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Diffstat (limited to 'vendor/github.com/gorilla/css/scanner/scanner.go')
| -rw-r--r-- | vendor/github.com/gorilla/css/scanner/scanner.go | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/vendor/github.com/gorilla/css/scanner/scanner.go b/vendor/github.com/gorilla/css/scanner/scanner.go new file mode 100644 index 0000000000..23fa7404ec --- /dev/null +++ b/vendor/github.com/gorilla/css/scanner/scanner.go @@ -0,0 +1,356 @@ +// Copyright 2012 The Gorilla Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package scanner + +import ( + "fmt" + "regexp" + "strings" + "unicode" + "unicode/utf8" +) + +// tokenType identifies the type of lexical tokens. +type tokenType int + +// String returns a string representation of the token type. +func (t tokenType) String() string { + return tokenNames[t] +} + +// Token represents a token and the corresponding string. +type Token struct { + Type tokenType + Value string + Line int + Column int +} + +// String returns a string representation of the token. +func (t *Token) String() string { + if len(t.Value) > 10 { + return fmt.Sprintf("%s (line: %d, column: %d): %.10q...", + t.Type, t.Line, t.Column, t.Value) + } + return fmt.Sprintf("%s (line: %d, column: %d): %q", + t.Type, t.Line, t.Column, t.Value) +} + +// All tokens ----------------------------------------------------------------- + +// The complete list of tokens in CSS3. +const ( + // Scanner flags. + TokenError tokenType = iota + TokenEOF + // From now on, only tokens from the CSS specification. + TokenIdent + TokenAtKeyword + TokenString + TokenHash + TokenNumber + TokenPercentage + TokenDimension + TokenURI + TokenUnicodeRange + TokenCDO + TokenCDC + TokenS + TokenComment + TokenFunction + TokenIncludes + TokenDashMatch + TokenPrefixMatch + TokenSuffixMatch + TokenSubstringMatch + TokenChar + TokenBOM +) + +// tokenNames maps tokenType's to their names. Used for conversion to string. +var tokenNames = map[tokenType]string{ + TokenError: "error", + TokenEOF: "EOF", + TokenIdent: "IDENT", + TokenAtKeyword: "ATKEYWORD", + TokenString: "STRING", + TokenHash: "HASH", + TokenNumber: "NUMBER", + TokenPercentage: "PERCENTAGE", + TokenDimension: "DIMENSION", + TokenURI: "URI", + TokenUnicodeRange: "UNICODE-RANGE", + TokenCDO: "CDO", + TokenCDC: "CDC", + TokenS: "S", + TokenComment: "COMMENT", + TokenFunction: "FUNCTION", + TokenIncludes: "INCLUDES", + TokenDashMatch: "DASHMATCH", + TokenPrefixMatch: "PREFIXMATCH", + TokenSuffixMatch: "SUFFIXMATCH", + TokenSubstringMatch: "SUBSTRINGMATCH", + TokenChar: "CHAR", + TokenBOM: "BOM", +} + +// Macros and productions ----------------------------------------------------- +// http://www.w3.org/TR/css3-syntax/#tokenization + +var macroRegexp = regexp.MustCompile(`\{[a-z]+\}`) + +// macros maps macro names to patterns to be expanded. +var macros = map[string]string{ + // must be escaped: `\.+*?()|[]{}^$` + "ident": `-?{nmstart}{nmchar}*`, + "name": `{nmchar}+`, + "nmstart": `[a-zA-Z_]|{nonascii}|{escape}`, + "nonascii": "[\u0080-\uD7FF\uE000-\uFFFD\U00010000-\U0010FFFF]", + "unicode": `\\[0-9a-fA-F]{1,6}{wc}?`, + "escape": "{unicode}|\\\\[\u0020-\u007E\u0080-\uD7FF\uE000-\uFFFD\U00010000-\U0010FFFF]", + "nmchar": `[a-zA-Z0-9_-]|{nonascii}|{escape}`, + "num": `[0-9]*\.[0-9]+|[0-9]+`, + "string": `"(?:{stringchar}|')*"|'(?:{stringchar}|")*'`, + "stringchar": `{urlchar}|[ ]|\\{nl}`, + "nl": `[\n\r\f]|\r\n`, + "w": `{wc}*`, + "wc": `[\t\n\f\r ]`, + + // urlchar should accept [(ascii characters minus those that need escaping)|{nonascii}|{escape}] + // ASCII characters range = `[\u0020-\u007e]` + // Skip space \u0020 = `[\u0021-\u007e]` + // Skip quotation mark \0022 = `[\u0021\u0023-\u007e]` + // Skip apostrophe \u0027 = `[\u0021\u0023-\u0026\u0028-\u007e]` + // Skip reverse solidus \u005c = `[\u0021\u0023-\u0026\u0028-\u005b\u005d\u007e]` + // Finally, the left square bracket (\u005b) and right (\u005d) needs escaping themselves + "urlchar": "[\u0021\u0023-\u0026\u0028-\\\u005b\\\u005d-\u007E]|{nonascii}|{escape}", +} + +// productions maps the list of tokens to patterns to be expanded. +var productions = map[tokenType]string{ + // Unused regexps (matched using other methods) are commented out. + TokenIdent: `{ident}`, + TokenAtKeyword: `@{ident}`, + TokenString: `{string}`, + TokenHash: `#{name}`, + TokenNumber: `{num}`, + TokenPercentage: `{num}%`, + TokenDimension: `{num}{ident}`, + TokenURI: `url\({w}(?:{string}|{urlchar}*?){w}\)`, + TokenUnicodeRange: `U\+[0-9A-F\?]{1,6}(?:-[0-9A-F]{1,6})?`, + //TokenCDO: `<!--`, + TokenCDC: `-->`, + TokenS: `{wc}+`, + TokenComment: `/\*[^\*]*[\*]+(?:[^/][^\*]*[\*]+)*/`, + TokenFunction: `{ident}\(`, + //TokenIncludes: `~=`, + //TokenDashMatch: `\|=`, + //TokenPrefixMatch: `\^=`, + //TokenSuffixMatch: `\$=`, + //TokenSubstringMatch: `\*=`, + //TokenChar: `[^"']`, + //TokenBOM: "\uFEFF", +} + +// matchers maps the list of tokens to compiled regular expressions. +// +// The map is filled on init() using the macros and productions defined in +// the CSS specification. +var matchers = map[tokenType]*regexp.Regexp{} + +// matchOrder is the order to test regexps when first-char shortcuts +// can't be used. +var matchOrder = []tokenType{ + TokenURI, + TokenFunction, + TokenUnicodeRange, + TokenIdent, + TokenDimension, + TokenPercentage, + TokenNumber, + TokenCDC, +} + +func init() { + // replace macros and compile regexps for productions. + replaceMacro := func(s string) string { + return "(?:" + macros[s[1:len(s)-1]] + ")" + } + for t, s := range productions { + for macroRegexp.MatchString(s) { + s = macroRegexp.ReplaceAllStringFunc(s, replaceMacro) + } + matchers[t] = regexp.MustCompile("^(?:" + s + ")") + } +} + +// Scanner -------------------------------------------------------------------- + +// New returns a new CSS scanner for the given input. +func New(input string) *Scanner { + // Normalize newlines. + input = strings.Replace(input, "\r\n", "\n", -1) + return &Scanner{ + input: input, + row: 1, + col: 1, + } +} + +// Scanner scans an input and emits tokens following the CSS3 specification. +type Scanner struct { + input string + pos int + row int + col int + err *Token +} + +// Next returns the next token from the input. +// +// At the end of the input the token type is TokenEOF. +// +// If the input can't be tokenized the token type is TokenError. This occurs +// in case of unclosed quotation marks or comments. +func (s *Scanner) Next() *Token { + if s.err != nil { + return s.err + } + if s.pos >= len(s.input) { + s.err = &Token{TokenEOF, "", s.row, s.col} + return s.err + } + if s.pos == 0 { + // Test BOM only once, at the beginning of the file. + if strings.HasPrefix(s.input, "\uFEFF") { + return s.emitSimple(TokenBOM, "\uFEFF") + } + } + // There's a lot we can guess based on the first byte so we'll take a + // shortcut before testing multiple regexps. + input := s.input[s.pos:] + switch input[0] { + case '\t', '\n', '\f', '\r', ' ': + // Whitespace. + return s.emitToken(TokenS, matchers[TokenS].FindString(input)) + case '.': + // Dot is too common to not have a quick check. + // We'll test if this is a Char; if it is followed by a number it is a + // dimension/percentage/number, and this will be matched later. + if len(input) > 1 && !unicode.IsDigit(rune(input[1])) { + return s.emitSimple(TokenChar, ".") + } + case '#': + // Another common one: Hash or Char. + if match := matchers[TokenHash].FindString(input); match != "" { + return s.emitToken(TokenHash, match) + } + return s.emitSimple(TokenChar, "#") + case '@': + // Another common one: AtKeyword or Char. + if match := matchers[TokenAtKeyword].FindString(input); match != "" { + return s.emitSimple(TokenAtKeyword, match) + } + return s.emitSimple(TokenChar, "@") + case ':', ',', ';', '%', '&', '+', '=', '>', '(', ')', '[', ']', '{', '}': + // More common chars. + return s.emitSimple(TokenChar, string(input[0])) + case '"', '\'': + // String or error. + match := matchers[TokenString].FindString(input) + if match != "" { + return s.emitToken(TokenString, match) + } + + s.err = &Token{TokenError, "unclosed quotation mark", s.row, s.col} + return s.err + case '/': + // Comment, error or Char. + if len(input) > 1 && input[1] == '*' { + match := matchers[TokenComment].FindString(input) + if match != "" { + return s.emitToken(TokenComment, match) + } else { + s.err = &Token{TokenError, "unclosed comment", s.row, s.col} + return s.err + } + } + return s.emitSimple(TokenChar, "/") + case '~': + // Includes or Char. + return s.emitPrefixOrChar(TokenIncludes, "~=") + case '|': + // DashMatch or Char. + return s.emitPrefixOrChar(TokenDashMatch, "|=") + case '^': + // PrefixMatch or Char. + return s.emitPrefixOrChar(TokenPrefixMatch, "^=") + case '$': + // SuffixMatch or Char. + return s.emitPrefixOrChar(TokenSuffixMatch, "$=") + case '*': + // SubstringMatch or Char. + return s.emitPrefixOrChar(TokenSubstringMatch, "*=") + case '<': + // CDO or Char. + return s.emitPrefixOrChar(TokenCDO, "<!--") + } + // Test all regexps, in order. + for _, token := range matchOrder { + if match := matchers[token].FindString(input); match != "" { + return s.emitToken(token, match) + } + } + // We already handled unclosed quotation marks and comments, + // so this can only be a Char. + r, width := utf8.DecodeRuneInString(input) + token := &Token{TokenChar, string(r), s.row, s.col} + s.col += width + s.pos += width + return token +} + +// updatePosition updates input coordinates based on the consumed text. +func (s *Scanner) updatePosition(text string) { + width := utf8.RuneCountInString(text) + lines := strings.Count(text, "\n") + s.row += lines + if lines == 0 { + s.col += width + } else { + s.col = utf8.RuneCountInString(text[strings.LastIndex(text, "\n"):]) + } + s.pos += len(text) // while col is a rune index, pos is a byte index +} + +// emitToken returns a Token for the string v and updates the scanner position. +func (s *Scanner) emitToken(t tokenType, v string) *Token { + token := &Token{t, v, s.row, s.col} + s.updatePosition(v) + return token +} + +// emitSimple returns a Token for the string v and updates the scanner +// position in a simplified manner. +// +// The string is known to have only ASCII characters and to not have a newline. +func (s *Scanner) emitSimple(t tokenType, v string) *Token { + token := &Token{t, v, s.row, s.col} + s.col += len(v) + s.pos += len(v) + return token +} + +// emitPrefixOrChar returns a Token for type t if the current position +// matches the given prefix. Otherwise it returns a Char token using the +// first character from the prefix. +// +// The prefix is known to have only ASCII characters and to not have a newline. +func (s *Scanner) emitPrefixOrChar(t tokenType, prefix string) *Token { + if strings.HasPrefix(s.input[s.pos:], prefix) { + return s.emitSimple(t, prefix) + } + return s.emitSimple(TokenChar, string(prefix[0])) +} |