[Tarantool-patches] [PATCH v4 17/53] sql: introduce mem_concat()

[Mergen Imeev via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

This patch introduces mem_concat(). Function mem_concat() concatenates
values from two MEMs in case these values are strings or binaries and
writes the result to the third MEM.

Part of #5818
---
 src/box/sql/mem.c  | 51 +++++++++++++++++++++++++++++++++++++++++++++
 src/box/sql/mem.h  |  7 +++++++
 src/box/sql/vdbe.c | 52 ++--------------------------------------------
 3 files changed, 60 insertions(+), 50 deletions(-)

diff --git a/src/box/sql/mem.c b/src/box/sql/mem.c
index 775474f69..f160439c9 100644
--- a/src/box/sql/mem.c
+++ b/src/box/sql/mem.c
@@ -319,6 +319,57 @@ mem_move(struct Mem *to, struct Mem *from)
 	return 0;
 }
 
+int
+mem_concat(struct Mem *left, struct Mem *right, struct Mem *result)
+{
+	assert(result != right);
+	sqlVdbeMemSetNull(result);
+	result->field_type = field_type_MAX;
+
+	if (((left->flags | right->flags) & MEM_Null) != 0) {
+		/* Force NULL be of type STRING. */
+		result->field_type = FIELD_TYPE_STRING;
+		return 0;
+	}
+
+	/* Concatenation operation can be applied only to strings and blobs. */
+	if ((right->flags & (MEM_Str | MEM_Blob)) == 0) {
+		diag_set(ClientError, ER_INCONSISTENT_TYPES,
+			 "text or varbinary", mem_type_to_str(right));
+		return -1;
+	}
+	if ((left->flags & (MEM_Str | MEM_Blob)) == 0) {
+		diag_set(ClientError, ER_INCONSISTENT_TYPES,
+			 "text or varbinary", mem_type_to_str(left));
+		return -1;
+	}
+
+	/* Moreover, both operands must be of the same type. */
+	if ((right->flags & MEM_Str) != (left->flags & MEM_Str)) {
+		diag_set(ClientError, ER_INCONSISTENT_TYPES,
+			 mem_type_to_str(left), mem_type_to_str(right));
+		return -1;
+	}
+
+	if (ExpandBlob(left) != 0 || ExpandBlob(right) != 0)
+		return -1;
+
+	uint32_t size = left->n + right->n;
+	if ((int)size > sql_get()->aLimit[SQL_LIMIT_LENGTH]) {
+		diag_set(ClientError, ER_SQL_EXECUTE, "string or blob too big");
+		return -1;
+	}
+	if (sqlVdbeMemGrow(result, size, result == left) != 0)
+		return -1;
+
+	result->flags = left->flags & (MEM_Str | MEM_Blob);
+	if (result != left)
+		memcpy(result->z, left->z, left->n);
+	memcpy(&result->z[left->n], right->z, right->n);
+	result->n = size;
+	return 0;
+}
+
 static inline bool
 mem_has_msgpack_subtype(struct Mem *mem)
 {
diff --git a/src/box/sql/mem.h b/src/box/sql/mem.h
index aead71df2..9b0eb8444 100644
--- a/src/box/sql/mem.h
+++ b/src/box/sql/mem.h
@@ -185,6 +185,13 @@ mem_copy_as_ephemeral(struct Mem *to, const struct Mem *from);
 int
 mem_move(struct Mem *to, struct Mem *from);
 
+/**
+ * Concatenate strings or binaries from the first and the second MEMs and write
+ * the result to the third MEM.
+ */
+int
+mem_concat(struct Mem *left, struct Mem *right, struct Mem *result);
+
 /* One or more of the following flags are set to indicate the validOK
  * representations of the value stored in the Mem struct.
  *
diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
index d76ba0b40..c04bd40f3 100644
--- a/src/box/sql/vdbe.c
+++ b/src/box/sql/vdbe.c
@@ -1028,59 +1028,11 @@ case OP_ResultRow: {
  * types (i.e. TEXT and BLOB).
  */
 case OP_Concat: {           /* same as TK_CONCAT, in1, in2, out3 */
-	i64 nByte;
-
 	pIn1 = &aMem[pOp->p1];
 	pIn2 = &aMem[pOp->p2];
-	pOut = vdbe_prepare_null_out(p, pOp->p3);
-	assert(pIn1!=pOut);
-	if (mem_is_null(pIn1) || mem_is_null(pIn2)) {
-		/* Force NULL be of type STRING. */
-		pOut->field_type = FIELD_TYPE_STRING;
-		break;
-	}
-	/*
-	 * Concatenation operation can be applied only to
-	 * strings and blobs.
-	 */
-	bool str_type_p1 = mem_is_varstring(pIn1);
-	bool str_type_p2 = mem_is_varstring(pIn2);
-	if (!str_type_p1 || !str_type_p2) {
-		char *inconsistent_type = !str_type_p1 ?
-					  mem_type_to_str(pIn1) :
-					  mem_type_to_str(pIn2);
-		diag_set(ClientError, ER_INCONSISTENT_TYPES,
-			 "text or varbinary", inconsistent_type);
-		goto abort_due_to_error;
-	}
-
-	/* Moreover, both operands must be of the same type. */
-	if (mem_is_string(pIn1) != mem_is_string(pIn2)) {
-		diag_set(ClientError, ER_INCONSISTENT_TYPES,
-			 mem_type_to_str(pIn2), mem_type_to_str(pIn1));
-		goto abort_due_to_error;
-	}
-	if (ExpandBlob(pIn1) != 0 || ExpandBlob(pIn2) != 0)
+	pOut = &aMem[pOp->p3];
+	if (mem_concat(pIn2, pIn1, pOut) != 0)
 		goto abort_due_to_error;
-	nByte = pIn1->n + pIn2->n;
-	if (nByte>db->aLimit[SQL_LIMIT_LENGTH]) {
-		goto too_big;
-	}
-	if (sqlVdbeMemGrow(pOut, (int)nByte+2, pOut==pIn2)) {
-		goto no_mem;
-	}
-	if (mem_is_string(pIn1))
-		MemSetTypeFlag(pOut, MEM_Str);
-	else
-		MemSetTypeFlag(pOut, MEM_Blob);
-	if (pOut!=pIn2) {
-		memcpy(pOut->z, pIn2->z, pIn2->n);
-	}
-	memcpy(&pOut->z[pIn2->n], pIn1->z, pIn1->n);
-	pOut->z[nByte]=0;
-	pOut->z[nByte+1] = 0;
-	pOut->flags |= MEM_Term;
-	pOut->n = (int)nByte;
 	UPDATE_MAX_BLOBSIZE(pOut);
 	break;
 }
-- 
2.25.1