[feat](lateral-view) Support execution of lateral view stmt (#7255)

1. Add table function node
2. Add 3 table functions: explode_split, explode_bitmap and explode_json_array

be/src/exprs/table_function/explode_split.cpp

@@ -0,0 +1,115 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "exprs/table_function/explode_split.h"
+
+#include "exprs/expr_context.h"
+#include "exprs/scalar_fn_call.h"
+#include "gutil/strings/split.h"
+
+namespace doris {
+
+ExplodeSplitTableFunction::ExplodeSplitTableFunction() {
+}
+
+ExplodeSplitTableFunction::~ExplodeSplitTableFunction() {
+}
+
+Status ExplodeSplitTableFunction::prepare() {
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::open() {
+    ScalarFnCall* fn_call = reinterpret_cast<ScalarFnCall*>(_expr_context->root());
+    FunctionContext* fn_ctx = _expr_context->fn_context(fn_call->get_fn_context_index());
+    CHECK(2 == fn_ctx->get_num_constant_args()) << fn_ctx->get_num_constant_args();
+    // check if the delimiter argument(the 2nd arg) is constant.
+    // if yes, cache it
+    if (fn_ctx->is_arg_constant(1)) {
+        _is_delimiter_constant = true; 
+        StringVal* delimiter = reinterpret_cast<StringVal*>(fn_ctx->get_constant_arg(1));
+        _const_delimter = StringPiece((char*) delimiter->ptr, delimiter->len);
+    }
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::process(TupleRow* tuple_row) {
+    CHECK(2 == _expr_context->root()->get_num_children()) << _expr_context->root()->get_num_children();
+    _is_current_empty = false;
+    _eos = false;
+
+    _data.clear();
+    StringVal text = _expr_context->root()->get_child(0)->get_string_val(_expr_context, tuple_row);
+    if (text.is_null) {
+        _is_current_empty = true;
+        _cur_size = 0;
+        _cur_offset = 0;
+    } else {
+        if (_is_delimiter_constant) {
+            _backup = strings::Split(StringPiece((char*) text.ptr, text.len), _const_delimter);
+        } else {
+            StringVal delimiter = _expr_context->root()->get_child(1)->get_string_val(_expr_context, tuple_row);
+            _backup = strings::Split(StringPiece((char*) text.ptr, text.len), StringPiece((char*) delimiter.ptr, delimiter.len));
+        }
+        for (const std::string str : _backup) {
+            _data.emplace_back(str);
+        }
+        _cur_size = _backup.size();
+        _cur_offset = 0;
+        _is_current_empty = (_cur_size == 0);
+    }
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::reset() {
+    _eos = false;
+    if (!_is_current_empty) {
+        _cur_offset = 0;
+    }
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::get_value(void** output) {
+    if (_is_current_empty) {
+        *output = nullptr;
+    } else {
+        *output = &_data[_cur_offset];
+    }
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::close() {
+    return Status::OK();
+}
+
+Status ExplodeSplitTableFunction::forward(bool* eos) {
+    if (_is_current_empty) {
+        *eos = true;
+        _eos = true;
+    } else {
+        ++_cur_offset;
+        if (_cur_offset == _cur_size) {
+            *eos = true;
+            _eos = true;
+        } else {
+            *eos = false;
+        }
+    }
+    return Status::OK();
+}
+
+} // namespace doris