEqToken {
if left, ok := expr.X.(*js.UnaryExpr); ok && left.Op == js.TypeofToken {
if right, ok := expr.Y.(*js.LiteralExpr); ok && right.TokenType == js.StringToken {
if expr.Op == js.EqEqEqToken {
expr.Op = js.EqEqToken
} else {
expr.Op = js.NotEqToken
}
}
} else if right, ok := expr.Y.(*js.UnaryExpr); ok && right.Op == js.TypeofToken {
if left, ok := expr.X.(*js.LiteralExpr); ok && left.TokenType == js.StringToken {
if expr.Op == js.EqEqEqToken {
expr.Op = js.EqEqToken
} else {
expr.Op = js.NotEqToken
}
}
}
}
m.write(expr.Op.Bytes())
if expr.Op == js.AddToken {
// +++ => + ++
m.writeSpaceBefore('+')
} else if expr.Op == js.SubToken {
// --- => - --
m.writeSpaceBefore('-')
} else if expr.Op == js.DivToken {
// // => / /
m.writeSpaceBefore('/')
}
m.minifyExpr(expr.Y, binaryRightPrecMap[expr.Op])
}
case *js.UnaryExpr:
if expr.Op == js.PostIncrToken || expr.Op == js.PostDecrToken {
m.minifyExpr(expr.X, unaryPrecMap[expr.Op])
m.write(expr.Op.Bytes())
} else {
isLtNot := expr.Op == js.NotToken && 0 < len(m.prev) && m.prev[len(m.prev)-1] == '<'
m.write(expr.Op.Bytes())
if expr.Op == js.DeleteToken || expr.Op == js.VoidToken || expr.Op == js.TypeofToken || expr.Op == js.AwaitToken {
m.writeSpaceBeforeIdent()
} else if expr.Op == js.PosToken {
// +++ => + ++
m.writeSpaceBefore('+')
} else if expr.Op == js.NegToken || isLtNot {
// --- => - --
// <!-- => <! --
m.writeSpaceBefore('-')
} else if expr.Op == js.NotToken {
if lit, ok := expr.X.(*js.LiteralExpr); ok && (lit.TokenType == js.StringToken || lit.TokenType == js.RegExpToken) {
// !"string" => !1
m.write(oneBytes)
break
} else if ok && lit.TokenType == js.DecimalToken {
// !123 => !1 (except for !0)
if num := minify.Number(lit.Data, m.o.Precision); len(num) == 1 && num[0] == '0' {
m.write(zeroBytes)
} else {
m.write(oneBytes)
}
break
}