2 files changed, 111 insertions, 0 deletions

diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index d0b91e881db..a9547aaef15 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -2450,6 +2450,69 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				break;
 			}
 
+		case T_JsonConstructorExpr:
+			{
+				JsonConstructorExpr *ctor = (JsonConstructorExpr *) node;
+				List	   *args = ctor->args;
+				ListCell   *lc;
+				int			nargs = list_length(args);
+				int			argno = 0;
+
+				if (ctor->func)
+				{
+					ExecInitExprRec(ctor->func, state, resv, resnull);
+				}
+				else
+				{
+					scratch.opcode = EEOP_JSON_CONSTRUCTOR;
+					scratch.d.json_constructor.constructor = ctor;
+					scratch.d.json_constructor.arg_values = palloc(sizeof(Datum) * nargs);
+					scratch.d.json_constructor.arg_nulls = palloc(sizeof(bool) * nargs);
+					scratch.d.json_constructor.arg_types = palloc(sizeof(Oid) * nargs);
+					scratch.d.json_constructor.nargs = nargs;
+
+					foreach(lc, args)
+					{
+						Expr	   *arg = (Expr *) lfirst(lc);
+
+						scratch.d.json_constructor.arg_types[argno] = exprType((Node *) arg);
+
+						if (IsA(arg, Const))
+						{
+							/* Don't evaluate const arguments every round */
+							Const	   *con = (Const *) arg;
+
+							scratch.d.json_constructor.arg_values[argno] = con->constvalue;
+							scratch.d.json_constructor.arg_nulls[argno] = con->constisnull;
+						}
+						else
+						{
+							ExecInitExprRec(arg, state,
+											&scratch.d.json_constructor.arg_values[argno],
+											&scratch.d.json_constructor.arg_nulls[argno]);
+						}
+						argno++;
+					}
+
+					ExprEvalPushStep(state, &scratch);
+				}
+
+				if (ctor->coercion)
+				{
+					Datum	   *innermost_caseval = state->innermost_caseval;
+					bool	   *innermost_isnull = state->innermost_casenull;
+
+					state->innermost_caseval = resv;
+					state->innermost_casenull = resnull;
+
+					ExecInitExprRec(ctor->coercion, state, resv, resnull);
+
+					state->innermost_caseval = innermost_caseval;
+					state->innermost_casenull = innermost_isnull;
+				}
+			}
+			break;
+
 		default:
 			elog(ERROR, "unrecognized node type: %d",
 				 (int) nodeTag(node));
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 64bd17b62e3..f2a0821a7ab 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -71,6 +71,8 @@
 #include "utils/date.h"
 #include "utils/datum.h"
 #include "utils/expandedrecord.h"
+#include "utils/json.h"
+#include "utils/jsonb.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/timestamp.h"
@@ -477,6 +479,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		&&CASE_EEOP_GROUPING_FUNC,
 		&&CASE_EEOP_WINDOW_FUNC,
 		&&CASE_EEOP_SUBPLAN,
+		&&CASE_EEOP_JSON_CONSTRUCTOR,
 		&&CASE_EEOP_AGG_STRICT_DESERIALIZE,
 		&&CASE_EEOP_AGG_DESERIALIZE,
 		&&CASE_EEOP_AGG_STRICT_INPUT_CHECK_ARGS,
@@ -1786,7 +1789,13 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		{
 			/* too complex for an inline implementation */
 			ExecEvalAggOrderedTransTuple(state, op, econtext);
+			EEO_NEXT();
+		}
 
+		EEO_CASE(EEOP_JSON_CONSTRUCTOR)
+		{
+			/* too complex for an inline implementation */
+			ExecEvalJsonConstructor(state, op, econtext);
 			EEO_NEXT();
 		}
 
@@ -4380,3 +4389,42 @@ ExecAggPlainTransByRef(AggState *aggstate, AggStatePerTrans pertrans,
 
 	MemoryContextSwitchTo(oldContext);
 }
+
+/*
+ * Evaluate a JSON constructor expression.
+ */
+void
+ExecEvalJsonConstructor(ExprState *state, ExprEvalStep *op,
+						ExprContext *econtext)
+{
+	Datum		res;
+	JsonConstructorExpr *ctor = op->d.json_constructor.constructor;
+	bool		is_jsonb = ctor->returning->format->format_type == JS_FORMAT_JSONB;
+	bool		isnull = false;
+
+	if (ctor->type == JSCTOR_JSON_ARRAY)
+		res = (is_jsonb ?
+			   jsonb_build_array_worker :
+			   json_build_array_worker)(op->d.json_constructor.nargs,
+										op->d.json_constructor.arg_values,
+										op->d.json_constructor.arg_nulls,
+										op->d.json_constructor.arg_types,
+										op->d.json_constructor.constructor->absent_on_null);
+	else if (ctor->type == JSCTOR_JSON_OBJECT)
+		res = (is_jsonb ?
+			   jsonb_build_object_worker :
+			   json_build_object_worker)(op->d.json_constructor.nargs,
+										 op->d.json_constructor.arg_values,
+										 op->d.json_constructor.arg_nulls,
+										 op->d.json_constructor.arg_types,
+										 op->d.json_constructor.constructor->absent_on_null,
+										 op->d.json_constructor.constructor->unique);
+	else
+	{
+		res = (Datum) 0;
+		elog(ERROR, "invalid JsonConstructorExpr type %d", ctor->type);
+	}
+
+	*op->resvalue = res;
+	*op->resnull = isnull;
+}