dom/serializers/nsXMLContentSerializer.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * nsIContentSerializer implementation that can be used with an
   9  * nsIDocumentEncoder to convert an XML DOM to an XML string that
  10  * could be parsed into more or less the original DOM.
  11  */
  12
  13 #ifndef nsXMLContentSerializer_h__
  14 #define nsXMLContentSerializer_h__
  15
  16 #include "mozilla/Attributes.h"
  17 #include "nsIContentSerializer.h"
  18 #include "nsISupportsUtils.h"
  19 #include "nsCOMPtr.h"
  20 #include "nsTArray.h"
  21 #include "nsString.h"
  22
  23 #define kIndentStr u"  "_ns
  24 #define kEndTag u"</"_ns
  25
  26 class nsAtom;
  27 class nsINode;
  28
  29 namespace mozilla {
  30 class Encoding;
  31 }
  32
  33 class nsXMLContentSerializer : public nsIContentSerializer {
  34  public:
  35   nsXMLContentSerializer();
  36
  37   NS_DECL_ISUPPORTS
  38
  39   NS_IMETHOD Init(uint32_t flags, uint32_t aWrapColumn,
  40                   const mozilla::Encoding* aEncoding, bool aIsCopying,
  41                   bool aRewriteEncodingDeclaration,
  42                   bool* aNeedsPreformatScanning, nsAString& aOutput) override;
  43
  44   NS_IMETHOD AppendText(nsIContent* aText, int32_t aStartOffset,
  45                         int32_t aEndOffset) override;
  46
  47   NS_IMETHOD AppendCDATASection(nsIContent* aCDATASection, int32_t aStartOffset,
  48                                 int32_t aEndOffset) override;
  49
  50   NS_IMETHOD AppendProcessingInstruction(
  51       mozilla::dom::ProcessingInstruction* aPI, int32_t aStartOffset,
  52       int32_t aEndOffset) override;
  53
  54   NS_IMETHOD AppendComment(mozilla::dom::Comment* aComment,
  55                            int32_t aStartOffset, int32_t aEndOffset) override;
  56
  57   NS_IMETHOD AppendDoctype(mozilla::dom::DocumentType* aDoctype) override;
  58
  59   NS_IMETHOD AppendElementStart(
  60       mozilla::dom::Element* aElement,
  61       mozilla::dom::Element* aOriginalElement) override;
  62
  63   NS_IMETHOD AppendElementEnd(mozilla::dom::Element* aElement,
  64                               mozilla::dom::Element* aOriginalElement) override;
  65
  66   NS_IMETHOD FlushAndFinish() override { return NS_OK; }
  67
  68   NS_IMETHOD Finish() override;
  69
  70   NS_IMETHOD GetOutputLength(uint32_t& aLength) const override;
  71
  72   NS_IMETHOD AppendDocumentStart(mozilla::dom::Document* aDocument) override;
  73
  74   NS_IMETHOD ScanElementForPreformat(mozilla::dom::Element* aElement) override {
  75     return NS_OK;
  76   }
  77   NS_IMETHOD ForgetElementForPreformat(
  78       mozilla::dom::Element* aElement) override {
  79     return NS_OK;
  80   }
  81
  82  protected:
  83   virtual ~nsXMLContentSerializer();
  84
  85   /**
  86    * Appends a char16_t character and increments the column position
  87    */
  88   [[nodiscard]] bool AppendToString(const char16_t aChar,
  89                                     nsAString& aOutputStr);
  90
  91   /**
  92    * Appends a nsAString string and increments the column position
  93    */
  94   [[nodiscard]] bool AppendToString(const nsAString& aStr,
  95                                     nsAString& aOutputStr);
  96
  97   /**
  98    * Appends a string by replacing all line-endings
  99    * by mLineBreak, except in the case of raw output.
 100    * It increments the column position.
 101    */
 102   [[nodiscard]] bool AppendToStringConvertLF(const nsAString& aStr,
 103                                              nsAString& aOutputStr);
 104
 105   /**
 106    * Appends a string by wrapping it when necessary.
 107    * It updates the column position.
 108    */
 109   [[nodiscard]] bool AppendToStringWrapped(const nsAString& aStr,
 110                                            nsAString& aOutputStr);
 111
 112   /**
 113    * Appends a string by formating and wrapping it when necessary
 114    * It updates the column position.
 115    */
 116   [[nodiscard]] bool AppendToStringFormatedWrapped(const nsAString& aStr,
 117                                                    nsAString& aOutputStr);
 118
 119   // used by AppendToStringWrapped
 120   [[nodiscard]] bool AppendWrapped_WhitespaceSequence(
 121       nsAString::const_char_iterator& aPos,
 122       const nsAString::const_char_iterator aEnd,
 123       const nsAString::const_char_iterator aSequenceStart,
 124       nsAString& aOutputStr);
 125
 126   // used by AppendToStringFormatedWrapped
 127   [[nodiscard]] bool AppendFormatedWrapped_WhitespaceSequence(
 128       nsAString::const_char_iterator& aPos,
 129       const nsAString::const_char_iterator aEnd,
 130       const nsAString::const_char_iterator aSequenceStart,
 131       bool& aMayIgnoreStartOfLineWhitespaceSequence, nsAString& aOutputStr);
 132
 133   // used by AppendToStringWrapped and AppendToStringFormatedWrapped
 134   [[nodiscard]] bool AppendWrapped_NonWhitespaceSequence(
 135       nsAString::const_char_iterator& aPos,
 136       const nsAString::const_char_iterator aEnd,
 137       const nsAString::const_char_iterator aSequenceStart,
 138       bool& aMayIgnoreStartOfLineWhitespaceSequence,
 139       bool& aSequenceStartAfterAWhiteSpace, nsAString& aOutputStr);
 140
 141   /**
 142    * add mLineBreak to the string
 143    * It updates the column position and other flags.
 144    */
 145   [[nodiscard]] bool AppendNewLineToString(nsAString& aOutputStr);
 146
 147   /**
 148    * Appends a string by translating entities
 149    * It doesn't increment the column position
 150    */
 151   [[nodiscard]] virtual bool AppendAndTranslateEntities(const nsAString& aStr,
 152                                                         nsAString& aOutputStr);
 153
 154   /**
 155    * Helper for virtual AppendAndTranslateEntities that does the actualy work.
 156    *
 157    * Do not call this directly.  Call it via the template helper below.
 158    */
 159  private:
 160   [[nodiscard]] static bool AppendAndTranslateEntities(
 161       const nsAString& aStr, nsAString& aOutputStr,
 162       const uint8_t aEntityTable[], uint16_t aMaxTableIndex,
 163       const char* const aStringTable[]);
 164
 165  protected:
 166   /**
 167    * Helper for calling AppendAndTranslateEntities in a way that guarantees we
 168    * don't mess up our aEntityTable sizing.  This is a bit more complicated than
 169    * it could be, becaue sometimes we don't want to use all of aEntityTable, so
 170    * we have to allow passing the amount to use independently.  But we can
 171    * statically ensure it's not too big.
 172    *
 173    * The first integer template argument, which callers need to specify
 174    * explicitly, is the index of the last entry in aEntityTable that should be
 175    * considered for encoding as an entity reference.  The second integer
 176    * argument will be deduced from the actual table passed in.
 177    *
 178    * aEntityTable contains as values indices into aStringTable.  Those represent
 179    * the strings that should be used to replace the characters that are used to
 180    * index into aEntityTable.  aStringTable[0] should be nullptr, and characters
 181    * that do not need replacement should map to 0 in aEntityTable.
 182    */
 183   template <uint16_t LargestIndex, uint16_t TableLength>
 184   [[nodiscard]] bool AppendAndTranslateEntities(
 185       const nsAString& aStr, nsAString& aOutputStr,
 186       const uint8_t (&aEntityTable)[TableLength],
 187       const char* const aStringTable[]) {
 188     static_assert(LargestIndex < TableLength,
 189                   "Largest allowed index must be smaller than table length");
 190     return AppendAndTranslateEntities(aStr, aOutputStr, aEntityTable,
 191                                       LargestIndex, aStringTable);
 192   }
 193
 194   /**
 195    * Max index that can be used with some of our entity tables.
 196    */
 197   static const uint16_t kGTVal = 62;
 198
 199   /**
 200    * retrieve the text content of the node and append it to the given string
 201    * It doesn't increment the column position
 202    */
 203   nsresult AppendTextData(nsIContent* aNode, int32_t aStartOffset,
 204                           int32_t aEndOffset, nsAString& aStr,
 205                           bool aTranslateEntities);
 206
 207   virtual nsresult PushNameSpaceDecl(const nsAString& aPrefix,
 208                                      const nsAString& aURI, nsIContent* aOwner);
 209   void PopNameSpaceDeclsFor(nsIContent* aOwner);
 210
 211   /**
 212    * The problem that ConfirmPrefix fixes is that anyone can insert nodes
 213    * through the DOM that have a namespace URI and a random or empty or
 214    * previously existing prefix that's totally unrelated to the prefixes
 215    * declared at that point through xmlns attributes.  So what ConfirmPrefix
 216    * does is ensure that we can map aPrefix to the namespace URI aURI (for
 217    * example, that the prefix is not already mapped to some other namespace).
 218    * aPrefix will be adjusted, if necessary, so the value of the prefix
 219    * _after_ this call is what should be serialized.
 220    * @param aPrefix the prefix that may need adjusting
 221    * @param aURI the namespace URI we want aPrefix to point to
 222    * @param aElement the element we're working with (needed for proper default
 223    *                 namespace handling)
 224    * @param aIsAttribute true if we're confirming a prefix for an attribute.
 225    * @return true if we need to push the (prefix, uri) pair on the namespace
 226    *                 stack (note that this can happen even if the prefix is
 227    *                 empty).
 228    */
 229   bool ConfirmPrefix(nsAString& aPrefix, const nsAString& aURI,
 230                      nsIContent* aElement, bool aIsAttribute);
 231   /**
 232    * GenerateNewPrefix generates a new prefix and writes it to aPrefix
 233    */
 234   void GenerateNewPrefix(nsAString& aPrefix);
 235
 236   uint32_t ScanNamespaceDeclarations(mozilla::dom::Element* aContent,
 237                                      mozilla::dom::Element* aOriginalElement,
 238                                      const nsAString& aTagNamespaceURI);
 239
 240   [[nodiscard]] virtual bool SerializeAttributes(
 241       mozilla::dom::Element* aContent, mozilla::dom::Element* aOriginalElement,
 242       nsAString& aTagPrefix, const nsAString& aTagNamespaceURI,
 243       nsAtom* aTagName, nsAString& aStr, uint32_t aSkipAttr, bool aAddNSAttr);
 244
 245   [[nodiscard]] bool SerializeAttr(const nsAString& aPrefix,
 246                                    const nsAString& aName,
 247                                    const nsAString& aValue, nsAString& aStr,
 248                                    bool aDoEscapeEntities);
 249
 250   bool IsJavaScript(nsIContent* aContent, nsAtom* aAttrNameAtom,
 251                     int32_t aAttrNamespaceID, const nsAString& aValueString);
 252
 253   /**
 254    * This method can be redefined to check if the element can be serialized.
 255    * It is called when the serialization of the start tag is asked
 256    * (AppendElementStart)
 257    * In this method you can also force the formating
 258    * by setting aForceFormat to true.
 259    * @return boolean  true if the element can be output
 260    */
 261   virtual bool CheckElementStart(mozilla::dom::Element* aElement,
 262                                  bool& aForceFormat, nsAString& aStr,
 263                                  nsresult& aResult);
 264
 265   /**
 266    * This method is responsible for appending the '>' at the end of the start
 267    * tag, possibly preceded by '/' and maybe a ' ' before that too.
 268    *
 269    * aElement and aOriginalElement are the same as the corresponding arguments
 270    * to AppendElementStart.
 271    */
 272   [[nodiscard]] bool AppendEndOfElementStart(
 273       mozilla::dom::Element* aEleemnt, mozilla::dom::Element* aOriginalElement,
 274       nsAString& aStr);
 275
 276   /**
 277    * This method can be redefine to serialize additional things just after
 278    * the serialization of the start tag.
 279    * (called at the end of AppendElementStart)
 280    */
 281   [[nodiscard]] virtual bool AfterElementStart(nsIContent* aContent,
 282                                                nsIContent* aOriginalElement,
 283                                                nsAString& aStr) {
 284     return true;
 285   };
 286
 287   /**
 288    * This method can be redefined to check if the element can be serialized.
 289    * It is called when the serialization of the end tag is asked
 290    * (AppendElementEnd)
 291    * In this method you can also force the formating
 292    * by setting aForceFormat to true.
 293    * @return boolean  true if the element can be output
 294    */
 295   virtual bool CheckElementEnd(mozilla::dom::Element* aElement,
 296                                mozilla::dom::Element* aOriginalElement,
 297                                bool& aForceFormat, nsAString& aStr);
 298
 299   /**
 300    * This method can be redefine to serialize additional things just after
 301    * the serialization of the end tag.
 302    * (called at the end of AppendElementStart)
 303    */
 304   virtual void AfterElementEnd(nsIContent* aContent, nsAString& aStr) {};
 305
 306   /**
 307    * Returns true if a line break should be inserted before an element open tag
 308    */
 309   virtual bool LineBreakBeforeOpen(int32_t aNamespaceID, nsAtom* aName);
 310
 311   /**
 312    * Returns true if a line break should be inserted after an element open tag
 313    */
 314   virtual bool LineBreakAfterOpen(int32_t aNamespaceID, nsAtom* aName);
 315
 316   /**
 317    * Returns true if a line break should be inserted after an element close tag
 318    */
 319   virtual bool LineBreakBeforeClose(int32_t aNamespaceID, nsAtom* aName);
 320
 321   /**
 322    * Returns true if a line break should be inserted after an element close tag
 323    */
 324   virtual bool LineBreakAfterClose(int32_t aNamespaceID, nsAtom* aName);
 325
 326   /**
 327    * add intendation. Call only in the case of formating and if the current
 328    * position is at 0. It updates the column position.
 329    */
 330   [[nodiscard]] bool AppendIndentation(nsAString& aStr);
 331
 332   [[nodiscard]] bool IncrIndentation(nsAtom* aName);
 333   void DecrIndentation(nsAtom* aName);
 334
 335   // Functions to check for newlines that needs to be added between nodes in
 336   // the root of a document. See mAddNewlineForRootNode
 337   [[nodiscard]] bool MaybeAddNewlineForRootNode(nsAString& aStr);
 338   void MaybeFlagNewlineForRootNode(nsINode* aNode);
 339
 340   // Functions to check if we enter in or leave from a preformated content
 341   virtual void MaybeEnterInPreContent(nsIContent* aNode);
 342   virtual void MaybeLeaveFromPreContent(nsIContent* aNode);
 343
 344   bool ShouldMaintainPreLevel() const;
 345   int32_t PreLevel() const {
 346     MOZ_ASSERT(ShouldMaintainPreLevel());
 347     return mPreLevel;
 348   }
 349   int32_t& PreLevel() {
 350     MOZ_ASSERT(ShouldMaintainPreLevel());
 351     return mPreLevel;
 352   }
 353
 354   bool MaybeSerializeIsValue(mozilla::dom::Element* aElement, nsAString& aStr);
 355
 356   int32_t mPrefixIndex;
 357
 358   struct NameSpaceDecl {
 359     nsString mPrefix;
 360     nsString mURI;
 361     nsIContent* mOwner;
 362   };
 363
 364   nsTArray<NameSpaceDecl> mNameSpaceStack;
 365
 366   // nsIDocumentEncoder flags
 367   MOZ_INIT_OUTSIDE_CTOR uint32_t mFlags;
 368
 369   // characters to use for line break
 370   nsString mLineBreak;
 371
 372   // The charset that was passed to Init()
 373   nsCString mCharset;
 374
 375   // current column position on the current line
 376   uint32_t mColPos;
 377
 378   // true = pretty formating should be done (OutputFormated flag)
 379   MOZ_INIT_OUTSIDE_CTOR bool mDoFormat;
 380
 381   // true = no formatting,(OutputRaw flag)
 382   // no newline convertion and no rewrap long lines even if OutputWrap is set.
 383   MOZ_INIT_OUTSIDE_CTOR bool mDoRaw;
 384
 385   // true = wrapping should be done (OutputWrap flag)
 386   MOZ_INIT_OUTSIDE_CTOR bool mDoWrap;
 387
 388   // true = we can break lines (OutputDisallowLineBreaking flag)
 389   MOZ_INIT_OUTSIDE_CTOR bool mAllowLineBreaking;
 390
 391   // number of maximum column in a line, in the wrap mode
 392   MOZ_INIT_OUTSIDE_CTOR uint32_t mMaxColumn;
 393
 394   // current indent value
 395   nsString mIndent;
 396
 397   // this is the indentation level after the indentation reached
 398   // the maximum length of indentation
 399   int32_t mIndentOverflow;
 400
 401   // says if the indentation has been already added on the current line
 402   bool mIsIndentationAddedOnCurrentLine;
 403
 404   // the string which is currently added is in an attribute
 405   bool mInAttribute;
 406
 407   // true = a newline character should be added. It's only
 408   // useful when serializing root nodes. see MaybeAddNewlineForRootNode and
 409   // MaybeFlagNewlineForRootNode
 410   bool mAddNewlineForRootNode;
 411
 412   // Indicates that a space will be added if and only if content is
 413   // continued on the same line while serializing source.  Otherwise,
 414   // the newline character acts as the whitespace and no space is needed.
 415   // used when mDoFormat = true
 416   bool mAddSpace;
 417
 418   // says that if the next string to add contains a newline character at the
 419   // begining, then this newline character should be ignored, because a
 420   // such character has already been added into the output string
 421   bool mMayIgnoreLineBreakSequence;
 422
 423   bool mBodyOnly;
 424   int32_t mInBody;
 425
 426   // Non-owning.
 427   nsAString* mOutput;
 428
 429  private:
 430   // number of nested elements which have preformated content
 431   MOZ_INIT_OUTSIDE_CTOR int32_t mPreLevel;
 432
 433   static const uint8_t kEntities[];
 434   static const uint8_t kAttrEntities[];
 435   static const char* const kEntityStrings[];
 436 };
 437
 438 nsresult NS_NewXMLContentSerializer(nsIContentSerializer** aSerializer);
 439
 440 #endif