From 487e15dc239ccdb3344d1c99ce120e872bab4a74 Mon Sep 17 00:00:00 2001 From: Hans-Christoph Steiner Date: Thu, 20 Sep 2012 18:34:38 -0400 Subject: Imported Upstream version 2.0.6 --- src/callback.c | 89 +++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 54 insertions(+), 35 deletions(-) (limited to 'src/callback.c') diff --git a/src/callback.c b/src/callback.c index ce84908..a515e05 100644 --- a/src/callback.c +++ b/src/callback.c @@ -223,38 +223,57 @@ CollSeq *sqlite3FindCollSeq( ** that uses encoding enc. The value returned indicates how well the ** request is matched. A higher value indicates a better match. ** +** If nArg is -1 that means to only return a match (non-zero) if p->nArg +** is also -1. In other words, we are searching for a function that +** takes a variable number of arguments. +** +** If nArg is -2 that means that we are searching for any function +** regardless of the number of arguments it uses, so return a positive +** match score for any +** ** The returned value is always between 0 and 6, as follows: ** -** 0: Not a match, or if nArg<0 and the function is has no implementation. -** 1: A variable arguments function that prefers UTF-8 when a UTF-16 -** encoding is requested, or vice versa. -** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is -** requested, or vice versa. -** 3: A variable arguments function using the same text encoding. -** 4: A function with the exact number of arguments requested that -** prefers UTF-8 when a UTF-16 encoding is requested, or vice versa. -** 5: A function with the exact number of arguments requested that -** prefers UTF-16LE when UTF-16BE is requested, or vice versa. -** 6: An exact match. +** 0: Not a match. +** 1: UTF8/16 conversion required and function takes any number of arguments. +** 2: UTF16 byte order change required and function takes any number of args. +** 3: encoding matches and function takes any number of arguments +** 4: UTF8/16 conversion required - argument count matches exactly +** 5: UTF16 byte order conversion required - argument count matches exactly +** 6: Perfect match: encoding and argument count match exactly. ** +** If nArg==(-2) then any function with a non-null xStep or xFunc is +** a perfect match and any function with both xStep and xFunc NULL is +** a non-match. */ -static int matchQuality(FuncDef *p, int nArg, u8 enc){ - int match = 0; - if( p->nArg==-1 || p->nArg==nArg - || (nArg==-1 && (p->xFunc!=0 || p->xStep!=0)) - ){ +#define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */ +static int matchQuality( + FuncDef *p, /* The function we are evaluating for match quality */ + int nArg, /* Desired number of arguments. (-1)==any */ + u8 enc /* Desired text encoding */ +){ + int match; + + /* nArg of -2 is a special case */ + if( nArg==(-2) ) return (p->xFunc==0 && p->xStep==0) ? 0 : FUNC_PERFECT_MATCH; + + /* Wrong number of arguments means "no match" */ + if( p->nArg!=nArg && p->nArg>=0 ) return 0; + + /* Give a better score to a function with a specific number of arguments + ** than to function that accepts any number of arguments. */ + if( p->nArg==nArg ){ + match = 4; + }else{ match = 1; - if( p->nArg==nArg || nArg==-1 ){ - match = 4; - } - if( enc==p->iPrefEnc ){ - match += 2; - } - else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) || - (enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){ - match += 1; - } } + + /* Bonus points if the text encoding matches */ + if( enc==p->iPrefEnc ){ + match += 2; /* Exact encoding match */ + }else if( (enc & p->iPrefEnc & 2)!=0 ){ + match += 1; /* Both are UTF16, but with different byte orders */ + } + return match; } @@ -310,13 +329,12 @@ void sqlite3FuncDefInsert( ** ** If the createFlag argument is true, then a new (blank) FuncDef ** structure is created and liked into the "db" structure if a -** no matching function previously existed. When createFlag is true -** and the nArg parameter is -1, then only a function that accepts -** any number of arguments will be returned. +** no matching function previously existed. ** -** If createFlag is false and nArg is -1, then the first valid -** function found is returned. A function is valid if either xFunc -** or xStep is non-zero. +** If nArg is -2, then the first valid function found is returned. A +** function is valid if either xFunc or xStep is non-zero. The nArg==(-2) +** case is used to see if zName is a valid function name for some number +** of arguments. If nArg is -2, then createFlag must be 0. ** ** If createFlag is false, then a function with the required name and ** number of arguments may be returned even if the eTextRep flag does not @@ -328,14 +346,15 @@ FuncDef *sqlite3FindFunction( int nName, /* Number of characters in the name */ int nArg, /* Number of arguments. -1 means any number */ u8 enc, /* Preferred text encoding */ - int createFlag /* Create new entry if true and does not otherwise exist */ + u8 createFlag /* Create new entry if true and does not otherwise exist */ ){ FuncDef *p; /* Iterator variable */ FuncDef *pBest = 0; /* Best match found so far */ int bestScore = 0; /* Score of best match */ int h; /* Hash value */ - + assert( nArg>=(-2) ); + assert( nArg>=(-1) || createFlag==0 ); assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE ); h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a); @@ -381,7 +400,7 @@ FuncDef *sqlite3FindFunction( ** exact match for the name, number of arguments and encoding, then add a ** new entry to the hash table and return it. */ - if( createFlag && (bestScore<6 || pBest->nArg!=nArg) && + if( createFlag && bestScorezName = (char *)&pBest[1]; pBest->nArg = (u16)nArg; -- cgit v1.2.3