From 1428ce0639f7ec715ce4707c2a3ef7ddbfb2fdbe Mon Sep 17 00:00:00 2001
From: Marko Budiselic <marko.budiselic@memgraph.io>
Date: Sat, 11 Mar 2017 13:47:11 +0100
Subject: [PATCH] Add basic interpreter skeleton.
---
src/query/frontend/ast/ast.hpp | 43 ++++++++++
src/query/frontend/interpret/interpret.hpp | 18 ++++
src/query/frontend/logical/operator.hpp | 82 +++++++++++++++++++
src/query/frontend/typecheck/symbol_table.hpp | 34 ++++++++
4 files changed, 177 insertions(+)
create mode 100644 src/query/frontend/ast/ast.hpp
create mode 100644 src/query/frontend/interpret/interpret.hpp
create mode 100644 src/query/frontend/logical/operator.hpp
create mode 100644 src/query/frontend/typecheck/symbol_table.hpp
diff --git a/src/query/frontend/ast/ast.hpp b/src/query/frontend/ast/ast.hpp
new file mode 100644
index 000000000..ef2f9dd30
--- /dev/null
+++ b/src/query/frontend/ast/ast.hpp
@@ -0,0 +1,43 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+
+#include "database/graph_db.hpp"
+
+namespace query {
+
+template <typename T>
+using sptr = std::shared_ptr<T>;
+
+template <typename T>
+using uptr = std::unique_ptr<T>;
+
+class Tree {
+public:
+ Tree(const int uid) : uid_(uid) {}
+ int uid() const { return uid_; }
+private:
+ const int uid_;
+};
+
+class Expr : public Tree {
+};
+
+class Ident : public Tree {
+public:
+ std::string identifier_;
+};
+
+class Part {
+};
+
+class NodePart : public Part {
+public:
+ Ident identifier_;
+ // TODO: Mislav call GraphDb::label(label_name) to populate labels_!
+ std::vector<GraphDb::Label> labels_;
+ // TODO: properties
+};
+
+}
diff --git a/src/query/frontend/interpret/interpret.hpp b/src/query/frontend/interpret/interpret.hpp
new file mode 100644
index 000000000..7a2240094
--- /dev/null
+++ b/src/query/frontend/interpret/interpret.hpp
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <vector>
+
+#include "query/backend/cpp/typed_value.hpp"
+
+class Frame {
+ public:
+ Frame(int size) : size_(size), elems_(size_) {}
+
+ auto& operator[](int pos) { return elems_[pos]; }
+ const auto& operator[](int pos) const { return elems_[pos]; }
+
+ private:
+ int size_;
+ std::vector<TypedValue> elems_;
+};
+
diff --git a/src/query/frontend/logical/operator.hpp b/src/query/frontend/logical/operator.hpp
new file mode 100644
index 000000000..96deb7132
--- /dev/null
+++ b/src/query/frontend/logical/operator.hpp
@@ -0,0 +1,82 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+
+#include "database/graph_db_accessor.hpp"
+#include "query/frontend/ast/ast.hpp"
+#include "query/frontend/interpret/interpret.hpp"
+#include "query/frontend/typecheck/symbol_table.hpp"
+
+namespace query {
+class Cursor {
+ public:
+ virtual bool pull(Frame&, SymbolTable&) = 0;
+ virtual ~Cursor() {}
+};
+
+class LogicalOperator {
+ public:
+ auto children() { return children_; };
+ virtual uptr<Cursor> MakeCursor(GraphDbAccessor db) = 0;
+ virtual ~LogicalOperator() {}
+
+ protected:
+ std::vector<std::shared_ptr<LogicalOperator>> children_;
+};
+
+class ScanAll : public LogicalOperator {
+ public:
+ ScanAll(sptr<NodePart> node_part) : node_part_(node_part) {}
+
+ private:
+ class ScanAllCursor : public Cursor {
+ public:
+ ScanAllCursor(ScanAll& parent, GraphDbAccessor db)
+ : parent_(parent), db_(db), vertices_(db.vertices()) {}
+ bool pull(Frame& frame, SymbolTable& symbol_table) override {
+ while (vertices_ != vertices_.end()) {
+ auto& vertex = *vertices_++;
+ if (evaluate(frame, symbol_table, vertex)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ private:
+ ScanAll& parent_;
+ GraphDbAccessor db_;
+ decltype(db_.vertices()) vertices_;
+
+ bool evaluate(Frame& frame, SymbolTable& symbol_table,
+ VertexAccessor& vertex) {
+ auto node_part = parent_.node_part_;
+ for (auto label : node_part->labels_) {
+ if (!vertex.has_label(label)) return false;
+ }
+ frame[symbol_table[parent_.node_part_->identifier_].position_] = vertex;
+ return true;
+ }
+ };
+
+ public:
+ uptr<Cursor> MakeCursor(GraphDbAccessor db) override {
+ return new ScanAllCursor(*this, db);
+ }
+
+ friend class ScanAll::ScanAllCursor;
+ sptr<NodePart> node_part_;
+};
+
+class Produce : public LogicalOperator {
+ public:
+ Produce(sptr<LogicalOperator> op, std::vector<sptr<Expr>> exprs)
+ : exprs_(exprs) {
+ children_.emplace_back(op);
+ }
+
+ private:
+ std::vector<sptr<Expr>> exprs_;
+};
+}
diff --git a/src/query/frontend/typecheck/symbol_table.hpp b/src/query/frontend/typecheck/symbol_table.hpp
new file mode 100644
index 000000000..f5305fc89
--- /dev/null
+++ b/src/query/frontend/typecheck/symbol_table.hpp
@@ -0,0 +1,34 @@
+#pragma once
+
+#include <map>
+#include <string>
+
+#include "query/frontend/ast/ast.hpp"
+
+namespace query {
+struct Symbol {
+ Symbol(std::string& name, int position) : name_(name), position_(position) {}
+ std::string name_;
+ int position_;
+};
+
+class SymbolTable {
+ public:
+ Symbol CreateSymbol(std::string& name) {
+ int position = position_++;
+ return Symbol(name, position);
+ }
+
+ void AssignSymbol(const Tree& tree, Symbol symbol) {
+ table_[tree.uid()] = symbol;
+ }
+
+ auto& operator[](const Tree& tree) { return table_[tree.uid()]; }
+
+ int max_position() const { return position_; }
+
+ private:
+ int position_{0};
+ std::map<int, Symbol> table_;
+};
+}