Files
esbuild/internal/css_printer/css_printer.go
2021-03-12 00:50:30 -08:00

650 lines
15 KiB
Go

package css_printer
import (
"fmt"
"strings"
"unicode/utf8"
"github.com/evanw/esbuild/internal/ast"
"github.com/evanw/esbuild/internal/css_ast"
"github.com/evanw/esbuild/internal/css_lexer"
)
const quoteForURL rune = -1
type printer struct {
options Options
importRecords []ast.ImportRecord
sb strings.Builder
}
type Options struct {
RemoveWhitespace bool
ASCIIOnly bool
}
func Print(tree css_ast.AST, options Options) string {
p := printer{
options: options,
importRecords: tree.ImportRecords,
}
for _, rule := range tree.Rules {
p.printRule(rule, 0, false)
}
return p.sb.String()
}
func (p *printer) printRule(rule css_ast.R, indent int32, omitTrailingSemicolon bool) {
if !p.options.RemoveWhitespace {
p.printIndent(indent)
}
switch r := rule.(type) {
case *css_ast.RAtCharset:
// It's not valid to remove the space in between these two tokens
p.print("@charset ")
// It's not valid to print the string with single quotes
p.printQuotedWithQuote(r.Encoding, '"')
p.print(";")
case *css_ast.RAtImport:
if p.options.RemoveWhitespace {
p.print("@import")
} else {
p.print("@import ")
}
p.printQuoted(p.importRecords[r.ImportRecordIndex].Path.Text)
p.printTokens(r.ImportConditions, printTokensOpts{})
p.print(";")
case *css_ast.RAtKeyframes:
p.print("@")
p.printIdent(r.AtToken, identNormal, mayNeedWhitespaceAfter)
p.print(" ")
if r.Name == "" {
p.print("\"\"")
} else {
p.printIdent(r.Name, identNormal, canDiscardWhitespaceAfter)
}
if !p.options.RemoveWhitespace {
p.print(" ")
}
if p.options.RemoveWhitespace {
p.print("{")
} else {
p.print("{\n")
}
indent++
for _, block := range r.Blocks {
if !p.options.RemoveWhitespace {
p.printIndent(indent)
}
for i, sel := range block.Selectors {
if i > 0 {
if p.options.RemoveWhitespace {
p.print(",")
} else {
p.print(", ")
}
}
p.print(sel)
}
if !p.options.RemoveWhitespace {
p.print(" ")
}
p.printRuleBlock(block.Rules, indent)
if !p.options.RemoveWhitespace {
p.print("\n")
}
}
indent--
if !p.options.RemoveWhitespace {
p.printIndent(indent)
}
p.print("}")
case *css_ast.RKnownAt:
p.print("@")
whitespace := mayNeedWhitespaceAfter
if len(r.Prelude) == 0 {
whitespace = canDiscardWhitespaceAfter
}
p.printIdent(r.AtToken, identNormal, whitespace)
if !p.options.RemoveWhitespace || len(r.Prelude) > 0 {
p.print(" ")
}
p.printTokens(r.Prelude, printTokensOpts{})
if !p.options.RemoveWhitespace && len(r.Prelude) > 0 {
p.print(" ")
}
p.printRuleBlock(r.Rules, indent)
case *css_ast.RUnknownAt:
p.print("@")
whitespace := mayNeedWhitespaceAfter
if len(r.Prelude) == 0 {
whitespace = canDiscardWhitespaceAfter
}
p.printIdent(r.AtToken, identNormal, whitespace)
if (!p.options.RemoveWhitespace && r.Block != nil) || len(r.Prelude) > 0 {
p.print(" ")
}
p.printTokens(r.Prelude, printTokensOpts{})
if !p.options.RemoveWhitespace && r.Block != nil && len(r.Prelude) > 0 {
p.print(" ")
}
if r.Block == nil {
p.print(";")
} else {
p.printTokens(r.Block, printTokensOpts{})
}
case *css_ast.RSelector:
p.printComplexSelectors(r.Selectors, indent)
if !p.options.RemoveWhitespace {
p.print(" ")
}
p.printRuleBlock(r.Rules, indent)
case *css_ast.RQualified:
hasWhitespaceAfter := p.printTokens(r.Prelude, printTokensOpts{})
if !hasWhitespaceAfter && !p.options.RemoveWhitespace {
p.print(" ")
}
p.printRuleBlock(r.Rules, indent)
case *css_ast.RDeclaration:
p.printIdent(r.KeyText, identNormal, canDiscardWhitespaceAfter)
p.print(":")
hasWhitespaceAfter := p.printTokens(r.Value, printTokensOpts{
indent: indent,
isDeclaration: true,
})
if r.Important {
if !hasWhitespaceAfter && !p.options.RemoveWhitespace && len(r.Value) > 0 {
p.print(" ")
}
p.print("!important")
}
if !omitTrailingSemicolon {
p.print(";")
}
case *css_ast.RBadDeclaration:
p.printTokens(r.Tokens, printTokensOpts{})
if !omitTrailingSemicolon {
p.print(";")
}
default:
panic("Internal error")
}
if !p.options.RemoveWhitespace {
p.print("\n")
}
}
func (p *printer) printRuleBlock(rules []css_ast.R, indent int32) {
if p.options.RemoveWhitespace {
p.print("{")
} else {
p.print("{\n")
}
for i, decl := range rules {
omitTrailingSemicolon := p.options.RemoveWhitespace && i+1 == len(rules)
p.printRule(decl, indent+1, omitTrailingSemicolon)
}
if !p.options.RemoveWhitespace {
p.printIndent(indent)
}
p.print("}")
}
func (p *printer) printComplexSelectors(selectors []css_ast.ComplexSelector, indent int32) {
for i, complex := range selectors {
if i > 0 {
if p.options.RemoveWhitespace {
p.print(",")
} else {
p.print(",\n")
p.printIndent(indent)
}
}
for j, compound := range complex.Selectors {
p.printCompoundSelector(compound, j == 0, j+1 == len(complex.Selectors))
}
}
}
func (p *printer) printCompoundSelector(sel css_ast.CompoundSelector, isFirst bool, isLast bool) {
if sel.HasNestPrefix {
p.print("&")
}
if sel.Combinator != "" {
if !p.options.RemoveWhitespace {
p.print(" ")
}
p.print(sel.Combinator)
if !p.options.RemoveWhitespace {
p.print(" ")
}
} else if !isFirst {
p.print(" ")
}
if sel.TypeSelector != nil {
whitespace := mayNeedWhitespaceAfter
if len(sel.SubclassSelectors) > 0 || len(sel.PseudoClassSelectors) > 0 {
// There is no chance of whitespace before a subclass selector or pseudo
// class selector
whitespace = canDiscardWhitespaceAfter
}
p.printNamespacedName(*sel.TypeSelector, whitespace)
}
for i, sub := range sel.SubclassSelectors {
whitespace := mayNeedWhitespaceAfter
// There is no chance of whitespace between subclass selectors
if i+1 < len(sel.SubclassSelectors) || len(sel.PseudoClassSelectors) > 0 {
whitespace = canDiscardWhitespaceAfter
}
switch s := sub.(type) {
case *css_ast.SSHash:
p.print("#")
// This deliberately does not use identHash. From the specification:
// "In <id-selector>, the <hash-token>'s value must be an identifier."
p.printIdent(s.Name, identNormal, whitespace)
case *css_ast.SSClass:
p.print(".")
p.printIdent(s.Name, identNormal, whitespace)
case *css_ast.SSAttribute:
p.print("[")
p.printNamespacedName(s.NamespacedName, canDiscardWhitespaceAfter)
if s.MatcherOp != "" {
p.print(s.MatcherOp)
printAsIdent := false
// Print the value as an identifier if it's possible
if css_lexer.WouldStartIdentifierWithoutEscapes(s.MatcherValue) {
printAsIdent = true
for _, c := range s.MatcherValue {
if !css_lexer.IsNameContinue(c) {
printAsIdent = false
break
}
}
}
if printAsIdent {
p.printIdent(s.MatcherValue, identNormal, canDiscardWhitespaceAfter)
} else {
p.printQuoted(s.MatcherValue)
}
}
if s.MatcherModifier != 0 {
p.print(" ")
p.print(string(rune(s.MatcherModifier)))
}
p.print("]")
case *css_ast.SSPseudoClass:
p.printPseudoClassSelector(*s, whitespace)
}
}
if len(sel.PseudoClassSelectors) > 0 {
p.print(":")
for i, pseudo := range sel.PseudoClassSelectors {
whitespace := mayNeedWhitespaceAfter
if i+1 < len(sel.PseudoClassSelectors) || isLast {
whitespace = canDiscardWhitespaceAfter
}
p.printPseudoClassSelector(pseudo, whitespace)
}
}
}
func (p *printer) printNamespacedName(nsName css_ast.NamespacedName, whitespace trailingWhitespace) {
if nsName.NamespacePrefix != nil {
switch nsName.NamespacePrefix.Kind {
case css_lexer.TIdent:
p.printIdent(nsName.NamespacePrefix.Text, identNormal, canDiscardWhitespaceAfter)
case css_lexer.TDelimAsterisk:
p.print("*")
default:
panic("Internal error")
}
p.print("|")
}
switch nsName.Name.Kind {
case css_lexer.TIdent:
p.printIdent(nsName.Name.Text, identNormal, whitespace)
case css_lexer.TDelimAsterisk:
p.print("*")
case css_lexer.TDelimAmpersand:
p.print("&")
default:
panic("Internal error")
}
}
func (p *printer) printPseudoClassSelector(pseudo css_ast.SSPseudoClass, whitespace trailingWhitespace) {
p.print(":")
if len(pseudo.Args) > 0 {
p.printIdent(pseudo.Name, identNormal, canDiscardWhitespaceAfter)
p.print("(")
p.printTokens(pseudo.Args, printTokensOpts{})
p.print(")")
} else {
p.printIdent(pseudo.Name, identNormal, whitespace)
}
}
func (p *printer) print(text string) {
p.sb.WriteString(text)
}
func bestQuoteCharForString(text string, forURL bool) rune {
forURLCost := 0
singleCost := 2
doubleCost := 2
for _, c := range text {
switch c {
case '\'':
forURLCost++
singleCost++
case '"':
forURLCost++
doubleCost++
case '(', ')', ' ', '\t':
forURLCost++
case '\\', '\n', '\r', '\f':
forURLCost++
singleCost++
doubleCost++
}
}
// Quotes can sometimes be omitted for URL tokens
if forURL && forURLCost < singleCost && forURLCost < doubleCost {
return quoteForURL
}
// Prefer double quotes to single quotes if there is no cost difference
if singleCost < doubleCost {
return '\''
}
return '"'
}
func (p *printer) printQuoted(text string) {
p.printQuotedWithQuote(text, bestQuoteCharForString(text, false))
}
type escapeKind uint8
const (
escapeNone escapeKind = iota
escapeBackslash
escapeHex
)
func (p *printer) printWithEscape(c rune, escape escapeKind, remainingText string, mayNeedWhitespaceAfter bool) {
if escape == escapeBackslash && ((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
// Hexadecimal characters cannot use a plain backslash escape
escape = escapeHex
}
switch escape {
case escapeNone:
p.sb.WriteRune(c)
case escapeBackslash:
p.sb.WriteRune('\\')
p.sb.WriteRune(c)
case escapeHex:
text := fmt.Sprintf("\\%x", c)
p.sb.WriteString(text)
// Make sure the next character is not interpreted as part of the escape sequence
if len(text) < 1+6 {
if next := utf8.RuneLen(c); next < len(remainingText) {
c = rune(remainingText[next])
if c == ' ' || c == '\t' || (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') {
p.sb.WriteRune(' ')
}
} else if mayNeedWhitespaceAfter {
// If the last character is a hexadecimal escape, print a space afterwards
// for the escape sequence to consume. That way we're sure it won't
// accidentally consume a semantically significant space afterward.
p.sb.WriteRune(' ')
}
}
}
}
func (p *printer) printQuotedWithQuote(text string, quote rune) {
if quote != quoteForURL {
p.sb.WriteRune(quote)
}
for i, c := range text {
escape := escapeNone
switch c {
case '\r', '\n', '\f':
// Use a hexadecimal escape for characters that would be invalid escapes
escape = escapeHex
case '\\', quote:
escape = escapeBackslash
case '(', ')', ' ', '\t', '"', '\'':
// These characters must be escaped in URL tokens
if quote == quoteForURL {
escape = escapeBackslash
}
default:
if p.options.ASCIIOnly && c >= 0x80 || c == '\uFEFF' {
escape = escapeHex
}
}
p.printWithEscape(c, escape, text[i:], false)
}
if quote != quoteForURL {
p.sb.WriteRune(quote)
}
}
type identMode uint8
const (
identNormal identMode = iota
identHash
identDimensionUnit
)
type trailingWhitespace uint8
const (
mayNeedWhitespaceAfter trailingWhitespace = iota
canDiscardWhitespaceAfter
)
func (p *printer) printIdent(text string, mode identMode, whitespace trailingWhitespace) {
for i, c := range text {
escape := escapeNone
if p.options.ASCIIOnly && c >= 0x80 {
escape = escapeHex
} else if c == '\r' || c == '\n' || c == '\f' || c == '\uFEFF' {
// Use a hexadecimal escape for characters that would be invalid escapes
escape = escapeHex
} else {
// Escape non-identifier characters
if !css_lexer.IsNameContinue(c) {
escape = escapeBackslash
}
// Special escape behavior for the first character
if i == 0 {
switch mode {
case identNormal:
if !css_lexer.WouldStartIdentifierWithoutEscapes(text) {
escape = escapeBackslash
}
case identDimensionUnit:
if !css_lexer.WouldStartIdentifierWithoutEscapes(text) {
escape = escapeBackslash
} else if c >= '0' && c <= '9' {
// Unit: "2x"
escape = escapeHex
} else if c == 'e' || c == 'E' {
if len(text) >= 2 && text[1] >= '0' && text[1] <= '9' {
// Unit: "e2x"
escape = escapeBackslash
} else if len(text) >= 3 && text[1] == '-' && text[2] >= '0' && text[2] <= '9' {
// Unit: "e-2x"
escape = escapeBackslash
}
}
}
}
}
// If the last character is a hexadecimal escape, print a space afterwards
// for the escape sequence to consume. That way we're sure it won't
// accidentally consume a semantically significant space afterward.
mayNeedWhitespaceAfter := whitespace == mayNeedWhitespaceAfter && escape != escapeNone && i+utf8.RuneLen(c) == len(text)
p.printWithEscape(c, escape, text[i:], mayNeedWhitespaceAfter)
}
}
func (p *printer) printIndent(indent int32) {
for i, n := 0, int(indent); i < n; i++ {
p.sb.WriteString(" ")
}
}
type printTokensOpts struct {
indent int32
isDeclaration bool
}
func (p *printer) printTokens(tokens []css_ast.Token, opts printTokensOpts) bool {
hasWhitespaceAfter := len(tokens) > 0 && (tokens[0].Whitespace&css_ast.WhitespaceBefore) != 0
// Pretty-print long comma-separated declarations of 3 or more items
isMultiLineValue := false
if !p.options.RemoveWhitespace && opts.isDeclaration {
commaCount := 0
for _, t := range tokens {
if t.Kind == css_lexer.TComma {
commaCount++
}
}
isMultiLineValue = commaCount >= 2
}
for i, t := range tokens {
if t.Kind == css_lexer.TWhitespace {
hasWhitespaceAfter = true
continue
}
if hasWhitespaceAfter {
if isMultiLineValue && (i == 0 || tokens[i-1].Kind == css_lexer.TComma) {
p.print("\n")
p.printIndent(opts.indent + 1)
} else {
p.print(" ")
}
}
hasWhitespaceAfter = (t.Whitespace&css_ast.WhitespaceAfter) != 0 ||
(i+1 < len(tokens) && (tokens[i+1].Whitespace&css_ast.WhitespaceBefore) != 0)
whitespace := mayNeedWhitespaceAfter
if !hasWhitespaceAfter {
whitespace = canDiscardWhitespaceAfter
}
switch t.Kind {
case css_lexer.TIdent:
p.printIdent(t.Text, identNormal, whitespace)
case css_lexer.TFunction:
p.printIdent(t.Text, identNormal, whitespace)
p.print("(")
case css_lexer.TDimension:
p.print(t.DimensionValue())
p.printIdent(t.DimensionUnit(), identDimensionUnit, whitespace)
case css_lexer.TAtKeyword:
p.print("@")
p.printIdent(t.Text, identNormal, whitespace)
case css_lexer.THash:
p.print("#")
p.printIdent(t.Text, identHash, whitespace)
case css_lexer.TString:
p.printQuoted(t.Text)
case css_lexer.TURL:
text := p.importRecords[t.ImportRecordIndex].Path.Text
p.print("url(")
p.printQuotedWithQuote(text, bestQuoteCharForString(text, true))
p.print(")")
default:
p.print(t.Text)
}
if t.Children != nil {
p.printTokens(*t.Children, printTokensOpts{})
switch t.Kind {
case css_lexer.TFunction:
p.print(")")
case css_lexer.TOpenParen:
p.print(")")
case css_lexer.TOpenBrace:
p.print("}")
case css_lexer.TOpenBracket:
p.print("]")
}
}
}
if hasWhitespaceAfter {
p.print(" ")
}
return hasWhitespaceAfter
}