Shared Keys

FLSharedKeys represents a mapping from short strings to small integers in the range [0...2047]. More...

Typedefs
typedef bool(*	FLSharedKeysReadCallback) (void *context, FLSharedKeys)
typedef struct _FLSharedKeyScope *	FLSharedKeyScope

Functions
FLSharedKeys	FLSharedKeys_New (void)
	Creates a new empty FLSharedKeys object, which must eventually be released. More...
FLSharedKeys	FLSharedKeys_NewWithRead (FLSharedKeysReadCallback, void *context)
FLSliceResult	FLSharedKeys_GetStateData (FLSharedKeys)
	Returns a data blob containing the current state (all the keys and their integers.) More...
bool	FLSharedKeys_LoadStateData (FLSharedKeys, FLSlice)
	Updates an FLSharedKeys with saved state data created by FLSharedKeys_GetStateData. More...
void	FLSharedKeys_WriteState (FLSharedKeys, FLEncoder)
	Writes the current state to a Fleece encoder as a single value, which can later be decoded and passed to FLSharedKeys_LoadState. More...
bool	FLSharedKeys_LoadState (FLSharedKeys, FLValue)
	Updates an FLSharedKeys object with saved state, a Fleece value previously written by FLSharedKeys_WriteState. More...
int	FLSharedKeys_Encode (FLSharedKeys, FLString, bool add)
	Maps a key string to a number in the range [0...2047], or returns -1 if it isn't mapped. More...
FLString	FLSharedKeys_Decode (FLSharedKeys, int key)
	Returns the key string that maps to the given integer key, else NULL. More...
unsigned	FLSharedKeys_Count (FLSharedKeys)
	Returns the number of keys in the mapping. More...
void	FLSharedKeys_RevertToCount (FLSharedKeys, unsigned oldCount)
	Reverts an FLSharedKeys by "forgetting" any keys added since it had the count oldCount. More...
FLSharedKeys	FLSharedKeys_Retain (FLSharedKeys)
	Increments the reference count of an FLSharedKeys. More...
void	FLSharedKeys_Release (FLSharedKeys)
	Decrements the reference count of an FLSharedKeys, freeing it when it reaches zero. More...
FLSharedKeyScope	FLSharedKeyScope_WithRange (FLSlice range, FLSharedKeys)
void	FLSharedKeyScope_Free (FLSharedKeyScope)

Detailed Description

FLSharedKeys represents a mapping from short strings to small integers in the range [0...2047].

It's used by FLDict to abbreviate dictionary keys. A shared key can be stored in a fixed two bytes and is faster to compare against. However, the same mapping has to be used when encoding and when accessing the Dict.

To use shared keys: Call FLSharedKeys_New to create a new empty mapping. After creating an FLEncoder, call FLEncoder_SetSharedKeys so dictionary keys will be added to the mapping and written in integer form. When loading Fleece data, use FLDoc_FromResultData and pass the FLSharedKeys as a parameter. Save the mapping somewhere by calling FLSharedKeys_GetStateData or FLSharedKeys_WriteState. You can later reconstitute the mapping by calling FLSharedKeys_LoadStateData or FLSharedKeys_LoadState on a new empty instance.

Typedef Documentation

FLSharedKeyScope

typedef struct _FLSharedKeyScope* FLSharedKeyScope

FLSharedKeysReadCallback

typedef bool(* FLSharedKeysReadCallback) (void *context, FLSharedKeys)

Function Documentation

FLSharedKeys_Count()

unsigned FLSharedKeys_Count

(

FLSharedKeys

)

Returns the number of keys in the mapping.

This number increases whenever the mapping is changed, and never decreases.

FLSharedKeys_Decode()

FLString FLSharedKeys_Decode	(	FLSharedKeys	,
		int	key
	)

Returns the key string that maps to the given integer key, else NULL.

FLSharedKeys_Encode()

int FLSharedKeys_Encode	(	FLSharedKeys	,
		FLString	,
		bool	add
	)

Maps a key string to a number in the range [0...2047], or returns -1 if it isn't mapped.

If the key doesn't already have a mapping, and the add flag is true, a new mapping is assigned and returned. However, the add flag has no effect if the key is unmappable (is longer than 16 bytes or contains non-identifier characters), or if all available integers have been assigned.

FLSharedKeys_GetStateData()

FLSliceResult FLSharedKeys_GetStateData

(

FLSharedKeys

)

Returns a data blob containing the current state (all the keys and their integers.)

FLSharedKeys_LoadState()

bool FLSharedKeys_LoadState	(	FLSharedKeys	,
		FLValue
	)

Updates an FLSharedKeys object with saved state, a Fleece value previously written by FLSharedKeys_WriteState.

FLSharedKeys_LoadStateData()

bool FLSharedKeys_LoadStateData	(	FLSharedKeys	,
		FLSlice
	)

Updates an FLSharedKeys with saved state data created by FLSharedKeys_GetStateData.

FLSharedKeys_New()

FLSharedKeys FLSharedKeys_New

(

void

)

Creates a new empty FLSharedKeys object, which must eventually be released.

FLSharedKeys_NewWithRead()

FLSharedKeys FLSharedKeys_NewWithRead	(	FLSharedKeysReadCallback	,
		void *	context
	)

FLSharedKeys_Release()

void FLSharedKeys_Release

(

FLSharedKeys

)

Decrements the reference count of an FLSharedKeys, freeing it when it reaches zero.

FLSharedKeys_Retain()

FLSharedKeys FLSharedKeys_Retain

(

FLSharedKeys

)

Increments the reference count of an FLSharedKeys.

FLSharedKeys_RevertToCount()

void FLSharedKeys_RevertToCount	(	FLSharedKeys	,
		unsigned	oldCount
	)

Reverts an FLSharedKeys by "forgetting" any keys added since it had the count oldCount.

FLSharedKeys_WriteState()

void FLSharedKeys_WriteState	(	FLSharedKeys	,
		FLEncoder
	)

Writes the current state to a Fleece encoder as a single value, which can later be decoded and passed to FLSharedKeys_LoadState.

FLSharedKeyScope_Free()

void FLSharedKeyScope_Free

(

FLSharedKeyScope

)

FLSharedKeyScope_WithRange()

FLSharedKeyScope FLSharedKeyScope_WithRange	(	FLSlice	range,
		FLSharedKeys
	)