Merge pull request #11365 from taosdata/feature/TD-14242

<feat>[query]: add cast function SQL syntax

source/libs/function/src/builtins.c

@@ -382,6 +382,16 @@ const SBuiltinFuncDefinition funcMgtBuiltins[] = {
     .sprocessFunc = substrFunction,
     .finalizeFunc = NULL
   },
+  {
+    .name = "cast",
+    .type = FUNCTION_TYPE_CAST,
+    .classification = FUNC_MGT_SCALAR_FUNC,
+    .checkFunc    = stubCheckAndGetResultType,
+    .getEnvFunc   = NULL,
+    .initFunc     = NULL,
+    .sprocessFunc = NULL,
+    .finalizeFunc = NULL
+  },
   {
     .name = "_rowts",
     .type = FUNCTION_TYPE_ROWTS,
@@ -588,6 +598,10 @@ int32_t stubCheckAndGetResultType(SFunctionNode* pFunc) {
       pFunc->node.resType = (SDataType) { .bytes = paraBytes, .type = paraType };
       break;
     }
+    case FUNCTION_TYPE_CAST: {
+      pFunc->node.resType = (SDataType) { .bytes = tDataTypes[TSDB_DATA_TYPE_BIGINT].bytes, .type = TSDB_DATA_TYPE_BIGINT };
+      break;
+    }
 
     case FUNCTION_TYPE_TBNAME: {
       // todo

source/libs/parser/inc/parAst.h

@@ -81,6 +81,7 @@ SToken getTokenFromRawExprNode(SAstCreateContext* pCxt, SNode* pNode);
 
 SNodeList* createNodeList(SAstCreateContext* pCxt, SNode* pNode);
 SNodeList* addNodeToList(SAstCreateContext* pCxt, SNodeList* pList, SNode* pNode);
+SNodeList* addValueNodeFromTypeToList(SAstCreateContext* pCxt, SDataType dataType, SNodeList* pList);
 
 SNode* createColumnNode(SAstCreateContext* pCxt, SToken* pTableAlias, SToken* pColumnName);
 SNode* createValueNode(SAstCreateContext* pCxt, int32_t dataType, const SToken* pLiteral);

source/libs/parser/inc/sql.y

@@ -534,6 +534,12 @@ expression(A) ::= pseudo_column(B).
 expression(A) ::= column_reference(B).                                            { A = B; }
 expression(A) ::= function_name(B) NK_LP expression_list(C) NK_RP(D).             { A = createRawExprNodeExt(pCxt, &B, &D, createFunctionNode(pCxt, &B, C)); }
 expression(A) ::= function_name(B) NK_LP NK_STAR(C) NK_RP(D).                     { A = createRawExprNodeExt(pCxt, &B, &D, createFunctionNode(pCxt, &B, createNodeList(pCxt, createColumnNode(pCxt, NULL, &C)))); }
+//for CAST function CAST(expr AS type_name)
+expression(A) ::= function_name(B) NK_LP expression(C) AS type_name(D) NK_RP(E).  {
+                                                                                    SNodeList *p = createNodeList(pCxt, releaseRawExprNode(pCxt, C));
+                                                                                    p = addValueNodeFromTypeToList(pCxt, D, p);
+                                                                                    A = createRawExprNodeExt(pCxt, &B, &E, createFunctionNode(pCxt, &B, p));
+                                                                                  }
 //expression(A) ::= cast_expression(B).                                             { A = B; }
 //expression(A) ::= case_expression(B).                                             { A = B; }
 expression(A) ::= subquery(B).                                                    { A = B; }

source/libs/parser/src/parAstCreater.c

@@ -251,6 +251,26 @@ SNode* createColumnNode(SAstCreateContext* pCxt, SToken* pTableAlias, SToken* pC
   return (SNode*)col;
 }
 
+SNodeList* addValueNodeFromTypeToList(SAstCreateContext* pCxt, SDataType dataType, SNodeList* pList) {
+  char buf[64] = {0};
+  //add value node for type
+  snprintf(buf, sizeof(buf), "%u", dataType.type);
+  SToken token = {.type = TSDB_DATA_TYPE_TINYINT, .n = strlen(buf), .z = buf};
+  SNode* pNode = createValueNode(pCxt, token.type, &token);
+  addNodeToList(pCxt, pList, pNode);
+
+  //add value node for bytes
+  memset(buf, 0, sizeof(buf));
+  snprintf(buf, sizeof(buf), "%u", dataType.bytes);
+  token.type = TSDB_DATA_TYPE_BIGINT;
+  token.n = strlen(buf);
+  token.z = buf;
+  pNode = createValueNode(pCxt, token.type, &token);
+  addNodeToList(pCxt, pList, pNode);
+
+  return pList;
+}
+
 SNode* createValueNode(SAstCreateContext* pCxt, int32_t dataType, const SToken* pLiteral) {
   SValueNode* val = (SValueNode*)nodesMakeNode(QUERY_NODE_VALUE);
   CHECK_OUT_OF_MEM(val);