Add generate_series(numeric, numeric).

Платон Малюгин
Reviewed by Michael Paquier, Ali Akbar and Marti Raudsepp

src/backend/utils/adt/numeric.c

@@ -28,6 +28,7 @@
 
 #include "access/hash.h"
 #include "catalog/pg_type.h"
+#include "funcapi.h"
 #include "libpq/pqformat.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
@@ -260,6 +261,18 @@ typedef struct NumericVar
 } NumericVar;
 
 
+/* ----------
+ * Data for generate_series
+ * ----------
+ */
+typedef struct
+{
+	NumericVar	current;
+	NumericVar	stop;
+	NumericVar	step;
+} generate_series_numeric_fctx;
+
+
 /* ----------
  * Some preinitialized constants
  * ----------
@@ -1229,6 +1242,117 @@ numeric_floor(PG_FUNCTION_ARGS)
 	PG_RETURN_NUMERIC(res);
 }
 
+
+/*
+ * generate_series_numeric() -
+ *
+ *  Generate series of numeric.
+ */
+Datum
+generate_series_numeric(PG_FUNCTION_ARGS)
+{
+	return generate_series_step_numeric(fcinfo);
+}
+
+Datum
+generate_series_step_numeric(PG_FUNCTION_ARGS)
+{
+	generate_series_numeric_fctx *fctx;
+	FuncCallContext *funcctx;
+	MemoryContext oldcontext;
+
+	if (SRF_IS_FIRSTCALL())
+	{
+		Numeric		start_num = PG_GETARG_NUMERIC(0);
+		Numeric		stop_num = PG_GETARG_NUMERIC(1);
+		NumericVar	steploc = const_one;
+
+		/* handle NaN in start and stop values */
+		if (NUMERIC_IS_NAN(start_num))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("start value cannot be NaN")));
+
+		if (NUMERIC_IS_NAN(stop_num))
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("stop value cannot be NaN")));
+
+		/* see if we were given an explicit step size */
+		if (PG_NARGS() == 3)
+		{
+			Numeric	step_num = PG_GETARG_NUMERIC(2);
+
+			if (NUMERIC_IS_NAN(step_num))
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("step size cannot be NaN")));
+
+			init_var_from_num(step_num, &steploc);
+
+			if (cmp_var(&steploc, &const_zero) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+						 errmsg("step size cannot equal zero")));
+		}
+
+		/* create a function context for cross-call persistence */
+		funcctx = SRF_FIRSTCALL_INIT();
+
+		/*
+		 * Switch to memory context appropriate for multiple function calls.
+		 */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		/* allocate memory for user context */
+		fctx = (generate_series_numeric_fctx *)
+			palloc(sizeof(generate_series_numeric_fctx));
+
+		/*
+		 * Use fctx to keep state from call to call. Seed current with the
+		 * original start value.
+		 */
+		init_var_from_num(start_num, &fctx->current);
+		init_var_from_num(stop_num, &fctx->stop);
+		init_var(&fctx->step);
+		set_var_from_var(&steploc, &fctx->step);
+
+		funcctx->user_fctx = fctx;
+		MemoryContextSwitchTo(oldcontext);
+	}
+
+	/* stuff done on every call of the function */
+	funcctx = SRF_PERCALL_SETUP();
+
+	/*
+	 * Get the saved state and use current state as the result of this
+	 * iteration.
+	 */
+	fctx = funcctx->user_fctx;
+
+	if ((fctx->step.sign == NUMERIC_POS &&
+		 cmp_var(&fctx->current, &fctx->stop) <= 0) ||
+		(fctx->step.sign == NUMERIC_NEG &&
+		 cmp_var(&fctx->current, &fctx->stop) >= 0))
+	{
+		Numeric	result = make_result(&fctx->current);
+
+		/* switch to memory context appropriate for iteration calculation */
+		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
+
+		/* increment current in preparation for next iteration */
+		add_var(&fctx->current, &fctx->step, &fctx->current);
+		MemoryContextSwitchTo(oldcontext);
+
+		/* do when there is more left to send */
+		SRF_RETURN_NEXT(funcctx, NumericGetDatum(result));
+	}
+	else
+		/* do when there is no more left */
+		SRF_RETURN_DONE(funcctx);
+}
+
+
 /*
  * Implements the numeric version of the width_bucket() function
  * defined by SQL2003. See also width_bucket_float8().