Use actual Ruby classes for parser result, instead of decoded JSON

This is essentialy to enable easy and fast two-way communication with
the C library, and as a bonus makes for a better interaction on the Ruby
side, as we are handling actual objects instead of hashes and arrays.

Note this also unifies the scan output into the same protobuf file,
although the scan result retains a different top-level protobuf
message (ScanResult).

lib/pg_query.rb

@@ -1,16 +1,15 @@
 require 'pg_query/version'
 require 'pg_query/parse_error'
 
-require 'pg_query/parse_tree_pb'
+require 'pg_query/pg_query_pb'
 
 require 'pg_query/pg_query'
+require 'pg_query/constants'
 require 'pg_query/parse'
 require 'pg_query/treewalker'
 require 'pg_query/node_types'
 require 'pg_query/deep_dup'
 
-require 'pg_query/legacy_parsetree'
-
 require 'pg_query/filter_columns'
 require 'pg_query/fingerprint'
 require 'pg_query/param_refs'

lib/pg_query/parse.rb

@@ -1,13 +1,19 @@
-require 'json'
+module PgQuery
+  class Node
+    def inspect
+      node ? format('<PgQuery::Node: %s: %s>', node, public_send(node).inspect) : '<PgQuery::Node>'
+    end
+  end
+end
 
 module PgQuery
   def self.parse(query)
-    tree, stderr = _raw_parse(query)
+    result, stderr = parse_protobuf(query)
 
     begin
-      tree = JSON.parse(tree, max_nesting: 1000)
-    rescue JSON::ParserError
-      raise ParseError.new('Failed to parse JSON', __FILE__, __LINE__, -1)
+      result = PgQuery::ParseResult.decode(result)
+    rescue Google::Protobuf::ParseError
+      raise PgQuery::ParseError.new('Failed to parse tree', __FILE__, __LINE__, -1)
     end
 
     warnings = []
@@ -16,10 +22,10 @@ def self.parse(query)
       warnings << line.strip
     end
 
-    PgQuery::ParseResult.new(query, tree, warnings)
+    PgQuery::ParserResult.new(query, result, warnings)
   end
 
-  class ParseResult
+  class ParserResult
     attr_reader :query
     attr_reader :tree
     attr_reader :warnings
@@ -71,134 +77,139 @@ def load_tables_and_aliases! # rubocop:disable Metrics/CyclomaticComplexity
       @cte_names = []
       @aliases = {}
 
-      statements = @tree.dup
+      statements = @tree.stmts.dup.to_a.map { |s| s.stmt }
       from_clause_items = [] # types: select, dml, ddl
       subselect_items = []
 
       loop do
         statement = statements.shift
         if statement
-          case statement.keys[0]
-          when RAW_STMT
-            statements << statement[RAW_STMT][STMT_FIELD]
+          case statement.node
+          when :list
+            statements += statement.list.items
           # The following statement types do not modify tables and are added to from_clause_items
           # (and subsequently @tables)
-          when SELECT_STMT
-            case statement[SELECT_STMT]['op']
-            when 0
-              (statement[SELECT_STMT][FROM_CLAUSE_FIELD] || []).each do |item|
-                if item[RANGE_SUBSELECT]
-                  statements << item[RANGE_SUBSELECT]['subquery']
+          when :select_stmt
+            subselect_items.concat(statement.select_stmt.target_list)
+            subselect_items << statement.select_stmt.where_clause if statement.select_stmt.where_clause
+            subselect_items.concat(statement.select_stmt.sort_clause.collect { |h| h.sort_by.node })
+            subselect_items.concat(statement.select_stmt.group_clause)
+            subselect_items << statement.select_stmt.having_clause if statement.select_stmt.having_clause
+
+            case statement.select_stmt.op
+            when :SETOP_NONE
+              (statement.select_stmt.from_clause || []).each do |item|
+                if item.node == :range_subselect
+                  statements << item.range_subselect.subquery
                 else
                   from_clause_items << { item: item, type: :select }
                 end
               end
-            when 1
-              statements << statement[SELECT_STMT]['larg'] if statement[SELECT_STMT]['larg']
-              statements << statement[SELECT_STMT]['rarg'] if statement[SELECT_STMT]['rarg']
+            when :SETOP_UNION
+              statements << PgQuery::Node.new(select_stmt: statement.select_stmt.larg) if statement.select_stmt.larg
+              statements << PgQuery::Node.new(select_stmt: statement.select_stmt.rarg) if statement.select_stmt.rarg
             end
 
-            if (with_clause = statement[SELECT_STMT]['withClause'])
-              cte_statements, cte_names = statements_and_cte_names_for_with_clause(with_clause)
+            if statement.select_stmt.with_clause
+              cte_statements, cte_names = statements_and_cte_names_for_with_clause(statement.select_stmt.with_clause)
               @cte_names.concat(cte_names)
               statements.concat(cte_statements)
             end
           # The following statements modify the contents of a table
-          when INSERT_STMT, UPDATE_STMT, DELETE_STMT
-            value = statement.values[0]
-            from_clause_items << { item: value['relation'], type: :dml }
-            statements << value['selectStmt'] if value.key?('selectStmt')
-            statements << value['withClause'] if value.key?('withClause')
+          when :insert_stmt, :update_stmt, :delete_stmt
+            value = statement.public_send(statement.node)
+            from_clause_items << { item: PgQuery::Node.new(range_var: value.relation), type: :dml }
+            statements << value.select_stmt if statement.node == :insert_stmt && value.select_stmt
+
+            subselect_items.concat(statement.update_stmt.target_list) if statement.node == :update_stmt
+            subselect_items << statement.update_stmt.where_clause if statement.node == :update_stmt && statement.update_stmt.where_clause
+            subselect_items << statement.delete_stmt.where_clause if statement.node == :delete_stmt && statement.delete_stmt.where_clause
 
-            if (with_clause = value['withClause'])
-              cte_statements, cte_names = statements_and_cte_names_for_with_clause(with_clause)
+            if value.with_clause
+              cte_statements, cte_names = statements_and_cte_names_for_with_clause(value.with_clause)
               @cte_names.concat(cte_names)
               statements.concat(cte_statements)
             end
-          when COPY_STMT
-            from_clause_items << { item: statement.values[0]['relation'], type: :dml } if statement.values[0]['relation']
-            statements << statement.values[0]['query']
+          when :copy_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.copy_stmt.relation), type: :dml } if statement.copy_stmt.relation
+            statements << statement.copy_stmt.query
           # The following statement types are DDL (changing table structure)
-          when ALTER_TABLE_STMT, CREATE_STMT
-            from_clause_items << { item: statement.values[0]['relation'], type: :ddl }
-          when CREATE_TABLE_AS_STMT
-            if statement[CREATE_TABLE_AS_STMT]['into'] && statement[CREATE_TABLE_AS_STMT]['into'][INTO_CLAUSE]['rel']
-              from_clause_items << { item: statement[CREATE_TABLE_AS_STMT]['into'][INTO_CLAUSE]['rel'], type: :ddl }
+          when :alter_table_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.alter_table_stmt.relation), type: :ddl }
+          when :create_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.create_stmt.relation), type: :ddl }
+          when :create_table_as_stmt
+            if statement.create_table_as_stmt.into && statement.create_table_as_stmt.into.rel
+              from_clause_items << { item: PgQuery::Node.new(range_var: statement.create_table_as_stmt.into.rel), type: :ddl }
             end
-            if statement[CREATE_TABLE_AS_STMT]['query']
-              statements << statement[CREATE_TABLE_AS_STMT]['query']
-            end
-          when TRUNCATE_STMT
-            from_clause_items += statement.values[0]['relations'].map { |r| { item: r, type: :ddl } }
-          when VIEW_STMT
-            from_clause_items << { item: statement[VIEW_STMT]['view'], type: :ddl }
-            statements << statement[VIEW_STMT]['query']
-          when INDEX_STMT, CREATE_TRIG_STMT, RULE_STMT
-            from_clause_items << { item: statement.values[0]['relation'], type: :ddl }
-          when VACUUM_STMT
-            from_clause_items += statement.values[0]['rels'].map { |r| { item: r[VACUUM_RELATION]['relation'], type: :ddl } }
-          when REFRESH_MAT_VIEW_STMT
-            from_clause_items << { item: statement[REFRESH_MAT_VIEW_STMT]['relation'], type: :ddl }
-          when DROP_STMT
-            objects = statement[DROP_STMT]['objects'].map do |obj|
-              if obj.is_a?(Array)
-                obj.map { |obj2| obj2['String'] && obj2['String']['str'] }
-              else
-                obj['String'] && obj['String']['str']
+            statements << statement.create_table_as_stmt.query if statement.create_table_as_stmt.query
+          when :truncate_stmt
+            from_clause_items += statement.truncate_stmt.relations.map { |r| { item: r, type: :ddl } }
+          when :view_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.view_stmt.view), type: :ddl }
+            statements << statement.view_stmt.query
+          when :index_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.index_stmt.relation), type: :ddl }
+          when :create_trig_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.create_trig_stmt.relation), type: :ddl }
+          when :rule_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.rule_stmt.relation), type: :ddl }
+          when :vacuum_stmt
+            from_clause_items += statement.vacuum_stmt.rels.map { |r| { item: PgQuery::Node.new(range_var: r.vacuum_relation.relation), type: :ddl } if r.node == :vacuum_relation }
+          when :refresh_mat_view_stmt
+            from_clause_items << { item: PgQuery::Node.new(range_var: statement.refresh_mat_view_stmt.relation), type: :ddl }
+          when :drop_stmt
+            objects = statement.drop_stmt.objects.map do |obj|
+              case obj.node
+              when :list
+                obj.list.items.map { |obj2| obj2.string.str if obj2.node == :string }
+              when :string
+                obj.string.str
               end
             end
-            case statement[DROP_STMT]['removeType']
-            when OBJECT_TYPE_TABLE
+            case statement.drop_stmt.remove_type
+            when :OBJECT_TABLE
               @tables += objects.map { |r| { name: r.join('.'), type: :ddl } }
-            when OBJECT_TYPE_RULE, OBJECT_TYPE_TRIGGER
+            when :OBJECT_RULE, :OBJECT_TRIGGER
               @tables += objects.map { |r| { name: r[0..-2].join('.'), type: :ddl } }
             end
-          when GRANT_STMT
-            objects = statement[GRANT_STMT]['objects']
-            case statement[GRANT_STMT]['objtype']
-            when OBJECT_TYPE_COLUMN # Column # rubocop:disable Lint/EmptyWhen
+          when :grant_stmt
+            objects = statement.grant_stmt.objects
+            case statement.grant_stmt.objtype
+            when :OBJECT_COLUMN # Column # rubocop:disable Lint/EmptyWhen
               # FIXME
-            when OBJECT_TYPE_TABLE # Table
+            when :OBJECT_TABLE # Table
               from_clause_items += objects.map { |o| { item: o, type: :ddl } }
-            when OBJECT_TYPE_SEQUENCE # Sequence # rubocop:disable Lint/EmptyWhen
+            when :OBJECT_SEQUENCE # Sequence # rubocop:disable Lint/EmptyWhen
               # FIXME
             end
-          when LOCK_STMT
-            from_clause_items += statement.values[0]['relations'].map { |r| { item: r, type: :ddl } }
+          when :lock_stmt
+            from_clause_items += statement.lock_stmt.relations.map { |r| { item: r, type: :ddl } }
           # The following are other statements that don't fit into query/DML/DDL
-          when EXPLAIN_STMT
-            statements << statement[EXPLAIN_STMT]['query']
-          end
-
-          statement_value = statement.values[0]
-          unless statement.empty?
-            subselect_items.concat(statement_value['targetList']) if statement_value['targetList']
-            subselect_items << statement_value['whereClause'] if statement_value['whereClause']
-            subselect_items.concat(statement_value['sortClause'].collect { |h| h[SORT_BY]['node'] }) if statement_value['sortClause']
-            subselect_items.concat(statement_value['groupClause']) if statement_value['groupClause']
-            subselect_items << statement_value['havingClause'] if statement_value['havingClause']
+          when :explain_stmt
+            statements << statement.explain_stmt.query
           end
         end
 
         next_item = subselect_items.shift
         if next_item
-          case next_item.keys[0]
-          when A_EXPR
+          case next_item.node
+          when :a_expr
             %w[lexpr rexpr].each do |side|
-              elem = next_item.values[0][side]
+              elem = next_item.a_expr.public_send(side)
               next unless elem
-              if elem.is_a?(Array)
+              if elem.is_a?(Array) # FIXME - this needs to traverse a list
                 subselect_items += elem
               else
                 subselect_items << elem
               end
             end
-          when BOOL_EXPR
-            subselect_items.concat(next_item.values[0]['args'])
-          when RES_TARGET
-            subselect_items << next_item[RES_TARGET]['val']
-          when SUB_LINK
-            statements << next_item[SUB_LINK]['subselect']
+          when :bool_expr
+            subselect_items.concat(next_item.bool_expr.args)
+          when :res_target
+            subselect_items << next_item.res_target.val
+          when :sub_link
+            statements << next_item.sub_link.subselect
           end
         end
 
@@ -209,31 +220,30 @@ def load_tables_and_aliases! # rubocop:disable Metrics/CyclomaticComplexity
         next_item = from_clause_items.shift
         break unless next_item && next_item[:item]
 
-        case next_item[:item].keys[0]
-        when JOIN_EXPR
-          %w[larg rarg].each do |side|
-            from_clause_items << { item: next_item[:item][JOIN_EXPR][side], type: next_item[:type] }
-          end
-        when ROW_EXPR
-          from_clause_items += next_item[:item][ROW_EXPR]['args'].map { |a| { item: a, type: next_item[:type] } }
-        when RANGE_VAR
-          rangevar = next_item[:item][RANGE_VAR]
-          next if !rangevar['schemaname'] && @cte_names.include?(rangevar['relname'])
+        case next_item[:item].node
+        when :join_expr
+          from_clause_items << { item: next_item[:item].join_expr.larg, type: next_item[:type] }
+          from_clause_items << { item: next_item[:item].join_expr.rarg, type: next_item[:type] }
+        when :row_expr
+          from_clause_items += next_item[:item].row_expr.args.map { |a| { item: a, type: next_item[:type] } }
+        when :range_var
+          rangevar = next_item[:item].range_var
+          next if rangevar.schemaname.empty? && @cte_names.include?(rangevar.relname)
 
-          table = [rangevar['schemaname'], rangevar['relname']].compact.join('.')
+          table = [rangevar.schemaname, rangevar.relname].reject { |s| s.nil? || s.empty? }.join('.')
           @tables << {
             name: table,
             type: next_item[:type],
-            location: rangevar['location'],
-            schemaname: rangevar['schemaname'],
-            relname: rangevar['relname'],
-            inh: rangevar['inh']
+            location: rangevar.location,
+            schemaname: (rangevar.schemaname if !rangevar.schemaname.empty?),
+            relname: rangevar.relname,
+            inh: rangevar.inh
           }
-          @aliases[rangevar['alias'][ALIAS]['aliasname']] = table if rangevar['alias']
-        when RANGE_SUBSELECT
-          from_clause_items << { item: next_item[:item][RANGE_SUBSELECT]['subquery'], type: next_item[:type] }
-        when SELECT_STMT
-          from_clause = next_item[:item][SELECT_STMT][FROM_CLAUSE_FIELD]
+          @aliases[rangevar.alias.aliasname] = table if rangevar.alias
+        when :range_subselect
+          from_clause_items << { item: next_item[:item].range_subselect.subquery, type: next_item[:type] }
+        when :select_stmt
+          from_clause = next_item[:item].select_stmt.from_clause
           from_clause_items += from_clause.map { |r| { item: r, type: next_item[:type] } } if from_clause
         end
       end
@@ -242,17 +252,17 @@ def load_tables_and_aliases! # rubocop:disable Metrics/CyclomaticComplexity
       @cte_names.uniq!
     end
 
-    def statements_and_cte_names_for_with_clause(with_clause)
+    def statements_and_cte_names_for_with_clause(with_clause) # FIXME
       statements = []
       cte_names = []
 
-      with_clause[WITH_CLAUSE]['ctes'].each do |item|
-        next unless item[COMMON_TABLE_EXPR]
-        cte_names << item[COMMON_TABLE_EXPR]['ctename']
-        statements << item[COMMON_TABLE_EXPR]['ctequery']
+      with_clause.ctes.each do |item|
+        next unless item.node == :common_table_expr
+        cte_names << item.common_table_expr.ctename
+        statements << item.common_table_expr.ctequery
       end
 
       [statements, cte_names]
     end
   end
-end
+end