![[Index]](../../../../a_stock/images/btn_index.gif)
![[Previous]](../../../../a_stock/images/btn_prev_top.gif)
![[Next]](../../../../a_stock/images/btn_next_top.gif)
|
|
|
|
|
|
||
class CBNFParser : public CBase, public MDataProviderObserver;
Base class for parsers that use a BNF tree to parse an input stream.
The BNF tree form used is a variation on Extended BNF described in the XML1.0 specification. The general form of the tree is as follows:
Each node in the tree defines a rule that the input stream must meet to satisfy the grammar.
1. a node type is set to the rule type, as defined in TParserNodeTypes
2. node data stores any string required by the rule: e.g. for a comparison rule, the string to match against
3. the parser allows callback functions to be called either before or after the rule is processed. If these are present, they are stored as attributes of the node.
4. some rules allow sub-rules: for example, the AND rule expects a number of sub-rules, all of which must be successful if the AND rule itself is to succeed. Each sub-rule is represented as a child node of the parent rule. Sub-rules in turn can have sub-rules.
5. reference rule nodes are also allowed: these do not define themselves rules, but direct the parser to another rule. They can link rules to each other and so build rule sequences more complex than a simple tree.
All the top-level rules are stored as attributes of the root node. The attribute type is a string that names the rule; the attribute value is a pointer to the node that implements the rule.
The class supplies functions that encapsulate adding rules appropriately to the tree. The parser provider creates a derived
class that implements the virtual method CBNFParser::TreeL() that uses these functions to create a BNF rule tree.
The user of the parser initialises the parser with CBNFParser::ResetL(), and then passes input data to the parser using ProcessData(). The parser supports partial parsing: the input stream does
not have to completed before parsing can begin. As soon as data is added, the parser attempts to parse it.
MDataProviderObserver - MDataProviderObserver provides a virtual interface for any class to observe any ...
CBase -
Base class for all classes to be instantiated on the heap.
CBNFParser - Base class for parsers that use a BNF tree to parse an input stream.
Defined in CBNFParser:
AddComponentAttributeL(CBNFNode &,CBNFNodeAttributeType,TInt)Adds an additional attribute to an existing rule node.AddRuleCallbackL(CBNFNode &,const TDesC *,TRuleCallback *)Adds a callback to a rule.AttributeLUT()constGets the attribute look-up table used by this parser.CBNFParser(CAttributeLookupTable &)Constructor.CRuleStackDefines a type to handle a stack of rules. CommitL()Notifies the parser that all the data has been passed in.CurrentRule()Gets a pointer to the rule node currently being processed. DeleteMark()Removes the latest mark. All the marks are stored in a stack and this removes th...EndConditional(TParserNodeTypes,TBool)ExecutePostRuleCallbackL(CBNFNode &)Executes a post-rule callback function.ExecutePreRuleCallbackL(CBNFNode &)Executes a pre-rule callback function.MDataProviderObserverReserved1()Intended Usage : Reserved for future expansion. MDataProviderObserverReserved2()Intended Usage : Reserved for future expansion. Mark()Set a mark to the current position of the input stream.MarkCallback(CBNFParser &)Inserts a mark to the current position of the stream being processed.MarkedL()Get string between the "cursor position" and the latest mark on the st...MarkedWithInitialTextL(const TDesC &)Gets the marked string with a string added before the mached string. NewBNFL()Creates a new rule tree root node.NewComponentL(CBNFNode &,TParserNodeTypes,HBufC *,TRuleCallback *,TRuleCallback *)Creates a new sub-rule, and makes it a child of a specified parent rule.NewComponentL(CBNFNode &,TParserNodeTypes,const TDesC &)Creates a new sub-rule, and makes it a child of a specified parent rule.NewComponentL(CBNFNode *,CBNFNode &,const TDesC &)Creates a new reference rule node, and adds it as a child of the specified paren...NewComponentL(CBNFNode *,const TDesC &)Creates a new reference rule node.NewComponentL(TParserNodeTypes,HBufC *,TRuleCallback *,TRuleCallback *)Creates a new rule node, but does not add it to the tree.NewComponentL(TParserNodeTypes,const TDesC &)Creates a new rule node, but does not add it to the tree.NewL(CAttributeLookupTable &)Allocates and constructs a new BNF parser.NewRuleL(CBNFNode *,const TDesC &,TParserNodeTypes,HBufC *,TRuleCallback *,TRuleCallback *)Creates a new rule node and adds it to the root of the rule tree.NewRuleL(CBNFNode *,const TDesC &,TParserNodeTypes,const TDesC &,TRuleCallback *,TRuleCallback *)Creates a new rule node and adds it to the root of the rule tree.OptionalMatched()constTests if an Optional node sub-rule matched.ParseL()ProcessDataL(HBufC8 &)Called by the data provider to add data for the parser to process.ResetL()Reset the parser to a state where it can accept and parse new input.RuleMatched()constTests if the used rule matched.SetBaseUriL(const TDesC *)Intended Usage : Set the URI that the DataProvider considers the base URI for th...SetDataExpected(TInt)Intended Usage : The report of how many bytes of data is expected to be passed t...SetDocumentTypeL(const TDesC &)Intended Usage : The request to construct a CDataHandler to process data of aDat...SetDocumentTypeL(const TDesC &,const TDesC &)Intended Usage : The request to construct a CDataHandler for aDataType with non ...SetState(TParseState)Sets the parser state.SetStatus(TInt)Called by the data provider to report its status to its observer.StartConditional(TParserNodeTypes)State()constGet the current state of the parser. StringL()constConcatenates the rest of the input stream (which hasn't yet been processed) into...TRuleCallbackType definition for a callback function pointer Callback functions need to get a...TreeL()Valid()constChecks if the input stream was completely processed iCurrentRuleThe BNF rule that is currently being processed. iLUTStorage object for all the attributes and identifiers in a tree iMatchedInput stream matched rule flag. iMoreCountStores attribute identifier for nmore count attributes. iMoreMaximumStores attribute identifier for nmore maximum attributes. iMoreMinimumStores attribute identifier for nmore minimum attributes. iOptionalMatchedFlag that indicates when returning to a rule in the rulestack if an optional rul...iParsingParser state. iPostRuleCallbackStores attribute identifier for post-rule callback attributes. iPreRuleCallbackStores attribute identifier for pre-rule callback attributes. iRangeEndStores attribute identifier for range end attributes. iRangeStartStores attribute identifier for range start attributes. iReferenceStringStores attribute identifier for reference string attributes. iRuleStackA stack of rules from iTree which are waiting to be completed. The stack basical...iStringAn utility object which stores all the buffers passed into the parser and repres...iStringCompleteFlag indicating if the input stream has been completely processed. iSubRuleThe child rule we are returning from (if any). If this is NULL we are new to thi...iSubRuleMatchedFlag that indicates when returning to a rule in the rulestack if the child rule ...iTreeThe BNF tree the parser is using to parse the input stream. ~CBNFParser()Destructor. Inherited from CBase:
Delete(CBase *)Deletes the specified object.Extension_(TUint,TAny *&,TAny *)Extension function operator new(TUint)Allocates the object from the heap and then initialises its contents to binary z...operator new(TUint,TAny *)Initialises the object to binary zeroes.operator new(TUint,TLeave)Allocates the object from the heap and then initialises its contents to binary z...operator new(TUint,TLeave,TUint)Allocates the object from the heap and then initialises its contents to binary z...operator new(TUint,TUint)Allocates the object from the heap and then initialises its contents to binary z...IMPORT_C static CBNFParser* NewL(CAttributeLookupTable &aLUT);
Allocates and constructs a new BNF parser.
|
|
protected: IMPORT_C CBNFParser(CAttributeLookupTable &aLUT);
Constructor.
|
|
|
IMPORT_C virtual void ResetL();
Reset the parser to a state where it can accept and parse new input.
If no BNF tree yet exists the virtual method CBNFParser::TreeL() is called to obtain the BNF tree for this parser. Any existing state of parsing and input data is destroyed.
inline TBool Valid() const;
Checks if the input stream was completely processed
|
inline HBufC* StringL() const;
Concatenates the rest of the input stream (which hasn't yet been processed) into a single string. The ownership of the string is given to the caller.
|
inline CBNFNode* CurrentRule();
Gets a pointer to the rule node currently being processed.
|
inline void Mark();
Set a mark to the current position of the input stream.
The mark acts as a tag in the stream currently being processed. As we process further along the stream after adding the mark, we can perform a rollback to the most previously set mark and start processing again (e.g. OR rule works this way). The string fragments won't be consumed (deleted) until all the marks on a fragment (and fragments before that) are deleted.
inline HBufC* MarkedL();
Get string between the "cursor position" and the latest mark on the stream.
|
inline HBufC* MarkedWithInitialTextL(const TDesC &aInitialText);
Gets the marked string with a string added before the mached string.
|
|
![[Top]](../../../../a_stock/images/arrow_up_2.gif){kind=icon}
CBNFParser::MarkedL()Get string between the "cursor position" and the latest mark on the st...inline void DeleteMark();
Removes the latest mark. All the marks are stored in a stack and this removes the topmost mark.
inline TBool RuleMatched() const;
Tests if the used rule matched.
This is typically used in post-rule callbacks.
|
inline TBool OptionalMatched() const;
Tests if an Optional node sub-rule matched.
|
IMPORT_C CBNFNode* NewBNFL();
Creates a new rule tree root node.
It creates a new single instance of CBNFNode as the root node of the rule tree. All the top-level rules are attached as attributes to this node. The root node should
have single child node, which should be a reference to the logical root of the rule tree. This can be done be attaching the
logical root rule as a component to the root rule.
|
IMPORT_C CBNFNode& NewRuleL(CBNFNode *aRootRule, const TDesC &aRuleName, TParserNodeTypes aRuleType, HBufC *aData, TRuleCallback
*aPreRule, TRuleCallback *aPostRule);
Creates a new rule node and adds it to the root of the rule tree.
This overload takes ownership of the node data.
|
|
IMPORT_C CBNFNode& NewRuleL(CBNFNode *aRootRule, const TDesC &aRuleName, TParserNodeTypes aRuleType, const TDesC &aData, TRuleCallback
*aPreRule, TRuleCallback *aPostRule);
Creates a new rule node and adds it to the root of the rule tree.
This overload takes a reference to the node data instead of owning it.
|
|
IMPORT_C CBNFNode* NewComponentL(TParserNodeTypes aRuleType, const TDesC &aData);
Creates a new rule node, but does not add it to the tree.
This overload sets no rule callbacks.
|
|
IMPORT_C CBNFNode* NewComponentL(TParserNodeTypes aRuleType, HBufC *aData=0, TRuleCallback *aPreRule=0, TRuleCallback *aPostRule=0);
Creates a new rule node, but does not add it to the tree.
This overload allows rule callbacks to be set.
|
|
IMPORT_C CBNFNode* NewComponentL(CBNFNode *aRootRule, const TDesC &aRuleName);
Creates a new reference rule node.
|
|
IMPORT_C CBNFNode& NewComponentL(CBNFNode &aParentRule, TParserNodeTypes aRuleType, const TDesC &aData);
Creates a new sub-rule, and makes it a child of a specified parent rule.
This overload sets no rule callbacks.
|
|
IMPORT_C CBNFNode& NewComponentL(CBNFNode &aParentRule, TParserNodeTypes aRuleType, HBufC *aData=0, TRuleCallback *aPreRule=0,
TRuleCallback *aPostRule=0);
Creates a new sub-rule, and makes it a child of a specified parent rule.
This overload sets rule callbacks.
|
|
IMPORT_C CBNFNode& NewComponentL(CBNFNode *aRootRule, CBNFNode &aParentRule, const TDesC &aRuleName);
Creates a new reference rule node, and adds it as a child of the specified parent.
Note that the function succeeds even if the target rule aRuleName does not yet exist.
|
|
IMPORT_C void AddComponentAttributeL(CBNFNode &aRule, CBNFNodeAttributeType aAttribute, TInt aInt);
Adds an additional attribute to an existing rule node.
For example, this is used with range rules, which specify the range boundaries using start and end attributes.
|
IMPORT_C virtual void ProcessDataL(HBufC8 &aData);
Called by the data provider to add data for the parser to process.
This implements MDataProviderObserver::ProcessDataL(HBufC8 &).
|
IMPORT_C virtual void SetStatus(TInt aStatus=KErrNone);
Called by the data provider to report its status to its observer.
This implements MDataProviderObserver::SetStatus(TInt).
|
IMPORT_C virtual void SetDocumentTypeL(const TDesC &);
Intended Usage : The request to construct a CDataHandler to process data of aDataType, where aDataType is a string to match against some plugins declared data handling ability.
|
IMPORT_C virtual void SetDocumentTypeL(const TDesC &, const TDesC &);
Intended Usage : The request to construct a CDataHandler for aDataType with non default document encoding where aDataType is a string to match against some plugins declared data handling ability.
|
IMPORT_C virtual void SetDataExpected(TInt);
Intended Usage : The report of how many bytes of data is expected to be passed to ProcessDataL, enabling age reporting capabilities.
|
IMPORT_C virtual void SetBaseUriL(const TDesC *aBaseUri);
Intended Usage : Set the URI that the DataProvider considers the base URI for the current data.
|
IMPORT_C virtual void MDataProviderObserverReserved1();
Intended Usage : Reserved for future expansion.
IMPORT_C virtual void MDataProviderObserverReserved2();
Intended Usage : Reserved for future expansion.
IMPORT_C void CommitL();
Notifies the parser that all the data has been passed in.
It causes the parser to parse any of the input stream not already parsed.
inline TParseState State() const;
Get the current state of the parser.
|
protected: IMPORT_C virtual TBool ReferenceL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes a reference rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual TBool ExactL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an EExact rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual TBool RangeL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an ERange rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual TBool SelectL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an ESelect rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
if (aMatched == CFragmentedString::EMatch)
|
|
protected: IMPORT_C virtual TBool WithoutL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an EWithout rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual TBool AndL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an EAnd rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
performedMatch = ETrue;
|
|
protected: IMPORT_C virtual TBool OrL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an EOr rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual TBool OptionalL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
|
|
protected: IMPORT_C virtual TBool NMoreL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Processes an ENMore rule node.
It is called by CBNFParser::PerformRuleL(CBNFNode &,CFragmentedString::TStringMatch &).
|
|
protected: IMPORT_C virtual void AddRuleCallbackL(CBNFNode &aRule, const TDesC *aCallbackID, TRuleCallback *aCallback);
Adds a callback to a rule.
|
protected: IMPORT_C virtual void ExecutePreRuleCallbackL(CBNFNode &aRule);
Executes a pre-rule callback function.
|
protected: IMPORT_C virtual void ExecutePostRuleCallbackL(CBNFNode &aRule);
Executes a post-rule callback function.
|
protected: IMPORT_C virtual void StartConditional(TParserNodeTypes aRuleType);
|
protected: IMPORT_C virtual void EndConditional(TParserNodeTypes aRuleType, TBool aSuccess);
|
protected: IMPORT_C static void MarkCallback(CBNFParser &aParser);
Inserts a mark to the current position of the stream being processed.
Adding a mark is a very common callback operation before starting to process a rule, so the method is provided by the parser.
|
protected: IMPORT_C CAttributeLookupTable& AttributeLUT() const;
Gets the attribute look-up table used by this parser.
|
protected: IMPORT_C virtual TBool PerformRuleL(CBNFNode &aRule, CFragmentedString::TStringMatch &aMatched);
Handles a node in the rule tree.
It calls the appropriate handler method for the rule type.
|
|
protected: inline void SetState(TParseState aState);
Sets the parser state.
|
|
|
protected: typedef CStack<CBNFNode, EFalse> CBNFParser::CRuleStack;
Defines a type to handle a stack of rules.
protected: typedef void( CBNFParser::TRuleCallback)(CBNFParser&);
Type definition for a callback function pointer Callback functions need to get a reference to the parser as parameter and they need to be static.
|
|
protected: CAttributeLookupTable & iLUT;
Storage object for all the attributes and identifiers in a tree
protected: CFragmentedString iString;
An utility object which stores all the buffers passed into the parser and represents them as if they would form a single, continuous string. This class also performs the actual physical matching/selection of the strings and holds the marks set onto the string.
protected: TBool iStringComplete;
Flag indicating if the input stream has been completely processed.
protected: CBNFNode * iTree;
The BNF tree the parser is using to parse the input stream.
protected: CRuleStack iRuleStack;
A stack of rules from iTree which are waiting to be completed. The stack basically holds the path along the rule tree.
protected: TBool iSubRuleMatched;
Flag that indicates when returning to a rule in the rulestack if the child rule matched correctly.
protected: TBool iOptionalMatched;
Flag that indicates when returning to a rule in the rulestack if an optional rule matched correctly.
protected: CBNFNode * iSubRule;
The child rule we are returning from (if any). If this is NULL we are new to this BNF rule.
protected: const TDesC * iReferenceString;
Stores attribute identifier for reference string attributes.
protected: const TDesC * iRangeStart;
Stores attribute identifier for range start attributes.
protected: const TDesC * iRangeEnd;
Stores attribute identifier for range end attributes.
protected: const TDesC * iMoreMinimum;
Stores attribute identifier for nmore minimum attributes.
protected: const TDesC * iMoreCount;
Stores attribute identifier for nmore count attributes.
protected: const TDesC * iMoreMaximum;
Stores attribute identifier for nmore maximum attributes.
protected: const TDesC * iPreRuleCallback;
Stores attribute identifier for pre-rule callback attributes.
protected: const TDesC * iPostRuleCallback;
Stores attribute identifier for post-rule callback attributes.
|
Copyright © 2005-2008 Symbian Software Ltd. |
|
![[Previous]](../../../../a_stock/images/btn_prev.gif)
![[Top]](../../../../a_stock/images/btn_top.gif)
![[Next]](../../../../a_stock/images/btn_next.gif)