layout/style/nsCSSScanner.h
author Markus Stange <mstange@themasta.com>
Fri, 18 May 2018 17:36:30 -0400
changeset 421027 1d38a4cf5a4a7e54adbdb5ffa31c944e41e27e18
parent 413143 8a94faa5cc60495da5d80d4b3c07bf5877d2e6d8
child 422542 ebe097110cd2b4c04d19aa7c50a3a58a159b34e8
permissions -rw-r--r--
Bug 1462784 - Remove EVENTS category. r=njn Categories are useful to indicate: This much % of time was spent in this category. The EVENTS category isn't a very good match for this. This category is currently only set on labels of functions that handle the processing of an event. But those functions are usually closer to the base of the stack, and the actual CPU work during the processing of an event is usually in another category closer to the top of the stack, e.g. in JS if we're running an event handler, or in LAYOUT if we're hit testing the position of the event. This changeset removes the EVENTS category and replaces all uses of it with the OTHER category. MozReview-Commit-ID: JPm5hQiBkvp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* tokenization of CSS style sheets */

#ifndef nsCSSScanner_h___
#define nsCSSScanner_h___

#include "nsString.h"

namespace mozilla {
namespace css {
class ErrorReporter;
} // namespace css
} // namespace mozilla

// Token types; in close but not perfect correspondence to the token
// categorization in section 4.1.1 of CSS2.1.  (The deviations are all
// the fault of css3-selectors, which has requirements that can only be
// met by changing the generic tokenization.)  The comment on each line
// illustrates the form of each identifier.

enum nsCSSTokenType {
  // White space of any kind.  No value fields are used.  Note that
  // comments do *not* count as white space; comments separate tokens
  // but are not themselves tokens.
  eCSSToken_Whitespace,     //
  // A comment.
  eCSSToken_Comment,        // /*...*/

  // Identifier-like tokens.  mIdent is the text of the identifier.
  // The difference between ID and Hash is: if the text after the #
  // would have been a valid Ident if the # hadn't been there, the
  // scanner produces an ID token.  Otherwise it produces a Hash token.
  // (This distinction is required by css3-selectors.)
  eCSSToken_Ident,          // word
  eCSSToken_Function,       // word(
  eCSSToken_AtKeyword,      // @word
  eCSSToken_ID,             // #word
  eCSSToken_Hash,           // #0word

  // Numeric tokens.  mNumber is the floating-point value of the
  // number, and mHasSign indicates whether there was an explicit sign
  // (+ or -) in front of the number.  If mIntegerValid is true, the
  // number had the lexical form of an integer, and mInteger is its
  // integer value.  Lexically integer values outside the range of a
  // 32-bit signed number are clamped to the maximum values; mNumber
  // will indicate a 'truer' value in that case.  Percentage tokens
  // are always considered not to be integers, even if their numeric
  // value is integral (100% => mNumber = 1.0).  For Dimension
  // tokens, mIdent holds the text of the unit.
  eCSSToken_Number,         // 1 -5 +2e3 3.14159 7.297352e-3
  eCSSToken_Dimension,      // 24px 8.5in
  eCSSToken_Percentage,     // 85% 1280.4%

  // String-like tokens.  In all cases, mIdent holds the text
  // belonging to the string, and mSymbol holds the delimiter
  // character, which may be ', ", or zero (only for unquoted URLs).
  // Bad_String and Bad_URL tokens are emitted when the closing
  // delimiter or parenthesis was missing.
  eCSSToken_String,         // 'foo bar' "foo bar"
  eCSSToken_Bad_String,     // 'foo bar
  eCSSToken_URL,            // url(foobar) url("foo bar")
  eCSSToken_Bad_URL,        // url(foo

  // Any one-character symbol.  mSymbol holds the character.
  eCSSToken_Symbol,         // . ; { } ! *

  // Match operators.  These are single tokens rather than pairs of
  // Symbol tokens because css3-selectors forbids the presence of
  // comments between the two characters.  No value fields are used;
  // the token type indicates which operator.
  eCSSToken_Includes,       // ~=
  eCSSToken_Dashmatch,      // |=
  eCSSToken_Beginsmatch,    // ^=
  eCSSToken_Endsmatch,      // $=
  eCSSToken_Containsmatch,  // *=

  // Unicode-range token: currently used only in @font-face.
  // The lexical rule for this token includes several forms that are
  // semantically invalid.  Therefore, mIdent always holds the
  // complete original text of the token (so we can print it
  // accurately in diagnostics), and mIntegerValid is true iff the
  // token is semantically valid.  In that case, mInteger holds the
  // lowest value included in the range, and mInteger2 holds the
  // highest value included in the range.
  eCSSToken_URange,         // U+007e U+01?? U+2000-206F

  // HTML comment delimiters, ignored as a unit when they appear at
  // the top level of a style sheet, for compatibility with websites
  // written for compatibility with pre-CSS browsers.  This token type
  // subsumes the css2.1 CDO and CDC tokens, which are always treated
  // the same by the parser.  mIdent holds the text of the token, for
  // diagnostics.
  eCSSToken_HTMLComment,    // <!-- -->
};

// Classification of tokens used to determine if a "/**/" string must be
// inserted if pasting token streams together when serializing.  We include
// values corresponding to eCSSToken_Dashmatch and eCSSToken_Containsmatch,
// as css-syntax does not treat these as whole tokens, but we will still
// need to insert a "/**/" string between a '|' delim and a '|=' dashmatch
// and between a '/' delim and a '*=' containsmatch.
//
// https://drafts.csswg.org/css-syntax/#serialization
enum nsCSSTokenSerializationType {
  eCSSTokenSerialization_Nothing,
  eCSSTokenSerialization_Whitespace,
  eCSSTokenSerialization_AtKeyword_or_Hash,
  eCSSTokenSerialization_Number,
  eCSSTokenSerialization_Dimension,
  eCSSTokenSerialization_Percentage,
  eCSSTokenSerialization_URange,
  eCSSTokenSerialization_URL_or_BadURL,
  eCSSTokenSerialization_Function,
  eCSSTokenSerialization_Ident,
  eCSSTokenSerialization_CDC,
  eCSSTokenSerialization_DashMatch,
  eCSSTokenSerialization_ContainsMatch,
  eCSSTokenSerialization_Symbol_Hash,         // '#'
  eCSSTokenSerialization_Symbol_At,           // '@'
  eCSSTokenSerialization_Symbol_Dot_or_Plus,  // '.', '+'
  eCSSTokenSerialization_Symbol_Minus,        // '-'
  eCSSTokenSerialization_Symbol_OpenParen,    // '('
  eCSSTokenSerialization_Symbol_Question,     // '?'
  eCSSTokenSerialization_Symbol_Assorted,     // '$', '^', '~'
  eCSSTokenSerialization_Symbol_Equals,       // '='
  eCSSTokenSerialization_Symbol_Bar,          // '|'
  eCSSTokenSerialization_Symbol_Slash,        // '/'
  eCSSTokenSerialization_Symbol_Asterisk,     // '*'
  eCSSTokenSerialization_Other                // anything else
};

// A single token returned from the scanner.  mType is always
// meaningful; comments above describe which other fields are
// meaningful for which token types.
struct nsCSSToken {
  nsAutoString    mIdent;
  float           mNumber;
  int32_t         mInteger;
  int32_t         mInteger2;
  nsCSSTokenType  mType;
  char16_t       mSymbol;
  bool            mIntegerValid;
  bool            mHasSign;

  nsCSSToken()
    : mNumber(0), mInteger(0), mInteger2(0), mType(eCSSToken_Whitespace),
      mSymbol('\0'), mIntegerValid(false), mHasSign(false)
  {}

  bool IsSymbol(char16_t aSymbol) const {
    return mType == eCSSToken_Symbol && mSymbol == aSymbol;
  }

  void AppendToString(nsString& aBuffer) const;
};

// Represents an nsCSSScanner's saved position in the input buffer.
class nsCSSScannerPosition {
  friend class nsCSSScanner;
public:
  nsCSSScannerPosition() : mInitialized(false) { }

  uint32_t LineNumber() {
    MOZ_ASSERT(mInitialized);
    return mLineNumber;
  }

  uint32_t LineOffset() {
    MOZ_ASSERT(mInitialized);
    return mLineOffset;
  }

private:
  uint32_t mOffset;
  uint32_t mLineNumber;
  uint32_t mLineOffset;
  uint32_t mTokenLineNumber;
  uint32_t mTokenLineOffset;
  uint32_t mTokenOffset;
  bool mInitialized;
};

enum nsCSSScannerExclude {
  // Return all tokens, including whitespace and comments.
  eCSSScannerExclude_None,
  // Include whitespace but exclude comments.
  eCSSScannerExclude_Comments,
  // Exclude whitespace and comments.
  eCSSScannerExclude_WhitespaceAndComments
};

// nsCSSScanner tokenizes an input stream using the CSS2.1 forward
// compatible tokenization rules.  Used internally by nsCSSParser;
// not available for use by other code.
class nsCSSScanner {
  public:
  // |aLineNumber == 1| is the beginning of a file, use |aLineNumber == 0|
  // when the line number is unknown.  The scanner does not take
  // ownership of |aBuffer|, so the caller must be sure to keep it
  // alive for the lifetime of the scanner.
  nsCSSScanner(const nsAString& aBuffer, uint32_t aLineNumber);
  ~nsCSSScanner();

  // Reset or check whether a BAD_URL or BAD_STRING token has been seen.
  void ClearSeenBadToken() { mSeenBadToken = false; }
  bool SeenBadToken() const { return mSeenBadToken; }

  // Reset or check whether a "var(" FUNCTION token has been seen.
  void ClearSeenVariableReference() { mSeenVariableReference = false; }
  bool SeenVariableReference() const { return mSeenVariableReference; }

  // Get the 1-based line number of the last character of
  // the most recently processed token.
  uint32_t GetLineNumber() const { return mTokenLineNumber; }

  // Get the 0-based column number of the first character of
  // the most recently processed token.
  uint32_t GetColumnNumber() const
  { return mTokenOffset - mTokenLineOffset; }

  uint32_t GetTokenOffset() const
  { return mTokenOffset; }

  uint32_t GetTokenEndOffset() const
  { return mOffset; }

  const nsAString& GetSourceMapURL() const
  { return mSourceMapURL; }

  const nsAString& GetSourceURL() const
  { return mSourceURL; }

  // Get the text of the line containing the first character of
  // the most recently processed token.
  nsDependentSubstring GetCurrentLine() const;

  // Get the next token.  Return false on EOF.  aTokenResult is filled
  // in with the data for the token.  aSkip controls whether
  // whitespace and/or comment tokens are ever returned.
  bool Next(nsCSSToken& aTokenResult, nsCSSScannerExclude aSkip);

  // Get the body of an URL token (everything after the 'url(').
  // This is exposed for use by nsCSSParser::ParseMozDocumentRule,
  // which, for historical reasons, must make additional function
  // tokens behave like url().  Please do not add new uses to the
  // parser.
  void NextURL(nsCSSToken& aTokenResult);

  // This is exposed for use by nsCSSParser::ParsePseudoClassWithNthPairArg,
  // because "2n-1" is a single DIMENSION token, and "n-1" is a single
  // IDENT token, but the :nth() selector syntax wants to interpret
  // them the same as "2n -1" and "n -1" respectively.  Please do not
  // add new uses to the parser.
  //
  // Note: this function may not be used to back up over a line boundary.
  void Backup(uint32_t n);

  // Starts recording the input stream from the current position.
  void StartRecording();

  // Abandons recording of the input stream.
  void StopRecording();

  // Stops recording of the input stream and appends the recorded
  // input to aBuffer.
  void StopRecording(nsString& aBuffer);

  // Returns the length of the current recording.
  uint32_t RecordingLength() const;

#ifdef DEBUG
  bool IsRecording() const;
#endif

  // Stores the current scanner offset into the specified object.
  void SavePosition(nsCSSScannerPosition& aState);

  // Resets the scanner offset to a position saved by SavePosition.
  void RestoreSavedPosition(const nsCSSScannerPosition& aState);

  enum EOFCharacters {
    eEOFCharacters_None =                    0x0000,

    // to handle \<EOF> inside strings
    eEOFCharacters_DropBackslash =           0x0001,

    // to handle \<EOF> outside strings
    eEOFCharacters_ReplacementChar =         0x0002,

    // to close comments
    eEOFCharacters_Asterisk =                0x0004,
    eEOFCharacters_Slash =                   0x0008,

    // to close double-quoted strings
    eEOFCharacters_DoubleQuote =             0x0010,

    // to close single-quoted strings
    eEOFCharacters_SingleQuote =             0x0020,

    // to close URLs
    eEOFCharacters_CloseParen =              0x0040,
  };

  // Appends any characters to the specified string the input stream to make the
  // last token not rely on special EOF handling behavior.
  //
  // If eEOFCharacters_DropBackslash is in aEOFCharacters, it is ignored.
  static void AppendImpliedEOFCharacters(EOFCharacters aEOFCharacters,
                                         nsAString& aString);

  EOFCharacters GetEOFCharacters() const {
#ifdef DEBUG
    AssertEOFCharactersValid(mEOFCharacters);
#endif
    return mEOFCharacters;
  }

#ifdef DEBUG
  static void AssertEOFCharactersValid(uint32_t c);
#endif

protected:
  int32_t Peek(uint32_t n = 0);
  void Advance(uint32_t n = 1);
  void AdvanceLine();

  void SkipWhitespace();
  bool CheckCommentDirective(const nsAString& aDirective);
  void SkipComment();

  bool GatherEscape(nsString& aOutput, bool aInString);
  bool GatherText(uint8_t aClass, nsString& aIdent);

  bool ScanIdent(nsCSSToken& aResult);
  bool ScanAtKeyword(nsCSSToken& aResult);
  bool ScanHash(nsCSSToken& aResult);
  bool ScanNumber(nsCSSToken& aResult);
  bool ScanString(nsCSSToken& aResult);
  bool ScanURange(nsCSSToken& aResult);

  void SetEOFCharacters(uint32_t aEOFCharacters);
  void AddEOFCharacters(uint32_t aEOFCharacters);

  const char16_t *mBuffer;
  uint32_t mOffset;
  uint32_t mCount;

  uint32_t mLineNumber;
  uint32_t mLineOffset;

  uint32_t mTokenLineNumber;
  uint32_t mTokenLineOffset;
  uint32_t mTokenOffset;

  uint32_t mRecordStartOffset;
  EOFCharacters mEOFCharacters;

  bool mRecording;
  bool mSeenBadToken;
  bool mSeenVariableReference;

  nsString mSourceMapURL;
  nsString mSourceURL;
};

// Token for the grid-template-areas micro-syntax
// http://dev.w3.org/csswg/css-grid/#propdef-grid-template-areas
struct MOZ_STACK_CLASS nsCSSGridTemplateAreaToken {
  nsAutoString mName;  // Empty for a null cell, non-empty for a named cell
  bool isTrash;  // True for a trash token, mName is ignored in this case.
};

// Scanner for the grid-template-areas micro-syntax
class nsCSSGridTemplateAreaScanner {
public:
  explicit nsCSSGridTemplateAreaScanner(const nsAString& aBuffer);

  // Get the next token.  Return false on EOF.
  // aTokenResult is filled in with the data for the token.
  bool Next(nsCSSGridTemplateAreaToken& aTokenResult);

private:
  const char16_t *mBuffer;
  uint32_t mOffset;
  uint32_t mCount;
};

#endif /* nsCSSScanner_h___ */