mirror of
https://github.com/miniflux/v2.git
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399 lines
10 KiB
Go
399 lines
10 KiB
Go
package css // import "github.com/tdewolff/parse/css"
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import (
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"bytes"
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"io"
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"strconv"
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"github.com/tdewolff/parse"
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)
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var wsBytes = []byte(" ")
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var endBytes = []byte("}")
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var emptyBytes = []byte("")
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// GrammarType determines the type of grammar.
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type GrammarType uint32
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// GrammarType values.
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const (
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ErrorGrammar GrammarType = iota // extra token when errors occur
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CommentGrammar
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AtRuleGrammar
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BeginAtRuleGrammar
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EndAtRuleGrammar
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QualifiedRuleGrammar
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BeginRulesetGrammar
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EndRulesetGrammar
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DeclarationGrammar
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TokenGrammar
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CustomPropertyGrammar
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)
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// String returns the string representation of a GrammarType.
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func (tt GrammarType) String() string {
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switch tt {
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case ErrorGrammar:
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return "Error"
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case CommentGrammar:
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return "Comment"
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case AtRuleGrammar:
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return "AtRule"
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case BeginAtRuleGrammar:
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return "BeginAtRule"
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case EndAtRuleGrammar:
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return "EndAtRule"
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case QualifiedRuleGrammar:
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return "QualifiedRule"
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case BeginRulesetGrammar:
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return "BeginRuleset"
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case EndRulesetGrammar:
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return "EndRuleset"
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case DeclarationGrammar:
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return "Declaration"
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case TokenGrammar:
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return "Token"
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case CustomPropertyGrammar:
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return "CustomProperty"
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}
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return "Invalid(" + strconv.Itoa(int(tt)) + ")"
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}
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////////////////////////////////////////////////////////////////
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// State is the state function the parser currently is in.
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type State func(*Parser) GrammarType
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// Token is a single TokenType and its associated data.
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type Token struct {
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TokenType
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Data []byte
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}
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// Parser is the state for the parser.
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type Parser struct {
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l *Lexer
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state []State
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err error
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buf []Token
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level int
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tt TokenType
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data []byte
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prevWS bool
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prevEnd bool
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}
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// NewParser returns a new CSS parser from an io.Reader. isInline specifies whether this is an inline style attribute.
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func NewParser(r io.Reader, isInline bool) *Parser {
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l := NewLexer(r)
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p := &Parser{
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l: l,
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state: make([]State, 0, 4),
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}
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if isInline {
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p.state = append(p.state, (*Parser).parseDeclarationList)
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} else {
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p.state = append(p.state, (*Parser).parseStylesheet)
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}
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return p
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}
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// Err returns the error encountered during parsing, this is often io.EOF but also other errors can be returned.
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func (p *Parser) Err() error {
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if p.err != nil {
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return p.err
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}
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return p.l.Err()
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}
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// Restore restores the NULL byte at the end of the buffer.
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func (p *Parser) Restore() {
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p.l.Restore()
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}
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// Next returns the next Grammar. It returns ErrorGrammar when an error was encountered. Using Err() one can retrieve the error message.
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func (p *Parser) Next() (GrammarType, TokenType, []byte) {
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p.err = nil
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if p.prevEnd {
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p.tt, p.data = RightBraceToken, endBytes
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p.prevEnd = false
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} else {
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p.tt, p.data = p.popToken(true)
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}
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gt := p.state[len(p.state)-1](p)
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return gt, p.tt, p.data
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}
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// Values returns a slice of Tokens for the last Grammar. Only AtRuleGrammar, BeginAtRuleGrammar, BeginRulesetGrammar and Declaration will return the at-rule components, ruleset selector and declaration values respectively.
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func (p *Parser) Values() []Token {
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return p.buf
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}
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func (p *Parser) popToken(allowComment bool) (TokenType, []byte) {
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p.prevWS = false
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tt, data := p.l.Next()
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for tt == WhitespaceToken || tt == CommentToken {
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if tt == WhitespaceToken {
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p.prevWS = true
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} else if allowComment && len(p.state) == 1 {
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break
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}
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tt, data = p.l.Next()
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}
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return tt, data
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}
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func (p *Parser) initBuf() {
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p.buf = p.buf[:0]
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}
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func (p *Parser) pushBuf(tt TokenType, data []byte) {
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p.buf = append(p.buf, Token{tt, data})
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}
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////////////////////////////////////////////////////////////////
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func (p *Parser) parseStylesheet() GrammarType {
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if p.tt == CDOToken || p.tt == CDCToken {
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return TokenGrammar
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} else if p.tt == AtKeywordToken {
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return p.parseAtRule()
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} else if p.tt == CommentToken {
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return CommentGrammar
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} else if p.tt == ErrorToken {
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return ErrorGrammar
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}
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return p.parseQualifiedRule()
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}
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func (p *Parser) parseDeclarationList() GrammarType {
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if p.tt == CommentToken {
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p.tt, p.data = p.popToken(false)
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}
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for p.tt == SemicolonToken {
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p.tt, p.data = p.popToken(false)
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}
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if p.tt == ErrorToken {
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return ErrorGrammar
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} else if p.tt == AtKeywordToken {
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return p.parseAtRule()
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} else if p.tt == IdentToken {
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return p.parseDeclaration()
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} else if p.tt == CustomPropertyNameToken {
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return p.parseCustomProperty()
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}
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// parse error
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p.initBuf()
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p.err = parse.NewErrorLexer("unexpected token in declaration", p.l.r)
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for {
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tt, data := p.popToken(false)
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if (tt == SemicolonToken || tt == RightBraceToken) && p.level == 0 || tt == ErrorToken {
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p.prevEnd = (tt == RightBraceToken)
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return ErrorGrammar
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}
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p.pushBuf(tt, data)
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}
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}
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////////////////////////////////////////////////////////////////
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func (p *Parser) parseAtRule() GrammarType {
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p.initBuf()
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parse.ToLower(p.data)
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atRuleName := p.data
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if len(atRuleName) > 0 && atRuleName[1] == '-' {
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if i := bytes.IndexByte(atRuleName[2:], '-'); i != -1 {
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atRuleName = atRuleName[i+2:] // skip vendor specific prefix
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}
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}
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atRule := ToHash(atRuleName[1:])
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first := true
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skipWS := false
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for {
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tt, data := p.popToken(false)
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if tt == LeftBraceToken && p.level == 0 {
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if atRule == Font_Face || atRule == Page {
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p.state = append(p.state, (*Parser).parseAtRuleDeclarationList)
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} else if atRule == Document || atRule == Keyframes || atRule == Media || atRule == Supports {
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p.state = append(p.state, (*Parser).parseAtRuleRuleList)
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} else {
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p.state = append(p.state, (*Parser).parseAtRuleUnknown)
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}
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return BeginAtRuleGrammar
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} else if (tt == SemicolonToken || tt == RightBraceToken) && p.level == 0 || tt == ErrorToken {
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p.prevEnd = (tt == RightBraceToken)
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return AtRuleGrammar
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} else if tt == LeftParenthesisToken || tt == LeftBraceToken || tt == LeftBracketToken || tt == FunctionToken {
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p.level++
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} else if tt == RightParenthesisToken || tt == RightBraceToken || tt == RightBracketToken {
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p.level--
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}
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if first {
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if tt == LeftParenthesisToken || tt == LeftBracketToken {
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p.prevWS = false
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}
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first = false
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}
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if len(data) == 1 && (data[0] == ',' || data[0] == ':') {
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skipWS = true
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} else if p.prevWS && !skipWS && tt != RightParenthesisToken {
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p.pushBuf(WhitespaceToken, wsBytes)
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} else {
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skipWS = false
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}
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if tt == LeftParenthesisToken {
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skipWS = true
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}
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p.pushBuf(tt, data)
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}
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}
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func (p *Parser) parseAtRuleRuleList() GrammarType {
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if p.tt == RightBraceToken || p.tt == ErrorToken {
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p.state = p.state[:len(p.state)-1]
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return EndAtRuleGrammar
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} else if p.tt == AtKeywordToken {
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return p.parseAtRule()
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} else {
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return p.parseQualifiedRule()
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}
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}
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func (p *Parser) parseAtRuleDeclarationList() GrammarType {
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for p.tt == SemicolonToken {
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p.tt, p.data = p.popToken(false)
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}
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if p.tt == RightBraceToken || p.tt == ErrorToken {
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p.state = p.state[:len(p.state)-1]
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return EndAtRuleGrammar
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}
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return p.parseDeclarationList()
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}
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func (p *Parser) parseAtRuleUnknown() GrammarType {
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if p.tt == RightBraceToken && p.level == 0 || p.tt == ErrorToken {
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p.state = p.state[:len(p.state)-1]
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return EndAtRuleGrammar
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}
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if p.tt == LeftParenthesisToken || p.tt == LeftBraceToken || p.tt == LeftBracketToken || p.tt == FunctionToken {
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p.level++
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} else if p.tt == RightParenthesisToken || p.tt == RightBraceToken || p.tt == RightBracketToken {
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p.level--
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}
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return TokenGrammar
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}
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func (p *Parser) parseQualifiedRule() GrammarType {
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p.initBuf()
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first := true
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inAttrSel := false
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skipWS := true
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var tt TokenType
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var data []byte
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for {
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if first {
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tt, data = p.tt, p.data
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p.tt = WhitespaceToken
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p.data = emptyBytes
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first = false
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} else {
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tt, data = p.popToken(false)
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}
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if tt == LeftBraceToken && p.level == 0 {
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p.state = append(p.state, (*Parser).parseQualifiedRuleDeclarationList)
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return BeginRulesetGrammar
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} else if tt == ErrorToken {
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p.err = parse.NewErrorLexer("unexpected ending in qualified rule, expected left brace token", p.l.r)
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return ErrorGrammar
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} else if tt == LeftParenthesisToken || tt == LeftBraceToken || tt == LeftBracketToken || tt == FunctionToken {
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p.level++
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} else if tt == RightParenthesisToken || tt == RightBraceToken || tt == RightBracketToken {
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p.level--
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}
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if len(data) == 1 && (data[0] == ',' || data[0] == '>' || data[0] == '+' || data[0] == '~') {
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if data[0] == ',' {
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return QualifiedRuleGrammar
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}
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skipWS = true
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} else if p.prevWS && !skipWS && !inAttrSel {
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p.pushBuf(WhitespaceToken, wsBytes)
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} else {
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skipWS = false
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}
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if tt == LeftBracketToken {
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inAttrSel = true
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} else if tt == RightBracketToken {
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inAttrSel = false
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}
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p.pushBuf(tt, data)
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}
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}
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func (p *Parser) parseQualifiedRuleDeclarationList() GrammarType {
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for p.tt == SemicolonToken {
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p.tt, p.data = p.popToken(false)
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}
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if p.tt == RightBraceToken || p.tt == ErrorToken {
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p.state = p.state[:len(p.state)-1]
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return EndRulesetGrammar
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}
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return p.parseDeclarationList()
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}
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func (p *Parser) parseDeclaration() GrammarType {
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p.initBuf()
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parse.ToLower(p.data)
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if tt, _ := p.popToken(false); tt != ColonToken {
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p.err = parse.NewErrorLexer("unexpected token in declaration", p.l.r)
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return ErrorGrammar
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}
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skipWS := true
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for {
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tt, data := p.popToken(false)
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if (tt == SemicolonToken || tt == RightBraceToken) && p.level == 0 || tt == ErrorToken {
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p.prevEnd = (tt == RightBraceToken)
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return DeclarationGrammar
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} else if tt == LeftParenthesisToken || tt == LeftBraceToken || tt == LeftBracketToken || tt == FunctionToken {
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p.level++
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} else if tt == RightParenthesisToken || tt == RightBraceToken || tt == RightBracketToken {
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p.level--
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}
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if len(data) == 1 && (data[0] == ',' || data[0] == '/' || data[0] == ':' || data[0] == '!' || data[0] == '=') {
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skipWS = true
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} else if p.prevWS && !skipWS {
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p.pushBuf(WhitespaceToken, wsBytes)
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} else {
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skipWS = false
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}
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p.pushBuf(tt, data)
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}
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}
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func (p *Parser) parseCustomProperty() GrammarType {
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p.initBuf()
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if tt, _ := p.popToken(false); tt != ColonToken {
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p.err = parse.NewErrorLexer("unexpected token in declaration", p.l.r)
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return ErrorGrammar
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}
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val := []byte{}
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for {
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tt, data := p.l.Next()
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if (tt == SemicolonToken || tt == RightBraceToken) && p.level == 0 || tt == ErrorToken {
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p.prevEnd = (tt == RightBraceToken)
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p.pushBuf(CustomPropertyValueToken, val)
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return CustomPropertyGrammar
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} else if tt == LeftParenthesisToken || tt == LeftBraceToken || tt == LeftBracketToken || tt == FunctionToken {
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p.level++
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} else if tt == RightParenthesisToken || tt == RightBraceToken || tt == RightBracketToken {
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p.level--
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}
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val = append(val, data...)
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}
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}
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