diff options
Diffstat (limited to 'src/window.c')
| -rw-r--r-- | src/window.c | 61 |
1 files changed, 60 insertions, 1 deletions
diff --git a/src/window.c b/src/window.c index bfb4ca119..94dc50e7c 100644 --- a/src/window.c +++ b/src/window.c @@ -191,7 +191,6 @@ struct NtileCtx { ** been coerced to: ** ** ROWS UNBOUNDED PRECEDING AND CURRENT ROW -** */ static void ntileStepFunc( sqlite3_context *pCtx, @@ -243,6 +242,59 @@ static void ntileValueFunc(sqlite3_context *pCtx){ } } +struct LastValueCtx { + sqlite3_value *pVal; + int nVal; +}; + +/* +** Implementation of last_value(). +*/ +static void last_valueStepFunc( + sqlite3_context *pCtx, + int nArg, + sqlite3_value **apArg +){ + struct LastValueCtx *p; + p = (struct LastValueCtx *)sqlite3_aggregate_context(pCtx, sizeof(*p)); + if( p ){ + sqlite3_value_free(p->pVal); + p->pVal = sqlite3_value_dup(apArg[0]); + p->nVal++; + } +} +static void last_valueInverseFunc( + sqlite3_context *pCtx, + int nArg, + sqlite3_value **apArg +){ + struct LastValueCtx *p; + p = (struct LastValueCtx *)sqlite3_aggregate_context(pCtx, sizeof(*p)); + if( p ){ + p->nVal--; + if( p->nVal==0 ){ + sqlite3_value_free(p->pVal); + p->pVal = 0; + } + } +} +static void last_valueValueFunc(sqlite3_context *pCtx){ + struct LastValueCtx *p; + p = (struct LastValueCtx *)sqlite3_aggregate_context(pCtx, sizeof(*p)); + if( p && p->pVal ){ + sqlite3_result_value(pCtx, p->pVal); + } +} +static void last_valueFinalizeFunc(sqlite3_context *pCtx){ + struct LastValueCtx *p; + p = (struct LastValueCtx *)sqlite3_aggregate_context(pCtx, sizeof(*p)); + if( p && p->pVal ){ + sqlite3_result_value(pCtx, p->pVal); + sqlite3_value_free(p->pVal); + p->pVal = 0; + } +} + static void nth_valueStepFunc( sqlite3_context *pCtx, int nArg, @@ -264,6 +316,12 @@ static void nth_valueValueFunc(sqlite3_context *pCtx){ name ## InverseFunc, #name \ } +#define WINDOWFUNCF(name,nArg,extra) { \ + nArg, (SQLITE_UTF8|SQLITE_FUNC_WINDOW|extra), 0, 0, \ + name ## StepFunc, name ## FinalizeFunc, name ## ValueFunc, \ + name ## InverseFunc, #name \ +} + /* ** Register those built-in window functions that are not also aggregates. */ @@ -275,6 +333,7 @@ void sqlite3WindowFunctions(void){ WINDOWFUNC(percent_rank, 0, SQLITE_FUNC_WINDOW_SIZE), WINDOWFUNC(cume_dist, 0, SQLITE_FUNC_WINDOW_SIZE), WINDOWFUNC(ntile, 1, SQLITE_FUNC_WINDOW_SIZE), + WINDOWFUNCF(last_value, 1, 0), WINDOWFUNC(nth_value, 2, 0), }; sqlite3InsertBuiltinFuncs(aWindowFuncs, ArraySize(aWindowFuncs)); |